7852 lines
244 KiB
C
7852 lines
244 KiB
C
/* Perform various loop optimizations, including strength reduction.
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Copyright (C) 1987, 88, 89, 91-97, 1998 Free Software Foundation, Inc.
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU CC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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/* This is the loop optimization pass of the compiler.
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It finds invariant computations within loops and moves them
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to the beginning of the loop. Then it identifies basic and
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general induction variables. Strength reduction is applied to the general
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induction variables, and induction variable elimination is applied to
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the basic induction variables.
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It also finds cases where
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a register is set within the loop by zero-extending a narrower value
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and changes these to zero the entire register once before the loop
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and merely copy the low part within the loop.
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Most of the complexity is in heuristics to decide when it is worth
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while to do these things. */
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#include "config.h"
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#include "system.h"
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#include "rtl.h"
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#include "obstack.h"
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#include "expr.h"
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#include "insn-config.h"
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#include "insn-flags.h"
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#include "regs.h"
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#include "hard-reg-set.h"
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#include "recog.h"
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#include "flags.h"
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#include "real.h"
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#include "loop.h"
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#include "except.h"
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#include "toplev.h"
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/* Vector mapping INSN_UIDs to luids.
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The luids are like uids but increase monotonically always.
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We use them to see whether a jump comes from outside a given loop. */
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int *uid_luid;
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/* Indexed by INSN_UID, contains the ordinal giving the (innermost) loop
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number the insn is contained in. */
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int *uid_loop_num;
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/* 1 + largest uid of any insn. */
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int max_uid_for_loop;
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/* 1 + luid of last insn. */
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static int max_luid;
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/* Number of loops detected in current function. Used as index to the
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next few tables. */
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static int max_loop_num;
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/* Indexed by loop number, contains the first and last insn of each loop. */
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static rtx *loop_number_loop_starts, *loop_number_loop_ends;
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/* For each loop, gives the containing loop number, -1 if none. */
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int *loop_outer_loop;
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#ifdef HAIFA
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/* The main output of analyze_loop_iterations is placed here */
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int *loop_can_insert_bct;
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/* For each loop, determines whether some of its inner loops has used
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count register */
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int *loop_used_count_register;
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/* loop parameters for arithmetic loops. These loops have a loop variable
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which is initialized to loop_start_value, incremented in each iteration
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by "loop_increment". At the end of the iteration the loop variable is
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compared to the loop_comparison_value (using loop_comparison_code). */
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rtx *loop_increment;
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rtx *loop_comparison_value;
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rtx *loop_start_value;
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enum rtx_code *loop_comparison_code;
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#endif /* HAIFA */
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/* For each loop, keep track of its unrolling factor.
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Potential values:
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0: unrolled
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1: not unrolled.
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-1: completely unrolled
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>0: holds the unroll exact factor. */
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int *loop_unroll_factor;
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/* Indexed by loop number, contains a nonzero value if the "loop" isn't
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really a loop (an insn outside the loop branches into it). */
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static char *loop_invalid;
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/* Indexed by loop number, links together all LABEL_REFs which refer to
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code labels outside the loop. Used by routines that need to know all
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loop exits, such as final_biv_value and final_giv_value.
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This does not include loop exits due to return instructions. This is
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because all bivs and givs are pseudos, and hence must be dead after a
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return, so the presense of a return does not affect any of the
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optimizations that use this info. It is simpler to just not include return
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instructions on this list. */
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rtx *loop_number_exit_labels;
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/* Indexed by loop number, counts the number of LABEL_REFs on
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loop_number_exit_labels for this loop and all loops nested inside it. */
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int *loop_number_exit_count;
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/* Holds the number of loop iterations. It is zero if the number could not be
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calculated. Must be unsigned since the number of iterations can
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be as high as 2^wordsize-1. For loops with a wider iterator, this number
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will be zero if the number of loop iterations is too large for an
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unsigned integer to hold. */
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unsigned HOST_WIDE_INT loop_n_iterations;
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/* Nonzero if there is a subroutine call in the current loop. */
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static int loop_has_call;
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/* Nonzero if there is a volatile memory reference in the current
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loop. */
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static int loop_has_volatile;
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/* Added loop_continue which is the NOTE_INSN_LOOP_CONT of the
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current loop. A continue statement will generate a branch to
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NEXT_INSN (loop_continue). */
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static rtx loop_continue;
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/* Indexed by register number, contains the number of times the reg
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is set during the loop being scanned.
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During code motion, a negative value indicates a reg that has been
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made a candidate; in particular -2 means that it is an candidate that
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we know is equal to a constant and -1 means that it is an candidate
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not known equal to a constant.
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After code motion, regs moved have 0 (which is accurate now)
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while the failed candidates have the original number of times set.
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Therefore, at all times, == 0 indicates an invariant register;
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< 0 a conditionally invariant one. */
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static int *n_times_set;
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/* Original value of n_times_set; same except that this value
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is not set negative for a reg whose sets have been made candidates
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and not set to 0 for a reg that is moved. */
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static int *n_times_used;
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/* Index by register number, 1 indicates that the register
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cannot be moved or strength reduced. */
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static char *may_not_optimize;
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/* Nonzero means reg N has already been moved out of one loop.
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This reduces the desire to move it out of another. */
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static char *moved_once;
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/* Array of MEMs that are stored in this loop. If there are too many to fit
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here, we just turn on unknown_address_altered. */
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#define NUM_STORES 30
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static rtx loop_store_mems[NUM_STORES];
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/* Index of first available slot in above array. */
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static int loop_store_mems_idx;
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/* The insn where the first of these was found. */
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static rtx first_loop_store_insn;
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/* Nonzero if we don't know what MEMs were changed in the current loop.
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This happens if the loop contains a call (in which case `loop_has_call'
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will also be set) or if we store into more than NUM_STORES MEMs. */
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static int unknown_address_altered;
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/* Count of movable (i.e. invariant) instructions discovered in the loop. */
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static int num_movables;
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/* Count of memory write instructions discovered in the loop. */
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static int num_mem_sets;
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/* Number of loops contained within the current one, including itself. */
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static int loops_enclosed;
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/* Bound on pseudo register number before loop optimization.
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A pseudo has valid regscan info if its number is < max_reg_before_loop. */
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int max_reg_before_loop;
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/* This obstack is used in product_cheap_p to allocate its rtl. It
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may call gen_reg_rtx which, in turn, may reallocate regno_reg_rtx.
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If we used the same obstack that it did, we would be deallocating
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that array. */
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static struct obstack temp_obstack;
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/* This is where the pointer to the obstack being used for RTL is stored. */
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extern struct obstack *rtl_obstack;
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#define obstack_chunk_alloc xmalloc
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#define obstack_chunk_free free
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/* During the analysis of a loop, a chain of `struct movable's
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is made to record all the movable insns found.
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Then the entire chain can be scanned to decide which to move. */
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struct movable
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{
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rtx insn; /* A movable insn */
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rtx set_src; /* The expression this reg is set from. */
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rtx set_dest; /* The destination of this SET. */
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rtx dependencies; /* When INSN is libcall, this is an EXPR_LIST
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of any registers used within the LIBCALL. */
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int consec; /* Number of consecutive following insns
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that must be moved with this one. */
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int regno; /* The register it sets */
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short lifetime; /* lifetime of that register;
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may be adjusted when matching movables
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that load the same value are found. */
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short savings; /* Number of insns we can move for this reg,
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including other movables that force this
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or match this one. */
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unsigned int cond : 1; /* 1 if only conditionally movable */
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unsigned int force : 1; /* 1 means MUST move this insn */
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unsigned int global : 1; /* 1 means reg is live outside this loop */
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/* If PARTIAL is 1, GLOBAL means something different:
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that the reg is live outside the range from where it is set
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to the following label. */
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unsigned int done : 1; /* 1 inhibits further processing of this */
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unsigned int partial : 1; /* 1 means this reg is used for zero-extending.
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In particular, moving it does not make it
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invariant. */
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unsigned int move_insn : 1; /* 1 means that we call emit_move_insn to
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load SRC, rather than copying INSN. */
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unsigned int move_insn_first:1;/* Same as above, if this is necessary for the
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first insn of a consecutive sets group. */
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unsigned int is_equiv : 1; /* 1 means a REG_EQUIV is present on INSN. */
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enum machine_mode savemode; /* Nonzero means it is a mode for a low part
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that we should avoid changing when clearing
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the rest of the reg. */
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struct movable *match; /* First entry for same value */
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struct movable *forces; /* An insn that must be moved if this is */
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struct movable *next;
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};
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FILE *loop_dump_stream;
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/* Forward declarations. */
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static void find_and_verify_loops PROTO((rtx));
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static void mark_loop_jump PROTO((rtx, int));
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static void prescan_loop PROTO((rtx, rtx));
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static int reg_in_basic_block_p PROTO((rtx, rtx));
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static int consec_sets_invariant_p PROTO((rtx, int, rtx));
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static rtx libcall_other_reg PROTO((rtx, rtx));
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static int labels_in_range_p PROTO((rtx, int));
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static void count_loop_regs_set PROTO((rtx, rtx, char *, rtx *, int *, int));
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static void note_addr_stored PROTO((rtx, rtx));
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static int loop_reg_used_before_p PROTO((rtx, rtx, rtx, rtx, rtx));
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static void scan_loop PROTO((rtx, rtx, int, int));
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#if 0
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static void replace_call_address PROTO((rtx, rtx, rtx));
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#endif
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static rtx skip_consec_insns PROTO((rtx, int));
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static int libcall_benefit PROTO((rtx));
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static void ignore_some_movables PROTO((struct movable *));
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static void force_movables PROTO((struct movable *));
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static void combine_movables PROTO((struct movable *, int));
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static int regs_match_p PROTO((rtx, rtx, struct movable *));
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static int rtx_equal_for_loop_p PROTO((rtx, rtx, struct movable *));
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static void add_label_notes PROTO((rtx, rtx));
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static void move_movables PROTO((struct movable *, int, int, rtx, rtx, int));
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static int count_nonfixed_reads PROTO((rtx));
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static void strength_reduce PROTO((rtx, rtx, rtx, int, rtx, rtx, int));
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static void find_single_use_in_loop PROTO((rtx, rtx, rtx *));
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static int valid_initial_value_p PROTO((rtx, rtx, int, rtx));
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static void find_mem_givs PROTO((rtx, rtx, int, rtx, rtx));
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static void record_biv PROTO((struct induction *, rtx, rtx, rtx, rtx, int, int));
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static void check_final_value PROTO((struct induction *, rtx, rtx));
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static void record_giv PROTO((struct induction *, rtx, rtx, rtx, rtx, rtx, int, enum g_types, int, rtx *, rtx, rtx));
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static void update_giv_derive PROTO((rtx));
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static int basic_induction_var PROTO((rtx, enum machine_mode, rtx, rtx, rtx *, rtx *));
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static rtx simplify_giv_expr PROTO((rtx, int *));
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static int general_induction_var PROTO((rtx, rtx *, rtx *, rtx *));
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static int consec_sets_giv PROTO((int, rtx, rtx, rtx, rtx *, rtx *));
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static int check_dbra_loop PROTO((rtx, int, rtx));
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#ifdef ADDRESS_COST
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static rtx express_from PROTO((struct induction *, struct induction *));
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#endif
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static int combine_givs_p PROTO((struct induction *, struct induction *));
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#ifdef GIV_SORT_CRITERION
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static int giv_sort PROTO((struct induction **, struct induction **));
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#endif
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static void combine_givs PROTO((struct iv_class *));
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static int product_cheap_p PROTO((rtx, rtx));
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static int maybe_eliminate_biv PROTO((struct iv_class *, rtx, rtx, int, int, int));
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static int maybe_eliminate_biv_1 PROTO((rtx, rtx, struct iv_class *, int, rtx));
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static int last_use_this_basic_block PROTO((rtx, rtx));
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static void record_initial PROTO((rtx, rtx));
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static void update_reg_last_use PROTO((rtx, rtx));
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#ifdef HAIFA
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/* This is extern from unroll.c */
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extern void iteration_info PROTO((rtx, rtx *, rtx *, rtx, rtx));
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/* Two main functions for implementing bct:
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first - to be called before loop unrolling, and the second - after */
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#ifdef HAVE_decrement_and_branch_on_count
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static void analyze_loop_iterations PROTO((rtx, rtx));
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static void insert_bct PROTO((rtx, rtx));
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/* Auxiliary function that inserts the bct pattern into the loop */
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static void instrument_loop_bct PROTO((rtx, rtx, rtx));
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#endif /* HAVE_decrement_and_branch_on_count */
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#endif /* HAIFA */
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/* Indirect_jump_in_function is computed once per function. */
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int indirect_jump_in_function = 0;
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static int indirect_jump_in_function_p PROTO((rtx));
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/* Relative gain of eliminating various kinds of operations. */
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int add_cost;
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#if 0
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int shift_cost;
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int mult_cost;
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#endif
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/* Benefit penalty, if a giv is not replaceable, i.e. must emit an insn to
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copy the value of the strength reduced giv to its original register. */
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int copy_cost;
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void
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init_loop ()
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{
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char *free_point = (char *) oballoc (1);
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rtx reg = gen_rtx_REG (word_mode, LAST_VIRTUAL_REGISTER + 1);
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add_cost = rtx_cost (gen_rtx_PLUS (word_mode, reg, reg), SET);
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/* We multiply by 2 to reconcile the difference in scale between
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these two ways of computing costs. Otherwise the cost of a copy
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will be far less than the cost of an add. */
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copy_cost = 2 * 2;
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/* Free the objects we just allocated. */
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obfree (free_point);
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/* Initialize the obstack used for rtl in product_cheap_p. */
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gcc_obstack_init (&temp_obstack);
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}
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/* Entry point of this file. Perform loop optimization
|
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on the current function. F is the first insn of the function
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and DUMPFILE is a stream for output of a trace of actions taken
|
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(or 0 if none should be output). */
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void
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loop_optimize (f, dumpfile, unroll_p)
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/* f is the first instruction of a chain of insns for one function */
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rtx f;
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FILE *dumpfile;
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int unroll_p;
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{
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register rtx insn;
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register int i;
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rtx last_insn;
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loop_dump_stream = dumpfile;
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init_recog_no_volatile ();
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max_reg_before_loop = max_reg_num ();
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||
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moved_once = (char *) alloca (max_reg_before_loop);
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bzero (moved_once, max_reg_before_loop);
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regs_may_share = 0;
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|
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/* Count the number of loops. */
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max_loop_num = 0;
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for (insn = f; insn; insn = NEXT_INSN (insn))
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{
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if (GET_CODE (insn) == NOTE
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&& NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
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max_loop_num++;
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}
|
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|
||
/* Don't waste time if no loops. */
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if (max_loop_num == 0)
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return;
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|
||
/* Get size to use for tables indexed by uids.
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Leave some space for labels allocated by find_and_verify_loops. */
|
||
max_uid_for_loop = get_max_uid () + 1 + max_loop_num * 32;
|
||
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uid_luid = (int *) alloca (max_uid_for_loop * sizeof (int));
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uid_loop_num = (int *) alloca (max_uid_for_loop * sizeof (int));
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bzero ((char *) uid_luid, max_uid_for_loop * sizeof (int));
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bzero ((char *) uid_loop_num, max_uid_for_loop * sizeof (int));
|
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|
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/* Allocate tables for recording each loop. We set each entry, so they need
|
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not be zeroed. */
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loop_number_loop_starts = (rtx *) alloca (max_loop_num * sizeof (rtx));
|
||
loop_number_loop_ends = (rtx *) alloca (max_loop_num * sizeof (rtx));
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loop_outer_loop = (int *) alloca (max_loop_num * sizeof (int));
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loop_invalid = (char *) alloca (max_loop_num * sizeof (char));
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||
loop_number_exit_labels = (rtx *) alloca (max_loop_num * sizeof (rtx));
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||
loop_number_exit_count = (int *) alloca (max_loop_num * sizeof (int));
|
||
|
||
/* This is initialized by the unrolling code, so we go ahead
|
||
and clear them just in case we are not performing loop
|
||
unrolling. */
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loop_unroll_factor = (int *) alloca (max_loop_num *sizeof (int));
|
||
bzero ((char *) loop_unroll_factor, max_loop_num * sizeof (int));
|
||
|
||
#ifdef HAIFA
|
||
/* Allocate for BCT optimization */
|
||
loop_can_insert_bct = (int *) alloca (max_loop_num * sizeof (int));
|
||
bzero ((char *) loop_can_insert_bct, max_loop_num * sizeof (int));
|
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loop_used_count_register = (int *) alloca (max_loop_num * sizeof (int));
|
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bzero ((char *) loop_used_count_register, max_loop_num * sizeof (int));
|
||
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loop_increment = (rtx *) alloca (max_loop_num * sizeof (rtx));
|
||
loop_comparison_value = (rtx *) alloca (max_loop_num * sizeof (rtx));
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||
loop_start_value = (rtx *) alloca (max_loop_num * sizeof (rtx));
|
||
bzero ((char *) loop_increment, max_loop_num * sizeof (rtx));
|
||
bzero ((char *) loop_comparison_value, max_loop_num * sizeof (rtx));
|
||
bzero ((char *) loop_start_value, max_loop_num * sizeof (rtx));
|
||
|
||
loop_comparison_code
|
||
= (enum rtx_code *) alloca (max_loop_num * sizeof (enum rtx_code));
|
||
bzero ((char *) loop_comparison_code, max_loop_num * sizeof (enum rtx_code));
|
||
#endif /* HAIFA */
|
||
|
||
/* Find and process each loop.
|
||
First, find them, and record them in order of their beginnings. */
|
||
find_and_verify_loops (f);
|
||
|
||
/* Now find all register lifetimes. This must be done after
|
||
find_and_verify_loops, because it might reorder the insns in the
|
||
function. */
|
||
reg_scan (f, max_reg_num (), 1);
|
||
|
||
/* This must occur after reg_scan so that registers created by gcse
|
||
will have entries in the register tables.
|
||
|
||
We could have added a call to reg_scan after gcse_main in toplev.c,
|
||
but moving this call to init_alias_analysis is more efficient. */
|
||
init_alias_analysis ();
|
||
|
||
/* See if we went too far. */
|
||
if (get_max_uid () > max_uid_for_loop)
|
||
abort ();
|
||
/* Now reset it to the actual size we need. See above. */
|
||
max_uid_for_loop = get_max_uid () + 1;
|
||
|
||
/* Compute the mapping from uids to luids.
|
||
LUIDs are numbers assigned to insns, like uids,
|
||
except that luids increase monotonically through the code.
|
||
Don't assign luids to line-number NOTEs, so that the distance in luids
|
||
between two insns is not affected by -g. */
|
||
|
||
for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
|
||
{
|
||
last_insn = insn;
|
||
if (GET_CODE (insn) != NOTE
|
||
|| NOTE_LINE_NUMBER (insn) <= 0)
|
||
uid_luid[INSN_UID (insn)] = ++i;
|
||
else
|
||
/* Give a line number note the same luid as preceding insn. */
|
||
uid_luid[INSN_UID (insn)] = i;
|
||
}
|
||
|
||
max_luid = i + 1;
|
||
|
||
/* Don't leave gaps in uid_luid for insns that have been
|
||
deleted. It is possible that the first or last insn
|
||
using some register has been deleted by cross-jumping.
|
||
Make sure that uid_luid for that former insn's uid
|
||
points to the general area where that insn used to be. */
|
||
for (i = 0; i < max_uid_for_loop; i++)
|
||
{
|
||
uid_luid[0] = uid_luid[i];
|
||
if (uid_luid[0] != 0)
|
||
break;
|
||
}
|
||
for (i = 0; i < max_uid_for_loop; i++)
|
||
if (uid_luid[i] == 0)
|
||
uid_luid[i] = uid_luid[i - 1];
|
||
|
||
/* Create a mapping from loops to BLOCK tree nodes. */
|
||
if (unroll_p && write_symbols != NO_DEBUG)
|
||
find_loop_tree_blocks ();
|
||
|
||
/* Determine if the function has indirect jump. On some systems
|
||
this prevents low overhead loop instructions from being used. */
|
||
indirect_jump_in_function = indirect_jump_in_function_p (f);
|
||
|
||
/* Now scan the loops, last ones first, since this means inner ones are done
|
||
before outer ones. */
|
||
for (i = max_loop_num-1; i >= 0; i--)
|
||
if (! loop_invalid[i] && loop_number_loop_ends[i])
|
||
scan_loop (loop_number_loop_starts[i], loop_number_loop_ends[i],
|
||
max_reg_num (), unroll_p);
|
||
|
||
/* If debugging and unrolling loops, we must replicate the tree nodes
|
||
corresponding to the blocks inside the loop, so that the original one
|
||
to one mapping will remain. */
|
||
if (unroll_p && write_symbols != NO_DEBUG)
|
||
unroll_block_trees ();
|
||
}
|
||
|
||
/* Optimize one loop whose start is LOOP_START and end is END.
|
||
LOOP_START is the NOTE_INSN_LOOP_BEG and END is the matching
|
||
NOTE_INSN_LOOP_END. */
|
||
|
||
/* ??? Could also move memory writes out of loops if the destination address
|
||
is invariant, the source is invariant, the memory write is not volatile,
|
||
and if we can prove that no read inside the loop can read this address
|
||
before the write occurs. If there is a read of this address after the
|
||
write, then we can also mark the memory read as invariant. */
|
||
|
||
static void
|
||
scan_loop (loop_start, end, nregs, unroll_p)
|
||
rtx loop_start, end;
|
||
int nregs;
|
||
int unroll_p;
|
||
{
|
||
register int i;
|
||
register rtx p;
|
||
/* 1 if we are scanning insns that could be executed zero times. */
|
||
int maybe_never = 0;
|
||
/* 1 if we are scanning insns that might never be executed
|
||
due to a subroutine call which might exit before they are reached. */
|
||
int call_passed = 0;
|
||
/* For a rotated loop that is entered near the bottom,
|
||
this is the label at the top. Otherwise it is zero. */
|
||
rtx loop_top = 0;
|
||
/* Jump insn that enters the loop, or 0 if control drops in. */
|
||
rtx loop_entry_jump = 0;
|
||
/* Place in the loop where control enters. */
|
||
rtx scan_start;
|
||
/* Number of insns in the loop. */
|
||
int insn_count;
|
||
int in_libcall = 0;
|
||
int tem;
|
||
rtx temp;
|
||
/* The SET from an insn, if it is the only SET in the insn. */
|
||
rtx set, set1;
|
||
/* Chain describing insns movable in current loop. */
|
||
struct movable *movables = 0;
|
||
/* Last element in `movables' -- so we can add elements at the end. */
|
||
struct movable *last_movable = 0;
|
||
/* Ratio of extra register life span we can justify
|
||
for saving an instruction. More if loop doesn't call subroutines
|
||
since in that case saving an insn makes more difference
|
||
and more registers are available. */
|
||
int threshold;
|
||
/* If we have calls, contains the insn in which a register was used
|
||
if it was used exactly once; contains const0_rtx if it was used more
|
||
than once. */
|
||
rtx *reg_single_usage = 0;
|
||
/* Nonzero if we are scanning instructions in a sub-loop. */
|
||
int loop_depth = 0;
|
||
|
||
n_times_set = (int *) alloca (nregs * sizeof (int));
|
||
n_times_used = (int *) alloca (nregs * sizeof (int));
|
||
may_not_optimize = (char *) alloca (nregs);
|
||
|
||
/* Determine whether this loop starts with a jump down to a test at
|
||
the end. This will occur for a small number of loops with a test
|
||
that is too complex to duplicate in front of the loop.
|
||
|
||
We search for the first insn or label in the loop, skipping NOTEs.
|
||
However, we must be careful not to skip past a NOTE_INSN_LOOP_BEG
|
||
(because we might have a loop executed only once that contains a
|
||
loop which starts with a jump to its exit test) or a NOTE_INSN_LOOP_END
|
||
(in case we have a degenerate loop).
|
||
|
||
Note that if we mistakenly think that a loop is entered at the top
|
||
when, in fact, it is entered at the exit test, the only effect will be
|
||
slightly poorer optimization. Making the opposite error can generate
|
||
incorrect code. Since very few loops now start with a jump to the
|
||
exit test, the code here to detect that case is very conservative. */
|
||
|
||
for (p = NEXT_INSN (loop_start);
|
||
p != end
|
||
&& GET_CODE (p) != CODE_LABEL && GET_RTX_CLASS (GET_CODE (p)) != 'i'
|
||
&& (GET_CODE (p) != NOTE
|
||
|| (NOTE_LINE_NUMBER (p) != NOTE_INSN_LOOP_BEG
|
||
&& NOTE_LINE_NUMBER (p) != NOTE_INSN_LOOP_END));
|
||
p = NEXT_INSN (p))
|
||
;
|
||
|
||
scan_start = p;
|
||
|
||
/* Set up variables describing this loop. */
|
||
prescan_loop (loop_start, end);
|
||
threshold = (loop_has_call ? 1 : 2) * (1 + n_non_fixed_regs);
|
||
|
||
/* If loop has a jump before the first label,
|
||
the true entry is the target of that jump.
|
||
Start scan from there.
|
||
But record in LOOP_TOP the place where the end-test jumps
|
||
back to so we can scan that after the end of the loop. */
|
||
if (GET_CODE (p) == JUMP_INSN)
|
||
{
|
||
loop_entry_jump = p;
|
||
|
||
/* Loop entry must be unconditional jump (and not a RETURN) */
|
||
if (simplejump_p (p)
|
||
&& JUMP_LABEL (p) != 0
|
||
/* Check to see whether the jump actually
|
||
jumps out of the loop (meaning it's no loop).
|
||
This case can happen for things like
|
||
do {..} while (0). If this label was generated previously
|
||
by loop, we can't tell anything about it and have to reject
|
||
the loop. */
|
||
&& INSN_UID (JUMP_LABEL (p)) < max_uid_for_loop
|
||
&& INSN_LUID (JUMP_LABEL (p)) >= INSN_LUID (loop_start)
|
||
&& INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (end))
|
||
{
|
||
loop_top = next_label (scan_start);
|
||
scan_start = JUMP_LABEL (p);
|
||
}
|
||
}
|
||
|
||
/* If SCAN_START was an insn created by loop, we don't know its luid
|
||
as required by loop_reg_used_before_p. So skip such loops. (This
|
||
test may never be true, but it's best to play it safe.)
|
||
|
||
Also, skip loops where we do not start scanning at a label. This
|
||
test also rejects loops starting with a JUMP_INSN that failed the
|
||
test above. */
|
||
|
||
if (INSN_UID (scan_start) >= max_uid_for_loop
|
||
|| GET_CODE (scan_start) != CODE_LABEL)
|
||
{
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "\nLoop from %d to %d is phony.\n\n",
|
||
INSN_UID (loop_start), INSN_UID (end));
|
||
return;
|
||
}
|
||
|
||
/* Count number of times each reg is set during this loop.
|
||
Set may_not_optimize[I] if it is not safe to move out
|
||
the setting of register I. If this loop has calls, set
|
||
reg_single_usage[I]. */
|
||
|
||
bzero ((char *) n_times_set, nregs * sizeof (int));
|
||
bzero (may_not_optimize, nregs);
|
||
|
||
if (loop_has_call)
|
||
{
|
||
reg_single_usage = (rtx *) alloca (nregs * sizeof (rtx));
|
||
bzero ((char *) reg_single_usage, nregs * sizeof (rtx));
|
||
}
|
||
|
||
count_loop_regs_set (loop_top ? loop_top : loop_start, end,
|
||
may_not_optimize, reg_single_usage, &insn_count, nregs);
|
||
|
||
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
|
||
may_not_optimize[i] = 1, n_times_set[i] = 1;
|
||
bcopy ((char *) n_times_set, (char *) n_times_used, nregs * sizeof (int));
|
||
|
||
if (loop_dump_stream)
|
||
{
|
||
fprintf (loop_dump_stream, "\nLoop from %d to %d: %d real insns.\n",
|
||
INSN_UID (loop_start), INSN_UID (end), insn_count);
|
||
if (loop_continue)
|
||
fprintf (loop_dump_stream, "Continue at insn %d.\n",
|
||
INSN_UID (loop_continue));
|
||
}
|
||
|
||
/* Scan through the loop finding insns that are safe to move.
|
||
Set n_times_set negative for the reg being set, so that
|
||
this reg will be considered invariant for subsequent insns.
|
||
We consider whether subsequent insns use the reg
|
||
in deciding whether it is worth actually moving.
|
||
|
||
MAYBE_NEVER is nonzero if we have passed a conditional jump insn
|
||
and therefore it is possible that the insns we are scanning
|
||
would never be executed. At such times, we must make sure
|
||
that it is safe to execute the insn once instead of zero times.
|
||
When MAYBE_NEVER is 0, all insns will be executed at least once
|
||
so that is not a problem. */
|
||
|
||
p = scan_start;
|
||
while (1)
|
||
{
|
||
p = NEXT_INSN (p);
|
||
/* At end of a straight-in loop, we are done.
|
||
At end of a loop entered at the bottom, scan the top. */
|
||
if (p == scan_start)
|
||
break;
|
||
if (p == end)
|
||
{
|
||
if (loop_top != 0)
|
||
p = loop_top;
|
||
else
|
||
break;
|
||
if (p == scan_start)
|
||
break;
|
||
}
|
||
|
||
if (GET_RTX_CLASS (GET_CODE (p)) == 'i'
|
||
&& find_reg_note (p, REG_LIBCALL, NULL_RTX))
|
||
in_libcall = 1;
|
||
else if (GET_RTX_CLASS (GET_CODE (p)) == 'i'
|
||
&& find_reg_note (p, REG_RETVAL, NULL_RTX))
|
||
in_libcall = 0;
|
||
|
||
if (GET_CODE (p) == INSN
|
||
&& (set = single_set (p))
|
||
&& GET_CODE (SET_DEST (set)) == REG
|
||
&& ! may_not_optimize[REGNO (SET_DEST (set))])
|
||
{
|
||
int tem1 = 0;
|
||
int tem2 = 0;
|
||
int move_insn = 0;
|
||
rtx src = SET_SRC (set);
|
||
rtx dependencies = 0;
|
||
|
||
/* Figure out what to use as a source of this insn. If a REG_EQUIV
|
||
note is given or if a REG_EQUAL note with a constant operand is
|
||
specified, use it as the source and mark that we should move
|
||
this insn by calling emit_move_insn rather that duplicating the
|
||
insn.
|
||
|
||
Otherwise, only use the REG_EQUAL contents if a REG_RETVAL note
|
||
is present. */
|
||
temp = find_reg_note (p, REG_EQUIV, NULL_RTX);
|
||
if (temp)
|
||
src = XEXP (temp, 0), move_insn = 1;
|
||
else
|
||
{
|
||
temp = find_reg_note (p, REG_EQUAL, NULL_RTX);
|
||
if (temp && CONSTANT_P (XEXP (temp, 0)))
|
||
src = XEXP (temp, 0), move_insn = 1;
|
||
if (temp && find_reg_note (p, REG_RETVAL, NULL_RTX))
|
||
{
|
||
src = XEXP (temp, 0);
|
||
/* A libcall block can use regs that don't appear in
|
||
the equivalent expression. To move the libcall,
|
||
we must move those regs too. */
|
||
dependencies = libcall_other_reg (p, src);
|
||
}
|
||
}
|
||
|
||
/* Don't try to optimize a register that was made
|
||
by loop-optimization for an inner loop.
|
||
We don't know its life-span, so we can't compute the benefit. */
|
||
if (REGNO (SET_DEST (set)) >= max_reg_before_loop)
|
||
;
|
||
/* In order to move a register, we need to have either:
|
||
(1) it is used only in the same basic block as the set
|
||
(2) the set is guaranteed to be executed once the loop starts,
|
||
and the reg is not used until after that. */
|
||
else if (! (reg_in_basic_block_p (p, SET_DEST (set))
|
||
|| (! maybe_never
|
||
&& ! loop_reg_used_before_p (set, p, loop_start,
|
||
scan_start, end))))
|
||
;
|
||
else if ((tem = invariant_p (src))
|
||
&& (dependencies == 0
|
||
|| (tem2 = invariant_p (dependencies)) != 0)
|
||
&& (n_times_set[REGNO (SET_DEST (set))] == 1
|
||
|| (tem1
|
||
= consec_sets_invariant_p (SET_DEST (set),
|
||
n_times_set[REGNO (SET_DEST (set))],
|
||
p)))
|
||
/* If the insn can cause a trap (such as divide by zero),
|
||
can't move it unless it's guaranteed to be executed
|
||
once loop is entered. Even a function call might
|
||
prevent the trap insn from being reached
|
||
(since it might exit!) */
|
||
&& ! ((maybe_never || call_passed)
|
||
&& may_trap_p (src)))
|
||
{
|
||
register struct movable *m;
|
||
register int regno = REGNO (SET_DEST (set));
|
||
|
||
/* A potential lossage is where we have a case where two insns
|
||
can be combined as long as they are both in the loop, but
|
||
we move one of them outside the loop. For large loops,
|
||
this can lose. The most common case of this is the address
|
||
of a function being called.
|
||
|
||
Therefore, if this register is marked as being used exactly
|
||
once if we are in a loop with calls (a "large loop"), see if
|
||
we can replace the usage of this register with the source
|
||
of this SET. If we can, delete this insn.
|
||
|
||
Don't do this if P has a REG_RETVAL note or if we have
|
||
SMALL_REGISTER_CLASSES and SET_SRC is a hard register. */
|
||
|
||
if (reg_single_usage && reg_single_usage[regno] != 0
|
||
&& reg_single_usage[regno] != const0_rtx
|
||
&& REGNO_FIRST_UID (regno) == INSN_UID (p)
|
||
&& (REGNO_LAST_UID (regno)
|
||
== INSN_UID (reg_single_usage[regno]))
|
||
&& n_times_set[REGNO (SET_DEST (set))] == 1
|
||
&& ! side_effects_p (SET_SRC (set))
|
||
&& ! find_reg_note (p, REG_RETVAL, NULL_RTX)
|
||
&& (! SMALL_REGISTER_CLASSES
|
||
|| (! (GET_CODE (SET_SRC (set)) == REG
|
||
&& REGNO (SET_SRC (set)) < FIRST_PSEUDO_REGISTER)))
|
||
/* This test is not redundant; SET_SRC (set) might be
|
||
a call-clobbered register and the life of REGNO
|
||
might span a call. */
|
||
&& ! modified_between_p (SET_SRC (set), p,
|
||
reg_single_usage[regno])
|
||
&& no_labels_between_p (p, reg_single_usage[regno])
|
||
&& validate_replace_rtx (SET_DEST (set), SET_SRC (set),
|
||
reg_single_usage[regno]))
|
||
{
|
||
/* Replace any usage in a REG_EQUAL note. Must copy the
|
||
new source, so that we don't get rtx sharing between the
|
||
SET_SOURCE and REG_NOTES of insn p. */
|
||
REG_NOTES (reg_single_usage[regno])
|
||
= replace_rtx (REG_NOTES (reg_single_usage[regno]),
|
||
SET_DEST (set), copy_rtx (SET_SRC (set)));
|
||
|
||
PUT_CODE (p, NOTE);
|
||
NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
|
||
NOTE_SOURCE_FILE (p) = 0;
|
||
n_times_set[regno] = 0;
|
||
continue;
|
||
}
|
||
|
||
m = (struct movable *) alloca (sizeof (struct movable));
|
||
m->next = 0;
|
||
m->insn = p;
|
||
m->set_src = src;
|
||
m->dependencies = dependencies;
|
||
m->set_dest = SET_DEST (set);
|
||
m->force = 0;
|
||
m->consec = n_times_set[REGNO (SET_DEST (set))] - 1;
|
||
m->done = 0;
|
||
m->forces = 0;
|
||
m->partial = 0;
|
||
m->move_insn = move_insn;
|
||
m->move_insn_first = 0;
|
||
m->is_equiv = (find_reg_note (p, REG_EQUIV, NULL_RTX) != 0);
|
||
m->savemode = VOIDmode;
|
||
m->regno = regno;
|
||
/* Set M->cond if either invariant_p or consec_sets_invariant_p
|
||
returned 2 (only conditionally invariant). */
|
||
m->cond = ((tem | tem1 | tem2) > 1);
|
||
m->global = (uid_luid[REGNO_LAST_UID (regno)] > INSN_LUID (end)
|
||
|| uid_luid[REGNO_FIRST_UID (regno)] < INSN_LUID (loop_start));
|
||
m->match = 0;
|
||
m->lifetime = (uid_luid[REGNO_LAST_UID (regno)]
|
||
- uid_luid[REGNO_FIRST_UID (regno)]);
|
||
m->savings = n_times_used[regno];
|
||
if (find_reg_note (p, REG_RETVAL, NULL_RTX))
|
||
m->savings += libcall_benefit (p);
|
||
n_times_set[regno] = move_insn ? -2 : -1;
|
||
/* Add M to the end of the chain MOVABLES. */
|
||
if (movables == 0)
|
||
movables = m;
|
||
else
|
||
last_movable->next = m;
|
||
last_movable = m;
|
||
|
||
if (m->consec > 0)
|
||
{
|
||
/* It is possible for the first instruction to have a
|
||
REG_EQUAL note but a non-invariant SET_SRC, so we must
|
||
remember the status of the first instruction in case
|
||
the last instruction doesn't have a REG_EQUAL note. */
|
||
m->move_insn_first = m->move_insn;
|
||
|
||
/* Skip this insn, not checking REG_LIBCALL notes. */
|
||
p = next_nonnote_insn (p);
|
||
/* Skip the consecutive insns, if there are any. */
|
||
p = skip_consec_insns (p, m->consec);
|
||
/* Back up to the last insn of the consecutive group. */
|
||
p = prev_nonnote_insn (p);
|
||
|
||
/* We must now reset m->move_insn, m->is_equiv, and possibly
|
||
m->set_src to correspond to the effects of all the
|
||
insns. */
|
||
temp = find_reg_note (p, REG_EQUIV, NULL_RTX);
|
||
if (temp)
|
||
m->set_src = XEXP (temp, 0), m->move_insn = 1;
|
||
else
|
||
{
|
||
temp = find_reg_note (p, REG_EQUAL, NULL_RTX);
|
||
if (temp && CONSTANT_P (XEXP (temp, 0)))
|
||
m->set_src = XEXP (temp, 0), m->move_insn = 1;
|
||
else
|
||
m->move_insn = 0;
|
||
|
||
}
|
||
m->is_equiv = (find_reg_note (p, REG_EQUIV, NULL_RTX) != 0);
|
||
}
|
||
}
|
||
/* If this register is always set within a STRICT_LOW_PART
|
||
or set to zero, then its high bytes are constant.
|
||
So clear them outside the loop and within the loop
|
||
just load the low bytes.
|
||
We must check that the machine has an instruction to do so.
|
||
Also, if the value loaded into the register
|
||
depends on the same register, this cannot be done. */
|
||
else if (SET_SRC (set) == const0_rtx
|
||
&& GET_CODE (NEXT_INSN (p)) == INSN
|
||
&& (set1 = single_set (NEXT_INSN (p)))
|
||
&& GET_CODE (set1) == SET
|
||
&& (GET_CODE (SET_DEST (set1)) == STRICT_LOW_PART)
|
||
&& (GET_CODE (XEXP (SET_DEST (set1), 0)) == SUBREG)
|
||
&& (SUBREG_REG (XEXP (SET_DEST (set1), 0))
|
||
== SET_DEST (set))
|
||
&& !reg_mentioned_p (SET_DEST (set), SET_SRC (set1)))
|
||
{
|
||
register int regno = REGNO (SET_DEST (set));
|
||
if (n_times_set[regno] == 2)
|
||
{
|
||
register struct movable *m;
|
||
m = (struct movable *) alloca (sizeof (struct movable));
|
||
m->next = 0;
|
||
m->insn = p;
|
||
m->set_dest = SET_DEST (set);
|
||
m->dependencies = 0;
|
||
m->force = 0;
|
||
m->consec = 0;
|
||
m->done = 0;
|
||
m->forces = 0;
|
||
m->move_insn = 0;
|
||
m->move_insn_first = 0;
|
||
m->partial = 1;
|
||
/* If the insn may not be executed on some cycles,
|
||
we can't clear the whole reg; clear just high part.
|
||
Not even if the reg is used only within this loop.
|
||
Consider this:
|
||
while (1)
|
||
while (s != t) {
|
||
if (foo ()) x = *s;
|
||
use (x);
|
||
}
|
||
Clearing x before the inner loop could clobber a value
|
||
being saved from the last time around the outer loop.
|
||
However, if the reg is not used outside this loop
|
||
and all uses of the register are in the same
|
||
basic block as the store, there is no problem.
|
||
|
||
If this insn was made by loop, we don't know its
|
||
INSN_LUID and hence must make a conservative
|
||
assumption. */
|
||
m->global = (INSN_UID (p) >= max_uid_for_loop
|
||
|| (uid_luid[REGNO_LAST_UID (regno)]
|
||
> INSN_LUID (end))
|
||
|| (uid_luid[REGNO_FIRST_UID (regno)]
|
||
< INSN_LUID (p))
|
||
|| (labels_in_range_p
|
||
(p, uid_luid[REGNO_FIRST_UID (regno)])));
|
||
if (maybe_never && m->global)
|
||
m->savemode = GET_MODE (SET_SRC (set1));
|
||
else
|
||
m->savemode = VOIDmode;
|
||
m->regno = regno;
|
||
m->cond = 0;
|
||
m->match = 0;
|
||
m->lifetime = (uid_luid[REGNO_LAST_UID (regno)]
|
||
- uid_luid[REGNO_FIRST_UID (regno)]);
|
||
m->savings = 1;
|
||
n_times_set[regno] = -1;
|
||
/* Add M to the end of the chain MOVABLES. */
|
||
if (movables == 0)
|
||
movables = m;
|
||
else
|
||
last_movable->next = m;
|
||
last_movable = m;
|
||
}
|
||
}
|
||
}
|
||
/* Past a call insn, we get to insns which might not be executed
|
||
because the call might exit. This matters for insns that trap.
|
||
Call insns inside a REG_LIBCALL/REG_RETVAL block always return,
|
||
so they don't count. */
|
||
else if (GET_CODE (p) == CALL_INSN && ! in_libcall)
|
||
call_passed = 1;
|
||
/* Past a label or a jump, we get to insns for which we
|
||
can't count on whether or how many times they will be
|
||
executed during each iteration. Therefore, we can
|
||
only move out sets of trivial variables
|
||
(those not used after the loop). */
|
||
/* Similar code appears twice in strength_reduce. */
|
||
else if ((GET_CODE (p) == CODE_LABEL || GET_CODE (p) == JUMP_INSN)
|
||
/* If we enter the loop in the middle, and scan around to the
|
||
beginning, don't set maybe_never for that. This must be an
|
||
unconditional jump, otherwise the code at the top of the
|
||
loop might never be executed. Unconditional jumps are
|
||
followed a by barrier then loop end. */
|
||
&& ! (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) == loop_top
|
||
&& NEXT_INSN (NEXT_INSN (p)) == end
|
||
&& simplejump_p (p)))
|
||
maybe_never = 1;
|
||
else if (GET_CODE (p) == NOTE)
|
||
{
|
||
/* At the virtual top of a converted loop, insns are again known to
|
||
be executed: logically, the loop begins here even though the exit
|
||
code has been duplicated. */
|
||
if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_VTOP && loop_depth == 0)
|
||
maybe_never = call_passed = 0;
|
||
else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_BEG)
|
||
loop_depth++;
|
||
else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_END)
|
||
loop_depth--;
|
||
}
|
||
}
|
||
|
||
/* If one movable subsumes another, ignore that other. */
|
||
|
||
ignore_some_movables (movables);
|
||
|
||
/* For each movable insn, see if the reg that it loads
|
||
leads when it dies right into another conditionally movable insn.
|
||
If so, record that the second insn "forces" the first one,
|
||
since the second can be moved only if the first is. */
|
||
|
||
force_movables (movables);
|
||
|
||
/* See if there are multiple movable insns that load the same value.
|
||
If there are, make all but the first point at the first one
|
||
through the `match' field, and add the priorities of them
|
||
all together as the priority of the first. */
|
||
|
||
combine_movables (movables, nregs);
|
||
|
||
/* Now consider each movable insn to decide whether it is worth moving.
|
||
Store 0 in n_times_set for each reg that is moved.
|
||
|
||
Generally this increases code size, so do not move moveables when
|
||
optimizing for code size. */
|
||
|
||
if (! optimize_size)
|
||
move_movables (movables, threshold,
|
||
insn_count, loop_start, end, nregs);
|
||
|
||
/* Now candidates that still are negative are those not moved.
|
||
Change n_times_set to indicate that those are not actually invariant. */
|
||
for (i = 0; i < nregs; i++)
|
||
if (n_times_set[i] < 0)
|
||
n_times_set[i] = n_times_used[i];
|
||
|
||
if (flag_strength_reduce)
|
||
strength_reduce (scan_start, end, loop_top,
|
||
insn_count, loop_start, end, unroll_p);
|
||
}
|
||
|
||
/* Add elements to *OUTPUT to record all the pseudo-regs
|
||
mentioned in IN_THIS but not mentioned in NOT_IN_THIS. */
|
||
|
||
void
|
||
record_excess_regs (in_this, not_in_this, output)
|
||
rtx in_this, not_in_this;
|
||
rtx *output;
|
||
{
|
||
enum rtx_code code;
|
||
char *fmt;
|
||
int i;
|
||
|
||
code = GET_CODE (in_this);
|
||
|
||
switch (code)
|
||
{
|
||
case PC:
|
||
case CC0:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case CONST:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
return;
|
||
|
||
case REG:
|
||
if (REGNO (in_this) >= FIRST_PSEUDO_REGISTER
|
||
&& ! reg_mentioned_p (in_this, not_in_this))
|
||
*output = gen_rtx_EXPR_LIST (VOIDmode, in_this, *output);
|
||
return;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
int j;
|
||
|
||
switch (fmt[i])
|
||
{
|
||
case 'E':
|
||
for (j = 0; j < XVECLEN (in_this, i); j++)
|
||
record_excess_regs (XVECEXP (in_this, i, j), not_in_this, output);
|
||
break;
|
||
|
||
case 'e':
|
||
record_excess_regs (XEXP (in_this, i), not_in_this, output);
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Check what regs are referred to in the libcall block ending with INSN,
|
||
aside from those mentioned in the equivalent value.
|
||
If there are none, return 0.
|
||
If there are one or more, return an EXPR_LIST containing all of them. */
|
||
|
||
static rtx
|
||
libcall_other_reg (insn, equiv)
|
||
rtx insn, equiv;
|
||
{
|
||
rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
|
||
rtx p = XEXP (note, 0);
|
||
rtx output = 0;
|
||
|
||
/* First, find all the regs used in the libcall block
|
||
that are not mentioned as inputs to the result. */
|
||
|
||
while (p != insn)
|
||
{
|
||
if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN
|
||
|| GET_CODE (p) == CALL_INSN)
|
||
record_excess_regs (PATTERN (p), equiv, &output);
|
||
p = NEXT_INSN (p);
|
||
}
|
||
|
||
return output;
|
||
}
|
||
|
||
/* Return 1 if all uses of REG
|
||
are between INSN and the end of the basic block. */
|
||
|
||
static int
|
||
reg_in_basic_block_p (insn, reg)
|
||
rtx insn, reg;
|
||
{
|
||
int regno = REGNO (reg);
|
||
rtx p;
|
||
|
||
if (REGNO_FIRST_UID (regno) != INSN_UID (insn))
|
||
return 0;
|
||
|
||
/* Search this basic block for the already recorded last use of the reg. */
|
||
for (p = insn; p; p = NEXT_INSN (p))
|
||
{
|
||
switch (GET_CODE (p))
|
||
{
|
||
case NOTE:
|
||
break;
|
||
|
||
case INSN:
|
||
case CALL_INSN:
|
||
/* Ordinary insn: if this is the last use, we win. */
|
||
if (REGNO_LAST_UID (regno) == INSN_UID (p))
|
||
return 1;
|
||
break;
|
||
|
||
case JUMP_INSN:
|
||
/* Jump insn: if this is the last use, we win. */
|
||
if (REGNO_LAST_UID (regno) == INSN_UID (p))
|
||
return 1;
|
||
/* Otherwise, it's the end of the basic block, so we lose. */
|
||
return 0;
|
||
|
||
case CODE_LABEL:
|
||
case BARRIER:
|
||
/* It's the end of the basic block, so we lose. */
|
||
return 0;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
}
|
||
|
||
/* The "last use" doesn't follow the "first use"?? */
|
||
abort ();
|
||
}
|
||
|
||
/* Compute the benefit of eliminating the insns in the block whose
|
||
last insn is LAST. This may be a group of insns used to compute a
|
||
value directly or can contain a library call. */
|
||
|
||
static int
|
||
libcall_benefit (last)
|
||
rtx last;
|
||
{
|
||
rtx insn;
|
||
int benefit = 0;
|
||
|
||
for (insn = XEXP (find_reg_note (last, REG_RETVAL, NULL_RTX), 0);
|
||
insn != last; insn = NEXT_INSN (insn))
|
||
{
|
||
if (GET_CODE (insn) == CALL_INSN)
|
||
benefit += 10; /* Assume at least this many insns in a library
|
||
routine. */
|
||
else if (GET_CODE (insn) == INSN
|
||
&& GET_CODE (PATTERN (insn)) != USE
|
||
&& GET_CODE (PATTERN (insn)) != CLOBBER)
|
||
benefit++;
|
||
}
|
||
|
||
return benefit;
|
||
}
|
||
|
||
/* Skip COUNT insns from INSN, counting library calls as 1 insn. */
|
||
|
||
static rtx
|
||
skip_consec_insns (insn, count)
|
||
rtx insn;
|
||
int count;
|
||
{
|
||
for (; count > 0; count--)
|
||
{
|
||
rtx temp;
|
||
|
||
/* If first insn of libcall sequence, skip to end. */
|
||
/* Do this at start of loop, since INSN is guaranteed to
|
||
be an insn here. */
|
||
if (GET_CODE (insn) != NOTE
|
||
&& (temp = find_reg_note (insn, REG_LIBCALL, NULL_RTX)))
|
||
insn = XEXP (temp, 0);
|
||
|
||
do insn = NEXT_INSN (insn);
|
||
while (GET_CODE (insn) == NOTE);
|
||
}
|
||
|
||
return insn;
|
||
}
|
||
|
||
/* Ignore any movable whose insn falls within a libcall
|
||
which is part of another movable.
|
||
We make use of the fact that the movable for the libcall value
|
||
was made later and so appears later on the chain. */
|
||
|
||
static void
|
||
ignore_some_movables (movables)
|
||
struct movable *movables;
|
||
{
|
||
register struct movable *m, *m1;
|
||
|
||
for (m = movables; m; m = m->next)
|
||
{
|
||
/* Is this a movable for the value of a libcall? */
|
||
rtx note = find_reg_note (m->insn, REG_RETVAL, NULL_RTX);
|
||
if (note)
|
||
{
|
||
rtx insn;
|
||
/* Check for earlier movables inside that range,
|
||
and mark them invalid. We cannot use LUIDs here because
|
||
insns created by loop.c for prior loops don't have LUIDs.
|
||
Rather than reject all such insns from movables, we just
|
||
explicitly check each insn in the libcall (since invariant
|
||
libcalls aren't that common). */
|
||
for (insn = XEXP (note, 0); insn != m->insn; insn = NEXT_INSN (insn))
|
||
for (m1 = movables; m1 != m; m1 = m1->next)
|
||
if (m1->insn == insn)
|
||
m1->done = 1;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* For each movable insn, see if the reg that it loads
|
||
leads when it dies right into another conditionally movable insn.
|
||
If so, record that the second insn "forces" the first one,
|
||
since the second can be moved only if the first is. */
|
||
|
||
static void
|
||
force_movables (movables)
|
||
struct movable *movables;
|
||
{
|
||
register struct movable *m, *m1;
|
||
for (m1 = movables; m1; m1 = m1->next)
|
||
/* Omit this if moving just the (SET (REG) 0) of a zero-extend. */
|
||
if (!m1->partial && !m1->done)
|
||
{
|
||
int regno = m1->regno;
|
||
for (m = m1->next; m; m = m->next)
|
||
/* ??? Could this be a bug? What if CSE caused the
|
||
register of M1 to be used after this insn?
|
||
Since CSE does not update regno_last_uid,
|
||
this insn M->insn might not be where it dies.
|
||
But very likely this doesn't matter; what matters is
|
||
that M's reg is computed from M1's reg. */
|
||
if (INSN_UID (m->insn) == REGNO_LAST_UID (regno)
|
||
&& !m->done)
|
||
break;
|
||
if (m != 0 && m->set_src == m1->set_dest
|
||
/* If m->consec, m->set_src isn't valid. */
|
||
&& m->consec == 0)
|
||
m = 0;
|
||
|
||
/* Increase the priority of the moving the first insn
|
||
since it permits the second to be moved as well. */
|
||
if (m != 0)
|
||
{
|
||
m->forces = m1;
|
||
m1->lifetime += m->lifetime;
|
||
m1->savings += m->savings;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Find invariant expressions that are equal and can be combined into
|
||
one register. */
|
||
|
||
static void
|
||
combine_movables (movables, nregs)
|
||
struct movable *movables;
|
||
int nregs;
|
||
{
|
||
register struct movable *m;
|
||
char *matched_regs = (char *) alloca (nregs);
|
||
enum machine_mode mode;
|
||
|
||
/* Regs that are set more than once are not allowed to match
|
||
or be matched. I'm no longer sure why not. */
|
||
/* Perhaps testing m->consec_sets would be more appropriate here? */
|
||
|
||
for (m = movables; m; m = m->next)
|
||
if (m->match == 0 && n_times_used[m->regno] == 1 && !m->partial)
|
||
{
|
||
register struct movable *m1;
|
||
int regno = m->regno;
|
||
|
||
bzero (matched_regs, nregs);
|
||
matched_regs[regno] = 1;
|
||
|
||
/* We want later insns to match the first one. Don't make the first
|
||
one match any later ones. So start this loop at m->next. */
|
||
for (m1 = m->next; m1; m1 = m1->next)
|
||
if (m != m1 && m1->match == 0 && n_times_used[m1->regno] == 1
|
||
/* A reg used outside the loop mustn't be eliminated. */
|
||
&& !m1->global
|
||
/* A reg used for zero-extending mustn't be eliminated. */
|
||
&& !m1->partial
|
||
&& (matched_regs[m1->regno]
|
||
||
|
||
(
|
||
/* Can combine regs with different modes loaded from the
|
||
same constant only if the modes are the same or
|
||
if both are integer modes with M wider or the same
|
||
width as M1. The check for integer is redundant, but
|
||
safe, since the only case of differing destination
|
||
modes with equal sources is when both sources are
|
||
VOIDmode, i.e., CONST_INT. */
|
||
(GET_MODE (m->set_dest) == GET_MODE (m1->set_dest)
|
||
|| (GET_MODE_CLASS (GET_MODE (m->set_dest)) == MODE_INT
|
||
&& GET_MODE_CLASS (GET_MODE (m1->set_dest)) == MODE_INT
|
||
&& (GET_MODE_BITSIZE (GET_MODE (m->set_dest))
|
||
>= GET_MODE_BITSIZE (GET_MODE (m1->set_dest)))))
|
||
/* See if the source of M1 says it matches M. */
|
||
&& ((GET_CODE (m1->set_src) == REG
|
||
&& matched_regs[REGNO (m1->set_src)])
|
||
|| rtx_equal_for_loop_p (m->set_src, m1->set_src,
|
||
movables))))
|
||
&& ((m->dependencies == m1->dependencies)
|
||
|| rtx_equal_p (m->dependencies, m1->dependencies)))
|
||
{
|
||
m->lifetime += m1->lifetime;
|
||
m->savings += m1->savings;
|
||
m1->done = 1;
|
||
m1->match = m;
|
||
matched_regs[m1->regno] = 1;
|
||
}
|
||
}
|
||
|
||
/* Now combine the regs used for zero-extension.
|
||
This can be done for those not marked `global'
|
||
provided their lives don't overlap. */
|
||
|
||
for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
|
||
mode = GET_MODE_WIDER_MODE (mode))
|
||
{
|
||
register struct movable *m0 = 0;
|
||
|
||
/* Combine all the registers for extension from mode MODE.
|
||
Don't combine any that are used outside this loop. */
|
||
for (m = movables; m; m = m->next)
|
||
if (m->partial && ! m->global
|
||
&& mode == GET_MODE (SET_SRC (PATTERN (NEXT_INSN (m->insn)))))
|
||
{
|
||
register struct movable *m1;
|
||
int first = uid_luid[REGNO_FIRST_UID (m->regno)];
|
||
int last = uid_luid[REGNO_LAST_UID (m->regno)];
|
||
|
||
if (m0 == 0)
|
||
{
|
||
/* First one: don't check for overlap, just record it. */
|
||
m0 = m;
|
||
continue;
|
||
}
|
||
|
||
/* Make sure they extend to the same mode.
|
||
(Almost always true.) */
|
||
if (GET_MODE (m->set_dest) != GET_MODE (m0->set_dest))
|
||
continue;
|
||
|
||
/* We already have one: check for overlap with those
|
||
already combined together. */
|
||
for (m1 = movables; m1 != m; m1 = m1->next)
|
||
if (m1 == m0 || (m1->partial && m1->match == m0))
|
||
if (! (uid_luid[REGNO_FIRST_UID (m1->regno)] > last
|
||
|| uid_luid[REGNO_LAST_UID (m1->regno)] < first))
|
||
goto overlap;
|
||
|
||
/* No overlap: we can combine this with the others. */
|
||
m0->lifetime += m->lifetime;
|
||
m0->savings += m->savings;
|
||
m->done = 1;
|
||
m->match = m0;
|
||
|
||
overlap: ;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Return 1 if regs X and Y will become the same if moved. */
|
||
|
||
static int
|
||
regs_match_p (x, y, movables)
|
||
rtx x, y;
|
||
struct movable *movables;
|
||
{
|
||
int xn = REGNO (x);
|
||
int yn = REGNO (y);
|
||
struct movable *mx, *my;
|
||
|
||
for (mx = movables; mx; mx = mx->next)
|
||
if (mx->regno == xn)
|
||
break;
|
||
|
||
for (my = movables; my; my = my->next)
|
||
if (my->regno == yn)
|
||
break;
|
||
|
||
return (mx && my
|
||
&& ((mx->match == my->match && mx->match != 0)
|
||
|| mx->match == my
|
||
|| mx == my->match));
|
||
}
|
||
|
||
/* Return 1 if X and Y are identical-looking rtx's.
|
||
This is the Lisp function EQUAL for rtx arguments.
|
||
|
||
If two registers are matching movables or a movable register and an
|
||
equivalent constant, consider them equal. */
|
||
|
||
static int
|
||
rtx_equal_for_loop_p (x, y, movables)
|
||
rtx x, y;
|
||
struct movable *movables;
|
||
{
|
||
register int i;
|
||
register int j;
|
||
register struct movable *m;
|
||
register enum rtx_code code;
|
||
register char *fmt;
|
||
|
||
if (x == y)
|
||
return 1;
|
||
if (x == 0 || y == 0)
|
||
return 0;
|
||
|
||
code = GET_CODE (x);
|
||
|
||
/* If we have a register and a constant, they may sometimes be
|
||
equal. */
|
||
if (GET_CODE (x) == REG && n_times_set[REGNO (x)] == -2
|
||
&& CONSTANT_P (y))
|
||
{
|
||
for (m = movables; m; m = m->next)
|
||
if (m->move_insn && m->regno == REGNO (x)
|
||
&& rtx_equal_p (m->set_src, y))
|
||
return 1;
|
||
}
|
||
else if (GET_CODE (y) == REG && n_times_set[REGNO (y)] == -2
|
||
&& CONSTANT_P (x))
|
||
{
|
||
for (m = movables; m; m = m->next)
|
||
if (m->move_insn && m->regno == REGNO (y)
|
||
&& rtx_equal_p (m->set_src, x))
|
||
return 1;
|
||
}
|
||
|
||
/* Otherwise, rtx's of different codes cannot be equal. */
|
||
if (code != GET_CODE (y))
|
||
return 0;
|
||
|
||
/* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
|
||
(REG:SI x) and (REG:HI x) are NOT equivalent. */
|
||
|
||
if (GET_MODE (x) != GET_MODE (y))
|
||
return 0;
|
||
|
||
/* These three types of rtx's can be compared nonrecursively. */
|
||
if (code == REG)
|
||
return (REGNO (x) == REGNO (y) || regs_match_p (x, y, movables));
|
||
|
||
if (code == LABEL_REF)
|
||
return XEXP (x, 0) == XEXP (y, 0);
|
||
if (code == SYMBOL_REF)
|
||
return XSTR (x, 0) == XSTR (y, 0);
|
||
|
||
/* Compare the elements. If any pair of corresponding elements
|
||
fail to match, return 0 for the whole things. */
|
||
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
switch (fmt[i])
|
||
{
|
||
case 'w':
|
||
if (XWINT (x, i) != XWINT (y, i))
|
||
return 0;
|
||
break;
|
||
|
||
case 'i':
|
||
if (XINT (x, i) != XINT (y, i))
|
||
return 0;
|
||
break;
|
||
|
||
case 'E':
|
||
/* Two vectors must have the same length. */
|
||
if (XVECLEN (x, i) != XVECLEN (y, i))
|
||
return 0;
|
||
|
||
/* And the corresponding elements must match. */
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
if (rtx_equal_for_loop_p (XVECEXP (x, i, j), XVECEXP (y, i, j), movables) == 0)
|
||
return 0;
|
||
break;
|
||
|
||
case 'e':
|
||
if (rtx_equal_for_loop_p (XEXP (x, i), XEXP (y, i), movables) == 0)
|
||
return 0;
|
||
break;
|
||
|
||
case 's':
|
||
if (strcmp (XSTR (x, i), XSTR (y, i)))
|
||
return 0;
|
||
break;
|
||
|
||
case 'u':
|
||
/* These are just backpointers, so they don't matter. */
|
||
break;
|
||
|
||
case '0':
|
||
break;
|
||
|
||
/* It is believed that rtx's at this level will never
|
||
contain anything but integers and other rtx's,
|
||
except for within LABEL_REFs and SYMBOL_REFs. */
|
||
default:
|
||
abort ();
|
||
}
|
||
}
|
||
return 1;
|
||
}
|
||
|
||
/* If X contains any LABEL_REF's, add REG_LABEL notes for them to all
|
||
insns in INSNS which use thet reference. */
|
||
|
||
static void
|
||
add_label_notes (x, insns)
|
||
rtx x;
|
||
rtx insns;
|
||
{
|
||
enum rtx_code code = GET_CODE (x);
|
||
int i, j;
|
||
char *fmt;
|
||
rtx insn;
|
||
|
||
if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x))
|
||
{
|
||
/* This code used to ignore labels that referred to dispatch tables to
|
||
avoid flow generating (slighly) worse code.
|
||
|
||
We no longer ignore such label references (see LABEL_REF handling in
|
||
mark_jump_label for additional information). */
|
||
for (insn = insns; insn; insn = NEXT_INSN (insn))
|
||
if (reg_mentioned_p (XEXP (x, 0), insn))
|
||
REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, XEXP (x, 0),
|
||
REG_NOTES (insn));
|
||
}
|
||
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
add_label_notes (XEXP (x, i), insns);
|
||
else if (fmt[i] == 'E')
|
||
for (j = XVECLEN (x, i) - 1; j >= 0; j--)
|
||
add_label_notes (XVECEXP (x, i, j), insns);
|
||
}
|
||
}
|
||
|
||
/* Scan MOVABLES, and move the insns that deserve to be moved.
|
||
If two matching movables are combined, replace one reg with the
|
||
other throughout. */
|
||
|
||
static void
|
||
move_movables (movables, threshold, insn_count, loop_start, end, nregs)
|
||
struct movable *movables;
|
||
int threshold;
|
||
int insn_count;
|
||
rtx loop_start;
|
||
rtx end;
|
||
int nregs;
|
||
{
|
||
rtx new_start = 0;
|
||
register struct movable *m;
|
||
register rtx p;
|
||
/* Map of pseudo-register replacements to handle combining
|
||
when we move several insns that load the same value
|
||
into different pseudo-registers. */
|
||
rtx *reg_map = (rtx *) alloca (nregs * sizeof (rtx));
|
||
char *already_moved = (char *) alloca (nregs);
|
||
|
||
bzero (already_moved, nregs);
|
||
bzero ((char *) reg_map, nregs * sizeof (rtx));
|
||
|
||
num_movables = 0;
|
||
|
||
for (m = movables; m; m = m->next)
|
||
{
|
||
/* Describe this movable insn. */
|
||
|
||
if (loop_dump_stream)
|
||
{
|
||
fprintf (loop_dump_stream, "Insn %d: regno %d (life %d), ",
|
||
INSN_UID (m->insn), m->regno, m->lifetime);
|
||
if (m->consec > 0)
|
||
fprintf (loop_dump_stream, "consec %d, ", m->consec);
|
||
if (m->cond)
|
||
fprintf (loop_dump_stream, "cond ");
|
||
if (m->force)
|
||
fprintf (loop_dump_stream, "force ");
|
||
if (m->global)
|
||
fprintf (loop_dump_stream, "global ");
|
||
if (m->done)
|
||
fprintf (loop_dump_stream, "done ");
|
||
if (m->move_insn)
|
||
fprintf (loop_dump_stream, "move-insn ");
|
||
if (m->match)
|
||
fprintf (loop_dump_stream, "matches %d ",
|
||
INSN_UID (m->match->insn));
|
||
if (m->forces)
|
||
fprintf (loop_dump_stream, "forces %d ",
|
||
INSN_UID (m->forces->insn));
|
||
}
|
||
|
||
/* Count movables. Value used in heuristics in strength_reduce. */
|
||
num_movables++;
|
||
|
||
/* Ignore the insn if it's already done (it matched something else).
|
||
Otherwise, see if it is now safe to move. */
|
||
|
||
if (!m->done
|
||
&& (! m->cond
|
||
|| (1 == invariant_p (m->set_src)
|
||
&& (m->dependencies == 0
|
||
|| 1 == invariant_p (m->dependencies))
|
||
&& (m->consec == 0
|
||
|| 1 == consec_sets_invariant_p (m->set_dest,
|
||
m->consec + 1,
|
||
m->insn))))
|
||
&& (! m->forces || m->forces->done))
|
||
{
|
||
register int regno;
|
||
register rtx p;
|
||
int savings = m->savings;
|
||
|
||
/* We have an insn that is safe to move.
|
||
Compute its desirability. */
|
||
|
||
p = m->insn;
|
||
regno = m->regno;
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "savings %d ", savings);
|
||
|
||
if (moved_once[regno])
|
||
{
|
||
insn_count *= 2;
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "halved since already moved ");
|
||
}
|
||
|
||
/* An insn MUST be moved if we already moved something else
|
||
which is safe only if this one is moved too: that is,
|
||
if already_moved[REGNO] is nonzero. */
|
||
|
||
/* An insn is desirable to move if the new lifetime of the
|
||
register is no more than THRESHOLD times the old lifetime.
|
||
If it's not desirable, it means the loop is so big
|
||
that moving won't speed things up much,
|
||
and it is liable to make register usage worse. */
|
||
|
||
/* It is also desirable to move if it can be moved at no
|
||
extra cost because something else was already moved. */
|
||
|
||
if (already_moved[regno]
|
||
|| flag_move_all_movables
|
||
|| (threshold * savings * m->lifetime) >= insn_count
|
||
|| (m->forces && m->forces->done
|
||
&& n_times_used[m->forces->regno] == 1))
|
||
{
|
||
int count;
|
||
register struct movable *m1;
|
||
rtx first;
|
||
|
||
/* Now move the insns that set the reg. */
|
||
|
||
if (m->partial && m->match)
|
||
{
|
||
rtx newpat, i1;
|
||
rtx r1, r2;
|
||
/* Find the end of this chain of matching regs.
|
||
Thus, we load each reg in the chain from that one reg.
|
||
And that reg is loaded with 0 directly,
|
||
since it has ->match == 0. */
|
||
for (m1 = m; m1->match; m1 = m1->match);
|
||
newpat = gen_move_insn (SET_DEST (PATTERN (m->insn)),
|
||
SET_DEST (PATTERN (m1->insn)));
|
||
i1 = emit_insn_before (newpat, loop_start);
|
||
|
||
/* Mark the moved, invariant reg as being allowed to
|
||
share a hard reg with the other matching invariant. */
|
||
REG_NOTES (i1) = REG_NOTES (m->insn);
|
||
r1 = SET_DEST (PATTERN (m->insn));
|
||
r2 = SET_DEST (PATTERN (m1->insn));
|
||
regs_may_share
|
||
= gen_rtx_EXPR_LIST (VOIDmode, r1,
|
||
gen_rtx_EXPR_LIST (VOIDmode, r2,
|
||
regs_may_share));
|
||
delete_insn (m->insn);
|
||
|
||
if (new_start == 0)
|
||
new_start = i1;
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, " moved to %d", INSN_UID (i1));
|
||
}
|
||
/* If we are to re-generate the item being moved with a
|
||
new move insn, first delete what we have and then emit
|
||
the move insn before the loop. */
|
||
else if (m->move_insn)
|
||
{
|
||
rtx i1, temp;
|
||
|
||
for (count = m->consec; count >= 0; count--)
|
||
{
|
||
/* If this is the first insn of a library call sequence,
|
||
skip to the end. */
|
||
if (GET_CODE (p) != NOTE
|
||
&& (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX)))
|
||
p = XEXP (temp, 0);
|
||
|
||
/* If this is the last insn of a libcall sequence, then
|
||
delete every insn in the sequence except the last.
|
||
The last insn is handled in the normal manner. */
|
||
if (GET_CODE (p) != NOTE
|
||
&& (temp = find_reg_note (p, REG_RETVAL, NULL_RTX)))
|
||
{
|
||
temp = XEXP (temp, 0);
|
||
while (temp != p)
|
||
temp = delete_insn (temp);
|
||
}
|
||
|
||
p = delete_insn (p);
|
||
while (p && GET_CODE (p) == NOTE)
|
||
p = NEXT_INSN (p);
|
||
}
|
||
|
||
start_sequence ();
|
||
emit_move_insn (m->set_dest, m->set_src);
|
||
temp = get_insns ();
|
||
end_sequence ();
|
||
|
||
add_label_notes (m->set_src, temp);
|
||
|
||
i1 = emit_insns_before (temp, loop_start);
|
||
if (! find_reg_note (i1, REG_EQUAL, NULL_RTX))
|
||
REG_NOTES (i1)
|
||
= gen_rtx_EXPR_LIST (m->is_equiv ? REG_EQUIV : REG_EQUAL,
|
||
m->set_src, REG_NOTES (i1));
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, " moved to %d", INSN_UID (i1));
|
||
|
||
/* The more regs we move, the less we like moving them. */
|
||
threshold -= 3;
|
||
}
|
||
else
|
||
{
|
||
for (count = m->consec; count >= 0; count--)
|
||
{
|
||
rtx i1, temp;
|
||
|
||
/* If first insn of libcall sequence, skip to end. */
|
||
/* Do this at start of loop, since p is guaranteed to
|
||
be an insn here. */
|
||
if (GET_CODE (p) != NOTE
|
||
&& (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX)))
|
||
p = XEXP (temp, 0);
|
||
|
||
/* If last insn of libcall sequence, move all
|
||
insns except the last before the loop. The last
|
||
insn is handled in the normal manner. */
|
||
if (GET_CODE (p) != NOTE
|
||
&& (temp = find_reg_note (p, REG_RETVAL, NULL_RTX)))
|
||
{
|
||
rtx fn_address = 0;
|
||
rtx fn_reg = 0;
|
||
rtx fn_address_insn = 0;
|
||
|
||
first = 0;
|
||
for (temp = XEXP (temp, 0); temp != p;
|
||
temp = NEXT_INSN (temp))
|
||
{
|
||
rtx body;
|
||
rtx n;
|
||
rtx next;
|
||
|
||
if (GET_CODE (temp) == NOTE)
|
||
continue;
|
||
|
||
body = PATTERN (temp);
|
||
|
||
/* Find the next insn after TEMP,
|
||
not counting USE or NOTE insns. */
|
||
for (next = NEXT_INSN (temp); next != p;
|
||
next = NEXT_INSN (next))
|
||
if (! (GET_CODE (next) == INSN
|
||
&& GET_CODE (PATTERN (next)) == USE)
|
||
&& GET_CODE (next) != NOTE)
|
||
break;
|
||
|
||
/* If that is the call, this may be the insn
|
||
that loads the function address.
|
||
|
||
Extract the function address from the insn
|
||
that loads it into a register.
|
||
If this insn was cse'd, we get incorrect code.
|
||
|
||
So emit a new move insn that copies the
|
||
function address into the register that the
|
||
call insn will use. flow.c will delete any
|
||
redundant stores that we have created. */
|
||
if (GET_CODE (next) == CALL_INSN
|
||
&& GET_CODE (body) == SET
|
||
&& GET_CODE (SET_DEST (body)) == REG
|
||
&& (n = find_reg_note (temp, REG_EQUAL,
|
||
NULL_RTX)))
|
||
{
|
||
fn_reg = SET_SRC (body);
|
||
if (GET_CODE (fn_reg) != REG)
|
||
fn_reg = SET_DEST (body);
|
||
fn_address = XEXP (n, 0);
|
||
fn_address_insn = temp;
|
||
}
|
||
/* We have the call insn.
|
||
If it uses the register we suspect it might,
|
||
load it with the correct address directly. */
|
||
if (GET_CODE (temp) == CALL_INSN
|
||
&& fn_address != 0
|
||
&& reg_referenced_p (fn_reg, body))
|
||
emit_insn_after (gen_move_insn (fn_reg,
|
||
fn_address),
|
||
fn_address_insn);
|
||
|
||
if (GET_CODE (temp) == CALL_INSN)
|
||
{
|
||
i1 = emit_call_insn_before (body, loop_start);
|
||
/* Because the USAGE information potentially
|
||
contains objects other than hard registers
|
||
we need to copy it. */
|
||
if (CALL_INSN_FUNCTION_USAGE (temp))
|
||
CALL_INSN_FUNCTION_USAGE (i1)
|
||
= copy_rtx (CALL_INSN_FUNCTION_USAGE (temp));
|
||
}
|
||
else
|
||
i1 = emit_insn_before (body, loop_start);
|
||
if (first == 0)
|
||
first = i1;
|
||
if (temp == fn_address_insn)
|
||
fn_address_insn = i1;
|
||
REG_NOTES (i1) = REG_NOTES (temp);
|
||
delete_insn (temp);
|
||
}
|
||
}
|
||
if (m->savemode != VOIDmode)
|
||
{
|
||
/* P sets REG to zero; but we should clear only
|
||
the bits that are not covered by the mode
|
||
m->savemode. */
|
||
rtx reg = m->set_dest;
|
||
rtx sequence;
|
||
rtx tem;
|
||
|
||
start_sequence ();
|
||
tem = expand_binop
|
||
(GET_MODE (reg), and_optab, reg,
|
||
GEN_INT ((((HOST_WIDE_INT) 1
|
||
<< GET_MODE_BITSIZE (m->savemode)))
|
||
- 1),
|
||
reg, 1, OPTAB_LIB_WIDEN);
|
||
if (tem == 0)
|
||
abort ();
|
||
if (tem != reg)
|
||
emit_move_insn (reg, tem);
|
||
sequence = gen_sequence ();
|
||
end_sequence ();
|
||
i1 = emit_insn_before (sequence, loop_start);
|
||
}
|
||
else if (GET_CODE (p) == CALL_INSN)
|
||
{
|
||
i1 = emit_call_insn_before (PATTERN (p), loop_start);
|
||
/* Because the USAGE information potentially
|
||
contains objects other than hard registers
|
||
we need to copy it. */
|
||
if (CALL_INSN_FUNCTION_USAGE (p))
|
||
CALL_INSN_FUNCTION_USAGE (i1)
|
||
= copy_rtx (CALL_INSN_FUNCTION_USAGE (p));
|
||
}
|
||
else if (count == m->consec && m->move_insn_first)
|
||
{
|
||
/* The SET_SRC might not be invariant, so we must
|
||
use the REG_EQUAL note. */
|
||
start_sequence ();
|
||
emit_move_insn (m->set_dest, m->set_src);
|
||
temp = get_insns ();
|
||
end_sequence ();
|
||
|
||
add_label_notes (m->set_src, temp);
|
||
|
||
i1 = emit_insns_before (temp, loop_start);
|
||
if (! find_reg_note (i1, REG_EQUAL, NULL_RTX))
|
||
REG_NOTES (i1)
|
||
= gen_rtx_EXPR_LIST ((m->is_equiv ? REG_EQUIV
|
||
: REG_EQUAL),
|
||
m->set_src, REG_NOTES (i1));
|
||
}
|
||
else
|
||
i1 = emit_insn_before (PATTERN (p), loop_start);
|
||
|
||
if (REG_NOTES (i1) == 0)
|
||
{
|
||
REG_NOTES (i1) = REG_NOTES (p);
|
||
|
||
/* If there is a REG_EQUAL note present whose value
|
||
is not loop invariant, then delete it, since it
|
||
may cause problems with later optimization passes.
|
||
It is possible for cse to create such notes
|
||
like this as a result of record_jump_cond. */
|
||
|
||
if ((temp = find_reg_note (i1, REG_EQUAL, NULL_RTX))
|
||
&& ! invariant_p (XEXP (temp, 0)))
|
||
remove_note (i1, temp);
|
||
}
|
||
|
||
if (new_start == 0)
|
||
new_start = i1;
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, " moved to %d",
|
||
INSN_UID (i1));
|
||
|
||
/* If library call, now fix the REG_NOTES that contain
|
||
insn pointers, namely REG_LIBCALL on FIRST
|
||
and REG_RETVAL on I1. */
|
||
if ((temp = find_reg_note (i1, REG_RETVAL, NULL_RTX)))
|
||
{
|
||
XEXP (temp, 0) = first;
|
||
temp = find_reg_note (first, REG_LIBCALL, NULL_RTX);
|
||
XEXP (temp, 0) = i1;
|
||
}
|
||
|
||
delete_insn (p);
|
||
do p = NEXT_INSN (p);
|
||
while (p && GET_CODE (p) == NOTE);
|
||
}
|
||
|
||
/* The more regs we move, the less we like moving them. */
|
||
threshold -= 3;
|
||
}
|
||
|
||
/* Any other movable that loads the same register
|
||
MUST be moved. */
|
||
already_moved[regno] = 1;
|
||
|
||
/* This reg has been moved out of one loop. */
|
||
moved_once[regno] = 1;
|
||
|
||
/* The reg set here is now invariant. */
|
||
if (! m->partial)
|
||
n_times_set[regno] = 0;
|
||
|
||
m->done = 1;
|
||
|
||
/* Change the length-of-life info for the register
|
||
to say it lives at least the full length of this loop.
|
||
This will help guide optimizations in outer loops. */
|
||
|
||
if (uid_luid[REGNO_FIRST_UID (regno)] > INSN_LUID (loop_start))
|
||
/* This is the old insn before all the moved insns.
|
||
We can't use the moved insn because it is out of range
|
||
in uid_luid. Only the old insns have luids. */
|
||
REGNO_FIRST_UID (regno) = INSN_UID (loop_start);
|
||
if (uid_luid[REGNO_LAST_UID (regno)] < INSN_LUID (end))
|
||
REGNO_LAST_UID (regno) = INSN_UID (end);
|
||
|
||
/* Combine with this moved insn any other matching movables. */
|
||
|
||
if (! m->partial)
|
||
for (m1 = movables; m1; m1 = m1->next)
|
||
if (m1->match == m)
|
||
{
|
||
rtx temp;
|
||
|
||
/* Schedule the reg loaded by M1
|
||
for replacement so that shares the reg of M.
|
||
If the modes differ (only possible in restricted
|
||
circumstances, make a SUBREG. */
|
||
if (GET_MODE (m->set_dest) == GET_MODE (m1->set_dest))
|
||
reg_map[m1->regno] = m->set_dest;
|
||
else
|
||
reg_map[m1->regno]
|
||
= gen_lowpart_common (GET_MODE (m1->set_dest),
|
||
m->set_dest);
|
||
|
||
/* Get rid of the matching insn
|
||
and prevent further processing of it. */
|
||
m1->done = 1;
|
||
|
||
/* if library call, delete all insn except last, which
|
||
is deleted below */
|
||
if ((temp = find_reg_note (m1->insn, REG_RETVAL,
|
||
NULL_RTX)))
|
||
{
|
||
for (temp = XEXP (temp, 0); temp != m1->insn;
|
||
temp = NEXT_INSN (temp))
|
||
delete_insn (temp);
|
||
}
|
||
delete_insn (m1->insn);
|
||
|
||
/* Any other movable that loads the same register
|
||
MUST be moved. */
|
||
already_moved[m1->regno] = 1;
|
||
|
||
/* The reg merged here is now invariant,
|
||
if the reg it matches is invariant. */
|
||
if (! m->partial)
|
||
n_times_set[m1->regno] = 0;
|
||
}
|
||
}
|
||
else if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "not desirable");
|
||
}
|
||
else if (loop_dump_stream && !m->match)
|
||
fprintf (loop_dump_stream, "not safe");
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "\n");
|
||
}
|
||
|
||
if (new_start == 0)
|
||
new_start = loop_start;
|
||
|
||
/* Go through all the instructions in the loop, making
|
||
all the register substitutions scheduled in REG_MAP. */
|
||
for (p = new_start; p != end; p = NEXT_INSN (p))
|
||
if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN
|
||
|| GET_CODE (p) == CALL_INSN)
|
||
{
|
||
replace_regs (PATTERN (p), reg_map, nregs, 0);
|
||
replace_regs (REG_NOTES (p), reg_map, nregs, 0);
|
||
INSN_CODE (p) = -1;
|
||
}
|
||
}
|
||
|
||
#if 0
|
||
/* Scan X and replace the address of any MEM in it with ADDR.
|
||
REG is the address that MEM should have before the replacement. */
|
||
|
||
static void
|
||
replace_call_address (x, reg, addr)
|
||
rtx x, reg, addr;
|
||
{
|
||
register enum rtx_code code;
|
||
register int i;
|
||
register char *fmt;
|
||
|
||
if (x == 0)
|
||
return;
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case PC:
|
||
case CC0:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case CONST:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
case REG:
|
||
return;
|
||
|
||
case SET:
|
||
/* Short cut for very common case. */
|
||
replace_call_address (XEXP (x, 1), reg, addr);
|
||
return;
|
||
|
||
case CALL:
|
||
/* Short cut for very common case. */
|
||
replace_call_address (XEXP (x, 0), reg, addr);
|
||
return;
|
||
|
||
case MEM:
|
||
/* If this MEM uses a reg other than the one we expected,
|
||
something is wrong. */
|
||
if (XEXP (x, 0) != reg)
|
||
abort ();
|
||
XEXP (x, 0) = addr;
|
||
return;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
replace_call_address (XEXP (x, i), reg, addr);
|
||
if (fmt[i] == 'E')
|
||
{
|
||
register int j;
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
replace_call_address (XVECEXP (x, i, j), reg, addr);
|
||
}
|
||
}
|
||
}
|
||
#endif
|
||
|
||
/* Return the number of memory refs to addresses that vary
|
||
in the rtx X. */
|
||
|
||
static int
|
||
count_nonfixed_reads (x)
|
||
rtx x;
|
||
{
|
||
register enum rtx_code code;
|
||
register int i;
|
||
register char *fmt;
|
||
int value;
|
||
|
||
if (x == 0)
|
||
return 0;
|
||
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case PC:
|
||
case CC0:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case CONST:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
case REG:
|
||
return 0;
|
||
|
||
case MEM:
|
||
return ((invariant_p (XEXP (x, 0)) != 1)
|
||
+ count_nonfixed_reads (XEXP (x, 0)));
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
value = 0;
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
value += count_nonfixed_reads (XEXP (x, i));
|
||
if (fmt[i] == 'E')
|
||
{
|
||
register int j;
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
value += count_nonfixed_reads (XVECEXP (x, i, j));
|
||
}
|
||
}
|
||
return value;
|
||
}
|
||
|
||
|
||
#if 0
|
||
/* P is an instruction that sets a register to the result of a ZERO_EXTEND.
|
||
Replace it with an instruction to load just the low bytes
|
||
if the machine supports such an instruction,
|
||
and insert above LOOP_START an instruction to clear the register. */
|
||
|
||
static void
|
||
constant_high_bytes (p, loop_start)
|
||
rtx p, loop_start;
|
||
{
|
||
register rtx new;
|
||
register int insn_code_number;
|
||
|
||
/* Try to change (SET (REG ...) (ZERO_EXTEND (..:B ...)))
|
||
to (SET (STRICT_LOW_PART (SUBREG:B (REG...))) ...). */
|
||
|
||
new = gen_rtx_SET (VOIDmode,
|
||
gen_rtx_STRICT_LOW_PART (VOIDmode,
|
||
gen_rtx_SUBREG (GET_MODE (XEXP (SET_SRC (PATTERN (p)), 0)),
|
||
SET_DEST (PATTERN (p)),
|
||
0)),
|
||
XEXP (SET_SRC (PATTERN (p)), 0));
|
||
insn_code_number = recog (new, p);
|
||
|
||
if (insn_code_number)
|
||
{
|
||
register int i;
|
||
|
||
/* Clear destination register before the loop. */
|
||
emit_insn_before (gen_rtx_SET (VOIDmode, SET_DEST (PATTERN (p)),
|
||
const0_rtx),
|
||
loop_start);
|
||
|
||
/* Inside the loop, just load the low part. */
|
||
PATTERN (p) = new;
|
||
}
|
||
}
|
||
#endif
|
||
|
||
/* Scan a loop setting the variables `unknown_address_altered',
|
||
`num_mem_sets', `loop_continue', loops_enclosed', `loop_has_call',
|
||
and `loop_has_volatile'.
|
||
Also, fill in the array `loop_store_mems'. */
|
||
|
||
static void
|
||
prescan_loop (start, end)
|
||
rtx start, end;
|
||
{
|
||
register int level = 1;
|
||
register rtx insn;
|
||
|
||
unknown_address_altered = 0;
|
||
loop_has_call = 0;
|
||
loop_has_volatile = 0;
|
||
first_loop_store_insn = NULL_RTX;
|
||
loop_store_mems_idx = 0;
|
||
|
||
num_mem_sets = 0;
|
||
loops_enclosed = 1;
|
||
loop_continue = 0;
|
||
|
||
for (insn = NEXT_INSN (start); insn != NEXT_INSN (end);
|
||
insn = NEXT_INSN (insn))
|
||
{
|
||
if (GET_CODE (insn) == NOTE)
|
||
{
|
||
if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
|
||
{
|
||
++level;
|
||
/* Count number of loops contained in this one. */
|
||
loops_enclosed++;
|
||
}
|
||
else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
|
||
{
|
||
--level;
|
||
if (level == 0)
|
||
{
|
||
end = insn;
|
||
break;
|
||
}
|
||
}
|
||
else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
|
||
{
|
||
if (level == 1)
|
||
loop_continue = insn;
|
||
}
|
||
}
|
||
else if (GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
if (! CONST_CALL_P (insn))
|
||
unknown_address_altered = 1;
|
||
loop_has_call = 1;
|
||
}
|
||
else
|
||
{
|
||
if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
|
||
{
|
||
if (volatile_refs_p (PATTERN (insn)))
|
||
loop_has_volatile = 1;
|
||
|
||
note_stores (PATTERN (insn), note_addr_stored);
|
||
if (! first_loop_store_insn && loop_store_mems_idx != 0)
|
||
first_loop_store_insn = insn;
|
||
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Scan the function looking for loops. Record the start and end of each loop.
|
||
Also mark as invalid loops any loops that contain a setjmp or are branched
|
||
to from outside the loop. */
|
||
|
||
static void
|
||
find_and_verify_loops (f)
|
||
rtx f;
|
||
{
|
||
rtx insn, label;
|
||
int current_loop = -1;
|
||
int next_loop = -1;
|
||
int loop;
|
||
|
||
/* If there are jumps to undefined labels,
|
||
treat them as jumps out of any/all loops.
|
||
This also avoids writing past end of tables when there are no loops. */
|
||
uid_loop_num[0] = -1;
|
||
|
||
/* Find boundaries of loops, mark which loops are contained within
|
||
loops, and invalidate loops that have setjmp. */
|
||
|
||
for (insn = f; insn; insn = NEXT_INSN (insn))
|
||
{
|
||
if (GET_CODE (insn) == NOTE)
|
||
switch (NOTE_LINE_NUMBER (insn))
|
||
{
|
||
case NOTE_INSN_LOOP_BEG:
|
||
loop_number_loop_starts[++next_loop] = insn;
|
||
loop_number_loop_ends[next_loop] = 0;
|
||
loop_outer_loop[next_loop] = current_loop;
|
||
loop_invalid[next_loop] = 0;
|
||
loop_number_exit_labels[next_loop] = 0;
|
||
loop_number_exit_count[next_loop] = 0;
|
||
current_loop = next_loop;
|
||
break;
|
||
|
||
case NOTE_INSN_SETJMP:
|
||
/* In this case, we must invalidate our current loop and any
|
||
enclosing loop. */
|
||
for (loop = current_loop; loop != -1; loop = loop_outer_loop[loop])
|
||
{
|
||
loop_invalid[loop] = 1;
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"\nLoop at %d ignored due to setjmp.\n",
|
||
INSN_UID (loop_number_loop_starts[loop]));
|
||
}
|
||
break;
|
||
|
||
case NOTE_INSN_LOOP_END:
|
||
if (current_loop == -1)
|
||
abort ();
|
||
|
||
loop_number_loop_ends[current_loop] = insn;
|
||
current_loop = loop_outer_loop[current_loop];
|
||
break;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
/* Note that this will mark the NOTE_INSN_LOOP_END note as being in the
|
||
enclosing loop, but this doesn't matter. */
|
||
uid_loop_num[INSN_UID (insn)] = current_loop;
|
||
}
|
||
|
||
/* Any loop containing a label used in an initializer must be invalidated,
|
||
because it can be jumped into from anywhere. */
|
||
|
||
for (label = forced_labels; label; label = XEXP (label, 1))
|
||
{
|
||
int loop_num;
|
||
|
||
for (loop_num = uid_loop_num[INSN_UID (XEXP (label, 0))];
|
||
loop_num != -1;
|
||
loop_num = loop_outer_loop[loop_num])
|
||
loop_invalid[loop_num] = 1;
|
||
}
|
||
|
||
/* Any loop containing a label used for an exception handler must be
|
||
invalidated, because it can be jumped into from anywhere. */
|
||
|
||
for (label = exception_handler_labels; label; label = XEXP (label, 1))
|
||
{
|
||
int loop_num;
|
||
|
||
for (loop_num = uid_loop_num[INSN_UID (XEXP (label, 0))];
|
||
loop_num != -1;
|
||
loop_num = loop_outer_loop[loop_num])
|
||
loop_invalid[loop_num] = 1;
|
||
}
|
||
|
||
/* Now scan all insn's in the function. If any JUMP_INSN branches into a
|
||
loop that it is not contained within, that loop is marked invalid.
|
||
If any INSN or CALL_INSN uses a label's address, then the loop containing
|
||
that label is marked invalid, because it could be jumped into from
|
||
anywhere.
|
||
|
||
Also look for blocks of code ending in an unconditional branch that
|
||
exits the loop. If such a block is surrounded by a conditional
|
||
branch around the block, move the block elsewhere (see below) and
|
||
invert the jump to point to the code block. This may eliminate a
|
||
label in our loop and will simplify processing by both us and a
|
||
possible second cse pass. */
|
||
|
||
for (insn = f; insn; insn = NEXT_INSN (insn))
|
||
if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
|
||
{
|
||
int this_loop_num = uid_loop_num[INSN_UID (insn)];
|
||
|
||
if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
rtx note = find_reg_note (insn, REG_LABEL, NULL_RTX);
|
||
if (note)
|
||
{
|
||
int loop_num;
|
||
|
||
for (loop_num = uid_loop_num[INSN_UID (XEXP (note, 0))];
|
||
loop_num != -1;
|
||
loop_num = loop_outer_loop[loop_num])
|
||
loop_invalid[loop_num] = 1;
|
||
}
|
||
}
|
||
|
||
if (GET_CODE (insn) != JUMP_INSN)
|
||
continue;
|
||
|
||
mark_loop_jump (PATTERN (insn), this_loop_num);
|
||
|
||
/* See if this is an unconditional branch outside the loop. */
|
||
if (this_loop_num != -1
|
||
&& (GET_CODE (PATTERN (insn)) == RETURN
|
||
|| (simplejump_p (insn)
|
||
&& (uid_loop_num[INSN_UID (JUMP_LABEL (insn))]
|
||
!= this_loop_num)))
|
||
&& get_max_uid () < max_uid_for_loop)
|
||
{
|
||
rtx p;
|
||
rtx our_next = next_real_insn (insn);
|
||
int dest_loop;
|
||
int outer_loop = -1;
|
||
|
||
/* Go backwards until we reach the start of the loop, a label,
|
||
or a JUMP_INSN. */
|
||
for (p = PREV_INSN (insn);
|
||
GET_CODE (p) != CODE_LABEL
|
||
&& ! (GET_CODE (p) == NOTE
|
||
&& NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_BEG)
|
||
&& GET_CODE (p) != JUMP_INSN;
|
||
p = PREV_INSN (p))
|
||
;
|
||
|
||
/* Check for the case where we have a jump to an inner nested
|
||
loop, and do not perform the optimization in that case. */
|
||
|
||
if (JUMP_LABEL (insn))
|
||
{
|
||
dest_loop = uid_loop_num[INSN_UID (JUMP_LABEL (insn))];
|
||
if (dest_loop != -1)
|
||
{
|
||
for (outer_loop = dest_loop; outer_loop != -1;
|
||
outer_loop = loop_outer_loop[outer_loop])
|
||
if (outer_loop == this_loop_num)
|
||
break;
|
||
}
|
||
}
|
||
|
||
/* Make sure that the target of P is within the current loop. */
|
||
|
||
if (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p)
|
||
&& uid_loop_num[INSN_UID (JUMP_LABEL (p))] != this_loop_num)
|
||
outer_loop = this_loop_num;
|
||
|
||
/* If we stopped on a JUMP_INSN to the next insn after INSN,
|
||
we have a block of code to try to move.
|
||
|
||
We look backward and then forward from the target of INSN
|
||
to find a BARRIER at the same loop depth as the target.
|
||
If we find such a BARRIER, we make a new label for the start
|
||
of the block, invert the jump in P and point it to that label,
|
||
and move the block of code to the spot we found. */
|
||
|
||
if (outer_loop == -1
|
||
&& GET_CODE (p) == JUMP_INSN
|
||
&& JUMP_LABEL (p) != 0
|
||
/* Just ignore jumps to labels that were never emitted.
|
||
These always indicate compilation errors. */
|
||
&& INSN_UID (JUMP_LABEL (p)) != 0
|
||
&& condjump_p (p)
|
||
&& ! simplejump_p (p)
|
||
&& next_real_insn (JUMP_LABEL (p)) == our_next)
|
||
{
|
||
rtx target
|
||
= JUMP_LABEL (insn) ? JUMP_LABEL (insn) : get_last_insn ();
|
||
int target_loop_num = uid_loop_num[INSN_UID (target)];
|
||
rtx loc;
|
||
|
||
for (loc = target; loc; loc = PREV_INSN (loc))
|
||
if (GET_CODE (loc) == BARRIER
|
||
&& uid_loop_num[INSN_UID (loc)] == target_loop_num)
|
||
break;
|
||
|
||
if (loc == 0)
|
||
for (loc = target; loc; loc = NEXT_INSN (loc))
|
||
if (GET_CODE (loc) == BARRIER
|
||
&& uid_loop_num[INSN_UID (loc)] == target_loop_num)
|
||
break;
|
||
|
||
if (loc)
|
||
{
|
||
rtx cond_label = JUMP_LABEL (p);
|
||
rtx new_label = get_label_after (p);
|
||
|
||
/* Ensure our label doesn't go away. */
|
||
LABEL_NUSES (cond_label)++;
|
||
|
||
/* Verify that uid_loop_num is large enough and that
|
||
we can invert P. */
|
||
if (invert_jump (p, new_label))
|
||
{
|
||
rtx q, r;
|
||
|
||
/* If no suitable BARRIER was found, create a suitable
|
||
one before TARGET. Since TARGET is a fall through
|
||
path, we'll need to insert an jump around our block
|
||
and a add a BARRIER before TARGET.
|
||
|
||
This creates an extra unconditional jump outside
|
||
the loop. However, the benefits of removing rarely
|
||
executed instructions from inside the loop usually
|
||
outweighs the cost of the extra unconditional jump
|
||
outside the loop. */
|
||
if (loc == 0)
|
||
{
|
||
rtx temp;
|
||
|
||
temp = gen_jump (JUMP_LABEL (insn));
|
||
temp = emit_jump_insn_before (temp, target);
|
||
JUMP_LABEL (temp) = JUMP_LABEL (insn);
|
||
LABEL_NUSES (JUMP_LABEL (insn))++;
|
||
loc = emit_barrier_before (target);
|
||
}
|
||
|
||
/* Include the BARRIER after INSN and copy the
|
||
block after LOC. */
|
||
new_label = squeeze_notes (new_label, NEXT_INSN (insn));
|
||
reorder_insns (new_label, NEXT_INSN (insn), loc);
|
||
|
||
/* All those insns are now in TARGET_LOOP_NUM. */
|
||
for (q = new_label; q != NEXT_INSN (NEXT_INSN (insn));
|
||
q = NEXT_INSN (q))
|
||
uid_loop_num[INSN_UID (q)] = target_loop_num;
|
||
|
||
/* The label jumped to by INSN is no longer a loop exit.
|
||
Unless INSN does not have a label (e.g., it is a
|
||
RETURN insn), search loop_number_exit_labels to find
|
||
its label_ref, and remove it. Also turn off
|
||
LABEL_OUTSIDE_LOOP_P bit. */
|
||
if (JUMP_LABEL (insn))
|
||
{
|
||
int loop_num;
|
||
|
||
for (q = 0,
|
||
r = loop_number_exit_labels[this_loop_num];
|
||
r; q = r, r = LABEL_NEXTREF (r))
|
||
if (XEXP (r, 0) == JUMP_LABEL (insn))
|
||
{
|
||
LABEL_OUTSIDE_LOOP_P (r) = 0;
|
||
if (q)
|
||
LABEL_NEXTREF (q) = LABEL_NEXTREF (r);
|
||
else
|
||
loop_number_exit_labels[this_loop_num]
|
||
= LABEL_NEXTREF (r);
|
||
break;
|
||
}
|
||
|
||
for (loop_num = this_loop_num;
|
||
loop_num != -1 && loop_num != target_loop_num;
|
||
loop_num = loop_outer_loop[loop_num])
|
||
loop_number_exit_count[loop_num]--;
|
||
|
||
/* If we didn't find it, then something is wrong. */
|
||
if (! r)
|
||
abort ();
|
||
}
|
||
|
||
/* P is now a jump outside the loop, so it must be put
|
||
in loop_number_exit_labels, and marked as such.
|
||
The easiest way to do this is to just call
|
||
mark_loop_jump again for P. */
|
||
mark_loop_jump (PATTERN (p), this_loop_num);
|
||
|
||
/* If INSN now jumps to the insn after it,
|
||
delete INSN. */
|
||
if (JUMP_LABEL (insn) != 0
|
||
&& (next_real_insn (JUMP_LABEL (insn))
|
||
== next_real_insn (insn)))
|
||
delete_insn (insn);
|
||
}
|
||
|
||
/* Continue the loop after where the conditional
|
||
branch used to jump, since the only branch insn
|
||
in the block (if it still remains) is an inter-loop
|
||
branch and hence needs no processing. */
|
||
insn = NEXT_INSN (cond_label);
|
||
|
||
if (--LABEL_NUSES (cond_label) == 0)
|
||
delete_insn (cond_label);
|
||
|
||
/* This loop will be continued with NEXT_INSN (insn). */
|
||
insn = PREV_INSN (insn);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* If any label in X jumps to a loop different from LOOP_NUM and any of the
|
||
loops it is contained in, mark the target loop invalid.
|
||
|
||
For speed, we assume that X is part of a pattern of a JUMP_INSN. */
|
||
|
||
static void
|
||
mark_loop_jump (x, loop_num)
|
||
rtx x;
|
||
int loop_num;
|
||
{
|
||
int dest_loop;
|
||
int outer_loop;
|
||
int i;
|
||
|
||
switch (GET_CODE (x))
|
||
{
|
||
case PC:
|
||
case USE:
|
||
case CLOBBER:
|
||
case REG:
|
||
case MEM:
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case RETURN:
|
||
return;
|
||
|
||
case CONST:
|
||
/* There could be a label reference in here. */
|
||
mark_loop_jump (XEXP (x, 0), loop_num);
|
||
return;
|
||
|
||
case PLUS:
|
||
case MINUS:
|
||
case MULT:
|
||
mark_loop_jump (XEXP (x, 0), loop_num);
|
||
mark_loop_jump (XEXP (x, 1), loop_num);
|
||
return;
|
||
|
||
case LO_SUM:
|
||
/* This may refer to a LABEL_REF or SYMBOL_REF. */
|
||
mark_loop_jump (XEXP (x, 1), loop_num);
|
||
return;
|
||
|
||
case SIGN_EXTEND:
|
||
case ZERO_EXTEND:
|
||
mark_loop_jump (XEXP (x, 0), loop_num);
|
||
return;
|
||
|
||
case LABEL_REF:
|
||
dest_loop = uid_loop_num[INSN_UID (XEXP (x, 0))];
|
||
|
||
/* Link together all labels that branch outside the loop. This
|
||
is used by final_[bg]iv_value and the loop unrolling code. Also
|
||
mark this LABEL_REF so we know that this branch should predict
|
||
false. */
|
||
|
||
/* A check to make sure the label is not in an inner nested loop,
|
||
since this does not count as a loop exit. */
|
||
if (dest_loop != -1)
|
||
{
|
||
for (outer_loop = dest_loop; outer_loop != -1;
|
||
outer_loop = loop_outer_loop[outer_loop])
|
||
if (outer_loop == loop_num)
|
||
break;
|
||
}
|
||
else
|
||
outer_loop = -1;
|
||
|
||
if (loop_num != -1 && outer_loop == -1)
|
||
{
|
||
LABEL_OUTSIDE_LOOP_P (x) = 1;
|
||
LABEL_NEXTREF (x) = loop_number_exit_labels[loop_num];
|
||
loop_number_exit_labels[loop_num] = x;
|
||
|
||
for (outer_loop = loop_num;
|
||
outer_loop != -1 && outer_loop != dest_loop;
|
||
outer_loop = loop_outer_loop[outer_loop])
|
||
loop_number_exit_count[outer_loop]++;
|
||
}
|
||
|
||
/* If this is inside a loop, but not in the current loop or one enclosed
|
||
by it, it invalidates at least one loop. */
|
||
|
||
if (dest_loop == -1)
|
||
return;
|
||
|
||
/* We must invalidate every nested loop containing the target of this
|
||
label, except those that also contain the jump insn. */
|
||
|
||
for (; dest_loop != -1; dest_loop = loop_outer_loop[dest_loop])
|
||
{
|
||
/* Stop when we reach a loop that also contains the jump insn. */
|
||
for (outer_loop = loop_num; outer_loop != -1;
|
||
outer_loop = loop_outer_loop[outer_loop])
|
||
if (dest_loop == outer_loop)
|
||
return;
|
||
|
||
/* If we get here, we know we need to invalidate a loop. */
|
||
if (loop_dump_stream && ! loop_invalid[dest_loop])
|
||
fprintf (loop_dump_stream,
|
||
"\nLoop at %d ignored due to multiple entry points.\n",
|
||
INSN_UID (loop_number_loop_starts[dest_loop]));
|
||
|
||
loop_invalid[dest_loop] = 1;
|
||
}
|
||
return;
|
||
|
||
case SET:
|
||
/* If this is not setting pc, ignore. */
|
||
if (SET_DEST (x) == pc_rtx)
|
||
mark_loop_jump (SET_SRC (x), loop_num);
|
||
return;
|
||
|
||
case IF_THEN_ELSE:
|
||
mark_loop_jump (XEXP (x, 1), loop_num);
|
||
mark_loop_jump (XEXP (x, 2), loop_num);
|
||
return;
|
||
|
||
case PARALLEL:
|
||
case ADDR_VEC:
|
||
for (i = 0; i < XVECLEN (x, 0); i++)
|
||
mark_loop_jump (XVECEXP (x, 0, i), loop_num);
|
||
return;
|
||
|
||
case ADDR_DIFF_VEC:
|
||
for (i = 0; i < XVECLEN (x, 1); i++)
|
||
mark_loop_jump (XVECEXP (x, 1, i), loop_num);
|
||
return;
|
||
|
||
default:
|
||
/* Strictly speaking this is not a jump into the loop, only a possible
|
||
jump out of the loop. However, we have no way to link the destination
|
||
of this jump onto the list of exit labels. To be safe we mark this
|
||
loop and any containing loops as invalid. */
|
||
if (loop_num != -1)
|
||
{
|
||
for (outer_loop = loop_num; outer_loop != -1;
|
||
outer_loop = loop_outer_loop[outer_loop])
|
||
{
|
||
if (loop_dump_stream && ! loop_invalid[outer_loop])
|
||
fprintf (loop_dump_stream,
|
||
"\nLoop at %d ignored due to unknown exit jump.\n",
|
||
INSN_UID (loop_number_loop_starts[outer_loop]));
|
||
loop_invalid[outer_loop] = 1;
|
||
}
|
||
}
|
||
return;
|
||
}
|
||
}
|
||
|
||
/* Return nonzero if there is a label in the range from
|
||
insn INSN to and including the insn whose luid is END
|
||
INSN must have an assigned luid (i.e., it must not have
|
||
been previously created by loop.c). */
|
||
|
||
static int
|
||
labels_in_range_p (insn, end)
|
||
rtx insn;
|
||
int end;
|
||
{
|
||
while (insn && INSN_LUID (insn) <= end)
|
||
{
|
||
if (GET_CODE (insn) == CODE_LABEL)
|
||
return 1;
|
||
insn = NEXT_INSN (insn);
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* Record that a memory reference X is being set. */
|
||
|
||
static void
|
||
note_addr_stored (x, y)
|
||
rtx x;
|
||
rtx y ATTRIBUTE_UNUSED;
|
||
{
|
||
register int i;
|
||
|
||
if (x == 0 || GET_CODE (x) != MEM)
|
||
return;
|
||
|
||
/* Count number of memory writes.
|
||
This affects heuristics in strength_reduce. */
|
||
num_mem_sets++;
|
||
|
||
/* BLKmode MEM means all memory is clobbered. */
|
||
if (GET_MODE (x) == BLKmode)
|
||
unknown_address_altered = 1;
|
||
|
||
if (unknown_address_altered)
|
||
return;
|
||
|
||
for (i = 0; i < loop_store_mems_idx; i++)
|
||
if (rtx_equal_p (XEXP (loop_store_mems[i], 0), XEXP (x, 0))
|
||
&& MEM_IN_STRUCT_P (x) == MEM_IN_STRUCT_P (loop_store_mems[i]))
|
||
{
|
||
/* We are storing at the same address as previously noted. Save the
|
||
wider reference. */
|
||
if (GET_MODE_SIZE (GET_MODE (x))
|
||
> GET_MODE_SIZE (GET_MODE (loop_store_mems[i])))
|
||
loop_store_mems[i] = x;
|
||
break;
|
||
}
|
||
|
||
if (i == NUM_STORES)
|
||
unknown_address_altered = 1;
|
||
|
||
else if (i == loop_store_mems_idx)
|
||
loop_store_mems[loop_store_mems_idx++] = x;
|
||
}
|
||
|
||
/* Return nonzero if the rtx X is invariant over the current loop.
|
||
|
||
The value is 2 if we refer to something only conditionally invariant.
|
||
|
||
If `unknown_address_altered' is nonzero, no memory ref is invariant.
|
||
Otherwise, a memory ref is invariant if it does not conflict with
|
||
anything stored in `loop_store_mems'. */
|
||
|
||
int
|
||
invariant_p (x)
|
||
register rtx x;
|
||
{
|
||
register int i;
|
||
register enum rtx_code code;
|
||
register char *fmt;
|
||
int conditional = 0;
|
||
|
||
if (x == 0)
|
||
return 1;
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case CONST_INT:
|
||
case CONST_DOUBLE:
|
||
case SYMBOL_REF:
|
||
case CONST:
|
||
return 1;
|
||
|
||
case LABEL_REF:
|
||
/* A LABEL_REF is normally invariant, however, if we are unrolling
|
||
loops, and this label is inside the loop, then it isn't invariant.
|
||
This is because each unrolled copy of the loop body will have
|
||
a copy of this label. If this was invariant, then an insn loading
|
||
the address of this label into a register might get moved outside
|
||
the loop, and then each loop body would end up using the same label.
|
||
|
||
We don't know the loop bounds here though, so just fail for all
|
||
labels. */
|
||
if (flag_unroll_loops)
|
||
return 0;
|
||
else
|
||
return 1;
|
||
|
||
case PC:
|
||
case CC0:
|
||
case UNSPEC_VOLATILE:
|
||
return 0;
|
||
|
||
case REG:
|
||
/* We used to check RTX_UNCHANGING_P (x) here, but that is invalid
|
||
since the reg might be set by initialization within the loop. */
|
||
|
||
if ((x == frame_pointer_rtx || x == hard_frame_pointer_rtx
|
||
|| x == arg_pointer_rtx)
|
||
&& ! current_function_has_nonlocal_goto)
|
||
return 1;
|
||
|
||
if (loop_has_call
|
||
&& REGNO (x) < FIRST_PSEUDO_REGISTER && call_used_regs[REGNO (x)])
|
||
return 0;
|
||
|
||
if (n_times_set[REGNO (x)] < 0)
|
||
return 2;
|
||
|
||
return n_times_set[REGNO (x)] == 0;
|
||
|
||
case MEM:
|
||
/* Volatile memory references must be rejected. Do this before
|
||
checking for read-only items, so that volatile read-only items
|
||
will be rejected also. */
|
||
if (MEM_VOLATILE_P (x))
|
||
return 0;
|
||
|
||
/* Read-only items (such as constants in a constant pool) are
|
||
invariant if their address is. */
|
||
if (RTX_UNCHANGING_P (x))
|
||
break;
|
||
|
||
/* If we filled the table (or had a subroutine call), any location
|
||
in memory could have been clobbered. */
|
||
if (unknown_address_altered)
|
||
return 0;
|
||
|
||
/* See if there is any dependence between a store and this load. */
|
||
for (i = loop_store_mems_idx - 1; i >= 0; i--)
|
||
if (true_dependence (loop_store_mems[i], VOIDmode, x, rtx_varies_p))
|
||
return 0;
|
||
|
||
/* It's not invalidated by a store in memory
|
||
but we must still verify the address is invariant. */
|
||
break;
|
||
|
||
case ASM_OPERANDS:
|
||
/* Don't mess with insns declared volatile. */
|
||
if (MEM_VOLATILE_P (x))
|
||
return 0;
|
||
break;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
{
|
||
int tem = invariant_p (XEXP (x, i));
|
||
if (tem == 0)
|
||
return 0;
|
||
if (tem == 2)
|
||
conditional = 1;
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
{
|
||
register int j;
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
{
|
||
int tem = invariant_p (XVECEXP (x, i, j));
|
||
if (tem == 0)
|
||
return 0;
|
||
if (tem == 2)
|
||
conditional = 1;
|
||
}
|
||
|
||
}
|
||
}
|
||
|
||
return 1 + conditional;
|
||
}
|
||
|
||
|
||
/* Return nonzero if all the insns in the loop that set REG
|
||
are INSN and the immediately following insns,
|
||
and if each of those insns sets REG in an invariant way
|
||
(not counting uses of REG in them).
|
||
|
||
The value is 2 if some of these insns are only conditionally invariant.
|
||
|
||
We assume that INSN itself is the first set of REG
|
||
and that its source is invariant. */
|
||
|
||
static int
|
||
consec_sets_invariant_p (reg, n_sets, insn)
|
||
int n_sets;
|
||
rtx reg, insn;
|
||
{
|
||
register rtx p = insn;
|
||
register int regno = REGNO (reg);
|
||
rtx temp;
|
||
/* Number of sets we have to insist on finding after INSN. */
|
||
int count = n_sets - 1;
|
||
int old = n_times_set[regno];
|
||
int value = 0;
|
||
int this;
|
||
|
||
/* If N_SETS hit the limit, we can't rely on its value. */
|
||
if (n_sets == 127)
|
||
return 0;
|
||
|
||
n_times_set[regno] = 0;
|
||
|
||
while (count > 0)
|
||
{
|
||
register enum rtx_code code;
|
||
rtx set;
|
||
|
||
p = NEXT_INSN (p);
|
||
code = GET_CODE (p);
|
||
|
||
/* If library call, skip to end of it. */
|
||
if (code == INSN && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX)))
|
||
p = XEXP (temp, 0);
|
||
|
||
this = 0;
|
||
if (code == INSN
|
||
&& (set = single_set (p))
|
||
&& GET_CODE (SET_DEST (set)) == REG
|
||
&& REGNO (SET_DEST (set)) == regno)
|
||
{
|
||
this = invariant_p (SET_SRC (set));
|
||
if (this != 0)
|
||
value |= this;
|
||
else if ((temp = find_reg_note (p, REG_EQUAL, NULL_RTX)))
|
||
{
|
||
/* If this is a libcall, then any invariant REG_EQUAL note is OK.
|
||
If this is an ordinary insn, then only CONSTANT_P REG_EQUAL
|
||
notes are OK. */
|
||
this = (CONSTANT_P (XEXP (temp, 0))
|
||
|| (find_reg_note (p, REG_RETVAL, NULL_RTX)
|
||
&& invariant_p (XEXP (temp, 0))));
|
||
if (this != 0)
|
||
value |= this;
|
||
}
|
||
}
|
||
if (this != 0)
|
||
count--;
|
||
else if (code != NOTE)
|
||
{
|
||
n_times_set[regno] = old;
|
||
return 0;
|
||
}
|
||
}
|
||
|
||
n_times_set[regno] = old;
|
||
/* If invariant_p ever returned 2, we return 2. */
|
||
return 1 + (value & 2);
|
||
}
|
||
|
||
#if 0
|
||
/* I don't think this condition is sufficient to allow INSN
|
||
to be moved, so we no longer test it. */
|
||
|
||
/* Return 1 if all insns in the basic block of INSN and following INSN
|
||
that set REG are invariant according to TABLE. */
|
||
|
||
static int
|
||
all_sets_invariant_p (reg, insn, table)
|
||
rtx reg, insn;
|
||
short *table;
|
||
{
|
||
register rtx p = insn;
|
||
register int regno = REGNO (reg);
|
||
|
||
while (1)
|
||
{
|
||
register enum rtx_code code;
|
||
p = NEXT_INSN (p);
|
||
code = GET_CODE (p);
|
||
if (code == CODE_LABEL || code == JUMP_INSN)
|
||
return 1;
|
||
if (code == INSN && GET_CODE (PATTERN (p)) == SET
|
||
&& GET_CODE (SET_DEST (PATTERN (p))) == REG
|
||
&& REGNO (SET_DEST (PATTERN (p))) == regno)
|
||
{
|
||
if (!invariant_p (SET_SRC (PATTERN (p)), table))
|
||
return 0;
|
||
}
|
||
}
|
||
}
|
||
#endif /* 0 */
|
||
|
||
/* Look at all uses (not sets) of registers in X. For each, if it is
|
||
the single use, set USAGE[REGNO] to INSN; if there was a previous use in
|
||
a different insn, set USAGE[REGNO] to const0_rtx. */
|
||
|
||
static void
|
||
find_single_use_in_loop (insn, x, usage)
|
||
rtx insn;
|
||
rtx x;
|
||
rtx *usage;
|
||
{
|
||
enum rtx_code code = GET_CODE (x);
|
||
char *fmt = GET_RTX_FORMAT (code);
|
||
int i, j;
|
||
|
||
if (code == REG)
|
||
usage[REGNO (x)]
|
||
= (usage[REGNO (x)] != 0 && usage[REGNO (x)] != insn)
|
||
? const0_rtx : insn;
|
||
|
||
else if (code == SET)
|
||
{
|
||
/* Don't count SET_DEST if it is a REG; otherwise count things
|
||
in SET_DEST because if a register is partially modified, it won't
|
||
show up as a potential movable so we don't care how USAGE is set
|
||
for it. */
|
||
if (GET_CODE (SET_DEST (x)) != REG)
|
||
find_single_use_in_loop (insn, SET_DEST (x), usage);
|
||
find_single_use_in_loop (insn, SET_SRC (x), usage);
|
||
}
|
||
else
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e' && XEXP (x, i) != 0)
|
||
find_single_use_in_loop (insn, XEXP (x, i), usage);
|
||
else if (fmt[i] == 'E')
|
||
for (j = XVECLEN (x, i) - 1; j >= 0; j--)
|
||
find_single_use_in_loop (insn, XVECEXP (x, i, j), usage);
|
||
}
|
||
}
|
||
|
||
/* Increment N_TIMES_SET at the index of each register
|
||
that is modified by an insn between FROM and TO.
|
||
If the value of an element of N_TIMES_SET becomes 127 or more,
|
||
stop incrementing it, to avoid overflow.
|
||
|
||
Store in SINGLE_USAGE[I] the single insn in which register I is
|
||
used, if it is only used once. Otherwise, it is set to 0 (for no
|
||
uses) or const0_rtx for more than one use. This parameter may be zero,
|
||
in which case this processing is not done.
|
||
|
||
Store in *COUNT_PTR the number of actual instruction
|
||
in the loop. We use this to decide what is worth moving out. */
|
||
|
||
/* last_set[n] is nonzero iff reg n has been set in the current basic block.
|
||
In that case, it is the insn that last set reg n. */
|
||
|
||
static void
|
||
count_loop_regs_set (from, to, may_not_move, single_usage, count_ptr, nregs)
|
||
register rtx from, to;
|
||
char *may_not_move;
|
||
rtx *single_usage;
|
||
int *count_ptr;
|
||
int nregs;
|
||
{
|
||
register rtx *last_set = (rtx *) alloca (nregs * sizeof (rtx));
|
||
register rtx insn;
|
||
register int count = 0;
|
||
register rtx dest;
|
||
|
||
bzero ((char *) last_set, nregs * sizeof (rtx));
|
||
for (insn = from; insn != to; insn = NEXT_INSN (insn))
|
||
{
|
||
if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
|
||
{
|
||
++count;
|
||
|
||
/* If requested, record registers that have exactly one use. */
|
||
if (single_usage)
|
||
{
|
||
find_single_use_in_loop (insn, PATTERN (insn), single_usage);
|
||
|
||
/* Include uses in REG_EQUAL notes. */
|
||
if (REG_NOTES (insn))
|
||
find_single_use_in_loop (insn, REG_NOTES (insn), single_usage);
|
||
}
|
||
|
||
if (GET_CODE (PATTERN (insn)) == CLOBBER
|
||
&& GET_CODE (XEXP (PATTERN (insn), 0)) == REG)
|
||
/* Don't move a reg that has an explicit clobber.
|
||
We might do so sometimes, but it's not worth the pain. */
|
||
may_not_move[REGNO (XEXP (PATTERN (insn), 0))] = 1;
|
||
|
||
if (GET_CODE (PATTERN (insn)) == SET
|
||
|| GET_CODE (PATTERN (insn)) == CLOBBER)
|
||
{
|
||
dest = SET_DEST (PATTERN (insn));
|
||
while (GET_CODE (dest) == SUBREG
|
||
|| GET_CODE (dest) == ZERO_EXTRACT
|
||
|| GET_CODE (dest) == SIGN_EXTRACT
|
||
|| GET_CODE (dest) == STRICT_LOW_PART)
|
||
dest = XEXP (dest, 0);
|
||
if (GET_CODE (dest) == REG)
|
||
{
|
||
register int regno = REGNO (dest);
|
||
/* If this is the first setting of this reg
|
||
in current basic block, and it was set before,
|
||
it must be set in two basic blocks, so it cannot
|
||
be moved out of the loop. */
|
||
if (n_times_set[regno] > 0 && last_set[regno] == 0)
|
||
may_not_move[regno] = 1;
|
||
/* If this is not first setting in current basic block,
|
||
see if reg was used in between previous one and this.
|
||
If so, neither one can be moved. */
|
||
if (last_set[regno] != 0
|
||
&& reg_used_between_p (dest, last_set[regno], insn))
|
||
may_not_move[regno] = 1;
|
||
if (n_times_set[regno] < 127)
|
||
++n_times_set[regno];
|
||
last_set[regno] = insn;
|
||
}
|
||
}
|
||
else if (GET_CODE (PATTERN (insn)) == PARALLEL)
|
||
{
|
||
register int i;
|
||
for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--)
|
||
{
|
||
register rtx x = XVECEXP (PATTERN (insn), 0, i);
|
||
if (GET_CODE (x) == CLOBBER && GET_CODE (XEXP (x, 0)) == REG)
|
||
/* Don't move a reg that has an explicit clobber.
|
||
It's not worth the pain to try to do it correctly. */
|
||
may_not_move[REGNO (XEXP (x, 0))] = 1;
|
||
|
||
if (GET_CODE (x) == SET || GET_CODE (x) == CLOBBER)
|
||
{
|
||
dest = SET_DEST (x);
|
||
while (GET_CODE (dest) == SUBREG
|
||
|| GET_CODE (dest) == ZERO_EXTRACT
|
||
|| GET_CODE (dest) == SIGN_EXTRACT
|
||
|| GET_CODE (dest) == STRICT_LOW_PART)
|
||
dest = XEXP (dest, 0);
|
||
if (GET_CODE (dest) == REG)
|
||
{
|
||
register int regno = REGNO (dest);
|
||
if (n_times_set[regno] > 0 && last_set[regno] == 0)
|
||
may_not_move[regno] = 1;
|
||
if (last_set[regno] != 0
|
||
&& reg_used_between_p (dest, last_set[regno], insn))
|
||
may_not_move[regno] = 1;
|
||
if (n_times_set[regno] < 127)
|
||
++n_times_set[regno];
|
||
last_set[regno] = insn;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
if (GET_CODE (insn) == CODE_LABEL || GET_CODE (insn) == JUMP_INSN)
|
||
bzero ((char *) last_set, nregs * sizeof (rtx));
|
||
}
|
||
*count_ptr = count;
|
||
}
|
||
|
||
/* Given a loop that is bounded by LOOP_START and LOOP_END
|
||
and that is entered at SCAN_START,
|
||
return 1 if the register set in SET contained in insn INSN is used by
|
||
any insn that precedes INSN in cyclic order starting
|
||
from the loop entry point.
|
||
|
||
We don't want to use INSN_LUID here because if we restrict INSN to those
|
||
that have a valid INSN_LUID, it means we cannot move an invariant out
|
||
from an inner loop past two loops. */
|
||
|
||
static int
|
||
loop_reg_used_before_p (set, insn, loop_start, scan_start, loop_end)
|
||
rtx set, insn, loop_start, scan_start, loop_end;
|
||
{
|
||
rtx reg = SET_DEST (set);
|
||
rtx p;
|
||
|
||
/* Scan forward checking for register usage. If we hit INSN, we
|
||
are done. Otherwise, if we hit LOOP_END, wrap around to LOOP_START. */
|
||
for (p = scan_start; p != insn; p = NEXT_INSN (p))
|
||
{
|
||
if (GET_RTX_CLASS (GET_CODE (p)) == 'i'
|
||
&& reg_overlap_mentioned_p (reg, PATTERN (p)))
|
||
return 1;
|
||
|
||
if (p == loop_end)
|
||
p = loop_start;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* A "basic induction variable" or biv is a pseudo reg that is set
|
||
(within this loop) only by incrementing or decrementing it. */
|
||
/* A "general induction variable" or giv is a pseudo reg whose
|
||
value is a linear function of a biv. */
|
||
|
||
/* Bivs are recognized by `basic_induction_var';
|
||
Givs by `general_induct_var'. */
|
||
|
||
/* Indexed by register number, indicates whether or not register is an
|
||
induction variable, and if so what type. */
|
||
|
||
enum iv_mode *reg_iv_type;
|
||
|
||
/* Indexed by register number, contains pointer to `struct induction'
|
||
if register is an induction variable. This holds general info for
|
||
all induction variables. */
|
||
|
||
struct induction **reg_iv_info;
|
||
|
||
/* Indexed by register number, contains pointer to `struct iv_class'
|
||
if register is a basic induction variable. This holds info describing
|
||
the class (a related group) of induction variables that the biv belongs
|
||
to. */
|
||
|
||
struct iv_class **reg_biv_class;
|
||
|
||
/* The head of a list which links together (via the next field)
|
||
every iv class for the current loop. */
|
||
|
||
struct iv_class *loop_iv_list;
|
||
|
||
/* Communication with routines called via `note_stores'. */
|
||
|
||
static rtx note_insn;
|
||
|
||
/* Dummy register to have non-zero DEST_REG for DEST_ADDR type givs. */
|
||
|
||
static rtx addr_placeholder;
|
||
|
||
/* ??? Unfinished optimizations, and possible future optimizations,
|
||
for the strength reduction code. */
|
||
|
||
/* ??? There is one more optimization you might be interested in doing: to
|
||
allocate pseudo registers for frequently-accessed memory locations.
|
||
If the same memory location is referenced each time around, it might
|
||
be possible to copy it into a register before and out after.
|
||
This is especially useful when the memory location is a variable which
|
||
is in a stack slot because somewhere its address is taken. If the
|
||
loop doesn't contain a function call and the variable isn't volatile,
|
||
it is safe to keep the value in a register for the duration of the
|
||
loop. One tricky thing is that the copying of the value back from the
|
||
register has to be done on all exits from the loop. You need to check that
|
||
all the exits from the loop go to the same place. */
|
||
|
||
/* ??? The interaction of biv elimination, and recognition of 'constant'
|
||
bivs, may cause problems. */
|
||
|
||
/* ??? Add heuristics so that DEST_ADDR strength reduction does not cause
|
||
performance problems.
|
||
|
||
Perhaps don't eliminate things that can be combined with an addressing
|
||
mode. Find all givs that have the same biv, mult_val, and add_val;
|
||
then for each giv, check to see if its only use dies in a following
|
||
memory address. If so, generate a new memory address and check to see
|
||
if it is valid. If it is valid, then store the modified memory address,
|
||
otherwise, mark the giv as not done so that it will get its own iv. */
|
||
|
||
/* ??? Could try to optimize branches when it is known that a biv is always
|
||
positive. */
|
||
|
||
/* ??? When replace a biv in a compare insn, we should replace with closest
|
||
giv so that an optimized branch can still be recognized by the combiner,
|
||
e.g. the VAX acb insn. */
|
||
|
||
/* ??? Many of the checks involving uid_luid could be simplified if regscan
|
||
was rerun in loop_optimize whenever a register was added or moved.
|
||
Also, some of the optimizations could be a little less conservative. */
|
||
|
||
/* Perform strength reduction and induction variable elimination. */
|
||
|
||
/* Pseudo registers created during this function will be beyond the last
|
||
valid index in several tables including n_times_set and regno_last_uid.
|
||
This does not cause a problem here, because the added registers cannot be
|
||
givs outside of their loop, and hence will never be reconsidered.
|
||
But scan_loop must check regnos to make sure they are in bounds. */
|
||
|
||
static void
|
||
strength_reduce (scan_start, end, loop_top, insn_count,
|
||
loop_start, loop_end, unroll_p)
|
||
rtx scan_start;
|
||
rtx end;
|
||
rtx loop_top;
|
||
int insn_count;
|
||
rtx loop_start;
|
||
rtx loop_end;
|
||
int unroll_p;
|
||
{
|
||
rtx p;
|
||
rtx set;
|
||
rtx inc_val;
|
||
rtx mult_val;
|
||
rtx dest_reg;
|
||
/* This is 1 if current insn is not executed at least once for every loop
|
||
iteration. */
|
||
int not_every_iteration = 0;
|
||
/* This is 1 if current insn may be executed more than once for every
|
||
loop iteration. */
|
||
int maybe_multiple = 0;
|
||
/* Temporary list pointers for traversing loop_iv_list. */
|
||
struct iv_class *bl, **backbl;
|
||
/* Ratio of extra register life span we can justify
|
||
for saving an instruction. More if loop doesn't call subroutines
|
||
since in that case saving an insn makes more difference
|
||
and more registers are available. */
|
||
/* ??? could set this to last value of threshold in move_movables */
|
||
int threshold = (loop_has_call ? 1 : 2) * (3 + n_non_fixed_regs);
|
||
/* Map of pseudo-register replacements. */
|
||
rtx *reg_map;
|
||
int call_seen;
|
||
rtx test;
|
||
rtx end_insert_before;
|
||
int loop_depth = 0;
|
||
|
||
reg_iv_type = (enum iv_mode *) alloca (max_reg_before_loop
|
||
* sizeof (enum iv_mode *));
|
||
bzero ((char *) reg_iv_type, max_reg_before_loop * sizeof (enum iv_mode *));
|
||
reg_iv_info = (struct induction **)
|
||
alloca (max_reg_before_loop * sizeof (struct induction *));
|
||
bzero ((char *) reg_iv_info, (max_reg_before_loop
|
||
* sizeof (struct induction *)));
|
||
reg_biv_class = (struct iv_class **)
|
||
alloca (max_reg_before_loop * sizeof (struct iv_class *));
|
||
bzero ((char *) reg_biv_class, (max_reg_before_loop
|
||
* sizeof (struct iv_class *)));
|
||
|
||
loop_iv_list = 0;
|
||
addr_placeholder = gen_reg_rtx (Pmode);
|
||
|
||
/* Save insn immediately after the loop_end. Insns inserted after loop_end
|
||
must be put before this insn, so that they will appear in the right
|
||
order (i.e. loop order).
|
||
|
||
If loop_end is the end of the current function, then emit a
|
||
NOTE_INSN_DELETED after loop_end and set end_insert_before to the
|
||
dummy note insn. */
|
||
if (NEXT_INSN (loop_end) != 0)
|
||
end_insert_before = NEXT_INSN (loop_end);
|
||
else
|
||
end_insert_before = emit_note_after (NOTE_INSN_DELETED, loop_end);
|
||
|
||
/* Scan through loop to find all possible bivs. */
|
||
|
||
p = scan_start;
|
||
while (1)
|
||
{
|
||
p = NEXT_INSN (p);
|
||
/* At end of a straight-in loop, we are done.
|
||
At end of a loop entered at the bottom, scan the top. */
|
||
if (p == scan_start)
|
||
break;
|
||
if (p == end)
|
||
{
|
||
if (loop_top != 0)
|
||
p = loop_top;
|
||
else
|
||
break;
|
||
if (p == scan_start)
|
||
break;
|
||
}
|
||
|
||
if (GET_CODE (p) == INSN
|
||
&& (set = single_set (p))
|
||
&& GET_CODE (SET_DEST (set)) == REG)
|
||
{
|
||
dest_reg = SET_DEST (set);
|
||
if (REGNO (dest_reg) < max_reg_before_loop
|
||
&& REGNO (dest_reg) >= FIRST_PSEUDO_REGISTER
|
||
&& reg_iv_type[REGNO (dest_reg)] != NOT_BASIC_INDUCT)
|
||
{
|
||
if (basic_induction_var (SET_SRC (set), GET_MODE (SET_SRC (set)),
|
||
dest_reg, p, &inc_val, &mult_val))
|
||
{
|
||
/* It is a possible basic induction variable.
|
||
Create and initialize an induction structure for it. */
|
||
|
||
struct induction *v
|
||
= (struct induction *) alloca (sizeof (struct induction));
|
||
|
||
record_biv (v, p, dest_reg, inc_val, mult_val,
|
||
not_every_iteration, maybe_multiple);
|
||
reg_iv_type[REGNO (dest_reg)] = BASIC_INDUCT;
|
||
}
|
||
else if (REGNO (dest_reg) < max_reg_before_loop)
|
||
reg_iv_type[REGNO (dest_reg)] = NOT_BASIC_INDUCT;
|
||
}
|
||
}
|
||
|
||
/* Past CODE_LABEL, we get to insns that may be executed multiple
|
||
times. The only way we can be sure that they can't is if every
|
||
jump insn between here and the end of the loop either
|
||
returns, exits the loop, is a forward jump, or is a jump
|
||
to the loop start. */
|
||
|
||
if (GET_CODE (p) == CODE_LABEL)
|
||
{
|
||
rtx insn = p;
|
||
|
||
maybe_multiple = 0;
|
||
|
||
while (1)
|
||
{
|
||
insn = NEXT_INSN (insn);
|
||
if (insn == scan_start)
|
||
break;
|
||
if (insn == end)
|
||
{
|
||
if (loop_top != 0)
|
||
insn = loop_top;
|
||
else
|
||
break;
|
||
if (insn == scan_start)
|
||
break;
|
||
}
|
||
|
||
if (GET_CODE (insn) == JUMP_INSN
|
||
&& GET_CODE (PATTERN (insn)) != RETURN
|
||
&& (! condjump_p (insn)
|
||
|| (JUMP_LABEL (insn) != 0
|
||
&& JUMP_LABEL (insn) != scan_start
|
||
&& (INSN_UID (JUMP_LABEL (insn)) >= max_uid_for_loop
|
||
|| INSN_UID (insn) >= max_uid_for_loop
|
||
|| (INSN_LUID (JUMP_LABEL (insn))
|
||
< INSN_LUID (insn))))))
|
||
{
|
||
maybe_multiple = 1;
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Past a jump, we get to insns for which we can't count
|
||
on whether they will be executed during each iteration. */
|
||
/* This code appears twice in strength_reduce. There is also similar
|
||
code in scan_loop. */
|
||
if (GET_CODE (p) == JUMP_INSN
|
||
/* If we enter the loop in the middle, and scan around to the
|
||
beginning, don't set not_every_iteration for that.
|
||
This can be any kind of jump, since we want to know if insns
|
||
will be executed if the loop is executed. */
|
||
&& ! (JUMP_LABEL (p) == loop_top
|
||
&& ((NEXT_INSN (NEXT_INSN (p)) == loop_end && simplejump_p (p))
|
||
|| (NEXT_INSN (p) == loop_end && condjump_p (p)))))
|
||
{
|
||
rtx label = 0;
|
||
|
||
/* If this is a jump outside the loop, then it also doesn't
|
||
matter. Check to see if the target of this branch is on the
|
||
loop_number_exits_labels list. */
|
||
|
||
for (label = loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]];
|
||
label;
|
||
label = LABEL_NEXTREF (label))
|
||
if (XEXP (label, 0) == JUMP_LABEL (p))
|
||
break;
|
||
|
||
if (! label)
|
||
not_every_iteration = 1;
|
||
}
|
||
|
||
else if (GET_CODE (p) == NOTE)
|
||
{
|
||
/* At the virtual top of a converted loop, insns are again known to
|
||
be executed each iteration: logically, the loop begins here
|
||
even though the exit code has been duplicated. */
|
||
if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_VTOP && loop_depth == 0)
|
||
not_every_iteration = 0;
|
||
else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_BEG)
|
||
loop_depth++;
|
||
else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_END)
|
||
loop_depth--;
|
||
}
|
||
|
||
/* Unlike in the code motion pass where MAYBE_NEVER indicates that
|
||
an insn may never be executed, NOT_EVERY_ITERATION indicates whether
|
||
or not an insn is known to be executed each iteration of the
|
||
loop, whether or not any iterations are known to occur.
|
||
|
||
Therefore, if we have just passed a label and have no more labels
|
||
between here and the test insn of the loop, we know these insns
|
||
will be executed each iteration. */
|
||
|
||
if (not_every_iteration && GET_CODE (p) == CODE_LABEL
|
||
&& no_labels_between_p (p, loop_end))
|
||
not_every_iteration = 0;
|
||
}
|
||
|
||
/* Scan loop_iv_list to remove all regs that proved not to be bivs.
|
||
Make a sanity check against n_times_set. */
|
||
for (backbl = &loop_iv_list, bl = *backbl; bl; bl = bl->next)
|
||
{
|
||
if (reg_iv_type[bl->regno] != BASIC_INDUCT
|
||
/* Above happens if register modified by subreg, etc. */
|
||
/* Make sure it is not recognized as a basic induction var: */
|
||
|| n_times_set[bl->regno] != bl->biv_count
|
||
/* If never incremented, it is invariant that we decided not to
|
||
move. So leave it alone. */
|
||
|| ! bl->incremented)
|
||
{
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "Reg %d: biv discarded, %s\n",
|
||
bl->regno,
|
||
(reg_iv_type[bl->regno] != BASIC_INDUCT
|
||
? "not induction variable"
|
||
: (! bl->incremented ? "never incremented"
|
||
: "count error")));
|
||
|
||
reg_iv_type[bl->regno] = NOT_BASIC_INDUCT;
|
||
*backbl = bl->next;
|
||
}
|
||
else
|
||
{
|
||
backbl = &bl->next;
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "Reg %d: biv verified\n", bl->regno);
|
||
}
|
||
}
|
||
|
||
/* Exit if there are no bivs. */
|
||
if (! loop_iv_list)
|
||
{
|
||
/* Can still unroll the loop anyways, but indicate that there is no
|
||
strength reduction info available. */
|
||
if (unroll_p)
|
||
unroll_loop (loop_end, insn_count, loop_start, end_insert_before, 0);
|
||
|
||
return;
|
||
}
|
||
|
||
/* Find initial value for each biv by searching backwards from loop_start,
|
||
halting at first label. Also record any test condition. */
|
||
|
||
call_seen = 0;
|
||
for (p = loop_start; p && GET_CODE (p) != CODE_LABEL; p = PREV_INSN (p))
|
||
{
|
||
note_insn = p;
|
||
|
||
if (GET_CODE (p) == CALL_INSN)
|
||
call_seen = 1;
|
||
|
||
if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN
|
||
|| GET_CODE (p) == CALL_INSN)
|
||
note_stores (PATTERN (p), record_initial);
|
||
|
||
/* Record any test of a biv that branches around the loop if no store
|
||
between it and the start of loop. We only care about tests with
|
||
constants and registers and only certain of those. */
|
||
if (GET_CODE (p) == JUMP_INSN
|
||
&& JUMP_LABEL (p) != 0
|
||
&& next_real_insn (JUMP_LABEL (p)) == next_real_insn (loop_end)
|
||
&& (test = get_condition_for_loop (p)) != 0
|
||
&& GET_CODE (XEXP (test, 0)) == REG
|
||
&& REGNO (XEXP (test, 0)) < max_reg_before_loop
|
||
&& (bl = reg_biv_class[REGNO (XEXP (test, 0))]) != 0
|
||
&& valid_initial_value_p (XEXP (test, 1), p, call_seen, loop_start)
|
||
&& bl->init_insn == 0)
|
||
{
|
||
/* If an NE test, we have an initial value! */
|
||
if (GET_CODE (test) == NE)
|
||
{
|
||
bl->init_insn = p;
|
||
bl->init_set = gen_rtx_SET (VOIDmode,
|
||
XEXP (test, 0), XEXP (test, 1));
|
||
}
|
||
else
|
||
bl->initial_test = test;
|
||
}
|
||
}
|
||
|
||
/* Look at the each biv and see if we can say anything better about its
|
||
initial value from any initializing insns set up above. (This is done
|
||
in two passes to avoid missing SETs in a PARALLEL.) */
|
||
for (bl = loop_iv_list; bl; bl = bl->next)
|
||
{
|
||
rtx src;
|
||
rtx note;
|
||
|
||
if (! bl->init_insn)
|
||
continue;
|
||
|
||
/* IF INIT_INSN has a REG_EQUAL or REG_EQUIV note and the value
|
||
is a constant, use the value of that. */
|
||
if (((note = find_reg_note (bl->init_insn, REG_EQUAL, 0)) != NULL
|
||
&& CONSTANT_P (XEXP (note, 0)))
|
||
|| ((note = find_reg_note (bl->init_insn, REG_EQUIV, 0)) != NULL
|
||
&& CONSTANT_P (XEXP (note, 0))))
|
||
src = XEXP (note, 0);
|
||
else
|
||
src = SET_SRC (bl->init_set);
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"Biv %d initialized at insn %d: initial value ",
|
||
bl->regno, INSN_UID (bl->init_insn));
|
||
|
||
if ((GET_MODE (src) == GET_MODE (regno_reg_rtx[bl->regno])
|
||
|| GET_MODE (src) == VOIDmode)
|
||
&& valid_initial_value_p (src, bl->init_insn, call_seen, loop_start))
|
||
{
|
||
bl->initial_value = src;
|
||
|
||
if (loop_dump_stream)
|
||
{
|
||
if (GET_CODE (src) == CONST_INT)
|
||
{
|
||
fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC, INTVAL (src));
|
||
fputc ('\n', loop_dump_stream);
|
||
}
|
||
else
|
||
{
|
||
print_rtl (loop_dump_stream, src);
|
||
fprintf (loop_dump_stream, "\n");
|
||
}
|
||
}
|
||
}
|
||
else
|
||
{
|
||
/* Biv initial value is not simple move,
|
||
so let it keep initial value of "itself". */
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "is complex\n");
|
||
}
|
||
}
|
||
|
||
/* Search the loop for general induction variables. */
|
||
|
||
/* A register is a giv if: it is only set once, it is a function of a
|
||
biv and a constant (or invariant), and it is not a biv. */
|
||
|
||
not_every_iteration = 0;
|
||
loop_depth = 0;
|
||
p = scan_start;
|
||
while (1)
|
||
{
|
||
p = NEXT_INSN (p);
|
||
/* At end of a straight-in loop, we are done.
|
||
At end of a loop entered at the bottom, scan the top. */
|
||
if (p == scan_start)
|
||
break;
|
||
if (p == end)
|
||
{
|
||
if (loop_top != 0)
|
||
p = loop_top;
|
||
else
|
||
break;
|
||
if (p == scan_start)
|
||
break;
|
||
}
|
||
|
||
/* Look for a general induction variable in a register. */
|
||
if (GET_CODE (p) == INSN
|
||
&& (set = single_set (p))
|
||
&& GET_CODE (SET_DEST (set)) == REG
|
||
&& ! may_not_optimize[REGNO (SET_DEST (set))])
|
||
{
|
||
rtx src_reg;
|
||
rtx add_val;
|
||
rtx mult_val;
|
||
int benefit;
|
||
rtx regnote = 0;
|
||
|
||
dest_reg = SET_DEST (set);
|
||
if (REGNO (dest_reg) < FIRST_PSEUDO_REGISTER)
|
||
continue;
|
||
|
||
if (/* SET_SRC is a giv. */
|
||
((benefit = general_induction_var (SET_SRC (set),
|
||
&src_reg, &add_val,
|
||
&mult_val))
|
||
/* Equivalent expression is a giv. */
|
||
|| ((regnote = find_reg_note (p, REG_EQUAL, NULL_RTX))
|
||
&& (benefit = general_induction_var (XEXP (regnote, 0),
|
||
&src_reg,
|
||
&add_val, &mult_val))))
|
||
/* Don't try to handle any regs made by loop optimization.
|
||
We have nothing on them in regno_first_uid, etc. */
|
||
&& REGNO (dest_reg) < max_reg_before_loop
|
||
/* Don't recognize a BASIC_INDUCT_VAR here. */
|
||
&& dest_reg != src_reg
|
||
/* This must be the only place where the register is set. */
|
||
&& (n_times_set[REGNO (dest_reg)] == 1
|
||
/* or all sets must be consecutive and make a giv. */
|
||
|| (benefit = consec_sets_giv (benefit, p,
|
||
src_reg, dest_reg,
|
||
&add_val, &mult_val))))
|
||
{
|
||
int count;
|
||
struct induction *v
|
||
= (struct induction *) alloca (sizeof (struct induction));
|
||
rtx temp;
|
||
|
||
/* If this is a library call, increase benefit. */
|
||
if (find_reg_note (p, REG_RETVAL, NULL_RTX))
|
||
benefit += libcall_benefit (p);
|
||
|
||
/* Skip the consecutive insns, if there are any. */
|
||
for (count = n_times_set[REGNO (dest_reg)] - 1;
|
||
count > 0; count--)
|
||
{
|
||
/* If first insn of libcall sequence, skip to end.
|
||
Do this at start of loop, since INSN is guaranteed to
|
||
be an insn here. */
|
||
if (GET_CODE (p) != NOTE
|
||
&& (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX)))
|
||
p = XEXP (temp, 0);
|
||
|
||
do p = NEXT_INSN (p);
|
||
while (GET_CODE (p) == NOTE);
|
||
}
|
||
|
||
record_giv (v, p, src_reg, dest_reg, mult_val, add_val, benefit,
|
||
DEST_REG, not_every_iteration, NULL_PTR, loop_start,
|
||
loop_end);
|
||
|
||
}
|
||
}
|
||
|
||
#ifndef DONT_REDUCE_ADDR
|
||
/* Look for givs which are memory addresses. */
|
||
/* This resulted in worse code on a VAX 8600. I wonder if it
|
||
still does. */
|
||
if (GET_CODE (p) == INSN)
|
||
find_mem_givs (PATTERN (p), p, not_every_iteration, loop_start,
|
||
loop_end);
|
||
#endif
|
||
|
||
/* Update the status of whether giv can derive other givs. This can
|
||
change when we pass a label or an insn that updates a biv. */
|
||
if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN
|
||
|| GET_CODE (p) == CODE_LABEL)
|
||
update_giv_derive (p);
|
||
|
||
/* Past a jump, we get to insns for which we can't count
|
||
on whether they will be executed during each iteration. */
|
||
/* This code appears twice in strength_reduce. There is also similar
|
||
code in scan_loop. */
|
||
if (GET_CODE (p) == JUMP_INSN
|
||
/* If we enter the loop in the middle, and scan around to the
|
||
beginning, don't set not_every_iteration for that.
|
||
This can be any kind of jump, since we want to know if insns
|
||
will be executed if the loop is executed. */
|
||
&& ! (JUMP_LABEL (p) == loop_top
|
||
&& ((NEXT_INSN (NEXT_INSN (p)) == loop_end && simplejump_p (p))
|
||
|| (NEXT_INSN (p) == loop_end && condjump_p (p)))))
|
||
{
|
||
rtx label = 0;
|
||
|
||
/* If this is a jump outside the loop, then it also doesn't
|
||
matter. Check to see if the target of this branch is on the
|
||
loop_number_exits_labels list. */
|
||
|
||
for (label = loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]];
|
||
label;
|
||
label = LABEL_NEXTREF (label))
|
||
if (XEXP (label, 0) == JUMP_LABEL (p))
|
||
break;
|
||
|
||
if (! label)
|
||
not_every_iteration = 1;
|
||
}
|
||
|
||
else if (GET_CODE (p) == NOTE)
|
||
{
|
||
/* At the virtual top of a converted loop, insns are again known to
|
||
be executed each iteration: logically, the loop begins here
|
||
even though the exit code has been duplicated. */
|
||
if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_VTOP && loop_depth == 0)
|
||
not_every_iteration = 0;
|
||
else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_BEG)
|
||
loop_depth++;
|
||
else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_END)
|
||
loop_depth--;
|
||
}
|
||
|
||
/* Unlike in the code motion pass where MAYBE_NEVER indicates that
|
||
an insn may never be executed, NOT_EVERY_ITERATION indicates whether
|
||
or not an insn is known to be executed each iteration of the
|
||
loop, whether or not any iterations are known to occur.
|
||
|
||
Therefore, if we have just passed a label and have no more labels
|
||
between here and the test insn of the loop, we know these insns
|
||
will be executed each iteration. */
|
||
|
||
if (not_every_iteration && GET_CODE (p) == CODE_LABEL
|
||
&& no_labels_between_p (p, loop_end))
|
||
not_every_iteration = 0;
|
||
}
|
||
|
||
/* Try to calculate and save the number of loop iterations. This is
|
||
set to zero if the actual number can not be calculated. This must
|
||
be called after all giv's have been identified, since otherwise it may
|
||
fail if the iteration variable is a giv. */
|
||
|
||
loop_n_iterations = loop_iterations (loop_start, loop_end);
|
||
|
||
/* Now for each giv for which we still don't know whether or not it is
|
||
replaceable, check to see if it is replaceable because its final value
|
||
can be calculated. This must be done after loop_iterations is called,
|
||
so that final_giv_value will work correctly. */
|
||
|
||
for (bl = loop_iv_list; bl; bl = bl->next)
|
||
{
|
||
struct induction *v;
|
||
|
||
for (v = bl->giv; v; v = v->next_iv)
|
||
if (! v->replaceable && ! v->not_replaceable)
|
||
check_final_value (v, loop_start, loop_end);
|
||
}
|
||
|
||
/* Try to prove that the loop counter variable (if any) is always
|
||
nonnegative; if so, record that fact with a REG_NONNEG note
|
||
so that "decrement and branch until zero" insn can be used. */
|
||
check_dbra_loop (loop_end, insn_count, loop_start);
|
||
|
||
#ifdef HAIFA
|
||
/* record loop-variables relevant for BCT optimization before unrolling
|
||
the loop. Unrolling may update part of this information, and the
|
||
correct data will be used for generating the BCT. */
|
||
#ifdef HAVE_decrement_and_branch_on_count
|
||
if (HAVE_decrement_and_branch_on_count)
|
||
analyze_loop_iterations (loop_start, loop_end);
|
||
#endif
|
||
#endif /* HAIFA */
|
||
|
||
/* Create reg_map to hold substitutions for replaceable giv regs. */
|
||
reg_map = (rtx *) alloca (max_reg_before_loop * sizeof (rtx));
|
||
bzero ((char *) reg_map, max_reg_before_loop * sizeof (rtx));
|
||
|
||
/* Examine each iv class for feasibility of strength reduction/induction
|
||
variable elimination. */
|
||
|
||
for (bl = loop_iv_list; bl; bl = bl->next)
|
||
{
|
||
struct induction *v;
|
||
int benefit;
|
||
int all_reduced;
|
||
rtx final_value = 0;
|
||
|
||
/* Test whether it will be possible to eliminate this biv
|
||
provided all givs are reduced. This is possible if either
|
||
the reg is not used outside the loop, or we can compute
|
||
what its final value will be.
|
||
|
||
For architectures with a decrement_and_branch_until_zero insn,
|
||
don't do this if we put a REG_NONNEG note on the endtest for
|
||
this biv. */
|
||
|
||
/* Compare against bl->init_insn rather than loop_start.
|
||
We aren't concerned with any uses of the biv between
|
||
init_insn and loop_start since these won't be affected
|
||
by the value of the biv elsewhere in the function, so
|
||
long as init_insn doesn't use the biv itself.
|
||
March 14, 1989 -- self@bayes.arc.nasa.gov */
|
||
|
||
if ((uid_luid[REGNO_LAST_UID (bl->regno)] < INSN_LUID (loop_end)
|
||
&& bl->init_insn
|
||
&& INSN_UID (bl->init_insn) < max_uid_for_loop
|
||
&& uid_luid[REGNO_FIRST_UID (bl->regno)] >= INSN_LUID (bl->init_insn)
|
||
#ifdef HAVE_decrement_and_branch_until_zero
|
||
&& ! bl->nonneg
|
||
#endif
|
||
&& ! reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set)))
|
||
|| ((final_value = final_biv_value (bl, loop_start, loop_end))
|
||
#ifdef HAVE_decrement_and_branch_until_zero
|
||
&& ! bl->nonneg
|
||
#endif
|
||
))
|
||
bl->eliminable = maybe_eliminate_biv (bl, loop_start, end, 0,
|
||
threshold, insn_count);
|
||
else
|
||
{
|
||
if (loop_dump_stream)
|
||
{
|
||
fprintf (loop_dump_stream,
|
||
"Cannot eliminate biv %d.\n",
|
||
bl->regno);
|
||
fprintf (loop_dump_stream,
|
||
"First use: insn %d, last use: insn %d.\n",
|
||
REGNO_FIRST_UID (bl->regno),
|
||
REGNO_LAST_UID (bl->regno));
|
||
}
|
||
}
|
||
|
||
/* Combine all giv's for this iv_class. */
|
||
combine_givs (bl);
|
||
|
||
/* This will be true at the end, if all givs which depend on this
|
||
biv have been strength reduced.
|
||
We can't (currently) eliminate the biv unless this is so. */
|
||
all_reduced = 1;
|
||
|
||
/* Check each giv in this class to see if we will benefit by reducing
|
||
it. Skip giv's combined with others. */
|
||
for (v = bl->giv; v; v = v->next_iv)
|
||
{
|
||
struct induction *tv;
|
||
|
||
if (v->ignore || v->same)
|
||
continue;
|
||
|
||
benefit = v->benefit;
|
||
|
||
/* Reduce benefit if not replaceable, since we will insert
|
||
a move-insn to replace the insn that calculates this giv.
|
||
Don't do this unless the giv is a user variable, since it
|
||
will often be marked non-replaceable because of the duplication
|
||
of the exit code outside the loop. In such a case, the copies
|
||
we insert are dead and will be deleted. So they don't have
|
||
a cost. Similar situations exist. */
|
||
/* ??? The new final_[bg]iv_value code does a much better job
|
||
of finding replaceable giv's, and hence this code may no longer
|
||
be necessary. */
|
||
if (! v->replaceable && ! bl->eliminable
|
||
&& REG_USERVAR_P (v->dest_reg))
|
||
benefit -= copy_cost;
|
||
|
||
/* Decrease the benefit to count the add-insns that we will
|
||
insert to increment the reduced reg for the giv. */
|
||
benefit -= add_cost * bl->biv_count;
|
||
|
||
/* Decide whether to strength-reduce this giv or to leave the code
|
||
unchanged (recompute it from the biv each time it is used).
|
||
This decision can be made independently for each giv. */
|
||
|
||
#ifdef AUTO_INC_DEC
|
||
/* Attempt to guess whether autoincrement will handle some of the
|
||
new add insns; if so, increase BENEFIT (undo the subtraction of
|
||
add_cost that was done above). */
|
||
if (v->giv_type == DEST_ADDR
|
||
&& GET_CODE (v->mult_val) == CONST_INT)
|
||
{
|
||
#if defined (HAVE_POST_INCREMENT) || defined (HAVE_PRE_INCREMENT)
|
||
if (INTVAL (v->mult_val) == GET_MODE_SIZE (v->mem_mode))
|
||
benefit += add_cost * bl->biv_count;
|
||
#endif
|
||
#if defined (HAVE_POST_DECREMENT) || defined (HAVE_PRE_DECREMENT)
|
||
if (-INTVAL (v->mult_val) == GET_MODE_SIZE (v->mem_mode))
|
||
benefit += add_cost * bl->biv_count;
|
||
#endif
|
||
}
|
||
#endif
|
||
|
||
/* If an insn is not to be strength reduced, then set its ignore
|
||
flag, and clear all_reduced. */
|
||
|
||
/* A giv that depends on a reversed biv must be reduced if it is
|
||
used after the loop exit, otherwise, it would have the wrong
|
||
value after the loop exit. To make it simple, just reduce all
|
||
of such giv's whether or not we know they are used after the loop
|
||
exit. */
|
||
|
||
if ( ! flag_reduce_all_givs && v->lifetime * threshold * benefit < insn_count
|
||
&& ! bl->reversed )
|
||
{
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"giv of insn %d not worth while, %d vs %d.\n",
|
||
INSN_UID (v->insn),
|
||
v->lifetime * threshold * benefit, insn_count);
|
||
v->ignore = 1;
|
||
all_reduced = 0;
|
||
}
|
||
else
|
||
{
|
||
/* Check that we can increment the reduced giv without a
|
||
multiply insn. If not, reject it. */
|
||
|
||
for (tv = bl->biv; tv; tv = tv->next_iv)
|
||
if (tv->mult_val == const1_rtx
|
||
&& ! product_cheap_p (tv->add_val, v->mult_val))
|
||
{
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"giv of insn %d: would need a multiply.\n",
|
||
INSN_UID (v->insn));
|
||
v->ignore = 1;
|
||
all_reduced = 0;
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Reduce each giv that we decided to reduce. */
|
||
|
||
for (v = bl->giv; v; v = v->next_iv)
|
||
{
|
||
struct induction *tv;
|
||
if (! v->ignore && v->same == 0)
|
||
{
|
||
int auto_inc_opt = 0;
|
||
|
||
v->new_reg = gen_reg_rtx (v->mode);
|
||
|
||
#ifdef AUTO_INC_DEC
|
||
/* If the target has auto-increment addressing modes, and
|
||
this is an address giv, then try to put the increment
|
||
immediately after its use, so that flow can create an
|
||
auto-increment addressing mode. */
|
||
if (v->giv_type == DEST_ADDR && bl->biv_count == 1
|
||
&& bl->biv->always_executed && ! bl->biv->maybe_multiple
|
||
/* We don't handle reversed biv's because bl->biv->insn
|
||
does not have a valid INSN_LUID. */
|
||
&& ! bl->reversed
|
||
&& v->always_executed && ! v->maybe_multiple
|
||
&& INSN_UID (v->insn) < max_uid_for_loop)
|
||
{
|
||
/* If other giv's have been combined with this one, then
|
||
this will work only if all uses of the other giv's occur
|
||
before this giv's insn. This is difficult to check.
|
||
|
||
We simplify this by looking for the common case where
|
||
there is one DEST_REG giv, and this giv's insn is the
|
||
last use of the dest_reg of that DEST_REG giv. If the
|
||
increment occurs after the address giv, then we can
|
||
perform the optimization. (Otherwise, the increment
|
||
would have to go before other_giv, and we would not be
|
||
able to combine it with the address giv to get an
|
||
auto-inc address.) */
|
||
if (v->combined_with)
|
||
{
|
||
struct induction *other_giv = 0;
|
||
|
||
for (tv = bl->giv; tv; tv = tv->next_iv)
|
||
if (tv->same == v)
|
||
{
|
||
if (other_giv)
|
||
break;
|
||
else
|
||
other_giv = tv;
|
||
}
|
||
if (! tv && other_giv
|
||
&& REGNO (other_giv->dest_reg) < max_reg_before_loop
|
||
&& (REGNO_LAST_UID (REGNO (other_giv->dest_reg))
|
||
== INSN_UID (v->insn))
|
||
&& INSN_LUID (v->insn) < INSN_LUID (bl->biv->insn))
|
||
auto_inc_opt = 1;
|
||
}
|
||
/* Check for case where increment is before the address
|
||
giv. Do this test in "loop order". */
|
||
else if ((INSN_LUID (v->insn) > INSN_LUID (bl->biv->insn)
|
||
&& (INSN_LUID (v->insn) < INSN_LUID (scan_start)
|
||
|| (INSN_LUID (bl->biv->insn)
|
||
> INSN_LUID (scan_start))))
|
||
|| (INSN_LUID (v->insn) < INSN_LUID (scan_start)
|
||
&& (INSN_LUID (scan_start)
|
||
< INSN_LUID (bl->biv->insn))))
|
||
auto_inc_opt = -1;
|
||
else
|
||
auto_inc_opt = 1;
|
||
|
||
#ifdef HAVE_cc0
|
||
{
|
||
rtx prev;
|
||
|
||
/* We can't put an insn immediately after one setting
|
||
cc0, or immediately before one using cc0. */
|
||
if ((auto_inc_opt == 1 && sets_cc0_p (PATTERN (v->insn)))
|
||
|| (auto_inc_opt == -1
|
||
&& (prev = prev_nonnote_insn (v->insn)) != 0
|
||
&& GET_RTX_CLASS (GET_CODE (prev)) == 'i'
|
||
&& sets_cc0_p (PATTERN (prev))))
|
||
auto_inc_opt = 0;
|
||
}
|
||
#endif
|
||
|
||
if (auto_inc_opt)
|
||
v->auto_inc_opt = 1;
|
||
}
|
||
#endif
|
||
|
||
/* For each place where the biv is incremented, add an insn
|
||
to increment the new, reduced reg for the giv. */
|
||
for (tv = bl->biv; tv; tv = tv->next_iv)
|
||
{
|
||
rtx insert_before;
|
||
|
||
if (! auto_inc_opt)
|
||
insert_before = tv->insn;
|
||
else if (auto_inc_opt == 1)
|
||
insert_before = NEXT_INSN (v->insn);
|
||
else
|
||
insert_before = v->insn;
|
||
|
||
if (tv->mult_val == const1_rtx)
|
||
emit_iv_add_mult (tv->add_val, v->mult_val,
|
||
v->new_reg, v->new_reg, insert_before);
|
||
else /* tv->mult_val == const0_rtx */
|
||
/* A multiply is acceptable here
|
||
since this is presumed to be seldom executed. */
|
||
emit_iv_add_mult (tv->add_val, v->mult_val,
|
||
v->add_val, v->new_reg, insert_before);
|
||
}
|
||
|
||
/* Add code at loop start to initialize giv's reduced reg. */
|
||
|
||
emit_iv_add_mult (bl->initial_value, v->mult_val,
|
||
v->add_val, v->new_reg, loop_start);
|
||
}
|
||
}
|
||
|
||
/* Rescan all givs. If a giv is the same as a giv not reduced, mark it
|
||
as not reduced.
|
||
|
||
For each giv register that can be reduced now: if replaceable,
|
||
substitute reduced reg wherever the old giv occurs;
|
||
else add new move insn "giv_reg = reduced_reg".
|
||
|
||
Also check for givs whose first use is their definition and whose
|
||
last use is the definition of another giv. If so, it is likely
|
||
dead and should not be used to eliminate a biv. */
|
||
for (v = bl->giv; v; v = v->next_iv)
|
||
{
|
||
if (v->same && v->same->ignore)
|
||
v->ignore = 1;
|
||
|
||
if (v->ignore)
|
||
continue;
|
||
|
||
if (v->giv_type == DEST_REG
|
||
&& REGNO_FIRST_UID (REGNO (v->dest_reg)) == INSN_UID (v->insn))
|
||
{
|
||
struct induction *v1;
|
||
|
||
for (v1 = bl->giv; v1; v1 = v1->next_iv)
|
||
if (REGNO_LAST_UID (REGNO (v->dest_reg)) == INSN_UID (v1->insn))
|
||
v->maybe_dead = 1;
|
||
}
|
||
|
||
/* Update expression if this was combined, in case other giv was
|
||
replaced. */
|
||
if (v->same)
|
||
v->new_reg = replace_rtx (v->new_reg,
|
||
v->same->dest_reg, v->same->new_reg);
|
||
|
||
if (v->giv_type == DEST_ADDR)
|
||
/* Store reduced reg as the address in the memref where we found
|
||
this giv. */
|
||
validate_change (v->insn, v->location, v->new_reg, 0);
|
||
else if (v->replaceable)
|
||
{
|
||
reg_map[REGNO (v->dest_reg)] = v->new_reg;
|
||
|
||
#if 0
|
||
/* I can no longer duplicate the original problem. Perhaps
|
||
this is unnecessary now? */
|
||
|
||
/* Replaceable; it isn't strictly necessary to delete the old
|
||
insn and emit a new one, because v->dest_reg is now dead.
|
||
|
||
However, especially when unrolling loops, the special
|
||
handling for (set REG0 REG1) in the second cse pass may
|
||
make v->dest_reg live again. To avoid this problem, emit
|
||
an insn to set the original giv reg from the reduced giv.
|
||
We can not delete the original insn, since it may be part
|
||
of a LIBCALL, and the code in flow that eliminates dead
|
||
libcalls will fail if it is deleted. */
|
||
emit_insn_after (gen_move_insn (v->dest_reg, v->new_reg),
|
||
v->insn);
|
||
#endif
|
||
}
|
||
else
|
||
{
|
||
/* Not replaceable; emit an insn to set the original giv reg from
|
||
the reduced giv, same as above. */
|
||
emit_insn_after (gen_move_insn (v->dest_reg, v->new_reg),
|
||
v->insn);
|
||
}
|
||
|
||
/* When a loop is reversed, givs which depend on the reversed
|
||
biv, and which are live outside the loop, must be set to their
|
||
correct final value. This insn is only needed if the giv is
|
||
not replaceable. The correct final value is the same as the
|
||
value that the giv starts the reversed loop with. */
|
||
if (bl->reversed && ! v->replaceable)
|
||
emit_iv_add_mult (bl->initial_value, v->mult_val,
|
||
v->add_val, v->dest_reg, end_insert_before);
|
||
else if (v->final_value)
|
||
{
|
||
rtx insert_before;
|
||
|
||
/* If the loop has multiple exits, emit the insn before the
|
||
loop to ensure that it will always be executed no matter
|
||
how the loop exits. Otherwise, emit the insn after the loop,
|
||
since this is slightly more efficient. */
|
||
if (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
|
||
insert_before = loop_start;
|
||
else
|
||
insert_before = end_insert_before;
|
||
emit_insn_before (gen_move_insn (v->dest_reg, v->final_value),
|
||
insert_before);
|
||
|
||
#if 0
|
||
/* If the insn to set the final value of the giv was emitted
|
||
before the loop, then we must delete the insn inside the loop
|
||
that sets it. If this is a LIBCALL, then we must delete
|
||
every insn in the libcall. Note, however, that
|
||
final_giv_value will only succeed when there are multiple
|
||
exits if the giv is dead at each exit, hence it does not
|
||
matter that the original insn remains because it is dead
|
||
anyways. */
|
||
/* Delete the insn inside the loop that sets the giv since
|
||
the giv is now set before (or after) the loop. */
|
||
delete_insn (v->insn);
|
||
#endif
|
||
}
|
||
|
||
if (loop_dump_stream)
|
||
{
|
||
fprintf (loop_dump_stream, "giv at %d reduced to ",
|
||
INSN_UID (v->insn));
|
||
print_rtl (loop_dump_stream, v->new_reg);
|
||
fprintf (loop_dump_stream, "\n");
|
||
}
|
||
}
|
||
|
||
/* All the givs based on the biv bl have been reduced if they
|
||
merit it. */
|
||
|
||
/* For each giv not marked as maybe dead that has been combined with a
|
||
second giv, clear any "maybe dead" mark on that second giv.
|
||
v->new_reg will either be or refer to the register of the giv it
|
||
combined with.
|
||
|
||
Doing this clearing avoids problems in biv elimination where a
|
||
giv's new_reg is a complex value that can't be put in the insn but
|
||
the giv combined with (with a reg as new_reg) is marked maybe_dead.
|
||
Since the register will be used in either case, we'd prefer it be
|
||
used from the simpler giv. */
|
||
|
||
for (v = bl->giv; v; v = v->next_iv)
|
||
if (! v->maybe_dead && v->same)
|
||
v->same->maybe_dead = 0;
|
||
|
||
/* Try to eliminate the biv, if it is a candidate.
|
||
This won't work if ! all_reduced,
|
||
since the givs we planned to use might not have been reduced.
|
||
|
||
We have to be careful that we didn't initially think we could eliminate
|
||
this biv because of a giv that we now think may be dead and shouldn't
|
||
be used as a biv replacement.
|
||
|
||
Also, there is the possibility that we may have a giv that looks
|
||
like it can be used to eliminate a biv, but the resulting insn
|
||
isn't valid. This can happen, for example, on the 88k, where a
|
||
JUMP_INSN can compare a register only with zero. Attempts to
|
||
replace it with a compare with a constant will fail.
|
||
|
||
Note that in cases where this call fails, we may have replaced some
|
||
of the occurrences of the biv with a giv, but no harm was done in
|
||
doing so in the rare cases where it can occur. */
|
||
|
||
if (all_reduced == 1 && bl->eliminable
|
||
&& maybe_eliminate_biv (bl, loop_start, end, 1,
|
||
threshold, insn_count))
|
||
|
||
{
|
||
/* ?? If we created a new test to bypass the loop entirely,
|
||
or otherwise drop straight in, based on this test, then
|
||
we might want to rewrite it also. This way some later
|
||
pass has more hope of removing the initialization of this
|
||
biv entirely. */
|
||
|
||
/* If final_value != 0, then the biv may be used after loop end
|
||
and we must emit an insn to set it just in case.
|
||
|
||
Reversed bivs already have an insn after the loop setting their
|
||
value, so we don't need another one. We can't calculate the
|
||
proper final value for such a biv here anyways. */
|
||
if (final_value != 0 && ! bl->reversed)
|
||
{
|
||
rtx insert_before;
|
||
|
||
/* If the loop has multiple exits, emit the insn before the
|
||
loop to ensure that it will always be executed no matter
|
||
how the loop exits. Otherwise, emit the insn after the
|
||
loop, since this is slightly more efficient. */
|
||
if (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
|
||
insert_before = loop_start;
|
||
else
|
||
insert_before = end_insert_before;
|
||
|
||
emit_insn_before (gen_move_insn (bl->biv->dest_reg, final_value),
|
||
end_insert_before);
|
||
}
|
||
|
||
#if 0
|
||
/* Delete all of the instructions inside the loop which set
|
||
the biv, as they are all dead. If is safe to delete them,
|
||
because an insn setting a biv will never be part of a libcall. */
|
||
/* However, deleting them will invalidate the regno_last_uid info,
|
||
so keeping them around is more convenient. Final_biv_value
|
||
will only succeed when there are multiple exits if the biv
|
||
is dead at each exit, hence it does not matter that the original
|
||
insn remains, because it is dead anyways. */
|
||
for (v = bl->biv; v; v = v->next_iv)
|
||
delete_insn (v->insn);
|
||
#endif
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "Reg %d: biv eliminated\n",
|
||
bl->regno);
|
||
}
|
||
}
|
||
|
||
/* Go through all the instructions in the loop, making all the
|
||
register substitutions scheduled in REG_MAP. */
|
||
|
||
for (p = loop_start; p != end; p = NEXT_INSN (p))
|
||
if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN
|
||
|| GET_CODE (p) == CALL_INSN)
|
||
{
|
||
replace_regs (PATTERN (p), reg_map, max_reg_before_loop, 0);
|
||
replace_regs (REG_NOTES (p), reg_map, max_reg_before_loop, 0);
|
||
INSN_CODE (p) = -1;
|
||
}
|
||
|
||
/* Unroll loops from within strength reduction so that we can use the
|
||
induction variable information that strength_reduce has already
|
||
collected. */
|
||
|
||
if (unroll_p)
|
||
unroll_loop (loop_end, insn_count, loop_start, end_insert_before, 1);
|
||
|
||
#ifdef HAIFA
|
||
/* instrument the loop with bct insn */
|
||
#ifdef HAVE_decrement_and_branch_on_count
|
||
if (HAVE_decrement_and_branch_on_count)
|
||
insert_bct (loop_start, loop_end);
|
||
#endif
|
||
#endif /* HAIFA */
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "\n");
|
||
}
|
||
|
||
/* Return 1 if X is a valid source for an initial value (or as value being
|
||
compared against in an initial test).
|
||
|
||
X must be either a register or constant and must not be clobbered between
|
||
the current insn and the start of the loop.
|
||
|
||
INSN is the insn containing X. */
|
||
|
||
static int
|
||
valid_initial_value_p (x, insn, call_seen, loop_start)
|
||
rtx x;
|
||
rtx insn;
|
||
int call_seen;
|
||
rtx loop_start;
|
||
{
|
||
if (CONSTANT_P (x))
|
||
return 1;
|
||
|
||
/* Only consider pseudos we know about initialized in insns whose luids
|
||
we know. */
|
||
if (GET_CODE (x) != REG
|
||
|| REGNO (x) >= max_reg_before_loop)
|
||
return 0;
|
||
|
||
/* Don't use call-clobbered registers across a call which clobbers it. On
|
||
some machines, don't use any hard registers at all. */
|
||
if (REGNO (x) < FIRST_PSEUDO_REGISTER
|
||
&& (SMALL_REGISTER_CLASSES
|
||
|| (call_used_regs[REGNO (x)] && call_seen)))
|
||
return 0;
|
||
|
||
/* Don't use registers that have been clobbered before the start of the
|
||
loop. */
|
||
if (reg_set_between_p (x, insn, loop_start))
|
||
return 0;
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* Scan X for memory refs and check each memory address
|
||
as a possible giv. INSN is the insn whose pattern X comes from.
|
||
NOT_EVERY_ITERATION is 1 if the insn might not be executed during
|
||
every loop iteration. */
|
||
|
||
static void
|
||
find_mem_givs (x, insn, not_every_iteration, loop_start, loop_end)
|
||
rtx x;
|
||
rtx insn;
|
||
int not_every_iteration;
|
||
rtx loop_start, loop_end;
|
||
{
|
||
register int i, j;
|
||
register enum rtx_code code;
|
||
register char *fmt;
|
||
|
||
if (x == 0)
|
||
return;
|
||
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case REG:
|
||
case CONST_INT:
|
||
case CONST:
|
||
case CONST_DOUBLE:
|
||
case SYMBOL_REF:
|
||
case LABEL_REF:
|
||
case PC:
|
||
case CC0:
|
||
case ADDR_VEC:
|
||
case ADDR_DIFF_VEC:
|
||
case USE:
|
||
case CLOBBER:
|
||
return;
|
||
|
||
case MEM:
|
||
{
|
||
rtx src_reg;
|
||
rtx add_val;
|
||
rtx mult_val;
|
||
int benefit;
|
||
|
||
benefit = general_induction_var (XEXP (x, 0),
|
||
&src_reg, &add_val, &mult_val);
|
||
|
||
/* Don't make a DEST_ADDR giv with mult_val == 1 && add_val == 0.
|
||
Such a giv isn't useful. */
|
||
if (benefit > 0 && (mult_val != const1_rtx || add_val != const0_rtx))
|
||
{
|
||
/* Found one; record it. */
|
||
struct induction *v
|
||
= (struct induction *) oballoc (sizeof (struct induction));
|
||
|
||
record_giv (v, insn, src_reg, addr_placeholder, mult_val,
|
||
add_val, benefit, DEST_ADDR, not_every_iteration,
|
||
&XEXP (x, 0), loop_start, loop_end);
|
||
|
||
v->mem_mode = GET_MODE (x);
|
||
}
|
||
}
|
||
return;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
/* Recursively scan the subexpressions for other mem refs. */
|
||
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
if (fmt[i] == 'e')
|
||
find_mem_givs (XEXP (x, i), insn, not_every_iteration, loop_start,
|
||
loop_end);
|
||
else if (fmt[i] == 'E')
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
find_mem_givs (XVECEXP (x, i, j), insn, not_every_iteration,
|
||
loop_start, loop_end);
|
||
}
|
||
|
||
/* Fill in the data about one biv update.
|
||
V is the `struct induction' in which we record the biv. (It is
|
||
allocated by the caller, with alloca.)
|
||
INSN is the insn that sets it.
|
||
DEST_REG is the biv's reg.
|
||
|
||
MULT_VAL is const1_rtx if the biv is being incremented here, in which case
|
||
INC_VAL is the increment. Otherwise, MULT_VAL is const0_rtx and the biv is
|
||
being set to INC_VAL.
|
||
|
||
NOT_EVERY_ITERATION is nonzero if this biv update is not know to be
|
||
executed every iteration; MAYBE_MULTIPLE is nonzero if this biv update
|
||
can be executed more than once per iteration. If MAYBE_MULTIPLE
|
||
and NOT_EVERY_ITERATION are both zero, we know that the biv update is
|
||
executed exactly once per iteration. */
|
||
|
||
static void
|
||
record_biv (v, insn, dest_reg, inc_val, mult_val,
|
||
not_every_iteration, maybe_multiple)
|
||
struct induction *v;
|
||
rtx insn;
|
||
rtx dest_reg;
|
||
rtx inc_val;
|
||
rtx mult_val;
|
||
int not_every_iteration;
|
||
int maybe_multiple;
|
||
{
|
||
struct iv_class *bl;
|
||
|
||
v->insn = insn;
|
||
v->src_reg = dest_reg;
|
||
v->dest_reg = dest_reg;
|
||
v->mult_val = mult_val;
|
||
v->add_val = inc_val;
|
||
v->mode = GET_MODE (dest_reg);
|
||
v->always_computable = ! not_every_iteration;
|
||
v->always_executed = ! not_every_iteration;
|
||
v->maybe_multiple = maybe_multiple;
|
||
|
||
/* Add this to the reg's iv_class, creating a class
|
||
if this is the first incrementation of the reg. */
|
||
|
||
bl = reg_biv_class[REGNO (dest_reg)];
|
||
if (bl == 0)
|
||
{
|
||
/* Create and initialize new iv_class. */
|
||
|
||
bl = (struct iv_class *) oballoc (sizeof (struct iv_class));
|
||
|
||
bl->regno = REGNO (dest_reg);
|
||
bl->biv = 0;
|
||
bl->giv = 0;
|
||
bl->biv_count = 0;
|
||
bl->giv_count = 0;
|
||
|
||
/* Set initial value to the reg itself. */
|
||
bl->initial_value = dest_reg;
|
||
/* We haven't seen the initializing insn yet */
|
||
bl->init_insn = 0;
|
||
bl->init_set = 0;
|
||
bl->initial_test = 0;
|
||
bl->incremented = 0;
|
||
bl->eliminable = 0;
|
||
bl->nonneg = 0;
|
||
bl->reversed = 0;
|
||
bl->total_benefit = 0;
|
||
|
||
/* Add this class to loop_iv_list. */
|
||
bl->next = loop_iv_list;
|
||
loop_iv_list = bl;
|
||
|
||
/* Put it in the array of biv register classes. */
|
||
reg_biv_class[REGNO (dest_reg)] = bl;
|
||
}
|
||
|
||
/* Update IV_CLASS entry for this biv. */
|
||
v->next_iv = bl->biv;
|
||
bl->biv = v;
|
||
bl->biv_count++;
|
||
if (mult_val == const1_rtx)
|
||
bl->incremented = 1;
|
||
|
||
if (loop_dump_stream)
|
||
{
|
||
fprintf (loop_dump_stream,
|
||
"Insn %d: possible biv, reg %d,",
|
||
INSN_UID (insn), REGNO (dest_reg));
|
||
if (GET_CODE (inc_val) == CONST_INT)
|
||
{
|
||
fprintf (loop_dump_stream, " const =");
|
||
fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC, INTVAL (inc_val));
|
||
fputc ('\n', loop_dump_stream);
|
||
}
|
||
else
|
||
{
|
||
fprintf (loop_dump_stream, " const = ");
|
||
print_rtl (loop_dump_stream, inc_val);
|
||
fprintf (loop_dump_stream, "\n");
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Fill in the data about one giv.
|
||
V is the `struct induction' in which we record the giv. (It is
|
||
allocated by the caller, with alloca.)
|
||
INSN is the insn that sets it.
|
||
BENEFIT estimates the savings from deleting this insn.
|
||
TYPE is DEST_REG or DEST_ADDR; it says whether the giv is computed
|
||
into a register or is used as a memory address.
|
||
|
||
SRC_REG is the biv reg which the giv is computed from.
|
||
DEST_REG is the giv's reg (if the giv is stored in a reg).
|
||
MULT_VAL and ADD_VAL are the coefficients used to compute the giv.
|
||
LOCATION points to the place where this giv's value appears in INSN. */
|
||
|
||
static void
|
||
record_giv (v, insn, src_reg, dest_reg, mult_val, add_val, benefit,
|
||
type, not_every_iteration, location, loop_start, loop_end)
|
||
struct induction *v;
|
||
rtx insn;
|
||
rtx src_reg;
|
||
rtx dest_reg;
|
||
rtx mult_val, add_val;
|
||
int benefit;
|
||
enum g_types type;
|
||
int not_every_iteration;
|
||
rtx *location;
|
||
rtx loop_start, loop_end;
|
||
{
|
||
struct induction *b;
|
||
struct iv_class *bl;
|
||
rtx set = single_set (insn);
|
||
|
||
v->insn = insn;
|
||
v->src_reg = src_reg;
|
||
v->giv_type = type;
|
||
v->dest_reg = dest_reg;
|
||
v->mult_val = mult_val;
|
||
v->add_val = add_val;
|
||
v->benefit = benefit;
|
||
v->location = location;
|
||
v->cant_derive = 0;
|
||
v->combined_with = 0;
|
||
v->maybe_multiple = 0;
|
||
v->maybe_dead = 0;
|
||
v->derive_adjustment = 0;
|
||
v->same = 0;
|
||
v->ignore = 0;
|
||
v->new_reg = 0;
|
||
v->final_value = 0;
|
||
v->same_insn = 0;
|
||
v->auto_inc_opt = 0;
|
||
v->unrolled = 0;
|
||
v->shared = 0;
|
||
|
||
/* The v->always_computable field is used in update_giv_derive, to
|
||
determine whether a giv can be used to derive another giv. For a
|
||
DEST_REG giv, INSN computes a new value for the giv, so its value
|
||
isn't computable if INSN insn't executed every iteration.
|
||
However, for a DEST_ADDR giv, INSN merely uses the value of the giv;
|
||
it does not compute a new value. Hence the value is always computable
|
||
regardless of whether INSN is executed each iteration. */
|
||
|
||
if (type == DEST_ADDR)
|
||
v->always_computable = 1;
|
||
else
|
||
v->always_computable = ! not_every_iteration;
|
||
|
||
v->always_executed = ! not_every_iteration;
|
||
|
||
if (type == DEST_ADDR)
|
||
{
|
||
v->mode = GET_MODE (*location);
|
||
v->lifetime = 1;
|
||
v->times_used = 1;
|
||
}
|
||
else /* type == DEST_REG */
|
||
{
|
||
v->mode = GET_MODE (SET_DEST (set));
|
||
|
||
v->lifetime = (uid_luid[REGNO_LAST_UID (REGNO (dest_reg))]
|
||
- uid_luid[REGNO_FIRST_UID (REGNO (dest_reg))]);
|
||
|
||
v->times_used = n_times_used[REGNO (dest_reg)];
|
||
|
||
/* If the lifetime is zero, it means that this register is
|
||
really a dead store. So mark this as a giv that can be
|
||
ignored. This will not prevent the biv from being eliminated. */
|
||
if (v->lifetime == 0)
|
||
v->ignore = 1;
|
||
|
||
reg_iv_type[REGNO (dest_reg)] = GENERAL_INDUCT;
|
||
reg_iv_info[REGNO (dest_reg)] = v;
|
||
}
|
||
|
||
/* Add the giv to the class of givs computed from one biv. */
|
||
|
||
bl = reg_biv_class[REGNO (src_reg)];
|
||
if (bl)
|
||
{
|
||
v->next_iv = bl->giv;
|
||
bl->giv = v;
|
||
/* Don't count DEST_ADDR. This is supposed to count the number of
|
||
insns that calculate givs. */
|
||
if (type == DEST_REG)
|
||
bl->giv_count++;
|
||
bl->total_benefit += benefit;
|
||
}
|
||
else
|
||
/* Fatal error, biv missing for this giv? */
|
||
abort ();
|
||
|
||
if (type == DEST_ADDR)
|
||
v->replaceable = 1;
|
||
else
|
||
{
|
||
/* The giv can be replaced outright by the reduced register only if all
|
||
of the following conditions are true:
|
||
- the insn that sets the giv is always executed on any iteration
|
||
on which the giv is used at all
|
||
(there are two ways to deduce this:
|
||
either the insn is executed on every iteration,
|
||
or all uses follow that insn in the same basic block),
|
||
- the giv is not used outside the loop
|
||
- no assignments to the biv occur during the giv's lifetime. */
|
||
|
||
if (REGNO_FIRST_UID (REGNO (dest_reg)) == INSN_UID (insn)
|
||
/* Previous line always fails if INSN was moved by loop opt. */
|
||
&& uid_luid[REGNO_LAST_UID (REGNO (dest_reg))] < INSN_LUID (loop_end)
|
||
&& (! not_every_iteration
|
||
|| last_use_this_basic_block (dest_reg, insn)))
|
||
{
|
||
/* Now check that there are no assignments to the biv within the
|
||
giv's lifetime. This requires two separate checks. */
|
||
|
||
/* Check each biv update, and fail if any are between the first
|
||
and last use of the giv.
|
||
|
||
If this loop contains an inner loop that was unrolled, then
|
||
the insn modifying the biv may have been emitted by the loop
|
||
unrolling code, and hence does not have a valid luid. Just
|
||
mark the biv as not replaceable in this case. It is not very
|
||
useful as a biv, because it is used in two different loops.
|
||
It is very unlikely that we would be able to optimize the giv
|
||
using this biv anyways. */
|
||
|
||
v->replaceable = 1;
|
||
for (b = bl->biv; b; b = b->next_iv)
|
||
{
|
||
if (INSN_UID (b->insn) >= max_uid_for_loop
|
||
|| ((uid_luid[INSN_UID (b->insn)]
|
||
>= uid_luid[REGNO_FIRST_UID (REGNO (dest_reg))])
|
||
&& (uid_luid[INSN_UID (b->insn)]
|
||
<= uid_luid[REGNO_LAST_UID (REGNO (dest_reg))])))
|
||
{
|
||
v->replaceable = 0;
|
||
v->not_replaceable = 1;
|
||
break;
|
||
}
|
||
}
|
||
|
||
/* If there are any backwards branches that go from after the
|
||
biv update to before it, then this giv is not replaceable. */
|
||
if (v->replaceable)
|
||
for (b = bl->biv; b; b = b->next_iv)
|
||
if (back_branch_in_range_p (b->insn, loop_start, loop_end))
|
||
{
|
||
v->replaceable = 0;
|
||
v->not_replaceable = 1;
|
||
break;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
/* May still be replaceable, we don't have enough info here to
|
||
decide. */
|
||
v->replaceable = 0;
|
||
v->not_replaceable = 0;
|
||
}
|
||
}
|
||
|
||
if (loop_dump_stream)
|
||
{
|
||
if (type == DEST_REG)
|
||
fprintf (loop_dump_stream, "Insn %d: giv reg %d",
|
||
INSN_UID (insn), REGNO (dest_reg));
|
||
else
|
||
fprintf (loop_dump_stream, "Insn %d: dest address",
|
||
INSN_UID (insn));
|
||
|
||
fprintf (loop_dump_stream, " src reg %d benefit %d",
|
||
REGNO (src_reg), v->benefit);
|
||
fprintf (loop_dump_stream, " used %d lifetime %d",
|
||
v->times_used, v->lifetime);
|
||
|
||
if (v->replaceable)
|
||
fprintf (loop_dump_stream, " replaceable");
|
||
|
||
if (GET_CODE (mult_val) == CONST_INT)
|
||
{
|
||
fprintf (loop_dump_stream, " mult ");
|
||
fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC, INTVAL (mult_val));
|
||
}
|
||
else
|
||
{
|
||
fprintf (loop_dump_stream, " mult ");
|
||
print_rtl (loop_dump_stream, mult_val);
|
||
}
|
||
|
||
if (GET_CODE (add_val) == CONST_INT)
|
||
{
|
||
fprintf (loop_dump_stream, " add ");
|
||
fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC, INTVAL (add_val));
|
||
}
|
||
else
|
||
{
|
||
fprintf (loop_dump_stream, " add ");
|
||
print_rtl (loop_dump_stream, add_val);
|
||
}
|
||
}
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "\n");
|
||
|
||
}
|
||
|
||
|
||
/* All this does is determine whether a giv can be made replaceable because
|
||
its final value can be calculated. This code can not be part of record_giv
|
||
above, because final_giv_value requires that the number of loop iterations
|
||
be known, and that can not be accurately calculated until after all givs
|
||
have been identified. */
|
||
|
||
static void
|
||
check_final_value (v, loop_start, loop_end)
|
||
struct induction *v;
|
||
rtx loop_start, loop_end;
|
||
{
|
||
struct iv_class *bl;
|
||
rtx final_value = 0;
|
||
|
||
bl = reg_biv_class[REGNO (v->src_reg)];
|
||
|
||
/* DEST_ADDR givs will never reach here, because they are always marked
|
||
replaceable above in record_giv. */
|
||
|
||
/* The giv can be replaced outright by the reduced register only if all
|
||
of the following conditions are true:
|
||
- the insn that sets the giv is always executed on any iteration
|
||
on which the giv is used at all
|
||
(there are two ways to deduce this:
|
||
either the insn is executed on every iteration,
|
||
or all uses follow that insn in the same basic block),
|
||
- its final value can be calculated (this condition is different
|
||
than the one above in record_giv)
|
||
- no assignments to the biv occur during the giv's lifetime. */
|
||
|
||
#if 0
|
||
/* This is only called now when replaceable is known to be false. */
|
||
/* Clear replaceable, so that it won't confuse final_giv_value. */
|
||
v->replaceable = 0;
|
||
#endif
|
||
|
||
if ((final_value = final_giv_value (v, loop_start, loop_end))
|
||
&& (v->always_computable || last_use_this_basic_block (v->dest_reg, v->insn)))
|
||
{
|
||
int biv_increment_seen = 0;
|
||
rtx p = v->insn;
|
||
rtx last_giv_use;
|
||
|
||
v->replaceable = 1;
|
||
|
||
/* When trying to determine whether or not a biv increment occurs
|
||
during the lifetime of the giv, we can ignore uses of the variable
|
||
outside the loop because final_value is true. Hence we can not
|
||
use regno_last_uid and regno_first_uid as above in record_giv. */
|
||
|
||
/* Search the loop to determine whether any assignments to the
|
||
biv occur during the giv's lifetime. Start with the insn
|
||
that sets the giv, and search around the loop until we come
|
||
back to that insn again.
|
||
|
||
Also fail if there is a jump within the giv's lifetime that jumps
|
||
to somewhere outside the lifetime but still within the loop. This
|
||
catches spaghetti code where the execution order is not linear, and
|
||
hence the above test fails. Here we assume that the giv lifetime
|
||
does not extend from one iteration of the loop to the next, so as
|
||
to make the test easier. Since the lifetime isn't known yet,
|
||
this requires two loops. See also record_giv above. */
|
||
|
||
last_giv_use = v->insn;
|
||
|
||
while (1)
|
||
{
|
||
p = NEXT_INSN (p);
|
||
if (p == loop_end)
|
||
p = NEXT_INSN (loop_start);
|
||
if (p == v->insn)
|
||
break;
|
||
|
||
if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN
|
||
|| GET_CODE (p) == CALL_INSN)
|
||
{
|
||
if (biv_increment_seen)
|
||
{
|
||
if (reg_mentioned_p (v->dest_reg, PATTERN (p)))
|
||
{
|
||
v->replaceable = 0;
|
||
v->not_replaceable = 1;
|
||
break;
|
||
}
|
||
}
|
||
else if (reg_set_p (v->src_reg, PATTERN (p)))
|
||
biv_increment_seen = 1;
|
||
else if (reg_mentioned_p (v->dest_reg, PATTERN (p)))
|
||
last_giv_use = p;
|
||
}
|
||
}
|
||
|
||
/* Now that the lifetime of the giv is known, check for branches
|
||
from within the lifetime to outside the lifetime if it is still
|
||
replaceable. */
|
||
|
||
if (v->replaceable)
|
||
{
|
||
p = v->insn;
|
||
while (1)
|
||
{
|
||
p = NEXT_INSN (p);
|
||
if (p == loop_end)
|
||
p = NEXT_INSN (loop_start);
|
||
if (p == last_giv_use)
|
||
break;
|
||
|
||
if (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p)
|
||
&& LABEL_NAME (JUMP_LABEL (p))
|
||
&& ((INSN_UID (JUMP_LABEL (p)) >= max_uid_for_loop)
|
||
|| (INSN_UID (v->insn) >= max_uid_for_loop)
|
||
|| (INSN_UID (last_giv_use) >= max_uid_for_loop)
|
||
|| (INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (v->insn)
|
||
&& INSN_LUID (JUMP_LABEL (p)) > INSN_LUID (loop_start))
|
||
|| (INSN_LUID (JUMP_LABEL (p)) > INSN_LUID (last_giv_use)
|
||
&& INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (loop_end))))
|
||
{
|
||
v->replaceable = 0;
|
||
v->not_replaceable = 1;
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"Found branch outside giv lifetime.\n");
|
||
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* If it is replaceable, then save the final value. */
|
||
if (v->replaceable)
|
||
v->final_value = final_value;
|
||
}
|
||
|
||
if (loop_dump_stream && v->replaceable)
|
||
fprintf (loop_dump_stream, "Insn %d: giv reg %d final_value replaceable\n",
|
||
INSN_UID (v->insn), REGNO (v->dest_reg));
|
||
}
|
||
|
||
/* Update the status of whether a giv can derive other givs.
|
||
|
||
We need to do something special if there is or may be an update to the biv
|
||
between the time the giv is defined and the time it is used to derive
|
||
another giv.
|
||
|
||
In addition, a giv that is only conditionally set is not allowed to
|
||
derive another giv once a label has been passed.
|
||
|
||
The cases we look at are when a label or an update to a biv is passed. */
|
||
|
||
static void
|
||
update_giv_derive (p)
|
||
rtx p;
|
||
{
|
||
struct iv_class *bl;
|
||
struct induction *biv, *giv;
|
||
rtx tem;
|
||
int dummy;
|
||
|
||
/* Search all IV classes, then all bivs, and finally all givs.
|
||
|
||
There are three cases we are concerned with. First we have the situation
|
||
of a giv that is only updated conditionally. In that case, it may not
|
||
derive any givs after a label is passed.
|
||
|
||
The second case is when a biv update occurs, or may occur, after the
|
||
definition of a giv. For certain biv updates (see below) that are
|
||
known to occur between the giv definition and use, we can adjust the
|
||
giv definition. For others, or when the biv update is conditional,
|
||
we must prevent the giv from deriving any other givs. There are two
|
||
sub-cases within this case.
|
||
|
||
If this is a label, we are concerned with any biv update that is done
|
||
conditionally, since it may be done after the giv is defined followed by
|
||
a branch here (actually, we need to pass both a jump and a label, but
|
||
this extra tracking doesn't seem worth it).
|
||
|
||
If this is a jump, we are concerned about any biv update that may be
|
||
executed multiple times. We are actually only concerned about
|
||
backward jumps, but it is probably not worth performing the test
|
||
on the jump again here.
|
||
|
||
If this is a biv update, we must adjust the giv status to show that a
|
||
subsequent biv update was performed. If this adjustment cannot be done,
|
||
the giv cannot derive further givs. */
|
||
|
||
for (bl = loop_iv_list; bl; bl = bl->next)
|
||
for (biv = bl->biv; biv; biv = biv->next_iv)
|
||
if (GET_CODE (p) == CODE_LABEL || GET_CODE (p) == JUMP_INSN
|
||
|| biv->insn == p)
|
||
{
|
||
for (giv = bl->giv; giv; giv = giv->next_iv)
|
||
{
|
||
/* If cant_derive is already true, there is no point in
|
||
checking all of these conditions again. */
|
||
if (giv->cant_derive)
|
||
continue;
|
||
|
||
/* If this giv is conditionally set and we have passed a label,
|
||
it cannot derive anything. */
|
||
if (GET_CODE (p) == CODE_LABEL && ! giv->always_computable)
|
||
giv->cant_derive = 1;
|
||
|
||
/* Skip givs that have mult_val == 0, since
|
||
they are really invariants. Also skip those that are
|
||
replaceable, since we know their lifetime doesn't contain
|
||
any biv update. */
|
||
else if (giv->mult_val == const0_rtx || giv->replaceable)
|
||
continue;
|
||
|
||
/* The only way we can allow this giv to derive another
|
||
is if this is a biv increment and we can form the product
|
||
of biv->add_val and giv->mult_val. In this case, we will
|
||
be able to compute a compensation. */
|
||
else if (biv->insn == p)
|
||
{
|
||
tem = 0;
|
||
|
||
if (biv->mult_val == const1_rtx)
|
||
tem = simplify_giv_expr (gen_rtx_MULT (giv->mode,
|
||
biv->add_val,
|
||
giv->mult_val),
|
||
&dummy);
|
||
|
||
if (tem && giv->derive_adjustment)
|
||
tem = simplify_giv_expr (gen_rtx_PLUS (giv->mode, tem,
|
||
giv->derive_adjustment),
|
||
&dummy);
|
||
if (tem)
|
||
giv->derive_adjustment = tem;
|
||
else
|
||
giv->cant_derive = 1;
|
||
}
|
||
else if ((GET_CODE (p) == CODE_LABEL && ! biv->always_computable)
|
||
|| (GET_CODE (p) == JUMP_INSN && biv->maybe_multiple))
|
||
giv->cant_derive = 1;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Check whether an insn is an increment legitimate for a basic induction var.
|
||
X is the source of insn P, or a part of it.
|
||
MODE is the mode in which X should be interpreted.
|
||
|
||
DEST_REG is the putative biv, also the destination of the insn.
|
||
We accept patterns of these forms:
|
||
REG = REG + INVARIANT (includes REG = REG - CONSTANT)
|
||
REG = INVARIANT + REG
|
||
|
||
If X is suitable, we return 1, set *MULT_VAL to CONST1_RTX,
|
||
and store the additive term into *INC_VAL.
|
||
|
||
If X is an assignment of an invariant into DEST_REG, we set
|
||
*MULT_VAL to CONST0_RTX, and store the invariant into *INC_VAL.
|
||
|
||
We also want to detect a BIV when it corresponds to a variable
|
||
whose mode was promoted via PROMOTED_MODE. In that case, an increment
|
||
of the variable may be a PLUS that adds a SUBREG of that variable to
|
||
an invariant and then sign- or zero-extends the result of the PLUS
|
||
into the variable.
|
||
|
||
Most GIVs in such cases will be in the promoted mode, since that is the
|
||
probably the natural computation mode (and almost certainly the mode
|
||
used for addresses) on the machine. So we view the pseudo-reg containing
|
||
the variable as the BIV, as if it were simply incremented.
|
||
|
||
Note that treating the entire pseudo as a BIV will result in making
|
||
simple increments to any GIVs based on it. However, if the variable
|
||
overflows in its declared mode but not its promoted mode, the result will
|
||
be incorrect. This is acceptable if the variable is signed, since
|
||
overflows in such cases are undefined, but not if it is unsigned, since
|
||
those overflows are defined. So we only check for SIGN_EXTEND and
|
||
not ZERO_EXTEND.
|
||
|
||
If we cannot find a biv, we return 0. */
|
||
|
||
static int
|
||
basic_induction_var (x, mode, dest_reg, p, inc_val, mult_val)
|
||
register rtx x;
|
||
enum machine_mode mode;
|
||
rtx p;
|
||
rtx dest_reg;
|
||
rtx *inc_val;
|
||
rtx *mult_val;
|
||
{
|
||
register enum rtx_code code;
|
||
rtx arg;
|
||
rtx insn, set = 0;
|
||
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case PLUS:
|
||
if (XEXP (x, 0) == dest_reg
|
||
|| (GET_CODE (XEXP (x, 0)) == SUBREG
|
||
&& SUBREG_PROMOTED_VAR_P (XEXP (x, 0))
|
||
&& SUBREG_REG (XEXP (x, 0)) == dest_reg))
|
||
arg = XEXP (x, 1);
|
||
else if (XEXP (x, 1) == dest_reg
|
||
|| (GET_CODE (XEXP (x, 1)) == SUBREG
|
||
&& SUBREG_PROMOTED_VAR_P (XEXP (x, 1))
|
||
&& SUBREG_REG (XEXP (x, 1)) == dest_reg))
|
||
arg = XEXP (x, 0);
|
||
else
|
||
return 0;
|
||
|
||
if (invariant_p (arg) != 1)
|
||
return 0;
|
||
|
||
*inc_val = convert_modes (GET_MODE (dest_reg), GET_MODE (x), arg, 0);
|
||
*mult_val = const1_rtx;
|
||
return 1;
|
||
|
||
case SUBREG:
|
||
/* If this is a SUBREG for a promoted variable, check the inner
|
||
value. */
|
||
if (SUBREG_PROMOTED_VAR_P (x))
|
||
return basic_induction_var (SUBREG_REG (x), GET_MODE (SUBREG_REG (x)),
|
||
dest_reg, p, inc_val, mult_val);
|
||
return 0;
|
||
|
||
case REG:
|
||
/* If this register is assigned in the previous insn, look at its
|
||
source, but don't go outside the loop or past a label. */
|
||
|
||
for (insn = PREV_INSN (p);
|
||
(insn && GET_CODE (insn) == NOTE
|
||
&& NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG);
|
||
insn = PREV_INSN (insn))
|
||
;
|
||
|
||
if (insn)
|
||
set = single_set (insn);
|
||
|
||
if (set != 0
|
||
&& (SET_DEST (set) == x
|
||
|| (GET_CODE (SET_DEST (set)) == SUBREG
|
||
&& (GET_MODE_SIZE (GET_MODE (SET_DEST (set)))
|
||
<= UNITS_PER_WORD)
|
||
&& SUBREG_REG (SET_DEST (set)) == x)))
|
||
return basic_induction_var (SET_SRC (set),
|
||
(GET_MODE (SET_SRC (set)) == VOIDmode
|
||
? GET_MODE (x)
|
||
: GET_MODE (SET_SRC (set))),
|
||
dest_reg, insn,
|
||
inc_val, mult_val);
|
||
/* ... fall through ... */
|
||
|
||
/* Can accept constant setting of biv only when inside inner most loop.
|
||
Otherwise, a biv of an inner loop may be incorrectly recognized
|
||
as a biv of the outer loop,
|
||
causing code to be moved INTO the inner loop. */
|
||
case MEM:
|
||
if (invariant_p (x) != 1)
|
||
return 0;
|
||
case CONST_INT:
|
||
case SYMBOL_REF:
|
||
case CONST:
|
||
/* convert_modes aborts if we try to convert to or from CCmode, so just
|
||
exclude that case. It is very unlikely that a condition code value
|
||
would be a useful iterator anyways. */
|
||
if (loops_enclosed == 1
|
||
&& GET_MODE_CLASS (mode) != MODE_CC
|
||
&& GET_MODE_CLASS (GET_MODE (dest_reg)) != MODE_CC)
|
||
{
|
||
/* Possible bug here? Perhaps we don't know the mode of X. */
|
||
*inc_val = convert_modes (GET_MODE (dest_reg), mode, x, 0);
|
||
*mult_val = const0_rtx;
|
||
return 1;
|
||
}
|
||
else
|
||
return 0;
|
||
|
||
case SIGN_EXTEND:
|
||
return basic_induction_var (XEXP (x, 0), GET_MODE (XEXP (x, 0)),
|
||
dest_reg, p, inc_val, mult_val);
|
||
case ASHIFTRT:
|
||
/* Similar, since this can be a sign extension. */
|
||
for (insn = PREV_INSN (p);
|
||
(insn && GET_CODE (insn) == NOTE
|
||
&& NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG);
|
||
insn = PREV_INSN (insn))
|
||
;
|
||
|
||
if (insn)
|
||
set = single_set (insn);
|
||
|
||
if (set && SET_DEST (set) == XEXP (x, 0)
|
||
&& GET_CODE (XEXP (x, 1)) == CONST_INT
|
||
&& INTVAL (XEXP (x, 1)) >= 0
|
||
&& GET_CODE (SET_SRC (set)) == ASHIFT
|
||
&& XEXP (x, 1) == XEXP (SET_SRC (set), 1))
|
||
return basic_induction_var (XEXP (SET_SRC (set), 0),
|
||
GET_MODE (XEXP (x, 0)),
|
||
dest_reg, insn, inc_val, mult_val);
|
||
return 0;
|
||
|
||
default:
|
||
return 0;
|
||
}
|
||
}
|
||
|
||
/* A general induction variable (giv) is any quantity that is a linear
|
||
function of a basic induction variable,
|
||
i.e. giv = biv * mult_val + add_val.
|
||
The coefficients can be any loop invariant quantity.
|
||
A giv need not be computed directly from the biv;
|
||
it can be computed by way of other givs. */
|
||
|
||
/* Determine whether X computes a giv.
|
||
If it does, return a nonzero value
|
||
which is the benefit from eliminating the computation of X;
|
||
set *SRC_REG to the register of the biv that it is computed from;
|
||
set *ADD_VAL and *MULT_VAL to the coefficients,
|
||
such that the value of X is biv * mult + add; */
|
||
|
||
static int
|
||
general_induction_var (x, src_reg, add_val, mult_val)
|
||
rtx x;
|
||
rtx *src_reg;
|
||
rtx *add_val;
|
||
rtx *mult_val;
|
||
{
|
||
rtx orig_x = x;
|
||
int benefit = 0;
|
||
char *storage;
|
||
|
||
/* If this is an invariant, forget it, it isn't a giv. */
|
||
if (invariant_p (x) == 1)
|
||
return 0;
|
||
|
||
/* See if the expression could be a giv and get its form.
|
||
Mark our place on the obstack in case we don't find a giv. */
|
||
storage = (char *) oballoc (0);
|
||
x = simplify_giv_expr (x, &benefit);
|
||
if (x == 0)
|
||
{
|
||
obfree (storage);
|
||
return 0;
|
||
}
|
||
|
||
switch (GET_CODE (x))
|
||
{
|
||
case USE:
|
||
case CONST_INT:
|
||
/* Since this is now an invariant and wasn't before, it must be a giv
|
||
with MULT_VAL == 0. It doesn't matter which BIV we associate this
|
||
with. */
|
||
*src_reg = loop_iv_list->biv->dest_reg;
|
||
*mult_val = const0_rtx;
|
||
*add_val = x;
|
||
break;
|
||
|
||
case REG:
|
||
/* This is equivalent to a BIV. */
|
||
*src_reg = x;
|
||
*mult_val = const1_rtx;
|
||
*add_val = const0_rtx;
|
||
break;
|
||
|
||
case PLUS:
|
||
/* Either (plus (biv) (invar)) or
|
||
(plus (mult (biv) (invar_1)) (invar_2)). */
|
||
if (GET_CODE (XEXP (x, 0)) == MULT)
|
||
{
|
||
*src_reg = XEXP (XEXP (x, 0), 0);
|
||
*mult_val = XEXP (XEXP (x, 0), 1);
|
||
}
|
||
else
|
||
{
|
||
*src_reg = XEXP (x, 0);
|
||
*mult_val = const1_rtx;
|
||
}
|
||
*add_val = XEXP (x, 1);
|
||
break;
|
||
|
||
case MULT:
|
||
/* ADD_VAL is zero. */
|
||
*src_reg = XEXP (x, 0);
|
||
*mult_val = XEXP (x, 1);
|
||
*add_val = const0_rtx;
|
||
break;
|
||
|
||
default:
|
||
abort ();
|
||
}
|
||
|
||
/* Remove any enclosing USE from ADD_VAL and MULT_VAL (there will be
|
||
unless they are CONST_INT). */
|
||
if (GET_CODE (*add_val) == USE)
|
||
*add_val = XEXP (*add_val, 0);
|
||
if (GET_CODE (*mult_val) == USE)
|
||
*mult_val = XEXP (*mult_val, 0);
|
||
|
||
benefit += rtx_cost (orig_x, SET);
|
||
|
||
/* Always return some benefit if this is a giv so it will be detected
|
||
as such. This allows elimination of bivs that might otherwise
|
||
not be eliminated. */
|
||
return benefit == 0 ? 1 : benefit;
|
||
}
|
||
|
||
/* Given an expression, X, try to form it as a linear function of a biv.
|
||
We will canonicalize it to be of the form
|
||
(plus (mult (BIV) (invar_1))
|
||
(invar_2))
|
||
with possible degeneracies.
|
||
|
||
The invariant expressions must each be of a form that can be used as a
|
||
machine operand. We surround then with a USE rtx (a hack, but localized
|
||
and certainly unambiguous!) if not a CONST_INT for simplicity in this
|
||
routine; it is the caller's responsibility to strip them.
|
||
|
||
If no such canonicalization is possible (i.e., two biv's are used or an
|
||
expression that is neither invariant nor a biv or giv), this routine
|
||
returns 0.
|
||
|
||
For a non-zero return, the result will have a code of CONST_INT, USE,
|
||
REG (for a BIV), PLUS, or MULT. No other codes will occur.
|
||
|
||
*BENEFIT will be incremented by the benefit of any sub-giv encountered. */
|
||
|
||
static rtx
|
||
simplify_giv_expr (x, benefit)
|
||
rtx x;
|
||
int *benefit;
|
||
{
|
||
enum machine_mode mode = GET_MODE (x);
|
||
rtx arg0, arg1;
|
||
rtx tem;
|
||
|
||
/* If this is not an integer mode, or if we cannot do arithmetic in this
|
||
mode, this can't be a giv. */
|
||
if (mode != VOIDmode
|
||
&& (GET_MODE_CLASS (mode) != MODE_INT
|
||
|| GET_MODE_BITSIZE (mode) > HOST_BITS_PER_WIDE_INT))
|
||
return 0;
|
||
|
||
switch (GET_CODE (x))
|
||
{
|
||
case PLUS:
|
||
arg0 = simplify_giv_expr (XEXP (x, 0), benefit);
|
||
arg1 = simplify_giv_expr (XEXP (x, 1), benefit);
|
||
if (arg0 == 0 || arg1 == 0)
|
||
return 0;
|
||
|
||
/* Put constant last, CONST_INT last if both constant. */
|
||
if ((GET_CODE (arg0) == USE
|
||
|| GET_CODE (arg0) == CONST_INT)
|
||
&& GET_CODE (arg1) != CONST_INT)
|
||
tem = arg0, arg0 = arg1, arg1 = tem;
|
||
|
||
/* Handle addition of zero, then addition of an invariant. */
|
||
if (arg1 == const0_rtx)
|
||
return arg0;
|
||
else if (GET_CODE (arg1) == CONST_INT || GET_CODE (arg1) == USE)
|
||
switch (GET_CODE (arg0))
|
||
{
|
||
case CONST_INT:
|
||
case USE:
|
||
/* Both invariant. Only valid if sum is machine operand.
|
||
First strip off possible USE on the operands. */
|
||
if (GET_CODE (arg0) == USE)
|
||
arg0 = XEXP (arg0, 0);
|
||
|
||
if (GET_CODE (arg1) == USE)
|
||
arg1 = XEXP (arg1, 0);
|
||
|
||
tem = 0;
|
||
if (CONSTANT_P (arg0) && GET_CODE (arg1) == CONST_INT)
|
||
{
|
||
tem = plus_constant (arg0, INTVAL (arg1));
|
||
if (GET_CODE (tem) != CONST_INT)
|
||
tem = gen_rtx_USE (mode, tem);
|
||
}
|
||
else
|
||
{
|
||
/* Adding two invariants must result in an invariant,
|
||
so enclose addition operation inside a USE and
|
||
return it. */
|
||
tem = gen_rtx_USE (mode, gen_rtx_PLUS (mode, arg0, arg1));
|
||
}
|
||
|
||
return tem;
|
||
|
||
case REG:
|
||
case MULT:
|
||
/* biv + invar or mult + invar. Return sum. */
|
||
return gen_rtx_PLUS (mode, arg0, arg1);
|
||
|
||
case PLUS:
|
||
/* (a + invar_1) + invar_2. Associate. */
|
||
return simplify_giv_expr (gen_rtx_PLUS (mode,
|
||
XEXP (arg0, 0),
|
||
gen_rtx_PLUS (mode,
|
||
XEXP (arg0, 1), arg1)),
|
||
benefit);
|
||
|
||
default:
|
||
abort ();
|
||
}
|
||
|
||
/* Each argument must be either REG, PLUS, or MULT. Convert REG to
|
||
MULT to reduce cases. */
|
||
if (GET_CODE (arg0) == REG)
|
||
arg0 = gen_rtx_MULT (mode, arg0, const1_rtx);
|
||
if (GET_CODE (arg1) == REG)
|
||
arg1 = gen_rtx_MULT (mode, arg1, const1_rtx);
|
||
|
||
/* Now have PLUS + PLUS, PLUS + MULT, MULT + PLUS, or MULT + MULT.
|
||
Put a MULT first, leaving PLUS + PLUS, MULT + PLUS, or MULT + MULT.
|
||
Recurse to associate the second PLUS. */
|
||
if (GET_CODE (arg1) == MULT)
|
||
tem = arg0, arg0 = arg1, arg1 = tem;
|
||
|
||
if (GET_CODE (arg1) == PLUS)
|
||
return simplify_giv_expr (gen_rtx_PLUS (mode,
|
||
gen_rtx_PLUS (mode, arg0,
|
||
XEXP (arg1, 0)),
|
||
XEXP (arg1, 1)),
|
||
benefit);
|
||
|
||
/* Now must have MULT + MULT. Distribute if same biv, else not giv. */
|
||
if (GET_CODE (arg0) != MULT || GET_CODE (arg1) != MULT)
|
||
abort ();
|
||
|
||
if (XEXP (arg0, 0) != XEXP (arg1, 0))
|
||
return 0;
|
||
|
||
return simplify_giv_expr (gen_rtx_MULT (mode,
|
||
XEXP (arg0, 0),
|
||
gen_rtx_PLUS (mode,
|
||
XEXP (arg0, 1),
|
||
XEXP (arg1, 1))),
|
||
benefit);
|
||
|
||
case MINUS:
|
||
/* Handle "a - b" as "a + b * (-1)". */
|
||
return simplify_giv_expr (gen_rtx_PLUS (mode,
|
||
XEXP (x, 0),
|
||
gen_rtx_MULT (mode, XEXP (x, 1),
|
||
constm1_rtx)),
|
||
benefit);
|
||
|
||
case MULT:
|
||
arg0 = simplify_giv_expr (XEXP (x, 0), benefit);
|
||
arg1 = simplify_giv_expr (XEXP (x, 1), benefit);
|
||
if (arg0 == 0 || arg1 == 0)
|
||
return 0;
|
||
|
||
/* Put constant last, CONST_INT last if both constant. */
|
||
if ((GET_CODE (arg0) == USE || GET_CODE (arg0) == CONST_INT)
|
||
&& GET_CODE (arg1) != CONST_INT)
|
||
tem = arg0, arg0 = arg1, arg1 = tem;
|
||
|
||
/* If second argument is not now constant, not giv. */
|
||
if (GET_CODE (arg1) != USE && GET_CODE (arg1) != CONST_INT)
|
||
return 0;
|
||
|
||
/* Handle multiply by 0 or 1. */
|
||
if (arg1 == const0_rtx)
|
||
return const0_rtx;
|
||
|
||
else if (arg1 == const1_rtx)
|
||
return arg0;
|
||
|
||
switch (GET_CODE (arg0))
|
||
{
|
||
case REG:
|
||
/* biv * invar. Done. */
|
||
return gen_rtx_MULT (mode, arg0, arg1);
|
||
|
||
case CONST_INT:
|
||
/* Product of two constants. */
|
||
return GEN_INT (INTVAL (arg0) * INTVAL (arg1));
|
||
|
||
case USE:
|
||
/* invar * invar. Not giv. */
|
||
return 0;
|
||
|
||
case MULT:
|
||
/* (a * invar_1) * invar_2. Associate. */
|
||
return simplify_giv_expr (gen_rtx_MULT (mode, XEXP (arg0, 0),
|
||
gen_rtx_MULT (mode,
|
||
XEXP (arg0, 1),
|
||
arg1)),
|
||
benefit);
|
||
|
||
case PLUS:
|
||
/* (a + invar_1) * invar_2. Distribute. */
|
||
return simplify_giv_expr (gen_rtx_PLUS (mode,
|
||
gen_rtx_MULT (mode,
|
||
XEXP (arg0, 0),
|
||
arg1),
|
||
gen_rtx_MULT (mode,
|
||
XEXP (arg0, 1),
|
||
arg1)),
|
||
benefit);
|
||
|
||
default:
|
||
abort ();
|
||
}
|
||
|
||
case ASHIFT:
|
||
/* Shift by constant is multiply by power of two. */
|
||
if (GET_CODE (XEXP (x, 1)) != CONST_INT)
|
||
return 0;
|
||
|
||
return simplify_giv_expr (gen_rtx_MULT (mode,
|
||
XEXP (x, 0),
|
||
GEN_INT ((HOST_WIDE_INT) 1
|
||
<< INTVAL (XEXP (x, 1)))),
|
||
benefit);
|
||
|
||
case NEG:
|
||
/* "-a" is "a * (-1)" */
|
||
return simplify_giv_expr (gen_rtx_MULT (mode, XEXP (x, 0), constm1_rtx),
|
||
benefit);
|
||
|
||
case NOT:
|
||
/* "~a" is "-a - 1". Silly, but easy. */
|
||
return simplify_giv_expr (gen_rtx_MINUS (mode,
|
||
gen_rtx_NEG (mode, XEXP (x, 0)),
|
||
const1_rtx),
|
||
benefit);
|
||
|
||
case USE:
|
||
/* Already in proper form for invariant. */
|
||
return x;
|
||
|
||
case REG:
|
||
/* If this is a new register, we can't deal with it. */
|
||
if (REGNO (x) >= max_reg_before_loop)
|
||
return 0;
|
||
|
||
/* Check for biv or giv. */
|
||
switch (reg_iv_type[REGNO (x)])
|
||
{
|
||
case BASIC_INDUCT:
|
||
return x;
|
||
case GENERAL_INDUCT:
|
||
{
|
||
struct induction *v = reg_iv_info[REGNO (x)];
|
||
|
||
/* Form expression from giv and add benefit. Ensure this giv
|
||
can derive another and subtract any needed adjustment if so. */
|
||
*benefit += v->benefit;
|
||
if (v->cant_derive)
|
||
return 0;
|
||
|
||
tem = gen_rtx_PLUS (mode, gen_rtx_MULT (mode, v->src_reg,
|
||
v->mult_val),
|
||
v->add_val);
|
||
if (v->derive_adjustment)
|
||
tem = gen_rtx_MINUS (mode, tem, v->derive_adjustment);
|
||
return simplify_giv_expr (tem, benefit);
|
||
}
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
/* Fall through to general case. */
|
||
default:
|
||
/* If invariant, return as USE (unless CONST_INT).
|
||
Otherwise, not giv. */
|
||
if (GET_CODE (x) == USE)
|
||
x = XEXP (x, 0);
|
||
|
||
if (invariant_p (x) == 1)
|
||
{
|
||
if (GET_CODE (x) == CONST_INT)
|
||
return x;
|
||
else
|
||
return gen_rtx_USE (mode, x);
|
||
}
|
||
else
|
||
return 0;
|
||
}
|
||
}
|
||
|
||
/* Help detect a giv that is calculated by several consecutive insns;
|
||
for example,
|
||
giv = biv * M
|
||
giv = giv + A
|
||
The caller has already identified the first insn P as having a giv as dest;
|
||
we check that all other insns that set the same register follow
|
||
immediately after P, that they alter nothing else,
|
||
and that the result of the last is still a giv.
|
||
|
||
The value is 0 if the reg set in P is not really a giv.
|
||
Otherwise, the value is the amount gained by eliminating
|
||
all the consecutive insns that compute the value.
|
||
|
||
FIRST_BENEFIT is the amount gained by eliminating the first insn, P.
|
||
SRC_REG is the reg of the biv; DEST_REG is the reg of the giv.
|
||
|
||
The coefficients of the ultimate giv value are stored in
|
||
*MULT_VAL and *ADD_VAL. */
|
||
|
||
static int
|
||
consec_sets_giv (first_benefit, p, src_reg, dest_reg,
|
||
add_val, mult_val)
|
||
int first_benefit;
|
||
rtx p;
|
||
rtx src_reg;
|
||
rtx dest_reg;
|
||
rtx *add_val;
|
||
rtx *mult_val;
|
||
{
|
||
int count;
|
||
enum rtx_code code;
|
||
int benefit;
|
||
rtx temp;
|
||
rtx set;
|
||
|
||
/* Indicate that this is a giv so that we can update the value produced in
|
||
each insn of the multi-insn sequence.
|
||
|
||
This induction structure will be used only by the call to
|
||
general_induction_var below, so we can allocate it on our stack.
|
||
If this is a giv, our caller will replace the induct var entry with
|
||
a new induction structure. */
|
||
struct induction *v
|
||
= (struct induction *) alloca (sizeof (struct induction));
|
||
v->src_reg = src_reg;
|
||
v->mult_val = *mult_val;
|
||
v->add_val = *add_val;
|
||
v->benefit = first_benefit;
|
||
v->cant_derive = 0;
|
||
v->derive_adjustment = 0;
|
||
|
||
reg_iv_type[REGNO (dest_reg)] = GENERAL_INDUCT;
|
||
reg_iv_info[REGNO (dest_reg)] = v;
|
||
|
||
count = n_times_set[REGNO (dest_reg)] - 1;
|
||
|
||
while (count > 0)
|
||
{
|
||
p = NEXT_INSN (p);
|
||
code = GET_CODE (p);
|
||
|
||
/* If libcall, skip to end of call sequence. */
|
||
if (code == INSN && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX)))
|
||
p = XEXP (temp, 0);
|
||
|
||
if (code == INSN
|
||
&& (set = single_set (p))
|
||
&& GET_CODE (SET_DEST (set)) == REG
|
||
&& SET_DEST (set) == dest_reg
|
||
&& ((benefit = general_induction_var (SET_SRC (set), &src_reg,
|
||
add_val, mult_val))
|
||
/* Giv created by equivalent expression. */
|
||
|| ((temp = find_reg_note (p, REG_EQUAL, NULL_RTX))
|
||
&& (benefit = general_induction_var (XEXP (temp, 0), &src_reg,
|
||
add_val, mult_val))))
|
||
&& src_reg == v->src_reg)
|
||
{
|
||
if (find_reg_note (p, REG_RETVAL, NULL_RTX))
|
||
benefit += libcall_benefit (p);
|
||
|
||
count--;
|
||
v->mult_val = *mult_val;
|
||
v->add_val = *add_val;
|
||
v->benefit = benefit;
|
||
}
|
||
else if (code != NOTE)
|
||
{
|
||
/* Allow insns that set something other than this giv to a
|
||
constant. Such insns are needed on machines which cannot
|
||
include long constants and should not disqualify a giv. */
|
||
if (code == INSN
|
||
&& (set = single_set (p))
|
||
&& SET_DEST (set) != dest_reg
|
||
&& CONSTANT_P (SET_SRC (set)))
|
||
continue;
|
||
|
||
reg_iv_type[REGNO (dest_reg)] = UNKNOWN_INDUCT;
|
||
return 0;
|
||
}
|
||
}
|
||
|
||
return v->benefit;
|
||
}
|
||
|
||
/* Return an rtx, if any, that expresses giv G2 as a function of the register
|
||
represented by G1. If no such expression can be found, or it is clear that
|
||
it cannot possibly be a valid address, 0 is returned.
|
||
|
||
To perform the computation, we note that
|
||
G1 = a * v + b and
|
||
G2 = c * v + d
|
||
where `v' is the biv.
|
||
|
||
So G2 = (c/a) * G1 + (d - b*c/a) */
|
||
|
||
#ifdef ADDRESS_COST
|
||
static rtx
|
||
express_from (g1, g2)
|
||
struct induction *g1, *g2;
|
||
{
|
||
rtx mult, add;
|
||
|
||
/* The value that G1 will be multiplied by must be a constant integer. Also,
|
||
the only chance we have of getting a valid address is if b*c/a (see above
|
||
for notation) is also an integer. */
|
||
if (GET_CODE (g1->mult_val) != CONST_INT
|
||
|| GET_CODE (g2->mult_val) != CONST_INT
|
||
|| GET_CODE (g1->add_val) != CONST_INT
|
||
|| g1->mult_val == const0_rtx
|
||
|| INTVAL (g2->mult_val) % INTVAL (g1->mult_val) != 0)
|
||
return 0;
|
||
|
||
mult = GEN_INT (INTVAL (g2->mult_val) / INTVAL (g1->mult_val));
|
||
add = plus_constant (g2->add_val, - INTVAL (g1->add_val) * INTVAL (mult));
|
||
|
||
/* Form simplified final result. */
|
||
if (mult == const0_rtx)
|
||
return add;
|
||
else if (mult == const1_rtx)
|
||
mult = g1->dest_reg;
|
||
else
|
||
mult = gen_rtx_MULT (g2->mode, g1->dest_reg, mult);
|
||
|
||
if (add == const0_rtx)
|
||
return mult;
|
||
else
|
||
return gen_rtx_PLUS (g2->mode, mult, add);
|
||
}
|
||
#endif
|
||
|
||
/* Return 1 if giv G2 can be combined with G1. This means that G2 can use
|
||
(either directly or via an address expression) a register used to represent
|
||
G1. Set g2->new_reg to a represtation of G1 (normally just
|
||
g1->dest_reg). */
|
||
|
||
static int
|
||
combine_givs_p (g1, g2)
|
||
struct induction *g1, *g2;
|
||
{
|
||
#ifdef ADDRESS_COST
|
||
rtx tem;
|
||
#endif
|
||
|
||
/* If these givs are identical, they can be combined. */
|
||
if (rtx_equal_p (g1->mult_val, g2->mult_val)
|
||
&& rtx_equal_p (g1->add_val, g2->add_val))
|
||
{
|
||
g2->new_reg = g1->dest_reg;
|
||
return 1;
|
||
}
|
||
|
||
#ifdef ADDRESS_COST
|
||
/* If G2 can be expressed as a function of G1 and that function is valid
|
||
as an address and no more expensive than using a register for G2,
|
||
the expression of G2 in terms of G1 can be used. */
|
||
if (g2->giv_type == DEST_ADDR
|
||
&& (tem = express_from (g1, g2)) != 0
|
||
&& memory_address_p (g2->mem_mode, tem)
|
||
&& ADDRESS_COST (tem) <= ADDRESS_COST (*g2->location))
|
||
{
|
||
g2->new_reg = tem;
|
||
return 1;
|
||
}
|
||
#endif
|
||
|
||
return 0;
|
||
}
|
||
|
||
#ifdef GIV_SORT_CRITERION
|
||
/* Compare two givs and sort the most desirable one for combinations first.
|
||
This is used only in one qsort call below. */
|
||
|
||
static int
|
||
giv_sort (x, y)
|
||
struct induction **x, **y;
|
||
{
|
||
GIV_SORT_CRITERION (*x, *y);
|
||
|
||
return 0;
|
||
}
|
||
#endif
|
||
|
||
/* Check all pairs of givs for iv_class BL and see if any can be combined with
|
||
any other. If so, point SAME to the giv combined with and set NEW_REG to
|
||
be an expression (in terms of the other giv's DEST_REG) equivalent to the
|
||
giv. Also, update BENEFIT and related fields for cost/benefit analysis. */
|
||
|
||
static void
|
||
combine_givs (bl)
|
||
struct iv_class *bl;
|
||
{
|
||
struct induction *g1, *g2, **giv_array;
|
||
int i, j, giv_count, pass;
|
||
|
||
/* Count givs, because bl->giv_count is incorrect here. */
|
||
giv_count = 0;
|
||
for (g1 = bl->giv; g1; g1 = g1->next_iv)
|
||
giv_count++;
|
||
|
||
giv_array
|
||
= (struct induction **) alloca (giv_count * sizeof (struct induction *));
|
||
i = 0;
|
||
for (g1 = bl->giv; g1; g1 = g1->next_iv)
|
||
giv_array[i++] = g1;
|
||
|
||
#ifdef GIV_SORT_CRITERION
|
||
/* Sort the givs if GIV_SORT_CRITERION is defined.
|
||
This is usually defined for processors which lack
|
||
negative register offsets so more givs may be combined. */
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "%d givs counted, sorting...\n", giv_count);
|
||
|
||
qsort (giv_array, giv_count, sizeof (struct induction *), giv_sort);
|
||
#endif
|
||
|
||
for (i = 0; i < giv_count; i++)
|
||
{
|
||
g1 = giv_array[i];
|
||
for (pass = 0; pass <= 1; pass++)
|
||
for (j = 0; j < giv_count; j++)
|
||
{
|
||
g2 = giv_array[j];
|
||
if (g1 != g2
|
||
/* First try to combine with replaceable givs, then all givs. */
|
||
&& (g1->replaceable || pass == 1)
|
||
/* If either has already been combined or is to be ignored, can't
|
||
combine. */
|
||
&& ! g1->ignore && ! g2->ignore && ! g1->same && ! g2->same
|
||
/* If something has been based on G2, G2 cannot itself be based
|
||
on something else. */
|
||
&& ! g2->combined_with
|
||
&& combine_givs_p (g1, g2))
|
||
{
|
||
/* g2->new_reg set by `combine_givs_p' */
|
||
g2->same = g1;
|
||
g1->combined_with = 1;
|
||
|
||
/* If one of these givs is a DEST_REG that was only used
|
||
once, by the other giv, this is actually a single use.
|
||
The DEST_REG has the correct cost, while the other giv
|
||
counts the REG use too often. */
|
||
if (g2->giv_type == DEST_REG
|
||
&& n_times_used[REGNO (g2->dest_reg)] == 1
|
||
&& reg_mentioned_p (g2->dest_reg, PATTERN (g1->insn)))
|
||
g1->benefit = g2->benefit;
|
||
else if (g1->giv_type != DEST_REG
|
||
|| n_times_used[REGNO (g1->dest_reg)] != 1
|
||
|| ! reg_mentioned_p (g1->dest_reg,
|
||
PATTERN (g2->insn)))
|
||
{
|
||
g1->benefit += g2->benefit;
|
||
g1->times_used += g2->times_used;
|
||
}
|
||
/* ??? The new final_[bg]iv_value code does a much better job
|
||
of finding replaceable giv's, and hence this code may no
|
||
longer be necessary. */
|
||
if (! g2->replaceable && REG_USERVAR_P (g2->dest_reg))
|
||
g1->benefit -= copy_cost;
|
||
g1->lifetime += g2->lifetime;
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "giv at %d combined with giv at %d\n",
|
||
INSN_UID (g2->insn), INSN_UID (g1->insn));
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* EMIT code before INSERT_BEFORE to set REG = B * M + A. */
|
||
|
||
void
|
||
emit_iv_add_mult (b, m, a, reg, insert_before)
|
||
rtx b; /* initial value of basic induction variable */
|
||
rtx m; /* multiplicative constant */
|
||
rtx a; /* additive constant */
|
||
rtx reg; /* destination register */
|
||
rtx insert_before;
|
||
{
|
||
rtx seq;
|
||
rtx result;
|
||
|
||
/* Prevent unexpected sharing of these rtx. */
|
||
a = copy_rtx (a);
|
||
b = copy_rtx (b);
|
||
|
||
/* Increase the lifetime of any invariants moved further in code. */
|
||
update_reg_last_use (a, insert_before);
|
||
update_reg_last_use (b, insert_before);
|
||
update_reg_last_use (m, insert_before);
|
||
|
||
start_sequence ();
|
||
result = expand_mult_add (b, reg, m, a, GET_MODE (reg), 0);
|
||
if (reg != result)
|
||
emit_move_insn (reg, result);
|
||
seq = gen_sequence ();
|
||
end_sequence ();
|
||
|
||
emit_insn_before (seq, insert_before);
|
||
|
||
/* It is entirely possible that the expansion created lots of new
|
||
registers. Iterate over the sequence we just created and
|
||
record them all. */
|
||
|
||
if (GET_CODE (seq) == SEQUENCE)
|
||
{
|
||
int i;
|
||
for (i = 0; i < XVECLEN (seq, 0); ++i)
|
||
{
|
||
rtx set = single_set (XVECEXP (seq, 0, i));
|
||
if (set && GET_CODE (SET_DEST (set)) == REG)
|
||
record_base_value (REGNO (SET_DEST (set)), SET_SRC (set), 0);
|
||
}
|
||
}
|
||
else if (GET_CODE (seq) == SET
|
||
&& GET_CODE (SET_DEST (seq)) == REG)
|
||
record_base_value (REGNO (SET_DEST (seq)), SET_SRC (seq), 0);
|
||
}
|
||
|
||
/* Test whether A * B can be computed without
|
||
an actual multiply insn. Value is 1 if so. */
|
||
|
||
static int
|
||
product_cheap_p (a, b)
|
||
rtx a;
|
||
rtx b;
|
||
{
|
||
int i;
|
||
rtx tmp;
|
||
struct obstack *old_rtl_obstack = rtl_obstack;
|
||
char *storage = (char *) obstack_alloc (&temp_obstack, 0);
|
||
int win = 1;
|
||
|
||
/* If only one is constant, make it B. */
|
||
if (GET_CODE (a) == CONST_INT)
|
||
tmp = a, a = b, b = tmp;
|
||
|
||
/* If first constant, both constant, so don't need multiply. */
|
||
if (GET_CODE (a) == CONST_INT)
|
||
return 1;
|
||
|
||
/* If second not constant, neither is constant, so would need multiply. */
|
||
if (GET_CODE (b) != CONST_INT)
|
||
return 0;
|
||
|
||
/* One operand is constant, so might not need multiply insn. Generate the
|
||
code for the multiply and see if a call or multiply, or long sequence
|
||
of insns is generated. */
|
||
|
||
rtl_obstack = &temp_obstack;
|
||
start_sequence ();
|
||
expand_mult (GET_MODE (a), a, b, NULL_RTX, 0);
|
||
tmp = gen_sequence ();
|
||
end_sequence ();
|
||
|
||
if (GET_CODE (tmp) == SEQUENCE)
|
||
{
|
||
if (XVEC (tmp, 0) == 0)
|
||
win = 1;
|
||
else if (XVECLEN (tmp, 0) > 3)
|
||
win = 0;
|
||
else
|
||
for (i = 0; i < XVECLEN (tmp, 0); i++)
|
||
{
|
||
rtx insn = XVECEXP (tmp, 0, i);
|
||
|
||
if (GET_CODE (insn) != INSN
|
||
|| (GET_CODE (PATTERN (insn)) == SET
|
||
&& GET_CODE (SET_SRC (PATTERN (insn))) == MULT)
|
||
|| (GET_CODE (PATTERN (insn)) == PARALLEL
|
||
&& GET_CODE (XVECEXP (PATTERN (insn), 0, 0)) == SET
|
||
&& GET_CODE (SET_SRC (XVECEXP (PATTERN (insn), 0, 0))) == MULT))
|
||
{
|
||
win = 0;
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
else if (GET_CODE (tmp) == SET
|
||
&& GET_CODE (SET_SRC (tmp)) == MULT)
|
||
win = 0;
|
||
else if (GET_CODE (tmp) == PARALLEL
|
||
&& GET_CODE (XVECEXP (tmp, 0, 0)) == SET
|
||
&& GET_CODE (SET_SRC (XVECEXP (tmp, 0, 0))) == MULT)
|
||
win = 0;
|
||
|
||
/* Free any storage we obtained in generating this multiply and restore rtl
|
||
allocation to its normal obstack. */
|
||
obstack_free (&temp_obstack, storage);
|
||
rtl_obstack = old_rtl_obstack;
|
||
|
||
return win;
|
||
}
|
||
|
||
/* Check to see if loop can be terminated by a "decrement and branch until
|
||
zero" instruction. If so, add a REG_NONNEG note to the branch insn if so.
|
||
Also try reversing an increment loop to a decrement loop
|
||
to see if the optimization can be performed.
|
||
Value is nonzero if optimization was performed. */
|
||
|
||
/* This is useful even if the architecture doesn't have such an insn,
|
||
because it might change a loops which increments from 0 to n to a loop
|
||
which decrements from n to 0. A loop that decrements to zero is usually
|
||
faster than one that increments from zero. */
|
||
|
||
/* ??? This could be rewritten to use some of the loop unrolling procedures,
|
||
such as approx_final_value, biv_total_increment, loop_iterations, and
|
||
final_[bg]iv_value. */
|
||
|
||
static int
|
||
check_dbra_loop (loop_end, insn_count, loop_start)
|
||
rtx loop_end;
|
||
int insn_count;
|
||
rtx loop_start;
|
||
{
|
||
struct iv_class *bl;
|
||
rtx reg;
|
||
rtx jump_label;
|
||
rtx final_value;
|
||
rtx start_value;
|
||
rtx new_add_val;
|
||
rtx comparison;
|
||
rtx before_comparison;
|
||
rtx p;
|
||
rtx jump;
|
||
rtx first_compare;
|
||
int compare_and_branch;
|
||
|
||
/* If last insn is a conditional branch, and the insn before tests a
|
||
register value, try to optimize it. Otherwise, we can't do anything. */
|
||
|
||
jump = PREV_INSN (loop_end);
|
||
comparison = get_condition_for_loop (jump);
|
||
if (comparison == 0)
|
||
return 0;
|
||
|
||
/* Try to compute whether the compare/branch at the loop end is one or
|
||
two instructions. */
|
||
get_condition (jump, &first_compare);
|
||
if (first_compare == jump)
|
||
compare_and_branch = 1;
|
||
else if (first_compare == prev_nonnote_insn (jump))
|
||
compare_and_branch = 2;
|
||
else
|
||
return 0;
|
||
|
||
/* Check all of the bivs to see if the compare uses one of them.
|
||
Skip biv's set more than once because we can't guarantee that
|
||
it will be zero on the last iteration. Also skip if the biv is
|
||
used between its update and the test insn. */
|
||
|
||
for (bl = loop_iv_list; bl; bl = bl->next)
|
||
{
|
||
if (bl->biv_count == 1
|
||
&& bl->biv->dest_reg == XEXP (comparison, 0)
|
||
&& ! reg_used_between_p (regno_reg_rtx[bl->regno], bl->biv->insn,
|
||
first_compare))
|
||
break;
|
||
}
|
||
|
||
if (! bl)
|
||
return 0;
|
||
|
||
/* Look for the case where the basic induction variable is always
|
||
nonnegative, and equals zero on the last iteration.
|
||
In this case, add a reg_note REG_NONNEG, which allows the
|
||
m68k DBRA instruction to be used. */
|
||
|
||
if (((GET_CODE (comparison) == GT
|
||
&& GET_CODE (XEXP (comparison, 1)) == CONST_INT
|
||
&& INTVAL (XEXP (comparison, 1)) == -1)
|
||
|| (GET_CODE (comparison) == NE && XEXP (comparison, 1) == const0_rtx))
|
||
&& GET_CODE (bl->biv->add_val) == CONST_INT
|
||
&& INTVAL (bl->biv->add_val) < 0)
|
||
{
|
||
/* Initial value must be greater than 0,
|
||
init_val % -dec_value == 0 to ensure that it equals zero on
|
||
the last iteration */
|
||
|
||
if (GET_CODE (bl->initial_value) == CONST_INT
|
||
&& INTVAL (bl->initial_value) > 0
|
||
&& (INTVAL (bl->initial_value)
|
||
% (-INTVAL (bl->biv->add_val))) == 0)
|
||
{
|
||
/* register always nonnegative, add REG_NOTE to branch */
|
||
REG_NOTES (PREV_INSN (loop_end))
|
||
= gen_rtx_EXPR_LIST (REG_NONNEG, NULL_RTX,
|
||
REG_NOTES (PREV_INSN (loop_end)));
|
||
bl->nonneg = 1;
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* If the decrement is 1 and the value was tested as >= 0 before
|
||
the loop, then we can safely optimize. */
|
||
for (p = loop_start; p; p = PREV_INSN (p))
|
||
{
|
||
if (GET_CODE (p) == CODE_LABEL)
|
||
break;
|
||
if (GET_CODE (p) != JUMP_INSN)
|
||
continue;
|
||
|
||
before_comparison = get_condition_for_loop (p);
|
||
if (before_comparison
|
||
&& XEXP (before_comparison, 0) == bl->biv->dest_reg
|
||
&& GET_CODE (before_comparison) == LT
|
||
&& XEXP (before_comparison, 1) == const0_rtx
|
||
&& ! reg_set_between_p (bl->biv->dest_reg, p, loop_start)
|
||
&& INTVAL (bl->biv->add_val) == -1)
|
||
{
|
||
REG_NOTES (PREV_INSN (loop_end))
|
||
= gen_rtx_EXPR_LIST (REG_NONNEG, NULL_RTX,
|
||
REG_NOTES (PREV_INSN (loop_end)));
|
||
bl->nonneg = 1;
|
||
|
||
return 1;
|
||
}
|
||
}
|
||
}
|
||
else if (num_mem_sets <= 1)
|
||
{
|
||
/* Try to change inc to dec, so can apply above optimization. */
|
||
/* Can do this if:
|
||
all registers modified are induction variables or invariant,
|
||
all memory references have non-overlapping addresses
|
||
(obviously true if only one write)
|
||
allow 2 insns for the compare/jump at the end of the loop. */
|
||
/* Also, we must avoid any instructions which use both the reversed
|
||
biv and another biv. Such instructions will fail if the loop is
|
||
reversed. We meet this condition by requiring that either
|
||
no_use_except_counting is true, or else that there is only
|
||
one biv. */
|
||
int num_nonfixed_reads = 0;
|
||
/* 1 if the iteration var is used only to count iterations. */
|
||
int no_use_except_counting = 0;
|
||
/* 1 if the loop has no memory store, or it has a single memory store
|
||
which is reversible. */
|
||
int reversible_mem_store = 1;
|
||
|
||
for (p = loop_start; p != loop_end; p = NEXT_INSN (p))
|
||
if (GET_RTX_CLASS (GET_CODE (p)) == 'i')
|
||
num_nonfixed_reads += count_nonfixed_reads (PATTERN (p));
|
||
|
||
if (bl->giv_count == 0
|
||
&& ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
|
||
{
|
||
rtx bivreg = regno_reg_rtx[bl->regno];
|
||
|
||
/* If there are no givs for this biv, and the only exit is the
|
||
fall through at the end of the loop, then
|
||
see if perhaps there are no uses except to count. */
|
||
no_use_except_counting = 1;
|
||
for (p = loop_start; p != loop_end; p = NEXT_INSN (p))
|
||
if (GET_RTX_CLASS (GET_CODE (p)) == 'i')
|
||
{
|
||
rtx set = single_set (p);
|
||
|
||
if (set && GET_CODE (SET_DEST (set)) == REG
|
||
&& REGNO (SET_DEST (set)) == bl->regno)
|
||
/* An insn that sets the biv is okay. */
|
||
;
|
||
else if (p == prev_nonnote_insn (prev_nonnote_insn (loop_end))
|
||
|| p == prev_nonnote_insn (loop_end))
|
||
/* Don't bother about the end test. */
|
||
;
|
||
else if (reg_mentioned_p (bivreg, PATTERN (p)))
|
||
/* Any other use of the biv is no good. */
|
||
{
|
||
no_use_except_counting = 0;
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* If the loop has a single store, and the destination address is
|
||
invariant, then we can't reverse the loop, because this address
|
||
might then have the wrong value at loop exit.
|
||
This would work if the source was invariant also, however, in that
|
||
case, the insn should have been moved out of the loop. */
|
||
|
||
if (num_mem_sets == 1)
|
||
{
|
||
struct induction *v;
|
||
|
||
reversible_mem_store
|
||
= (! unknown_address_altered
|
||
&& ! invariant_p (XEXP (loop_store_mems[0], 0)));
|
||
|
||
/* If the store depends on a register that is set after the
|
||
store, it depends on the initial value, and is thus not
|
||
reversible. */
|
||
for (v = bl->giv; reversible_mem_store && v; v = v->next_iv)
|
||
{
|
||
if (v->giv_type == DEST_REG
|
||
&& reg_mentioned_p (v->dest_reg, loop_store_mems[0])
|
||
&& (INSN_UID (v->insn) >= max_uid_for_loop
|
||
|| (INSN_LUID (v->insn)
|
||
> INSN_LUID (first_loop_store_insn))))
|
||
reversible_mem_store = 0;
|
||
}
|
||
}
|
||
|
||
/* This code only acts for innermost loops. Also it simplifies
|
||
the memory address check by only reversing loops with
|
||
zero or one memory access.
|
||
Two memory accesses could involve parts of the same array,
|
||
and that can't be reversed. */
|
||
|
||
if (num_nonfixed_reads <= 1
|
||
&& !loop_has_call
|
||
&& !loop_has_volatile
|
||
&& reversible_mem_store
|
||
&& (no_use_except_counting
|
||
|| ((bl->giv_count + bl->biv_count + num_mem_sets
|
||
+ num_movables + compare_and_branch == insn_count)
|
||
&& (bl == loop_iv_list && bl->next == 0))))
|
||
{
|
||
rtx tem;
|
||
|
||
/* Loop can be reversed. */
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "Can reverse loop\n");
|
||
|
||
/* Now check other conditions:
|
||
|
||
The increment must be a constant, as must the initial value,
|
||
and the comparison code must be LT.
|
||
|
||
This test can probably be improved since +/- 1 in the constant
|
||
can be obtained by changing LT to LE and vice versa; this is
|
||
confusing. */
|
||
|
||
if (comparison
|
||
&& GET_CODE (XEXP (comparison, 1)) == CONST_INT
|
||
/* LE gets turned into LT */
|
||
&& GET_CODE (comparison) == LT
|
||
&& GET_CODE (bl->initial_value) == CONST_INT)
|
||
{
|
||
HOST_WIDE_INT add_val, comparison_val;
|
||
rtx initial_value;
|
||
|
||
add_val = INTVAL (bl->biv->add_val);
|
||
comparison_val = INTVAL (XEXP (comparison, 1));
|
||
final_value = XEXP (comparison, 1);
|
||
initial_value = bl->initial_value;
|
||
|
||
/* Normalize the initial value if it is an integer and
|
||
has no other use except as a counter. This will allow
|
||
a few more loops to be reversed. */
|
||
if (no_use_except_counting
|
||
&& GET_CODE (initial_value) == CONST_INT)
|
||
{
|
||
comparison_val = comparison_val - INTVAL (bl->initial_value);
|
||
/* Check for overflow. If comparison_val ends up as a
|
||
negative value, then we can't reverse the loop. */
|
||
if (comparison_val >= 0)
|
||
initial_value = const0_rtx;
|
||
}
|
||
|
||
/* If the initial value is not zero, or if the comparison
|
||
value is not an exact multiple of the increment, then we
|
||
can not reverse this loop. */
|
||
if (initial_value != const0_rtx
|
||
|| (comparison_val % add_val) != 0)
|
||
return 0;
|
||
|
||
/* Reset these in case we normalized the initial value
|
||
and comparison value above. */
|
||
bl->initial_value = initial_value;
|
||
XEXP (comparison, 1) = GEN_INT (comparison_val);
|
||
|
||
/* Register will always be nonnegative, with value
|
||
0 on last iteration if loop reversed */
|
||
|
||
/* Save some info needed to produce the new insns. */
|
||
reg = bl->biv->dest_reg;
|
||
jump_label = XEXP (SET_SRC (PATTERN (PREV_INSN (loop_end))), 1);
|
||
if (jump_label == pc_rtx)
|
||
jump_label = XEXP (SET_SRC (PATTERN (PREV_INSN (loop_end))), 2);
|
||
new_add_val = GEN_INT (- INTVAL (bl->biv->add_val));
|
||
|
||
start_value = GEN_INT (INTVAL (XEXP (comparison, 1))
|
||
- INTVAL (bl->biv->add_val));
|
||
|
||
/* Initialize biv to start_value before loop start.
|
||
The old initializing insn will be deleted as a
|
||
dead store by flow.c. */
|
||
emit_insn_before (gen_move_insn (reg, start_value), loop_start);
|
||
|
||
/* Add insn to decrement register, and delete insn
|
||
that incremented the register. */
|
||
p = emit_insn_before (gen_add2_insn (reg, new_add_val),
|
||
bl->biv->insn);
|
||
delete_insn (bl->biv->insn);
|
||
|
||
/* Update biv info to reflect its new status. */
|
||
bl->biv->insn = p;
|
||
bl->initial_value = start_value;
|
||
bl->biv->add_val = new_add_val;
|
||
|
||
/* Inc LABEL_NUSES so that delete_insn will
|
||
not delete the label. */
|
||
LABEL_NUSES (XEXP (jump_label, 0)) ++;
|
||
|
||
/* Emit an insn after the end of the loop to set the biv's
|
||
proper exit value if it is used anywhere outside the loop. */
|
||
if ((REGNO_LAST_UID (bl->regno) != INSN_UID (first_compare))
|
||
|| ! bl->init_insn
|
||
|| REGNO_FIRST_UID (bl->regno) != INSN_UID (bl->init_insn))
|
||
emit_insn_after (gen_move_insn (reg, final_value),
|
||
loop_end);
|
||
|
||
/* Delete compare/branch at end of loop. */
|
||
delete_insn (PREV_INSN (loop_end));
|
||
if (compare_and_branch == 2)
|
||
delete_insn (first_compare);
|
||
|
||
/* Add new compare/branch insn at end of loop. */
|
||
start_sequence ();
|
||
emit_cmp_insn (reg, const0_rtx, GE, NULL_RTX,
|
||
GET_MODE (reg), 0, 0);
|
||
emit_jump_insn (gen_bge (XEXP (jump_label, 0)));
|
||
tem = gen_sequence ();
|
||
end_sequence ();
|
||
emit_jump_insn_before (tem, loop_end);
|
||
|
||
for (tem = PREV_INSN (loop_end);
|
||
tem && GET_CODE (tem) != JUMP_INSN; tem = PREV_INSN (tem))
|
||
;
|
||
if (tem)
|
||
{
|
||
JUMP_LABEL (tem) = XEXP (jump_label, 0);
|
||
|
||
/* Increment of LABEL_NUSES done above. */
|
||
/* Register is now always nonnegative,
|
||
so add REG_NONNEG note to the branch. */
|
||
REG_NOTES (tem) = gen_rtx_EXPR_LIST (REG_NONNEG, NULL_RTX,
|
||
REG_NOTES (tem));
|
||
}
|
||
|
||
bl->nonneg = 1;
|
||
|
||
/* Mark that this biv has been reversed. Each giv which depends
|
||
on this biv, and which is also live past the end of the loop
|
||
will have to be fixed up. */
|
||
|
||
bl->reversed = 1;
|
||
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"Reversed loop and added reg_nonneg\n");
|
||
|
||
return 1;
|
||
}
|
||
}
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* Verify whether the biv BL appears to be eliminable,
|
||
based on the insns in the loop that refer to it.
|
||
LOOP_START is the first insn of the loop, and END is the end insn.
|
||
|
||
If ELIMINATE_P is non-zero, actually do the elimination.
|
||
|
||
THRESHOLD and INSN_COUNT are from loop_optimize and are used to
|
||
determine whether invariant insns should be placed inside or at the
|
||
start of the loop. */
|
||
|
||
static int
|
||
maybe_eliminate_biv (bl, loop_start, end, eliminate_p, threshold, insn_count)
|
||
struct iv_class *bl;
|
||
rtx loop_start;
|
||
rtx end;
|
||
int eliminate_p;
|
||
int threshold, insn_count;
|
||
{
|
||
rtx reg = bl->biv->dest_reg;
|
||
rtx p;
|
||
|
||
/* Scan all insns in the loop, stopping if we find one that uses the
|
||
biv in a way that we cannot eliminate. */
|
||
|
||
for (p = loop_start; p != end; p = NEXT_INSN (p))
|
||
{
|
||
enum rtx_code code = GET_CODE (p);
|
||
rtx where = threshold >= insn_count ? loop_start : p;
|
||
|
||
if ((code == INSN || code == JUMP_INSN || code == CALL_INSN)
|
||
&& reg_mentioned_p (reg, PATTERN (p))
|
||
&& ! maybe_eliminate_biv_1 (PATTERN (p), p, bl, eliminate_p, where))
|
||
{
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"Cannot eliminate biv %d: biv used in insn %d.\n",
|
||
bl->regno, INSN_UID (p));
|
||
break;
|
||
}
|
||
}
|
||
|
||
if (p == end)
|
||
{
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "biv %d %s eliminated.\n",
|
||
bl->regno, eliminate_p ? "was" : "can be");
|
||
return 1;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* If BL appears in X (part of the pattern of INSN), see if we can
|
||
eliminate its use. If so, return 1. If not, return 0.
|
||
|
||
If BIV does not appear in X, return 1.
|
||
|
||
If ELIMINATE_P is non-zero, actually do the elimination. WHERE indicates
|
||
where extra insns should be added. Depending on how many items have been
|
||
moved out of the loop, it will either be before INSN or at the start of
|
||
the loop. */
|
||
|
||
static int
|
||
maybe_eliminate_biv_1 (x, insn, bl, eliminate_p, where)
|
||
rtx x, insn;
|
||
struct iv_class *bl;
|
||
int eliminate_p;
|
||
rtx where;
|
||
{
|
||
enum rtx_code code = GET_CODE (x);
|
||
rtx reg = bl->biv->dest_reg;
|
||
enum machine_mode mode = GET_MODE (reg);
|
||
struct induction *v;
|
||
rtx arg, tem;
|
||
#ifdef HAVE_cc0
|
||
rtx new;
|
||
#endif
|
||
int arg_operand;
|
||
char *fmt;
|
||
int i, j;
|
||
|
||
switch (code)
|
||
{
|
||
case REG:
|
||
/* If we haven't already been able to do something with this BIV,
|
||
we can't eliminate it. */
|
||
if (x == reg)
|
||
return 0;
|
||
return 1;
|
||
|
||
case SET:
|
||
/* If this sets the BIV, it is not a problem. */
|
||
if (SET_DEST (x) == reg)
|
||
return 1;
|
||
|
||
/* If this is an insn that defines a giv, it is also ok because
|
||
it will go away when the giv is reduced. */
|
||
for (v = bl->giv; v; v = v->next_iv)
|
||
if (v->giv_type == DEST_REG && SET_DEST (x) == v->dest_reg)
|
||
return 1;
|
||
|
||
#ifdef HAVE_cc0
|
||
/* The idea here is to replace the SET of cc0 by a REG with
|
||
a comparison involving related induction variables.
|
||
Unfortunately, however, such a replacement does not work
|
||
correctly if the REG is being used as signed and the
|
||
replacement value is unsigned, or vice versa. For
|
||
example, in:
|
||
|
||
for (int i = n; i >= 0; --i)
|
||
s[i] = 3;
|
||
|
||
`s' is an address (an unsigned quantity), while `i' is a
|
||
signed quantity. The exit test for the loop might look
|
||
something like:
|
||
|
||
(SET cc0 i)
|
||
(JUMP (SET (PC) (IF_THEN_ELSE (LT (CC0) (CONST_INT 0))
|
||
(LABEL_REF L) (PC))))
|
||
|
||
If we replace the SET of cc0 with a comparison of the
|
||
induction variable for `s + i' and the original value of `s',
|
||
however, we should be change the comparison in the
|
||
IF_THEN_ELSE to be unsigned. Otherwise, an array the spans
|
||
the boundary between "negative" and "positive" addresses will
|
||
confuse us.
|
||
|
||
There are related problems with overflow. If an induction
|
||
variable "wraps around" but the original value doest not, we
|
||
can get confused when doing the comparison.
|
||
|
||
Pointers can't wrap around, or overflow, in a conformant
|
||
program. Therefore, it's safe to do these optimizations if
|
||
both the original REG and the values in the replacement are
|
||
pointers. For now, though, we just disable these
|
||
optimizations. */
|
||
|
||
if (0 && SET_DEST (x) == cc0_rtx && SET_SRC (x) == reg)
|
||
{
|
||
/* Can replace with any giv that was reduced and
|
||
that has (MULT_VAL != 0) and (ADD_VAL == 0).
|
||
Require a constant for MULT_VAL, so we know it's nonzero.
|
||
??? We disable this optimization to avoid potential
|
||
overflows. */
|
||
|
||
for (v = bl->giv; v; v = v->next_iv)
|
||
if (CONSTANT_P (v->mult_val) && v->mult_val != const0_rtx
|
||
&& v->add_val == const0_rtx
|
||
&& ! v->ignore && ! v->maybe_dead && v->always_computable
|
||
&& v->mode == mode
|
||
&& 0)
|
||
{
|
||
/* If the giv V had the auto-inc address optimization applied
|
||
to it, and INSN occurs between the giv insn and the biv
|
||
insn, then we must adjust the value used here.
|
||
This is rare, so we don't bother to do so. */
|
||
if (v->auto_inc_opt
|
||
&& ((INSN_LUID (v->insn) < INSN_LUID (insn)
|
||
&& INSN_LUID (insn) < INSN_LUID (bl->biv->insn))
|
||
|| (INSN_LUID (v->insn) > INSN_LUID (insn)
|
||
&& INSN_LUID (insn) > INSN_LUID (bl->biv->insn))))
|
||
continue;
|
||
|
||
if (! eliminate_p)
|
||
return 1;
|
||
|
||
/* If the giv has the opposite direction of change,
|
||
then reverse the comparison. */
|
||
if (INTVAL (v->mult_val) < 0)
|
||
new = gen_rtx_COMPARE (GET_MODE (v->new_reg),
|
||
const0_rtx, v->new_reg);
|
||
else
|
||
new = v->new_reg;
|
||
|
||
/* We can probably test that giv's reduced reg. */
|
||
if (validate_change (insn, &SET_SRC (x), new, 0))
|
||
return 1;
|
||
}
|
||
|
||
/* Look for a giv with (MULT_VAL != 0) and (ADD_VAL != 0);
|
||
replace test insn with a compare insn (cmp REDUCED_GIV ADD_VAL).
|
||
Require a constant for MULT_VAL, so we know it's nonzero.
|
||
??? Do this only if ADD_VAL is a pointer to avoid a potential
|
||
overflow problem. */
|
||
|
||
for (v = bl->giv; v; v = v->next_iv)
|
||
if (CONSTANT_P (v->mult_val) && v->mult_val != const0_rtx
|
||
&& ! v->ignore && ! v->maybe_dead && v->always_computable
|
||
&& v->mode == mode
|
||
&& (GET_CODE (v->add_val) == SYMBOL_REF
|
||
|| GET_CODE (v->add_val) == LABEL_REF
|
||
|| GET_CODE (v->add_val) == CONST
|
||
|| (GET_CODE (v->add_val) == REG
|
||
&& REGNO_POINTER_FLAG (REGNO (v->add_val)))))
|
||
{
|
||
/* If the giv V had the auto-inc address optimization applied
|
||
to it, and INSN occurs between the giv insn and the biv
|
||
insn, then we must adjust the value used here.
|
||
This is rare, so we don't bother to do so. */
|
||
if (v->auto_inc_opt
|
||
&& ((INSN_LUID (v->insn) < INSN_LUID (insn)
|
||
&& INSN_LUID (insn) < INSN_LUID (bl->biv->insn))
|
||
|| (INSN_LUID (v->insn) > INSN_LUID (insn)
|
||
&& INSN_LUID (insn) > INSN_LUID (bl->biv->insn))))
|
||
continue;
|
||
|
||
if (! eliminate_p)
|
||
return 1;
|
||
|
||
/* If the giv has the opposite direction of change,
|
||
then reverse the comparison. */
|
||
if (INTVAL (v->mult_val) < 0)
|
||
new = gen_rtx_COMPARE (VOIDmode, copy_rtx (v->add_val),
|
||
v->new_reg);
|
||
else
|
||
new = gen_rtx_COMPARE (VOIDmode, v->new_reg,
|
||
copy_rtx (v->add_val));
|
||
|
||
/* Replace biv with the giv's reduced register. */
|
||
update_reg_last_use (v->add_val, insn);
|
||
if (validate_change (insn, &SET_SRC (PATTERN (insn)), new, 0))
|
||
return 1;
|
||
|
||
/* Insn doesn't support that constant or invariant. Copy it
|
||
into a register (it will be a loop invariant.) */
|
||
tem = gen_reg_rtx (GET_MODE (v->new_reg));
|
||
|
||
emit_insn_before (gen_move_insn (tem, copy_rtx (v->add_val)),
|
||
where);
|
||
|
||
/* Substitute the new register for its invariant value in
|
||
the compare expression. */
|
||
XEXP (new, (INTVAL (v->mult_val) < 0) ? 0 : 1) = tem;
|
||
if (validate_change (insn, &SET_SRC (PATTERN (insn)), new, 0))
|
||
return 1;
|
||
}
|
||
}
|
||
#endif
|
||
break;
|
||
|
||
case COMPARE:
|
||
case EQ: case NE:
|
||
case GT: case GE: case GTU: case GEU:
|
||
case LT: case LE: case LTU: case LEU:
|
||
/* See if either argument is the biv. */
|
||
if (XEXP (x, 0) == reg)
|
||
arg = XEXP (x, 1), arg_operand = 1;
|
||
else if (XEXP (x, 1) == reg)
|
||
arg = XEXP (x, 0), arg_operand = 0;
|
||
else
|
||
break;
|
||
|
||
if (CONSTANT_P (arg))
|
||
{
|
||
/* First try to replace with any giv that has constant positive
|
||
mult_val and constant add_val. We might be able to support
|
||
negative mult_val, but it seems complex to do it in general. */
|
||
|
||
for (v = bl->giv; v; v = v->next_iv)
|
||
if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0
|
||
&& (GET_CODE (v->add_val) == SYMBOL_REF
|
||
|| GET_CODE (v->add_val) == LABEL_REF
|
||
|| GET_CODE (v->add_val) == CONST
|
||
|| (GET_CODE (v->add_val) == REG
|
||
&& REGNO_POINTER_FLAG (REGNO (v->add_val))))
|
||
&& ! v->ignore && ! v->maybe_dead && v->always_computable
|
||
&& v->mode == mode)
|
||
{
|
||
/* If the giv V had the auto-inc address optimization applied
|
||
to it, and INSN occurs between the giv insn and the biv
|
||
insn, then we must adjust the value used here.
|
||
This is rare, so we don't bother to do so. */
|
||
if (v->auto_inc_opt
|
||
&& ((INSN_LUID (v->insn) < INSN_LUID (insn)
|
||
&& INSN_LUID (insn) < INSN_LUID (bl->biv->insn))
|
||
|| (INSN_LUID (v->insn) > INSN_LUID (insn)
|
||
&& INSN_LUID (insn) > INSN_LUID (bl->biv->insn))))
|
||
continue;
|
||
|
||
if (! eliminate_p)
|
||
return 1;
|
||
|
||
/* Replace biv with the giv's reduced reg. */
|
||
XEXP (x, 1-arg_operand) = v->new_reg;
|
||
|
||
/* If all constants are actually constant integers and
|
||
the derived constant can be directly placed in the COMPARE,
|
||
do so. */
|
||
if (GET_CODE (arg) == CONST_INT
|
||
&& GET_CODE (v->mult_val) == CONST_INT
|
||
&& GET_CODE (v->add_val) == CONST_INT
|
||
&& validate_change (insn, &XEXP (x, arg_operand),
|
||
GEN_INT (INTVAL (arg)
|
||
* INTVAL (v->mult_val)
|
||
+ INTVAL (v->add_val)), 0))
|
||
return 1;
|
||
|
||
/* Otherwise, load it into a register. */
|
||
tem = gen_reg_rtx (mode);
|
||
emit_iv_add_mult (arg, v->mult_val, v->add_val, tem, where);
|
||
if (validate_change (insn, &XEXP (x, arg_operand), tem, 0))
|
||
return 1;
|
||
|
||
/* If that failed, put back the change we made above. */
|
||
XEXP (x, 1-arg_operand) = reg;
|
||
}
|
||
|
||
/* Look for giv with positive constant mult_val and nonconst add_val.
|
||
Insert insns to calculate new compare value.
|
||
??? Turn this off due to possible overflow. */
|
||
|
||
for (v = bl->giv; v; v = v->next_iv)
|
||
if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0
|
||
&& ! v->ignore && ! v->maybe_dead && v->always_computable
|
||
&& v->mode == mode
|
||
&& 0)
|
||
{
|
||
rtx tem;
|
||
|
||
/* If the giv V had the auto-inc address optimization applied
|
||
to it, and INSN occurs between the giv insn and the biv
|
||
insn, then we must adjust the value used here.
|
||
This is rare, so we don't bother to do so. */
|
||
if (v->auto_inc_opt
|
||
&& ((INSN_LUID (v->insn) < INSN_LUID (insn)
|
||
&& INSN_LUID (insn) < INSN_LUID (bl->biv->insn))
|
||
|| (INSN_LUID (v->insn) > INSN_LUID (insn)
|
||
&& INSN_LUID (insn) > INSN_LUID (bl->biv->insn))))
|
||
continue;
|
||
|
||
if (! eliminate_p)
|
||
return 1;
|
||
|
||
tem = gen_reg_rtx (mode);
|
||
|
||
/* Replace biv with giv's reduced register. */
|
||
validate_change (insn, &XEXP (x, 1 - arg_operand),
|
||
v->new_reg, 1);
|
||
|
||
/* Compute value to compare against. */
|
||
emit_iv_add_mult (arg, v->mult_val, v->add_val, tem, where);
|
||
/* Use it in this insn. */
|
||
validate_change (insn, &XEXP (x, arg_operand), tem, 1);
|
||
if (apply_change_group ())
|
||
return 1;
|
||
}
|
||
}
|
||
else if (GET_CODE (arg) == REG || GET_CODE (arg) == MEM)
|
||
{
|
||
if (invariant_p (arg) == 1)
|
||
{
|
||
/* Look for giv with constant positive mult_val and nonconst
|
||
add_val. Insert insns to compute new compare value.
|
||
??? Turn this off due to possible overflow. */
|
||
|
||
for (v = bl->giv; v; v = v->next_iv)
|
||
if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0
|
||
&& ! v->ignore && ! v->maybe_dead && v->always_computable
|
||
&& v->mode == mode
|
||
&& 0)
|
||
{
|
||
rtx tem;
|
||
|
||
/* If the giv V had the auto-inc address optimization applied
|
||
to it, and INSN occurs between the giv insn and the biv
|
||
insn, then we must adjust the value used here.
|
||
This is rare, so we don't bother to do so. */
|
||
if (v->auto_inc_opt
|
||
&& ((INSN_LUID (v->insn) < INSN_LUID (insn)
|
||
&& INSN_LUID (insn) < INSN_LUID (bl->biv->insn))
|
||
|| (INSN_LUID (v->insn) > INSN_LUID (insn)
|
||
&& INSN_LUID (insn) > INSN_LUID (bl->biv->insn))))
|
||
continue;
|
||
|
||
if (! eliminate_p)
|
||
return 1;
|
||
|
||
tem = gen_reg_rtx (mode);
|
||
|
||
/* Replace biv with giv's reduced register. */
|
||
validate_change (insn, &XEXP (x, 1 - arg_operand),
|
||
v->new_reg, 1);
|
||
|
||
/* Compute value to compare against. */
|
||
emit_iv_add_mult (arg, v->mult_val, v->add_val,
|
||
tem, where);
|
||
validate_change (insn, &XEXP (x, arg_operand), tem, 1);
|
||
if (apply_change_group ())
|
||
return 1;
|
||
}
|
||
}
|
||
|
||
/* This code has problems. Basically, you can't know when
|
||
seeing if we will eliminate BL, whether a particular giv
|
||
of ARG will be reduced. If it isn't going to be reduced,
|
||
we can't eliminate BL. We can try forcing it to be reduced,
|
||
but that can generate poor code.
|
||
|
||
The problem is that the benefit of reducing TV, below should
|
||
be increased if BL can actually be eliminated, but this means
|
||
we might have to do a topological sort of the order in which
|
||
we try to process biv. It doesn't seem worthwhile to do
|
||
this sort of thing now. */
|
||
|
||
#if 0
|
||
/* Otherwise the reg compared with had better be a biv. */
|
||
if (GET_CODE (arg) != REG
|
||
|| reg_iv_type[REGNO (arg)] != BASIC_INDUCT)
|
||
return 0;
|
||
|
||
/* Look for a pair of givs, one for each biv,
|
||
with identical coefficients. */
|
||
for (v = bl->giv; v; v = v->next_iv)
|
||
{
|
||
struct induction *tv;
|
||
|
||
if (v->ignore || v->maybe_dead || v->mode != mode)
|
||
continue;
|
||
|
||
for (tv = reg_biv_class[REGNO (arg)]->giv; tv; tv = tv->next_iv)
|
||
if (! tv->ignore && ! tv->maybe_dead
|
||
&& rtx_equal_p (tv->mult_val, v->mult_val)
|
||
&& rtx_equal_p (tv->add_val, v->add_val)
|
||
&& tv->mode == mode)
|
||
{
|
||
/* If the giv V had the auto-inc address optimization applied
|
||
to it, and INSN occurs between the giv insn and the biv
|
||
insn, then we must adjust the value used here.
|
||
This is rare, so we don't bother to do so. */
|
||
if (v->auto_inc_opt
|
||
&& ((INSN_LUID (v->insn) < INSN_LUID (insn)
|
||
&& INSN_LUID (insn) < INSN_LUID (bl->biv->insn))
|
||
|| (INSN_LUID (v->insn) > INSN_LUID (insn)
|
||
&& INSN_LUID (insn) > INSN_LUID (bl->biv->insn))))
|
||
continue;
|
||
|
||
if (! eliminate_p)
|
||
return 1;
|
||
|
||
/* Replace biv with its giv's reduced reg. */
|
||
XEXP (x, 1-arg_operand) = v->new_reg;
|
||
/* Replace other operand with the other giv's
|
||
reduced reg. */
|
||
XEXP (x, arg_operand) = tv->new_reg;
|
||
return 1;
|
||
}
|
||
}
|
||
#endif
|
||
}
|
||
|
||
/* If we get here, the biv can't be eliminated. */
|
||
return 0;
|
||
|
||
case MEM:
|
||
/* If this address is a DEST_ADDR giv, it doesn't matter if the
|
||
biv is used in it, since it will be replaced. */
|
||
for (v = bl->giv; v; v = v->next_iv)
|
||
if (v->giv_type == DEST_ADDR && v->location == &XEXP (x, 0))
|
||
return 1;
|
||
break;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
|
||
/* See if any subexpression fails elimination. */
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
switch (fmt[i])
|
||
{
|
||
case 'e':
|
||
if (! maybe_eliminate_biv_1 (XEXP (x, i), insn, bl,
|
||
eliminate_p, where))
|
||
return 0;
|
||
break;
|
||
|
||
case 'E':
|
||
for (j = XVECLEN (x, i) - 1; j >= 0; j--)
|
||
if (! maybe_eliminate_biv_1 (XVECEXP (x, i, j), insn, bl,
|
||
eliminate_p, where))
|
||
return 0;
|
||
break;
|
||
}
|
||
}
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* Return nonzero if the last use of REG
|
||
is in an insn following INSN in the same basic block. */
|
||
|
||
static int
|
||
last_use_this_basic_block (reg, insn)
|
||
rtx reg;
|
||
rtx insn;
|
||
{
|
||
rtx n;
|
||
for (n = insn;
|
||
n && GET_CODE (n) != CODE_LABEL && GET_CODE (n) != JUMP_INSN;
|
||
n = NEXT_INSN (n))
|
||
{
|
||
if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (n))
|
||
return 1;
|
||
}
|
||
return 0;
|
||
}
|
||
|
||
/* Called via `note_stores' to record the initial value of a biv. Here we
|
||
just record the location of the set and process it later. */
|
||
|
||
static void
|
||
record_initial (dest, set)
|
||
rtx dest;
|
||
rtx set;
|
||
{
|
||
struct iv_class *bl;
|
||
|
||
if (GET_CODE (dest) != REG
|
||
|| REGNO (dest) >= max_reg_before_loop
|
||
|| reg_iv_type[REGNO (dest)] != BASIC_INDUCT)
|
||
return;
|
||
|
||
bl = reg_biv_class[REGNO (dest)];
|
||
|
||
/* If this is the first set found, record it. */
|
||
if (bl->init_insn == 0)
|
||
{
|
||
bl->init_insn = note_insn;
|
||
bl->init_set = set;
|
||
}
|
||
}
|
||
|
||
/* If any of the registers in X are "old" and currently have a last use earlier
|
||
than INSN, update them to have a last use of INSN. Their actual last use
|
||
will be the previous insn but it will not have a valid uid_luid so we can't
|
||
use it. */
|
||
|
||
static void
|
||
update_reg_last_use (x, insn)
|
||
rtx x;
|
||
rtx insn;
|
||
{
|
||
/* Check for the case where INSN does not have a valid luid. In this case,
|
||
there is no need to modify the regno_last_uid, as this can only happen
|
||
when code is inserted after the loop_end to set a pseudo's final value,
|
||
and hence this insn will never be the last use of x. */
|
||
if (GET_CODE (x) == REG && REGNO (x) < max_reg_before_loop
|
||
&& INSN_UID (insn) < max_uid_for_loop
|
||
&& uid_luid[REGNO_LAST_UID (REGNO (x))] < uid_luid[INSN_UID (insn)])
|
||
REGNO_LAST_UID (REGNO (x)) = INSN_UID (insn);
|
||
else
|
||
{
|
||
register int i, j;
|
||
register char *fmt = GET_RTX_FORMAT (GET_CODE (x));
|
||
for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
update_reg_last_use (XEXP (x, i), insn);
|
||
else if (fmt[i] == 'E')
|
||
for (j = XVECLEN (x, i) - 1; j >= 0; j--)
|
||
update_reg_last_use (XVECEXP (x, i, j), insn);
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Given a jump insn JUMP, return the condition that will cause it to branch
|
||
to its JUMP_LABEL. If the condition cannot be understood, or is an
|
||
inequality floating-point comparison which needs to be reversed, 0 will
|
||
be returned.
|
||
|
||
If EARLIEST is non-zero, it is a pointer to a place where the earliest
|
||
insn used in locating the condition was found. If a replacement test
|
||
of the condition is desired, it should be placed in front of that
|
||
insn and we will be sure that the inputs are still valid.
|
||
|
||
The condition will be returned in a canonical form to simplify testing by
|
||
callers. Specifically:
|
||
|
||
(1) The code will always be a comparison operation (EQ, NE, GT, etc.).
|
||
(2) Both operands will be machine operands; (cc0) will have been replaced.
|
||
(3) If an operand is a constant, it will be the second operand.
|
||
(4) (LE x const) will be replaced with (LT x <const+1>) and similarly
|
||
for GE, GEU, and LEU. */
|
||
|
||
rtx
|
||
get_condition (jump, earliest)
|
||
rtx jump;
|
||
rtx *earliest;
|
||
{
|
||
enum rtx_code code;
|
||
rtx prev = jump;
|
||
rtx set;
|
||
rtx tem;
|
||
rtx op0, op1;
|
||
int reverse_code = 0;
|
||
int did_reverse_condition = 0;
|
||
enum machine_mode mode;
|
||
|
||
/* If this is not a standard conditional jump, we can't parse it. */
|
||
if (GET_CODE (jump) != JUMP_INSN
|
||
|| ! condjump_p (jump) || simplejump_p (jump))
|
||
return 0;
|
||
|
||
code = GET_CODE (XEXP (SET_SRC (PATTERN (jump)), 0));
|
||
mode = GET_MODE (XEXP (SET_SRC (PATTERN (jump)), 0));
|
||
op0 = XEXP (XEXP (SET_SRC (PATTERN (jump)), 0), 0);
|
||
op1 = XEXP (XEXP (SET_SRC (PATTERN (jump)), 0), 1);
|
||
|
||
if (earliest)
|
||
*earliest = jump;
|
||
|
||
/* If this branches to JUMP_LABEL when the condition is false, reverse
|
||
the condition. */
|
||
if (GET_CODE (XEXP (SET_SRC (PATTERN (jump)), 2)) == LABEL_REF
|
||
&& XEXP (XEXP (SET_SRC (PATTERN (jump)), 2), 0) == JUMP_LABEL (jump))
|
||
code = reverse_condition (code), did_reverse_condition ^= 1;
|
||
|
||
/* If we are comparing a register with zero, see if the register is set
|
||
in the previous insn to a COMPARE or a comparison operation. Perform
|
||
the same tests as a function of STORE_FLAG_VALUE as find_comparison_args
|
||
in cse.c */
|
||
|
||
while (GET_RTX_CLASS (code) == '<' && op1 == CONST0_RTX (GET_MODE (op0)))
|
||
{
|
||
/* Set non-zero when we find something of interest. */
|
||
rtx x = 0;
|
||
|
||
#ifdef HAVE_cc0
|
||
/* If comparison with cc0, import actual comparison from compare
|
||
insn. */
|
||
if (op0 == cc0_rtx)
|
||
{
|
||
if ((prev = prev_nonnote_insn (prev)) == 0
|
||
|| GET_CODE (prev) != INSN
|
||
|| (set = single_set (prev)) == 0
|
||
|| SET_DEST (set) != cc0_rtx)
|
||
return 0;
|
||
|
||
op0 = SET_SRC (set);
|
||
op1 = CONST0_RTX (GET_MODE (op0));
|
||
if (earliest)
|
||
*earliest = prev;
|
||
}
|
||
#endif
|
||
|
||
/* If this is a COMPARE, pick up the two things being compared. */
|
||
if (GET_CODE (op0) == COMPARE)
|
||
{
|
||
op1 = XEXP (op0, 1);
|
||
op0 = XEXP (op0, 0);
|
||
continue;
|
||
}
|
||
else if (GET_CODE (op0) != REG)
|
||
break;
|
||
|
||
/* Go back to the previous insn. Stop if it is not an INSN. We also
|
||
stop if it isn't a single set or if it has a REG_INC note because
|
||
we don't want to bother dealing with it. */
|
||
|
||
if ((prev = prev_nonnote_insn (prev)) == 0
|
||
|| GET_CODE (prev) != INSN
|
||
|| FIND_REG_INC_NOTE (prev, 0)
|
||
|| (set = single_set (prev)) == 0)
|
||
break;
|
||
|
||
/* If this is setting OP0, get what it sets it to if it looks
|
||
relevant. */
|
||
if (rtx_equal_p (SET_DEST (set), op0))
|
||
{
|
||
enum machine_mode inner_mode = GET_MODE (SET_SRC (set));
|
||
|
||
/* ??? We may not combine comparisons done in a CCmode with
|
||
comparisons not done in a CCmode. This is to aid targets
|
||
like Alpha that have an IEEE compliant EQ instruction, and
|
||
a non-IEEE compliant BEQ instruction. The use of CCmode is
|
||
actually artificial, simply to prevent the combination, but
|
||
should not affect other platforms. */
|
||
|
||
if ((GET_CODE (SET_SRC (set)) == COMPARE
|
||
|| (((code == NE
|
||
|| (code == LT
|
||
&& GET_MODE_CLASS (inner_mode) == MODE_INT
|
||
&& (GET_MODE_BITSIZE (inner_mode)
|
||
<= HOST_BITS_PER_WIDE_INT)
|
||
&& (STORE_FLAG_VALUE
|
||
& ((HOST_WIDE_INT) 1
|
||
<< (GET_MODE_BITSIZE (inner_mode) - 1))))
|
||
#ifdef FLOAT_STORE_FLAG_VALUE
|
||
|| (code == LT
|
||
&& GET_MODE_CLASS (inner_mode) == MODE_FLOAT
|
||
&& FLOAT_STORE_FLAG_VALUE < 0)
|
||
#endif
|
||
))
|
||
&& GET_RTX_CLASS (GET_CODE (SET_SRC (set))) == '<'))
|
||
&& ((GET_MODE_CLASS (mode) == MODE_CC)
|
||
!= (GET_MODE_CLASS (inner_mode) == MODE_CC)))
|
||
x = SET_SRC (set);
|
||
else if (((code == EQ
|
||
|| (code == GE
|
||
&& (GET_MODE_BITSIZE (inner_mode)
|
||
<= HOST_BITS_PER_WIDE_INT)
|
||
&& GET_MODE_CLASS (inner_mode) == MODE_INT
|
||
&& (STORE_FLAG_VALUE
|
||
& ((HOST_WIDE_INT) 1
|
||
<< (GET_MODE_BITSIZE (inner_mode) - 1))))
|
||
#ifdef FLOAT_STORE_FLAG_VALUE
|
||
|| (code == GE
|
||
&& GET_MODE_CLASS (inner_mode) == MODE_FLOAT
|
||
&& FLOAT_STORE_FLAG_VALUE < 0)
|
||
#endif
|
||
))
|
||
&& GET_RTX_CLASS (GET_CODE (SET_SRC (set))) == '<'
|
||
&& ((GET_MODE_CLASS (mode) == MODE_CC)
|
||
!= (GET_MODE_CLASS (inner_mode) == MODE_CC)))
|
||
{
|
||
/* We might have reversed a LT to get a GE here. But this wasn't
|
||
actually the comparison of data, so we don't flag that we
|
||
have had to reverse the condition. */
|
||
did_reverse_condition ^= 1;
|
||
reverse_code = 1;
|
||
x = SET_SRC (set);
|
||
}
|
||
else
|
||
break;
|
||
}
|
||
|
||
else if (reg_set_p (op0, prev))
|
||
/* If this sets OP0, but not directly, we have to give up. */
|
||
break;
|
||
|
||
if (x)
|
||
{
|
||
if (GET_RTX_CLASS (GET_CODE (x)) == '<')
|
||
code = GET_CODE (x);
|
||
if (reverse_code)
|
||
{
|
||
code = reverse_condition (code);
|
||
did_reverse_condition ^= 1;
|
||
reverse_code = 0;
|
||
}
|
||
|
||
op0 = XEXP (x, 0), op1 = XEXP (x, 1);
|
||
if (earliest)
|
||
*earliest = prev;
|
||
}
|
||
}
|
||
|
||
/* If constant is first, put it last. */
|
||
if (CONSTANT_P (op0))
|
||
code = swap_condition (code), tem = op0, op0 = op1, op1 = tem;
|
||
|
||
/* If OP0 is the result of a comparison, we weren't able to find what
|
||
was really being compared, so fail. */
|
||
if (GET_MODE_CLASS (GET_MODE (op0)) == MODE_CC)
|
||
return 0;
|
||
|
||
/* Canonicalize any ordered comparison with integers involving equality
|
||
if we can do computations in the relevant mode and we do not
|
||
overflow. */
|
||
|
||
if (GET_CODE (op1) == CONST_INT
|
||
&& GET_MODE (op0) != VOIDmode
|
||
&& GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT)
|
||
{
|
||
HOST_WIDE_INT const_val = INTVAL (op1);
|
||
unsigned HOST_WIDE_INT uconst_val = const_val;
|
||
unsigned HOST_WIDE_INT max_val
|
||
= (unsigned HOST_WIDE_INT) GET_MODE_MASK (GET_MODE (op0));
|
||
|
||
switch (code)
|
||
{
|
||
case LE:
|
||
if (const_val != max_val >> 1)
|
||
code = LT, op1 = GEN_INT (const_val + 1);
|
||
break;
|
||
|
||
/* When cross-compiling, const_val might be sign-extended from
|
||
BITS_PER_WORD to HOST_BITS_PER_WIDE_INT */
|
||
case GE:
|
||
if ((const_val & max_val)
|
||
!= (((HOST_WIDE_INT) 1
|
||
<< (GET_MODE_BITSIZE (GET_MODE (op0)) - 1))))
|
||
code = GT, op1 = GEN_INT (const_val - 1);
|
||
break;
|
||
|
||
case LEU:
|
||
if (uconst_val < max_val)
|
||
code = LTU, op1 = GEN_INT (uconst_val + 1);
|
||
break;
|
||
|
||
case GEU:
|
||
if (uconst_val != 0)
|
||
code = GTU, op1 = GEN_INT (uconst_val - 1);
|
||
break;
|
||
|
||
default:
|
||
break;
|
||
}
|
||
}
|
||
|
||
/* If this was floating-point and we reversed anything other than an
|
||
EQ or NE, return zero. */
|
||
if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
|
||
&& did_reverse_condition && code != NE && code != EQ
|
||
&& ! flag_fast_math
|
||
&& GET_MODE_CLASS (GET_MODE (op0)) == MODE_FLOAT)
|
||
return 0;
|
||
|
||
#ifdef HAVE_cc0
|
||
/* Never return CC0; return zero instead. */
|
||
if (op0 == cc0_rtx)
|
||
return 0;
|
||
#endif
|
||
|
||
return gen_rtx_fmt_ee (code, VOIDmode, op0, op1);
|
||
}
|
||
|
||
/* Similar to above routine, except that we also put an invariant last
|
||
unless both operands are invariants. */
|
||
|
||
rtx
|
||
get_condition_for_loop (x)
|
||
rtx x;
|
||
{
|
||
rtx comparison = get_condition (x, NULL_PTR);
|
||
|
||
if (comparison == 0
|
||
|| ! invariant_p (XEXP (comparison, 0))
|
||
|| invariant_p (XEXP (comparison, 1)))
|
||
return comparison;
|
||
|
||
return gen_rtx_fmt_ee (swap_condition (GET_CODE (comparison)), VOIDmode,
|
||
XEXP (comparison, 1), XEXP (comparison, 0));
|
||
}
|
||
|
||
#ifdef HAIFA
|
||
/* Analyze a loop in order to instrument it with the use of count register.
|
||
loop_start and loop_end are the first and last insns of the loop.
|
||
This function works in cooperation with insert_bct ().
|
||
loop_can_insert_bct[loop_num] is set according to whether the optimization
|
||
is applicable to the loop. When it is applicable, the following variables
|
||
are also set:
|
||
loop_start_value[loop_num]
|
||
loop_comparison_value[loop_num]
|
||
loop_increment[loop_num]
|
||
loop_comparison_code[loop_num] */
|
||
|
||
#ifdef HAVE_decrement_and_branch_on_count
|
||
static
|
||
void analyze_loop_iterations (loop_start, loop_end)
|
||
rtx loop_start, loop_end;
|
||
{
|
||
rtx comparison, comparison_value;
|
||
rtx iteration_var, initial_value, increment;
|
||
enum rtx_code comparison_code;
|
||
|
||
rtx last_loop_insn;
|
||
rtx insn;
|
||
int i;
|
||
|
||
/* loop_variable mode */
|
||
enum machine_mode original_mode;
|
||
|
||
/* find the number of the loop */
|
||
int loop_num = uid_loop_num [INSN_UID (loop_start)];
|
||
|
||
/* we change our mind only when we are sure that loop will be instrumented */
|
||
loop_can_insert_bct[loop_num] = 0;
|
||
|
||
/* is the optimization suppressed. */
|
||
if ( !flag_branch_on_count_reg )
|
||
return;
|
||
|
||
/* make sure that count-reg is not in use */
|
||
if (loop_used_count_register[loop_num]){
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"analyze_loop_iterations %d: BCT instrumentation failed: count register already in use\n",
|
||
loop_num);
|
||
return;
|
||
}
|
||
|
||
/* make sure that the function has no indirect jumps. */
|
||
if (indirect_jump_in_function){
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"analyze_loop_iterations %d: BCT instrumentation failed: indirect jump in function\n",
|
||
loop_num);
|
||
return;
|
||
}
|
||
|
||
/* make sure that the last loop insn is a conditional jump */
|
||
last_loop_insn = PREV_INSN (loop_end);
|
||
if (GET_CODE (last_loop_insn) != JUMP_INSN || !condjump_p (last_loop_insn)) {
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"analyze_loop_iterations %d: BCT instrumentation failed: invalid jump at loop end\n",
|
||
loop_num);
|
||
return;
|
||
}
|
||
|
||
/* First find the iteration variable. If the last insn is a conditional
|
||
branch, and the insn preceding it tests a register value, make that
|
||
register the iteration variable. */
|
||
|
||
/* We used to use prev_nonnote_insn here, but that fails because it might
|
||
accidentally get the branch for a contained loop if the branch for this
|
||
loop was deleted. We can only trust branches immediately before the
|
||
loop_end. */
|
||
|
||
comparison = get_condition_for_loop (last_loop_insn);
|
||
/* ??? Get_condition may switch position of induction variable and
|
||
invariant register when it canonicalizes the comparison. */
|
||
|
||
if (comparison == 0) {
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"analyze_loop_iterations %d: BCT instrumentation failed: comparison not found\n",
|
||
loop_num);
|
||
return;
|
||
}
|
||
|
||
comparison_code = GET_CODE (comparison);
|
||
iteration_var = XEXP (comparison, 0);
|
||
comparison_value = XEXP (comparison, 1);
|
||
|
||
original_mode = GET_MODE (iteration_var);
|
||
if (GET_MODE_CLASS (original_mode) != MODE_INT
|
||
|| GET_MODE_SIZE (original_mode) != UNITS_PER_WORD) {
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"analyze_loop_iterations %d: BCT Instrumentation failed: loop variable not integer\n",
|
||
loop_num);
|
||
return;
|
||
}
|
||
|
||
/* get info about loop bounds and increment */
|
||
iteration_info (iteration_var, &initial_value, &increment,
|
||
loop_start, loop_end);
|
||
|
||
/* make sure that all required loop data were found */
|
||
if (!(initial_value && increment && comparison_value
|
||
&& invariant_p (comparison_value) && invariant_p (increment)
|
||
&& ! indirect_jump_in_function))
|
||
{
|
||
if (loop_dump_stream) {
|
||
fprintf (loop_dump_stream,
|
||
"analyze_loop_iterations %d: BCT instrumentation failed because of wrong loop: ", loop_num);
|
||
if (!(initial_value && increment && comparison_value)) {
|
||
fprintf (loop_dump_stream, "\tbounds not available: ");
|
||
if ( ! initial_value )
|
||
fprintf (loop_dump_stream, "initial ");
|
||
if ( ! increment )
|
||
fprintf (loop_dump_stream, "increment ");
|
||
if ( ! comparison_value )
|
||
fprintf (loop_dump_stream, "comparison ");
|
||
fprintf (loop_dump_stream, "\n");
|
||
}
|
||
if (!invariant_p (comparison_value) || !invariant_p (increment))
|
||
fprintf (loop_dump_stream, "\tloop bounds not invariant\n");
|
||
}
|
||
return;
|
||
}
|
||
|
||
/* make sure that the increment is constant */
|
||
if (GET_CODE (increment) != CONST_INT) {
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"analyze_loop_iterations %d: instrumentation failed: not arithmetic loop\n",
|
||
loop_num);
|
||
return;
|
||
}
|
||
|
||
/* make sure that the loop contains neither function call, nor jump on table.
|
||
(the count register might be altered by the called function, and might
|
||
be used for a branch on table). */
|
||
for (insn = loop_start; insn && insn != loop_end; insn = NEXT_INSN (insn)) {
|
||
if (GET_CODE (insn) == CALL_INSN){
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"analyze_loop_iterations %d: BCT instrumentation failed: function call in the loop\n",
|
||
loop_num);
|
||
return;
|
||
}
|
||
|
||
if (GET_CODE (insn) == JUMP_INSN
|
||
&& (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
|
||
|| GET_CODE (PATTERN (insn)) == ADDR_VEC)){
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"analyze_loop_iterations %d: BCT instrumentation failed: computed branch in the loop\n",
|
||
loop_num);
|
||
return;
|
||
}
|
||
}
|
||
|
||
/* At this point, we are sure that the loop can be instrumented with BCT.
|
||
Some of the loops, however, will not be instrumented - the final decision
|
||
is taken by insert_bct () */
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"analyze_loop_iterations: loop (luid =%d) can be BCT instrumented.\n",
|
||
loop_num);
|
||
|
||
/* mark all enclosing loops that they cannot use count register */
|
||
/* ???: In fact, since insert_bct may decide not to instrument this loop,
|
||
marking here may prevent instrumenting an enclosing loop that could
|
||
actually be instrumented. But since this is rare, it is safer to mark
|
||
here in case the order of calling (analyze/insert)_bct would be changed. */
|
||
for (i=loop_num; i != -1; i = loop_outer_loop[i])
|
||
loop_used_count_register[i] = 1;
|
||
|
||
/* Set data structures which will be used by the instrumentation phase */
|
||
loop_start_value[loop_num] = initial_value;
|
||
loop_comparison_value[loop_num] = comparison_value;
|
||
loop_increment[loop_num] = increment;
|
||
loop_comparison_code[loop_num] = comparison_code;
|
||
loop_can_insert_bct[loop_num] = 1;
|
||
}
|
||
|
||
|
||
/* instrument loop for insertion of bct instruction. We distinguish between
|
||
loops with compile-time bounds, to those with run-time bounds. The loop
|
||
behaviour is analized according to the following characteristics/variables:
|
||
; Input variables:
|
||
; comparison-value: the value to which the iteration counter is compared.
|
||
; initial-value: iteration-counter initial value.
|
||
; increment: iteration-counter increment.
|
||
; Computed variables:
|
||
; increment-direction: the sign of the increment.
|
||
; compare-direction: '1' for GT, GTE, '-1' for LT, LTE, '0' for NE.
|
||
; range-direction: sign (comparison-value - initial-value)
|
||
We give up on the following cases:
|
||
; loop variable overflow.
|
||
; run-time loop bounds with comparison code NE.
|
||
*/
|
||
|
||
static void
|
||
insert_bct (loop_start, loop_end)
|
||
rtx loop_start, loop_end;
|
||
{
|
||
rtx initial_value, comparison_value, increment;
|
||
enum rtx_code comparison_code;
|
||
|
||
int increment_direction, compare_direction;
|
||
int unsigned_p = 0;
|
||
|
||
/* if the loop condition is <= or >=, the number of iteration
|
||
is 1 more than the range of the bounds of the loop */
|
||
int add_iteration = 0;
|
||
|
||
/* the only machine mode we work with - is the integer of the size that the
|
||
machine has */
|
||
enum machine_mode loop_var_mode = SImode;
|
||
|
||
int loop_num = uid_loop_num [INSN_UID (loop_start)];
|
||
|
||
/* get loop-variables. No need to check that these are valid - already
|
||
checked in analyze_loop_iterations (). */
|
||
comparison_code = loop_comparison_code[loop_num];
|
||
initial_value = loop_start_value[loop_num];
|
||
comparison_value = loop_comparison_value[loop_num];
|
||
increment = loop_increment[loop_num];
|
||
|
||
/* check analyze_loop_iterations decision for this loop. */
|
||
if (! loop_can_insert_bct[loop_num]){
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"insert_bct: [%d] - was decided not to instrument by analyze_loop_iterations ()\n",
|
||
loop_num);
|
||
return;
|
||
}
|
||
|
||
/* It's impossible to instrument a competely unrolled loop. */
|
||
if (loop_unroll_factor [loop_num] == -1)
|
||
return;
|
||
|
||
/* make sure that the last loop insn is a conditional jump .
|
||
This check is repeated from analyze_loop_iterations (),
|
||
because unrolling might have changed that. */
|
||
if (GET_CODE (PREV_INSN (loop_end)) != JUMP_INSN
|
||
|| !condjump_p (PREV_INSN (loop_end))) {
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"insert_bct: not instrumenting BCT because of invalid branch\n");
|
||
return;
|
||
}
|
||
|
||
/* fix increment in case loop was unrolled. */
|
||
if (loop_unroll_factor [loop_num] > 1)
|
||
increment = GEN_INT ( INTVAL (increment) * loop_unroll_factor [loop_num] );
|
||
|
||
/* determine properties and directions of the loop */
|
||
increment_direction = (INTVAL (increment) > 0) ? 1:-1;
|
||
switch ( comparison_code ) {
|
||
case LEU:
|
||
unsigned_p = 1;
|
||
/* fallthrough */
|
||
case LE:
|
||
compare_direction = 1;
|
||
add_iteration = 1;
|
||
break;
|
||
case GEU:
|
||
unsigned_p = 1;
|
||
/* fallthrough */
|
||
case GE:
|
||
compare_direction = -1;
|
||
add_iteration = 1;
|
||
break;
|
||
case EQ:
|
||
/* in this case we cannot know the number of iterations */
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"insert_bct: %d: loop cannot be instrumented: == in condition\n",
|
||
loop_num);
|
||
return;
|
||
case LTU:
|
||
unsigned_p = 1;
|
||
/* fallthrough */
|
||
case LT:
|
||
compare_direction = 1;
|
||
break;
|
||
case GTU:
|
||
unsigned_p = 1;
|
||
/* fallthrough */
|
||
case GT:
|
||
compare_direction = -1;
|
||
break;
|
||
case NE:
|
||
compare_direction = 0;
|
||
break;
|
||
default:
|
||
abort ();
|
||
}
|
||
|
||
|
||
/* make sure that the loop does not end by an overflow */
|
||
if (compare_direction != increment_direction) {
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"insert_bct: %d: loop cannot be instrumented: terminated by overflow\n",
|
||
loop_num);
|
||
return;
|
||
}
|
||
|
||
/* try to instrument the loop. */
|
||
|
||
/* Handle the simpler case, where the bounds are known at compile time. */
|
||
if (GET_CODE (initial_value) == CONST_INT && GET_CODE (comparison_value) == CONST_INT)
|
||
{
|
||
int n_iterations;
|
||
int increment_value_abs = INTVAL (increment) * increment_direction;
|
||
|
||
/* check the relation between compare-val and initial-val */
|
||
int difference = INTVAL (comparison_value) - INTVAL (initial_value);
|
||
int range_direction = (difference > 0) ? 1 : -1;
|
||
|
||
/* make sure the loop executes enough iterations to gain from BCT */
|
||
if (difference > -3 && difference < 3) {
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"insert_bct: loop %d not BCT instrumented: too small iteration count.\n",
|
||
loop_num);
|
||
return;
|
||
}
|
||
|
||
/* make sure that the loop executes at least once */
|
||
if ((range_direction == 1 && compare_direction == -1)
|
||
|| (range_direction == -1 && compare_direction == 1))
|
||
{
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"insert_bct: loop %d: does not iterate even once. Not instrumenting.\n",
|
||
loop_num);
|
||
return;
|
||
}
|
||
|
||
/* make sure that the loop does not end by an overflow (in compile time
|
||
bounds we must have an additional check for overflow, because here
|
||
we also support the compare code of 'NE'. */
|
||
if (comparison_code == NE
|
||
&& increment_direction != range_direction) {
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"insert_bct (compile time bounds): %d: loop not instrumented: terminated by overflow\n",
|
||
loop_num);
|
||
return;
|
||
}
|
||
|
||
/* Determine the number of iterations by:
|
||
;
|
||
; compare-val - initial-val + (increment -1) + additional-iteration
|
||
; num_iterations = -----------------------------------------------------------------
|
||
; increment
|
||
*/
|
||
difference = (range_direction > 0) ? difference : -difference;
|
||
#if 0
|
||
fprintf (stderr, "difference is: %d\n", difference); /* @*/
|
||
fprintf (stderr, "increment_value_abs is: %d\n", increment_value_abs); /* @*/
|
||
fprintf (stderr, "add_iteration is: %d\n", add_iteration); /* @*/
|
||
fprintf (stderr, "INTVAL (comparison_value) is: %d\n", INTVAL (comparison_value)); /* @*/
|
||
fprintf (stderr, "INTVAL (initial_value) is: %d\n", INTVAL (initial_value)); /* @*/
|
||
#endif
|
||
|
||
if (increment_value_abs == 0) {
|
||
fprintf (stderr, "insert_bct: error: increment == 0 !!!\n");
|
||
abort ();
|
||
}
|
||
n_iterations = (difference + increment_value_abs - 1 + add_iteration)
|
||
/ increment_value_abs;
|
||
|
||
#if 0
|
||
fprintf (stderr, "number of iterations is: %d\n", n_iterations); /* @*/
|
||
#endif
|
||
instrument_loop_bct (loop_start, loop_end, GEN_INT (n_iterations));
|
||
|
||
/* Done with this loop. */
|
||
return;
|
||
}
|
||
|
||
/* Handle the more complex case, that the bounds are NOT known at compile time. */
|
||
/* In this case we generate run_time calculation of the number of iterations */
|
||
|
||
/* With runtime bounds, if the compare is of the form '!=' we give up */
|
||
if (comparison_code == NE) {
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"insert_bct: fail for loop %d: runtime bounds with != comparison\n",
|
||
loop_num);
|
||
return;
|
||
}
|
||
|
||
else {
|
||
/* We rely on the existence of run-time guard to ensure that the
|
||
loop executes at least once. */
|
||
rtx sequence;
|
||
rtx iterations_num_reg;
|
||
|
||
int increment_value_abs = INTVAL (increment) * increment_direction;
|
||
|
||
/* make sure that the increment is a power of two, otherwise (an
|
||
expensive) divide is needed. */
|
||
if (exact_log2 (increment_value_abs) == -1)
|
||
{
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream,
|
||
"insert_bct: not instrumenting BCT because the increment is not power of 2\n");
|
||
return;
|
||
}
|
||
|
||
/* compute the number of iterations */
|
||
start_sequence ();
|
||
{
|
||
rtx temp_reg;
|
||
|
||
/* Again, the number of iterations is calculated by:
|
||
;
|
||
; compare-val - initial-val + (increment -1) + additional-iteration
|
||
; num_iterations = -----------------------------------------------------------------
|
||
; increment
|
||
*/
|
||
/* ??? Do we have to call copy_rtx here before passing rtx to
|
||
expand_binop? */
|
||
if (compare_direction > 0) {
|
||
/* <, <= :the loop variable is increasing */
|
||
temp_reg = expand_binop (loop_var_mode, sub_optab, comparison_value,
|
||
initial_value, NULL_RTX, 0, OPTAB_LIB_WIDEN);
|
||
}
|
||
else {
|
||
temp_reg = expand_binop (loop_var_mode, sub_optab, initial_value,
|
||
comparison_value, NULL_RTX, 0, OPTAB_LIB_WIDEN);
|
||
}
|
||
|
||
if (increment_value_abs - 1 + add_iteration != 0)
|
||
temp_reg = expand_binop (loop_var_mode, add_optab, temp_reg,
|
||
GEN_INT (increment_value_abs - 1 + add_iteration),
|
||
NULL_RTX, 0, OPTAB_LIB_WIDEN);
|
||
|
||
if (increment_value_abs != 1)
|
||
{
|
||
/* ??? This will generate an expensive divide instruction for
|
||
most targets. The original authors apparently expected this
|
||
to be a shift, since they test for power-of-2 divisors above,
|
||
but just naively generating a divide instruction will not give
|
||
a shift. It happens to work for the PowerPC target because
|
||
the rs6000.md file has a divide pattern that emits shifts.
|
||
It will probably not work for any other target. */
|
||
iterations_num_reg = expand_binop (loop_var_mode, sdiv_optab,
|
||
temp_reg,
|
||
GEN_INT (increment_value_abs),
|
||
NULL_RTX, 0, OPTAB_LIB_WIDEN);
|
||
}
|
||
else
|
||
iterations_num_reg = temp_reg;
|
||
}
|
||
sequence = gen_sequence ();
|
||
end_sequence ();
|
||
emit_insn_before (sequence, loop_start);
|
||
instrument_loop_bct (loop_start, loop_end, iterations_num_reg);
|
||
}
|
||
}
|
||
|
||
/* instrument loop by inserting a bct in it. This is done in the following way:
|
||
1. A new register is created and assigned the hard register number of the count
|
||
register.
|
||
2. In the head of the loop the new variable is initialized by the value passed in the
|
||
loop_num_iterations parameter.
|
||
3. At the end of the loop, comparison of the register with 0 is generated.
|
||
The created comparison follows the pattern defined for the
|
||
decrement_and_branch_on_count insn, so this insn will be generated in assembly
|
||
generation phase.
|
||
4. The compare&branch on the old variable is deleted. So, if the loop-variable was
|
||
not used elsewhere, it will be eliminated by data-flow analisys. */
|
||
|
||
static void
|
||
instrument_loop_bct (loop_start, loop_end, loop_num_iterations)
|
||
rtx loop_start, loop_end;
|
||
rtx loop_num_iterations;
|
||
{
|
||
rtx temp_reg1, temp_reg2;
|
||
rtx start_label;
|
||
|
||
rtx sequence;
|
||
enum machine_mode loop_var_mode = SImode;
|
||
|
||
if (HAVE_decrement_and_branch_on_count)
|
||
{
|
||
if (loop_dump_stream)
|
||
fprintf (loop_dump_stream, "Loop: Inserting BCT\n");
|
||
|
||
/* eliminate the check on the old variable */
|
||
delete_insn (PREV_INSN (loop_end));
|
||
delete_insn (PREV_INSN (loop_end));
|
||
|
||
/* insert the label which will delimit the start of the loop */
|
||
start_label = gen_label_rtx ();
|
||
emit_label_after (start_label, loop_start);
|
||
|
||
/* insert initialization of the count register into the loop header */
|
||
start_sequence ();
|
||
temp_reg1 = gen_reg_rtx (loop_var_mode);
|
||
emit_insn (gen_move_insn (temp_reg1, loop_num_iterations));
|
||
|
||
/* this will be count register */
|
||
temp_reg2 = gen_rtx_REG (loop_var_mode, COUNT_REGISTER_REGNUM);
|
||
/* we have to move the value to the count register from an GPR
|
||
because rtx pointed to by loop_num_iterations could contain
|
||
expression which cannot be moved into count register */
|
||
emit_insn (gen_move_insn (temp_reg2, temp_reg1));
|
||
|
||
sequence = gen_sequence ();
|
||
end_sequence ();
|
||
emit_insn_after (sequence, loop_start);
|
||
|
||
/* insert new comparison on the count register instead of the
|
||
old one, generating the needed BCT pattern (that will be
|
||
later recognized by assembly generation phase). */
|
||
emit_jump_insn_before (gen_decrement_and_branch_on_count (temp_reg2, start_label),
|
||
loop_end);
|
||
LABEL_NUSES (start_label)++;
|
||
}
|
||
|
||
}
|
||
#endif /* HAVE_decrement_and_branch_on_count */
|
||
|
||
#endif /* HAIFA */
|
||
|
||
/* Scan the function and determine whether it has indirect (computed) jumps.
|
||
|
||
This is taken mostly from flow.c; similar code exists elsewhere
|
||
in the compiler. It may be useful to put this into rtlanal.c. */
|
||
static int
|
||
indirect_jump_in_function_p (start)
|
||
rtx start;
|
||
{
|
||
rtx insn;
|
||
|
||
for (insn = start; insn; insn = NEXT_INSN (insn))
|
||
if (computed_jump_p (insn))
|
||
return 1;
|
||
|
||
return 0;
|
||
}
|