a4cd5630b0
non-i386, non-unix, and generatable files have been trimmed, but can easily be added in later if needed. gcc-2.7.2.1 will follow shortly, it's a very small delta to this and it's handy to have both available for reference for such little cost. The freebsd-specific changes will then be committed, and once the dust has settled, the bmakefiles will be committed to use this code.
2957 lines
93 KiB
C
2957 lines
93 KiB
C
/* Data flow analysis for GNU compiler.
|
||
Copyright (C) 1987, 88, 92, 93, 94, 1995 Free Software Foundation, Inc.
|
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|
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This file is part of GNU CC.
|
||
|
||
GNU CC is free software; you can redistribute it and/or modify
|
||
it under the terms of the GNU General Public License as published by
|
||
the Free Software Foundation; either version 2, or (at your option)
|
||
any later version.
|
||
|
||
GNU CC is distributed in the hope that it will be useful,
|
||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
GNU General Public License for more details.
|
||
|
||
You should have received a copy of the GNU General Public License
|
||
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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|
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/* This file contains the data flow analysis pass of the compiler.
|
||
It computes data flow information
|
||
which tells combine_instructions which insns to consider combining
|
||
and controls register allocation.
|
||
|
||
Additional data flow information that is too bulky to record
|
||
is generated during the analysis, and is used at that time to
|
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create autoincrement and autodecrement addressing.
|
||
|
||
The first step is dividing the function into basic blocks.
|
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find_basic_blocks does this. Then life_analysis determines
|
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where each register is live and where it is dead.
|
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|
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** find_basic_blocks **
|
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|
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find_basic_blocks divides the current function's rtl
|
||
into basic blocks. It records the beginnings and ends of the
|
||
basic blocks in the vectors basic_block_head and basic_block_end,
|
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and the number of blocks in n_basic_blocks.
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|
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find_basic_blocks also finds any unreachable loops
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and deletes them.
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** life_analysis **
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|
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life_analysis is called immediately after find_basic_blocks.
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It uses the basic block information to determine where each
|
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hard or pseudo register is live.
|
||
|
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** live-register info **
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The information about where each register is live is in two parts:
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the REG_NOTES of insns, and the vector basic_block_live_at_start.
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basic_block_live_at_start has an element for each basic block,
|
||
and the element is a bit-vector with a bit for each hard or pseudo
|
||
register. The bit is 1 if the register is live at the beginning
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of the basic block.
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Two types of elements can be added to an insn's REG_NOTES.
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A REG_DEAD note is added to an insn's REG_NOTES for any register
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that meets both of two conditions: The value in the register is not
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needed in subsequent insns and the insn does not replace the value in
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the register (in the case of multi-word hard registers, the value in
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each register must be replaced by the insn to avoid a REG_DEAD note).
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In the vast majority of cases, an object in a REG_DEAD note will be
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used somewhere in the insn. The (rare) exception to this is if an
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insn uses a multi-word hard register and only some of the registers are
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needed in subsequent insns. In that case, REG_DEAD notes will be
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provided for those hard registers that are not subsequently needed.
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Partial REG_DEAD notes of this type do not occur when an insn sets
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only some of the hard registers used in such a multi-word operand;
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omitting REG_DEAD notes for objects stored in an insn is optional and
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the desire to do so does not justify the complexity of the partial
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REG_DEAD notes.
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REG_UNUSED notes are added for each register that is set by the insn
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but is unused subsequently (if every register set by the insn is unused
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and the insn does not reference memory or have some other side-effect,
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the insn is deleted instead). If only part of a multi-word hard
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register is used in a subsequent insn, REG_UNUSED notes are made for
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the parts that will not be used.
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To determine which registers are live after any insn, one can
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start from the beginning of the basic block and scan insns, noting
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which registers are set by each insn and which die there.
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** Other actions of life_analysis **
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life_analysis sets up the LOG_LINKS fields of insns because the
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information needed to do so is readily available.
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life_analysis deletes insns whose only effect is to store a value
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that is never used.
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life_analysis notices cases where a reference to a register as
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a memory address can be combined with a preceding or following
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incrementation or decrementation of the register. The separate
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instruction to increment or decrement is deleted and the address
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is changed to a POST_INC or similar rtx.
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Each time an incrementing or decrementing address is created,
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a REG_INC element is added to the insn's REG_NOTES list.
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life_analysis fills in certain vectors containing information about
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register usage: reg_n_refs, reg_n_deaths, reg_n_sets, reg_live_length,
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reg_n_calls_crosses and reg_basic_block. */
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#include <stdio.h>
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#include "config.h"
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#include "rtl.h"
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#include "basic-block.h"
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#include "insn-config.h"
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#include "regs.h"
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#include "hard-reg-set.h"
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#include "flags.h"
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#include "output.h"
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#include "obstack.h"
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#define obstack_chunk_alloc xmalloc
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#define obstack_chunk_free free
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/* List of labels that must never be deleted. */
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extern rtx forced_labels;
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|
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/* Get the basic block number of an insn.
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This info should not be expected to remain available
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after the end of life_analysis. */
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/* This is the limit of the allocated space in the following two arrays. */
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static int max_uid_for_flow;
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#define BLOCK_NUM(INSN) uid_block_number[INSN_UID (INSN)]
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/* This is where the BLOCK_NUM values are really stored.
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This is set up by find_basic_blocks and used there and in life_analysis,
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and then freed. */
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static int *uid_block_number;
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/* INSN_VOLATILE (insn) is 1 if the insn refers to anything volatile. */
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#define INSN_VOLATILE(INSN) uid_volatile[INSN_UID (INSN)]
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static char *uid_volatile;
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/* Number of basic blocks in the current function. */
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int n_basic_blocks;
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/* Maximum register number used in this function, plus one. */
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int max_regno;
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/* Maximum number of SCRATCH rtx's used in any basic block of this function. */
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int max_scratch;
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/* Number of SCRATCH rtx's in the current block. */
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static int num_scratch;
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/* Indexed by n, gives number of basic block that (REG n) is used in.
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If the value is REG_BLOCK_GLOBAL (-2),
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it means (REG n) is used in more than one basic block.
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REG_BLOCK_UNKNOWN (-1) means it hasn't been seen yet so we don't know.
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This information remains valid for the rest of the compilation
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of the current function; it is used to control register allocation. */
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int *reg_basic_block;
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/* Indexed by n, gives number of times (REG n) is used or set, each
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weighted by its loop-depth.
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This information remains valid for the rest of the compilation
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of the current function; it is used to control register allocation. */
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int *reg_n_refs;
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/* Indexed by N; says whether a pseudo register N was ever used
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within a SUBREG that changes the size of the reg. Some machines prohibit
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such objects to be in certain (usually floating-point) registers. */
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char *reg_changes_size;
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/* Indexed by N, gives number of places register N dies.
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This information remains valid for the rest of the compilation
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of the current function; it is used to control register allocation. */
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short *reg_n_deaths;
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/* Indexed by N, gives 1 if that reg is live across any CALL_INSNs.
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This information remains valid for the rest of the compilation
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of the current function; it is used to control register allocation. */
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int *reg_n_calls_crossed;
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/* Total number of instructions at which (REG n) is live.
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The larger this is, the less priority (REG n) gets for
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allocation in a real register.
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This information remains valid for the rest of the compilation
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of the current function; it is used to control register allocation.
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local-alloc.c may alter this number to change the priority.
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Negative values are special.
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-1 is used to mark a pseudo reg which has a constant or memory equivalent
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and is used infrequently enough that it should not get a hard register.
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-2 is used to mark a pseudo reg for a parameter, when a frame pointer
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is not required. global.c makes an allocno for this but does
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not try to assign a hard register to it. */
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int *reg_live_length;
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/* Element N is the next insn that uses (hard or pseudo) register number N
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within the current basic block; or zero, if there is no such insn.
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This is valid only during the final backward scan in propagate_block. */
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static rtx *reg_next_use;
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/* Size of a regset for the current function,
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in (1) bytes and (2) elements. */
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int regset_bytes;
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int regset_size;
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/* Element N is first insn in basic block N.
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This info lasts until we finish compiling the function. */
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rtx *basic_block_head;
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/* Element N is last insn in basic block N.
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This info lasts until we finish compiling the function. */
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rtx *basic_block_end;
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/* Element N is a regset describing the registers live
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at the start of basic block N.
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This info lasts until we finish compiling the function. */
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regset *basic_block_live_at_start;
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/* Regset of regs live when calls to `setjmp'-like functions happen. */
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regset regs_live_at_setjmp;
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/* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
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that have to go in the same hard reg.
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The first two regs in the list are a pair, and the next two
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are another pair, etc. */
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rtx regs_may_share;
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/* Element N is nonzero if control can drop into basic block N
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from the preceding basic block. Freed after life_analysis. */
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static char *basic_block_drops_in;
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/* Element N is depth within loops of the last insn in basic block number N.
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Freed after life_analysis. */
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static short *basic_block_loop_depth;
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/* Element N nonzero if basic block N can actually be reached.
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Vector exists only during find_basic_blocks. */
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static char *block_live_static;
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/* Depth within loops of basic block being scanned for lifetime analysis,
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plus one. This is the weight attached to references to registers. */
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||
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static int loop_depth;
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||
/* During propagate_block, this is non-zero if the value of CC0 is live. */
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static int cc0_live;
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/* During propagate_block, this contains the last MEM stored into. It
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is used to eliminate consecutive stores to the same location. */
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static rtx last_mem_set;
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/* Set of registers that may be eliminable. These are handled specially
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in updating regs_ever_live. */
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static HARD_REG_SET elim_reg_set;
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/* Forward declarations */
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static void find_basic_blocks PROTO((rtx, rtx));
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static int uses_reg_or_mem PROTO((rtx));
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static void mark_label_ref PROTO((rtx, rtx, int));
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static void life_analysis PROTO((rtx, int));
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void allocate_for_life_analysis PROTO((void));
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static void init_regset_vector PROTO((regset *, regset, int, int));
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static void propagate_block PROTO((regset, rtx, rtx, int,
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regset, int));
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static rtx flow_delete_insn PROTO((rtx));
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static int insn_dead_p PROTO((rtx, regset, int));
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static int libcall_dead_p PROTO((rtx, regset, rtx, rtx));
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static void mark_set_regs PROTO((regset, regset, rtx,
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rtx, regset));
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static void mark_set_1 PROTO((regset, regset, rtx,
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rtx, regset));
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static void find_auto_inc PROTO((regset, rtx, rtx));
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static void mark_used_regs PROTO((regset, regset, rtx, int, rtx));
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static int try_pre_increment_1 PROTO((rtx));
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static int try_pre_increment PROTO((rtx, rtx, HOST_WIDE_INT));
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static rtx find_use_as_address PROTO((rtx, rtx, HOST_WIDE_INT));
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void dump_flow_info PROTO((FILE *));
|
||
|
||
/* Find basic blocks of the current function and perform data flow analysis.
|
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F is the first insn of the function and NREGS the number of register numbers
|
||
in use. */
|
||
|
||
void
|
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flow_analysis (f, nregs, file)
|
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rtx f;
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int nregs;
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FILE *file;
|
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{
|
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register rtx insn;
|
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register int i;
|
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rtx nonlocal_label_list = nonlocal_label_rtx_list ();
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||
|
||
#ifdef ELIMINABLE_REGS
|
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static struct {int from, to; } eliminables[] = ELIMINABLE_REGS;
|
||
#endif
|
||
|
||
/* Record which registers will be eliminated. We use this in
|
||
mark_used_regs. */
|
||
|
||
CLEAR_HARD_REG_SET (elim_reg_set);
|
||
|
||
#ifdef ELIMINABLE_REGS
|
||
for (i = 0; i < sizeof eliminables / sizeof eliminables[0]; i++)
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SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
|
||
#else
|
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SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
|
||
#endif
|
||
|
||
/* Count the basic blocks. Also find maximum insn uid value used. */
|
||
|
||
{
|
||
register RTX_CODE prev_code = JUMP_INSN;
|
||
register RTX_CODE code;
|
||
|
||
max_uid_for_flow = 0;
|
||
|
||
for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
|
||
{
|
||
code = GET_CODE (insn);
|
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if (INSN_UID (insn) > max_uid_for_flow)
|
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max_uid_for_flow = INSN_UID (insn);
|
||
if (code == CODE_LABEL
|
||
|| (GET_RTX_CLASS (code) == 'i'
|
||
&& (prev_code == JUMP_INSN
|
||
|| (prev_code == CALL_INSN
|
||
&& nonlocal_label_list != 0)
|
||
|| prev_code == BARRIER)))
|
||
i++;
|
||
if (code != NOTE)
|
||
prev_code = code;
|
||
}
|
||
}
|
||
|
||
#ifdef AUTO_INC_DEC
|
||
/* Leave space for insns we make in some cases for auto-inc. These cases
|
||
are rare, so we don't need too much space. */
|
||
max_uid_for_flow += max_uid_for_flow / 10;
|
||
#endif
|
||
|
||
/* Allocate some tables that last till end of compiling this function
|
||
and some needed only in find_basic_blocks and life_analysis. */
|
||
|
||
n_basic_blocks = i;
|
||
basic_block_head = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
|
||
basic_block_end = (rtx *) oballoc (n_basic_blocks * sizeof (rtx));
|
||
basic_block_drops_in = (char *) alloca (n_basic_blocks);
|
||
basic_block_loop_depth = (short *) alloca (n_basic_blocks * sizeof (short));
|
||
uid_block_number
|
||
= (int *) alloca ((max_uid_for_flow + 1) * sizeof (int));
|
||
uid_volatile = (char *) alloca (max_uid_for_flow + 1);
|
||
bzero (uid_volatile, max_uid_for_flow + 1);
|
||
|
||
find_basic_blocks (f, nonlocal_label_list);
|
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life_analysis (f, nregs);
|
||
if (file)
|
||
dump_flow_info (file);
|
||
|
||
basic_block_drops_in = 0;
|
||
uid_block_number = 0;
|
||
basic_block_loop_depth = 0;
|
||
}
|
||
|
||
/* Find all basic blocks of the function whose first insn is F.
|
||
Store the correct data in the tables that describe the basic blocks,
|
||
set up the chains of references for each CODE_LABEL, and
|
||
delete any entire basic blocks that cannot be reached.
|
||
|
||
NONLOCAL_LABEL_LIST is the same local variable from flow_analysis. */
|
||
|
||
static void
|
||
find_basic_blocks (f, nonlocal_label_list)
|
||
rtx f, nonlocal_label_list;
|
||
{
|
||
register rtx insn;
|
||
register int i;
|
||
register char *block_live = (char *) alloca (n_basic_blocks);
|
||
register char *block_marked = (char *) alloca (n_basic_blocks);
|
||
/* List of label_refs to all labels whose addresses are taken
|
||
and used as data. */
|
||
rtx label_value_list;
|
||
rtx x, note;
|
||
enum rtx_code prev_code, code;
|
||
int depth, pass;
|
||
|
||
pass = 1;
|
||
restart:
|
||
|
||
label_value_list = 0;
|
||
block_live_static = block_live;
|
||
bzero (block_live, n_basic_blocks);
|
||
bzero (block_marked, n_basic_blocks);
|
||
|
||
/* Initialize with just block 0 reachable and no blocks marked. */
|
||
if (n_basic_blocks > 0)
|
||
block_live[0] = 1;
|
||
|
||
/* Initialize the ref chain of each label to 0. Record where all the
|
||
blocks start and end and their depth in loops. For each insn, record
|
||
the block it is in. Also mark as reachable any blocks headed by labels
|
||
that must not be deleted. */
|
||
|
||
for (insn = f, i = -1, prev_code = JUMP_INSN, depth = 1;
|
||
insn; insn = NEXT_INSN (insn))
|
||
{
|
||
code = GET_CODE (insn);
|
||
if (code == NOTE)
|
||
{
|
||
if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
|
||
depth++;
|
||
else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
|
||
depth--;
|
||
}
|
||
|
||
/* A basic block starts at label, or after something that can jump. */
|
||
else if (code == CODE_LABEL
|
||
|| (GET_RTX_CLASS (code) == 'i'
|
||
&& (prev_code == JUMP_INSN
|
||
|| (prev_code == CALL_INSN
|
||
&& nonlocal_label_list != 0)
|
||
|| prev_code == BARRIER)))
|
||
{
|
||
basic_block_head[++i] = insn;
|
||
basic_block_end[i] = insn;
|
||
basic_block_loop_depth[i] = depth;
|
||
|
||
if (code == CODE_LABEL)
|
||
{
|
||
LABEL_REFS (insn) = insn;
|
||
/* Any label that cannot be deleted
|
||
is considered to start a reachable block. */
|
||
if (LABEL_PRESERVE_P (insn))
|
||
block_live[i] = 1;
|
||
}
|
||
}
|
||
|
||
else if (GET_RTX_CLASS (code) == 'i')
|
||
{
|
||
basic_block_end[i] = insn;
|
||
basic_block_loop_depth[i] = depth;
|
||
}
|
||
|
||
if (GET_RTX_CLASS (code) == 'i')
|
||
{
|
||
/* Make a list of all labels referred to other than by jumps. */
|
||
for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
|
||
if (REG_NOTE_KIND (note) == REG_LABEL)
|
||
label_value_list = gen_rtx (EXPR_LIST, VOIDmode, XEXP (note, 0),
|
||
label_value_list);
|
||
}
|
||
|
||
BLOCK_NUM (insn) = i;
|
||
|
||
if (code != NOTE)
|
||
prev_code = code;
|
||
}
|
||
|
||
/* During the second pass, `n_basic_blocks' is only an upper bound.
|
||
Only perform the sanity check for the first pass, and on the second
|
||
pass ensure `n_basic_blocks' is set to the correct value. */
|
||
if (pass == 1 && i + 1 != n_basic_blocks)
|
||
abort ();
|
||
n_basic_blocks = i + 1;
|
||
|
||
/* Don't delete the labels (in this function)
|
||
that are referenced by non-jump instructions. */
|
||
|
||
for (x = label_value_list; x; x = XEXP (x, 1))
|
||
if (! LABEL_REF_NONLOCAL_P (x))
|
||
block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
|
||
|
||
for (x = forced_labels; x; x = XEXP (x, 1))
|
||
if (! LABEL_REF_NONLOCAL_P (x))
|
||
block_live[BLOCK_NUM (XEXP (x, 0))] = 1;
|
||
|
||
/* Record which basic blocks control can drop in to. */
|
||
|
||
for (i = 0; i < n_basic_blocks; i++)
|
||
{
|
||
for (insn = PREV_INSN (basic_block_head[i]);
|
||
insn && GET_CODE (insn) == NOTE; insn = PREV_INSN (insn))
|
||
;
|
||
|
||
basic_block_drops_in[i] = insn && GET_CODE (insn) != BARRIER;
|
||
}
|
||
|
||
/* Now find which basic blocks can actually be reached
|
||
and put all jump insns' LABEL_REFS onto the ref-chains
|
||
of their target labels. */
|
||
|
||
if (n_basic_blocks > 0)
|
||
{
|
||
int something_marked = 1;
|
||
int deleted;
|
||
|
||
/* Find all indirect jump insns and mark them as possibly jumping to all
|
||
the labels whose addresses are explicitly used. This is because,
|
||
when there are computed gotos, we can't tell which labels they jump
|
||
to, of all the possibilities.
|
||
|
||
Tablejumps and casesi insns are OK and we can recognize them by
|
||
a (use (label_ref)). */
|
||
|
||
for (insn = f; insn; insn = NEXT_INSN (insn))
|
||
if (GET_CODE (insn) == JUMP_INSN)
|
||
{
|
||
rtx pat = PATTERN (insn);
|
||
int computed_jump = 0;
|
||
|
||
if (GET_CODE (pat) == PARALLEL)
|
||
{
|
||
int len = XVECLEN (pat, 0);
|
||
int has_use_labelref = 0;
|
||
|
||
for (i = len - 1; i >= 0; i--)
|
||
if (GET_CODE (XVECEXP (pat, 0, i)) == USE
|
||
&& (GET_CODE (XEXP (XVECEXP (pat, 0, i), 0))
|
||
== LABEL_REF))
|
||
has_use_labelref = 1;
|
||
|
||
if (! has_use_labelref)
|
||
for (i = len - 1; i >= 0; i--)
|
||
if (GET_CODE (XVECEXP (pat, 0, i)) == SET
|
||
&& SET_DEST (XVECEXP (pat, 0, i)) == pc_rtx
|
||
&& uses_reg_or_mem (SET_SRC (XVECEXP (pat, 0, i))))
|
||
computed_jump = 1;
|
||
}
|
||
else if (GET_CODE (pat) == SET
|
||
&& SET_DEST (pat) == pc_rtx
|
||
&& uses_reg_or_mem (SET_SRC (pat)))
|
||
computed_jump = 1;
|
||
|
||
if (computed_jump)
|
||
{
|
||
for (x = label_value_list; x; x = XEXP (x, 1))
|
||
mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
|
||
insn, 0);
|
||
|
||
for (x = forced_labels; x; x = XEXP (x, 1))
|
||
mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
|
||
insn, 0);
|
||
}
|
||
}
|
||
|
||
/* Find all call insns and mark them as possibly jumping
|
||
to all the nonlocal goto handler labels. */
|
||
|
||
for (insn = f; insn; insn = NEXT_INSN (insn))
|
||
if (GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
for (x = nonlocal_label_list; x; x = XEXP (x, 1))
|
||
mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)),
|
||
insn, 0);
|
||
|
||
/* ??? This could be made smarter:
|
||
in some cases it's possible to tell that certain
|
||
calls will not do a nonlocal goto.
|
||
|
||
For example, if the nested functions that do the
|
||
nonlocal gotos do not have their addresses taken, then
|
||
only calls to those functions or to other nested
|
||
functions that use them could possibly do nonlocal
|
||
gotos. */
|
||
}
|
||
|
||
/* Pass over all blocks, marking each block that is reachable
|
||
and has not yet been marked.
|
||
Keep doing this until, in one pass, no blocks have been marked.
|
||
Then blocks_live and blocks_marked are identical and correct.
|
||
In addition, all jumps actually reachable have been marked. */
|
||
|
||
while (something_marked)
|
||
{
|
||
something_marked = 0;
|
||
for (i = 0; i < n_basic_blocks; i++)
|
||
if (block_live[i] && !block_marked[i])
|
||
{
|
||
block_marked[i] = 1;
|
||
something_marked = 1;
|
||
if (i + 1 < n_basic_blocks && basic_block_drops_in[i + 1])
|
||
block_live[i + 1] = 1;
|
||
insn = basic_block_end[i];
|
||
if (GET_CODE (insn) == JUMP_INSN)
|
||
mark_label_ref (PATTERN (insn), insn, 0);
|
||
}
|
||
}
|
||
|
||
/* ??? See if we have a "live" basic block that is not reachable.
|
||
This can happen if it is headed by a label that is preserved or
|
||
in one of the label lists, but no call or computed jump is in
|
||
the loop. It's not clear if we can delete the block or not,
|
||
but don't for now. However, we will mess up register status if
|
||
it remains unreachable, so add a fake reachability from the
|
||
previous block. */
|
||
|
||
for (i = 1; i < n_basic_blocks; i++)
|
||
if (block_live[i] && ! basic_block_drops_in[i]
|
||
&& GET_CODE (basic_block_head[i]) == CODE_LABEL
|
||
&& LABEL_REFS (basic_block_head[i]) == basic_block_head[i])
|
||
basic_block_drops_in[i] = 1;
|
||
|
||
/* Now delete the code for any basic blocks that can't be reached.
|
||
They can occur because jump_optimize does not recognize
|
||
unreachable loops as unreachable. */
|
||
|
||
deleted = 0;
|
||
for (i = 0; i < n_basic_blocks; i++)
|
||
if (!block_live[i])
|
||
{
|
||
deleted++;
|
||
|
||
/* Delete the insns in a (non-live) block. We physically delete
|
||
every non-note insn except the start and end (so
|
||
basic_block_head/end needn't be updated), we turn the latter
|
||
into NOTE_INSN_DELETED notes.
|
||
We use to "delete" the insns by turning them into notes, but
|
||
we may be deleting lots of insns that subsequent passes would
|
||
otherwise have to process. Secondly, lots of deleted blocks in
|
||
a row can really slow down propagate_block since it will
|
||
otherwise process insn-turned-notes multiple times when it
|
||
looks for loop begin/end notes. */
|
||
if (basic_block_head[i] != basic_block_end[i])
|
||
{
|
||
/* It would be quicker to delete all of these with a single
|
||
unchaining, rather than one at a time, but we need to keep
|
||
the NOTE's. */
|
||
insn = NEXT_INSN (basic_block_head[i]);
|
||
while (insn != basic_block_end[i])
|
||
{
|
||
if (GET_CODE (insn) == BARRIER)
|
||
abort ();
|
||
else if (GET_CODE (insn) != NOTE)
|
||
insn = flow_delete_insn (insn);
|
||
else
|
||
insn = NEXT_INSN (insn);
|
||
}
|
||
}
|
||
insn = basic_block_head[i];
|
||
if (GET_CODE (insn) != NOTE)
|
||
{
|
||
/* Turn the head into a deleted insn note. */
|
||
if (GET_CODE (insn) == BARRIER)
|
||
abort ();
|
||
PUT_CODE (insn, NOTE);
|
||
NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
|
||
NOTE_SOURCE_FILE (insn) = 0;
|
||
}
|
||
insn = basic_block_end[i];
|
||
if (GET_CODE (insn) != NOTE)
|
||
{
|
||
/* Turn the tail into a deleted insn note. */
|
||
if (GET_CODE (insn) == BARRIER)
|
||
abort ();
|
||
PUT_CODE (insn, NOTE);
|
||
NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
|
||
NOTE_SOURCE_FILE (insn) = 0;
|
||
}
|
||
/* BARRIERs are between basic blocks, not part of one.
|
||
Delete a BARRIER if the preceding jump is deleted.
|
||
We cannot alter a BARRIER into a NOTE
|
||
because it is too short; but we can really delete
|
||
it because it is not part of a basic block. */
|
||
if (NEXT_INSN (insn) != 0
|
||
&& GET_CODE (NEXT_INSN (insn)) == BARRIER)
|
||
delete_insn (NEXT_INSN (insn));
|
||
|
||
/* Each time we delete some basic blocks,
|
||
see if there is a jump around them that is
|
||
being turned into a no-op. If so, delete it. */
|
||
|
||
if (block_live[i - 1])
|
||
{
|
||
register int j;
|
||
for (j = i + 1; j < n_basic_blocks; j++)
|
||
if (block_live[j])
|
||
{
|
||
rtx label;
|
||
insn = basic_block_end[i - 1];
|
||
if (GET_CODE (insn) == JUMP_INSN
|
||
/* An unconditional jump is the only possibility
|
||
we must check for, since a conditional one
|
||
would make these blocks live. */
|
||
&& simplejump_p (insn)
|
||
&& (label = XEXP (SET_SRC (PATTERN (insn)), 0), 1)
|
||
&& INSN_UID (label) != 0
|
||
&& BLOCK_NUM (label) == j)
|
||
{
|
||
PUT_CODE (insn, NOTE);
|
||
NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
|
||
NOTE_SOURCE_FILE (insn) = 0;
|
||
if (GET_CODE (NEXT_INSN (insn)) != BARRIER)
|
||
abort ();
|
||
delete_insn (NEXT_INSN (insn));
|
||
}
|
||
break;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* There are pathological cases where one function calling hundreds of
|
||
nested inline functions can generate lots and lots of unreachable
|
||
blocks that jump can't delete. Since we don't use sparse matrices
|
||
a lot of memory will be needed to compile such functions.
|
||
Implementing sparse matrices is a fair bit of work and it is not
|
||
clear that they win more than they lose (we don't want to
|
||
unnecessarily slow down compilation of normal code). By making
|
||
another pass for the pathological case, we can greatly speed up
|
||
their compilation without hurting normal code. This works because
|
||
all the insns in the unreachable blocks have either been deleted or
|
||
turned into notes.
|
||
Note that we're talking about reducing memory usage by 10's of
|
||
megabytes and reducing compilation time by several minutes. */
|
||
/* ??? The choice of when to make another pass is a bit arbitrary,
|
||
and was derived from empirical data. */
|
||
if (pass == 1
|
||
&& deleted > 200)
|
||
{
|
||
pass++;
|
||
n_basic_blocks -= deleted;
|
||
/* `n_basic_blocks' may not be correct at this point: two previously
|
||
separate blocks may now be merged. That's ok though as we
|
||
recalculate it during the second pass. It certainly can't be
|
||
any larger than the current value. */
|
||
goto restart;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Subroutines of find_basic_blocks. */
|
||
|
||
/* Return 1 if X contain a REG or MEM that is not in the constant pool. */
|
||
|
||
static int
|
||
uses_reg_or_mem (x)
|
||
rtx x;
|
||
{
|
||
enum rtx_code code = GET_CODE (x);
|
||
int i, j;
|
||
char *fmt;
|
||
|
||
if (code == REG
|
||
|| (code == MEM
|
||
&& ! (GET_CODE (XEXP (x, 0)) == SYMBOL_REF
|
||
&& CONSTANT_POOL_ADDRESS_P (XEXP (x, 0)))))
|
||
return 1;
|
||
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e'
|
||
&& uses_reg_or_mem (XEXP (x, i)))
|
||
return 1;
|
||
|
||
if (fmt[i] == 'E')
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
if (uses_reg_or_mem (XVECEXP (x, i, j)))
|
||
return 1;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* Check expression X for label references;
|
||
if one is found, add INSN to the label's chain of references.
|
||
|
||
CHECKDUP means check for and avoid creating duplicate references
|
||
from the same insn. Such duplicates do no serious harm but
|
||
can slow life analysis. CHECKDUP is set only when duplicates
|
||
are likely. */
|
||
|
||
static void
|
||
mark_label_ref (x, insn, checkdup)
|
||
rtx x, insn;
|
||
int checkdup;
|
||
{
|
||
register RTX_CODE code;
|
||
register int i;
|
||
register char *fmt;
|
||
|
||
/* We can be called with NULL when scanning label_value_list. */
|
||
if (x == 0)
|
||
return;
|
||
|
||
code = GET_CODE (x);
|
||
if (code == LABEL_REF)
|
||
{
|
||
register rtx label = XEXP (x, 0);
|
||
register rtx y;
|
||
if (GET_CODE (label) != CODE_LABEL)
|
||
abort ();
|
||
/* If the label was never emitted, this insn is junk,
|
||
but avoid a crash trying to refer to BLOCK_NUM (label).
|
||
This can happen as a result of a syntax error
|
||
and a diagnostic has already been printed. */
|
||
if (INSN_UID (label) == 0)
|
||
return;
|
||
CONTAINING_INSN (x) = insn;
|
||
/* if CHECKDUP is set, check for duplicate ref from same insn
|
||
and don't insert. */
|
||
if (checkdup)
|
||
for (y = LABEL_REFS (label); y != label; y = LABEL_NEXTREF (y))
|
||
if (CONTAINING_INSN (y) == insn)
|
||
return;
|
||
LABEL_NEXTREF (x) = LABEL_REFS (label);
|
||
LABEL_REFS (label) = x;
|
||
block_live_static[BLOCK_NUM (label)] = 1;
|
||
return;
|
||
}
|
||
|
||
fmt = GET_RTX_FORMAT (code);
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
mark_label_ref (XEXP (x, i), insn, 0);
|
||
if (fmt[i] == 'E')
|
||
{
|
||
register int j;
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
mark_label_ref (XVECEXP (x, i, j), insn, 1);
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Delete INSN by patching it out.
|
||
Return the next insn. */
|
||
|
||
static rtx
|
||
flow_delete_insn (insn)
|
||
rtx insn;
|
||
{
|
||
/* ??? For the moment we assume we don't have to watch for NULLs here
|
||
since the start/end of basic blocks aren't deleted like this. */
|
||
NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
|
||
PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
|
||
return NEXT_INSN (insn);
|
||
}
|
||
|
||
/* Determine which registers are live at the start of each
|
||
basic block of the function whose first insn is F.
|
||
NREGS is the number of registers used in F.
|
||
We allocate the vector basic_block_live_at_start
|
||
and the regsets that it points to, and fill them with the data.
|
||
regset_size and regset_bytes are also set here. */
|
||
|
||
static void
|
||
life_analysis (f, nregs)
|
||
rtx f;
|
||
int nregs;
|
||
{
|
||
register regset tem;
|
||
int first_pass;
|
||
int changed;
|
||
/* For each basic block, a bitmask of regs
|
||
live on exit from the block. */
|
||
regset *basic_block_live_at_end;
|
||
/* For each basic block, a bitmask of regs
|
||
live on entry to a successor-block of this block.
|
||
If this does not match basic_block_live_at_end,
|
||
that must be updated, and the block must be rescanned. */
|
||
regset *basic_block_new_live_at_end;
|
||
/* For each basic block, a bitmask of regs
|
||
whose liveness at the end of the basic block
|
||
can make a difference in which regs are live on entry to the block.
|
||
These are the regs that are set within the basic block,
|
||
possibly excluding those that are used after they are set. */
|
||
regset *basic_block_significant;
|
||
register int i;
|
||
rtx insn;
|
||
|
||
struct obstack flow_obstack;
|
||
|
||
gcc_obstack_init (&flow_obstack);
|
||
|
||
max_regno = nregs;
|
||
|
||
bzero (regs_ever_live, sizeof regs_ever_live);
|
||
|
||
/* Allocate and zero out many data structures
|
||
that will record the data from lifetime analysis. */
|
||
|
||
allocate_for_life_analysis ();
|
||
|
||
reg_next_use = (rtx *) alloca (nregs * sizeof (rtx));
|
||
bzero ((char *) reg_next_use, nregs * sizeof (rtx));
|
||
|
||
/* Set up several regset-vectors used internally within this function.
|
||
Their meanings are documented above, with their declarations. */
|
||
|
||
basic_block_live_at_end
|
||
= (regset *) alloca (n_basic_blocks * sizeof (regset));
|
||
|
||
/* Don't use alloca since that leads to a crash rather than an error message
|
||
if there isn't enough space.
|
||
Don't use oballoc since we may need to allocate other things during
|
||
this function on the temporary obstack. */
|
||
tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
|
||
bzero ((char *) tem, n_basic_blocks * regset_bytes);
|
||
init_regset_vector (basic_block_live_at_end, tem,
|
||
n_basic_blocks, regset_bytes);
|
||
|
||
basic_block_new_live_at_end
|
||
= (regset *) alloca (n_basic_blocks * sizeof (regset));
|
||
tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
|
||
bzero ((char *) tem, n_basic_blocks * regset_bytes);
|
||
init_regset_vector (basic_block_new_live_at_end, tem,
|
||
n_basic_blocks, regset_bytes);
|
||
|
||
basic_block_significant
|
||
= (regset *) alloca (n_basic_blocks * sizeof (regset));
|
||
tem = (regset) obstack_alloc (&flow_obstack, n_basic_blocks * regset_bytes);
|
||
bzero ((char *) tem, n_basic_blocks * regset_bytes);
|
||
init_regset_vector (basic_block_significant, tem,
|
||
n_basic_blocks, regset_bytes);
|
||
|
||
/* Record which insns refer to any volatile memory
|
||
or for any reason can't be deleted just because they are dead stores.
|
||
Also, delete any insns that copy a register to itself. */
|
||
|
||
for (insn = f; insn; insn = NEXT_INSN (insn))
|
||
{
|
||
enum rtx_code code1 = GET_CODE (insn);
|
||
if (code1 == CALL_INSN)
|
||
INSN_VOLATILE (insn) = 1;
|
||
else if (code1 == INSN || code1 == JUMP_INSN)
|
||
{
|
||
/* Delete (in effect) any obvious no-op moves. */
|
||
if (GET_CODE (PATTERN (insn)) == SET
|
||
&& GET_CODE (SET_DEST (PATTERN (insn))) == REG
|
||
&& GET_CODE (SET_SRC (PATTERN (insn))) == REG
|
||
&& REGNO (SET_DEST (PATTERN (insn))) ==
|
||
REGNO (SET_SRC (PATTERN (insn)))
|
||
/* Insns carrying these notes are useful later on. */
|
||
&& ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
|
||
{
|
||
PUT_CODE (insn, NOTE);
|
||
NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
|
||
NOTE_SOURCE_FILE (insn) = 0;
|
||
}
|
||
else if (GET_CODE (PATTERN (insn)) == PARALLEL)
|
||
{
|
||
/* If nothing but SETs of registers to themselves,
|
||
this insn can also be deleted. */
|
||
for (i = 0; i < XVECLEN (PATTERN (insn), 0); i++)
|
||
{
|
||
rtx tem = XVECEXP (PATTERN (insn), 0, i);
|
||
|
||
if (GET_CODE (tem) == USE
|
||
|| GET_CODE (tem) == CLOBBER)
|
||
continue;
|
||
|
||
if (GET_CODE (tem) != SET
|
||
|| GET_CODE (SET_DEST (tem)) != REG
|
||
|| GET_CODE (SET_SRC (tem)) != REG
|
||
|| REGNO (SET_DEST (tem)) != REGNO (SET_SRC (tem)))
|
||
break;
|
||
}
|
||
|
||
if (i == XVECLEN (PATTERN (insn), 0)
|
||
/* Insns carrying these notes are useful later on. */
|
||
&& ! find_reg_note (insn, REG_EQUAL, NULL_RTX))
|
||
{
|
||
PUT_CODE (insn, NOTE);
|
||
NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
|
||
NOTE_SOURCE_FILE (insn) = 0;
|
||
}
|
||
else
|
||
INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
|
||
}
|
||
else if (GET_CODE (PATTERN (insn)) != USE)
|
||
INSN_VOLATILE (insn) = volatile_refs_p (PATTERN (insn));
|
||
/* A SET that makes space on the stack cannot be dead.
|
||
(Such SETs occur only for allocating variable-size data,
|
||
so they will always have a PLUS or MINUS according to the
|
||
direction of stack growth.)
|
||
Even if this function never uses this stack pointer value,
|
||
signal handlers do! */
|
||
else if (code1 == INSN && GET_CODE (PATTERN (insn)) == SET
|
||
&& SET_DEST (PATTERN (insn)) == stack_pointer_rtx
|
||
#ifdef STACK_GROWS_DOWNWARD
|
||
&& GET_CODE (SET_SRC (PATTERN (insn))) == MINUS
|
||
#else
|
||
&& GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
|
||
#endif
|
||
&& XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx)
|
||
INSN_VOLATILE (insn) = 1;
|
||
}
|
||
}
|
||
|
||
if (n_basic_blocks > 0)
|
||
#ifdef EXIT_IGNORE_STACK
|
||
if (! EXIT_IGNORE_STACK
|
||
|| (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
|
||
#endif
|
||
{
|
||
/* If exiting needs the right stack value,
|
||
consider the stack pointer live at the end of the function. */
|
||
basic_block_live_at_end[n_basic_blocks - 1]
|
||
[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
|
||
|= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
|
||
basic_block_new_live_at_end[n_basic_blocks - 1]
|
||
[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
|
||
|= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
|
||
}
|
||
|
||
/* Mark the frame pointer is needed at the end of the function. If
|
||
we end up eliminating it, it will be removed from the live list
|
||
of each basic block by reload. */
|
||
|
||
if (n_basic_blocks > 0)
|
||
{
|
||
basic_block_live_at_end[n_basic_blocks - 1]
|
||
[FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
|
||
|= (REGSET_ELT_TYPE) 1 << (FRAME_POINTER_REGNUM % REGSET_ELT_BITS);
|
||
basic_block_new_live_at_end[n_basic_blocks - 1]
|
||
[FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
|
||
|= (REGSET_ELT_TYPE) 1 << (FRAME_POINTER_REGNUM % REGSET_ELT_BITS);
|
||
#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
|
||
/* If they are different, also mark the hard frame pointer as live */
|
||
basic_block_live_at_end[n_basic_blocks - 1]
|
||
[HARD_FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
|
||
|= (REGSET_ELT_TYPE) 1 << (HARD_FRAME_POINTER_REGNUM
|
||
% REGSET_ELT_BITS);
|
||
basic_block_new_live_at_end[n_basic_blocks - 1]
|
||
[HARD_FRAME_POINTER_REGNUM / REGSET_ELT_BITS]
|
||
|= (REGSET_ELT_TYPE) 1 << (HARD_FRAME_POINTER_REGNUM
|
||
% REGSET_ELT_BITS);
|
||
#endif
|
||
}
|
||
|
||
/* Mark all global registers as being live at the end of the function
|
||
since they may be referenced by our caller. */
|
||
|
||
if (n_basic_blocks > 0)
|
||
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
|
||
if (global_regs[i])
|
||
{
|
||
basic_block_live_at_end[n_basic_blocks - 1]
|
||
[i / REGSET_ELT_BITS]
|
||
|= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
|
||
basic_block_new_live_at_end[n_basic_blocks - 1]
|
||
[i / REGSET_ELT_BITS]
|
||
|= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
|
||
}
|
||
|
||
/* Propagate life info through the basic blocks
|
||
around the graph of basic blocks.
|
||
|
||
This is a relaxation process: each time a new register
|
||
is live at the end of the basic block, we must scan the block
|
||
to determine which registers are, as a consequence, live at the beginning
|
||
of that block. These registers must then be marked live at the ends
|
||
of all the blocks that can transfer control to that block.
|
||
The process continues until it reaches a fixed point. */
|
||
|
||
first_pass = 1;
|
||
changed = 1;
|
||
while (changed)
|
||
{
|
||
changed = 0;
|
||
for (i = n_basic_blocks - 1; i >= 0; i--)
|
||
{
|
||
int consider = first_pass;
|
||
int must_rescan = first_pass;
|
||
register int j;
|
||
|
||
if (!first_pass)
|
||
{
|
||
/* Set CONSIDER if this block needs thinking about at all
|
||
(that is, if the regs live now at the end of it
|
||
are not the same as were live at the end of it when
|
||
we last thought about it).
|
||
Set must_rescan if it needs to be thought about
|
||
instruction by instruction (that is, if any additional
|
||
reg that is live at the end now but was not live there before
|
||
is one of the significant regs of this basic block). */
|
||
|
||
for (j = 0; j < regset_size; j++)
|
||
{
|
||
register REGSET_ELT_TYPE x
|
||
= (basic_block_new_live_at_end[i][j]
|
||
& ~basic_block_live_at_end[i][j]);
|
||
if (x)
|
||
consider = 1;
|
||
if (x & basic_block_significant[i][j])
|
||
{
|
||
must_rescan = 1;
|
||
consider = 1;
|
||
break;
|
||
}
|
||
}
|
||
|
||
if (! consider)
|
||
continue;
|
||
}
|
||
|
||
/* The live_at_start of this block may be changing,
|
||
so another pass will be required after this one. */
|
||
changed = 1;
|
||
|
||
if (! must_rescan)
|
||
{
|
||
/* No complete rescan needed;
|
||
just record those variables newly known live at end
|
||
as live at start as well. */
|
||
for (j = 0; j < regset_size; j++)
|
||
{
|
||
register REGSET_ELT_TYPE x
|
||
= (basic_block_new_live_at_end[i][j]
|
||
& ~basic_block_live_at_end[i][j]);
|
||
basic_block_live_at_start[i][j] |= x;
|
||
basic_block_live_at_end[i][j] |= x;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
/* Update the basic_block_live_at_start
|
||
by propagation backwards through the block. */
|
||
bcopy ((char *) basic_block_new_live_at_end[i],
|
||
(char *) basic_block_live_at_end[i], regset_bytes);
|
||
bcopy ((char *) basic_block_live_at_end[i],
|
||
(char *) basic_block_live_at_start[i], regset_bytes);
|
||
propagate_block (basic_block_live_at_start[i],
|
||
basic_block_head[i], basic_block_end[i], 0,
|
||
first_pass ? basic_block_significant[i]
|
||
: (regset) 0,
|
||
i);
|
||
}
|
||
|
||
{
|
||
register rtx jump, head;
|
||
|
||
/* Update the basic_block_new_live_at_end's of the block
|
||
that falls through into this one (if any). */
|
||
head = basic_block_head[i];
|
||
if (basic_block_drops_in[i])
|
||
{
|
||
register int j;
|
||
for (j = 0; j < regset_size; j++)
|
||
basic_block_new_live_at_end[i-1][j]
|
||
|= basic_block_live_at_start[i][j];
|
||
}
|
||
|
||
/* Update the basic_block_new_live_at_end's of
|
||
all the blocks that jump to this one. */
|
||
if (GET_CODE (head) == CODE_LABEL)
|
||
for (jump = LABEL_REFS (head);
|
||
jump != head;
|
||
jump = LABEL_NEXTREF (jump))
|
||
{
|
||
register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
|
||
register int j;
|
||
for (j = 0; j < regset_size; j++)
|
||
basic_block_new_live_at_end[from_block][j]
|
||
|= basic_block_live_at_start[i][j];
|
||
}
|
||
}
|
||
#ifdef USE_C_ALLOCA
|
||
alloca (0);
|
||
#endif
|
||
}
|
||
first_pass = 0;
|
||
}
|
||
|
||
/* The only pseudos that are live at the beginning of the function are
|
||
those that were not set anywhere in the function. local-alloc doesn't
|
||
know how to handle these correctly, so mark them as not local to any
|
||
one basic block. */
|
||
|
||
if (n_basic_blocks > 0)
|
||
for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
|
||
if (basic_block_live_at_start[0][i / REGSET_ELT_BITS]
|
||
& ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
|
||
reg_basic_block[i] = REG_BLOCK_GLOBAL;
|
||
|
||
/* Now the life information is accurate.
|
||
Make one more pass over each basic block
|
||
to delete dead stores, create autoincrement addressing
|
||
and record how many times each register is used, is set, or dies.
|
||
|
||
To save time, we operate directly in basic_block_live_at_end[i],
|
||
thus destroying it (in fact, converting it into a copy of
|
||
basic_block_live_at_start[i]). This is ok now because
|
||
basic_block_live_at_end[i] is no longer used past this point. */
|
||
|
||
max_scratch = 0;
|
||
|
||
for (i = 0; i < n_basic_blocks; i++)
|
||
{
|
||
propagate_block (basic_block_live_at_end[i],
|
||
basic_block_head[i], basic_block_end[i], 1,
|
||
(regset) 0, i);
|
||
#ifdef USE_C_ALLOCA
|
||
alloca (0);
|
||
#endif
|
||
}
|
||
|
||
#if 0
|
||
/* Something live during a setjmp should not be put in a register
|
||
on certain machines which restore regs from stack frames
|
||
rather than from the jmpbuf.
|
||
But we don't need to do this for the user's variables, since
|
||
ANSI says only volatile variables need this. */
|
||
#ifdef LONGJMP_RESTORE_FROM_STACK
|
||
for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
|
||
if (regs_live_at_setjmp[i / REGSET_ELT_BITS]
|
||
& ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS))
|
||
&& regno_reg_rtx[i] != 0 && ! REG_USERVAR_P (regno_reg_rtx[i]))
|
||
{
|
||
reg_live_length[i] = -1;
|
||
reg_basic_block[i] = -1;
|
||
}
|
||
#endif
|
||
#endif
|
||
|
||
/* We have a problem with any pseudoreg that
|
||
lives across the setjmp. ANSI says that if a
|
||
user variable does not change in value
|
||
between the setjmp and the longjmp, then the longjmp preserves it.
|
||
This includes longjmp from a place where the pseudo appears dead.
|
||
(In principle, the value still exists if it is in scope.)
|
||
If the pseudo goes in a hard reg, some other value may occupy
|
||
that hard reg where this pseudo is dead, thus clobbering the pseudo.
|
||
Conclusion: such a pseudo must not go in a hard reg. */
|
||
for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++)
|
||
if ((regs_live_at_setjmp[i / REGSET_ELT_BITS]
|
||
& ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS)))
|
||
&& regno_reg_rtx[i] != 0)
|
||
{
|
||
reg_live_length[i] = -1;
|
||
reg_basic_block[i] = -1;
|
||
}
|
||
|
||
obstack_free (&flow_obstack, NULL_PTR);
|
||
}
|
||
|
||
/* Subroutines of life analysis. */
|
||
|
||
/* Allocate the permanent data structures that represent the results
|
||
of life analysis. Not static since used also for stupid life analysis. */
|
||
|
||
void
|
||
allocate_for_life_analysis ()
|
||
{
|
||
register int i;
|
||
register regset tem;
|
||
|
||
regset_size = ((max_regno + REGSET_ELT_BITS - 1) / REGSET_ELT_BITS);
|
||
regset_bytes = regset_size * sizeof (*(regset)0);
|
||
|
||
reg_n_refs = (int *) oballoc (max_regno * sizeof (int));
|
||
bzero ((char *) reg_n_refs, max_regno * sizeof (int));
|
||
|
||
reg_n_sets = (short *) oballoc (max_regno * sizeof (short));
|
||
bzero ((char *) reg_n_sets, max_regno * sizeof (short));
|
||
|
||
reg_n_deaths = (short *) oballoc (max_regno * sizeof (short));
|
||
bzero ((char *) reg_n_deaths, max_regno * sizeof (short));
|
||
|
||
reg_changes_size = (char *) oballoc (max_regno * sizeof (char));
|
||
bzero (reg_changes_size, max_regno * sizeof (char));;
|
||
|
||
reg_live_length = (int *) oballoc (max_regno * sizeof (int));
|
||
bzero ((char *) reg_live_length, max_regno * sizeof (int));
|
||
|
||
reg_n_calls_crossed = (int *) oballoc (max_regno * sizeof (int));
|
||
bzero ((char *) reg_n_calls_crossed, max_regno * sizeof (int));
|
||
|
||
reg_basic_block = (int *) oballoc (max_regno * sizeof (int));
|
||
for (i = 0; i < max_regno; i++)
|
||
reg_basic_block[i] = REG_BLOCK_UNKNOWN;
|
||
|
||
basic_block_live_at_start
|
||
= (regset *) oballoc (n_basic_blocks * sizeof (regset));
|
||
tem = (regset) oballoc (n_basic_blocks * regset_bytes);
|
||
bzero ((char *) tem, n_basic_blocks * regset_bytes);
|
||
init_regset_vector (basic_block_live_at_start, tem,
|
||
n_basic_blocks, regset_bytes);
|
||
|
||
regs_live_at_setjmp = (regset) oballoc (regset_bytes);
|
||
bzero ((char *) regs_live_at_setjmp, regset_bytes);
|
||
}
|
||
|
||
/* Make each element of VECTOR point at a regset,
|
||
taking the space for all those regsets from SPACE.
|
||
SPACE is of type regset, but it is really as long as NELTS regsets.
|
||
BYTES_PER_ELT is the number of bytes in one regset. */
|
||
|
||
static void
|
||
init_regset_vector (vector, space, nelts, bytes_per_elt)
|
||
regset *vector;
|
||
regset space;
|
||
int nelts;
|
||
int bytes_per_elt;
|
||
{
|
||
register int i;
|
||
register regset p = space;
|
||
|
||
for (i = 0; i < nelts; i++)
|
||
{
|
||
vector[i] = p;
|
||
p += bytes_per_elt / sizeof (*p);
|
||
}
|
||
}
|
||
|
||
/* Compute the registers live at the beginning of a basic block
|
||
from those live at the end.
|
||
|
||
When called, OLD contains those live at the end.
|
||
On return, it contains those live at the beginning.
|
||
FIRST and LAST are the first and last insns of the basic block.
|
||
|
||
FINAL is nonzero if we are doing the final pass which is not
|
||
for computing the life info (since that has already been done)
|
||
but for acting on it. On this pass, we delete dead stores,
|
||
set up the logical links and dead-variables lists of instructions,
|
||
and merge instructions for autoincrement and autodecrement addresses.
|
||
|
||
SIGNIFICANT is nonzero only the first time for each basic block.
|
||
If it is nonzero, it points to a regset in which we store
|
||
a 1 for each register that is set within the block.
|
||
|
||
BNUM is the number of the basic block. */
|
||
|
||
static void
|
||
propagate_block (old, first, last, final, significant, bnum)
|
||
register regset old;
|
||
rtx first;
|
||
rtx last;
|
||
int final;
|
||
regset significant;
|
||
int bnum;
|
||
{
|
||
register rtx insn;
|
||
rtx prev;
|
||
regset live;
|
||
regset dead;
|
||
|
||
/* The following variables are used only if FINAL is nonzero. */
|
||
/* This vector gets one element for each reg that has been live
|
||
at any point in the basic block that has been scanned so far.
|
||
SOMETIMES_MAX says how many elements are in use so far.
|
||
In each element, OFFSET is the byte-number within a regset
|
||
for the register described by the element, and BIT is a mask
|
||
for that register's bit within the byte. */
|
||
register struct sometimes { short offset; short bit; } *regs_sometimes_live;
|
||
int sometimes_max = 0;
|
||
/* This regset has 1 for each reg that we have seen live so far.
|
||
It and REGS_SOMETIMES_LIVE are updated together. */
|
||
regset maxlive;
|
||
|
||
/* The loop depth may change in the middle of a basic block. Since we
|
||
scan from end to beginning, we start with the depth at the end of the
|
||
current basic block, and adjust as we pass ends and starts of loops. */
|
||
loop_depth = basic_block_loop_depth[bnum];
|
||
|
||
dead = (regset) alloca (regset_bytes);
|
||
live = (regset) alloca (regset_bytes);
|
||
|
||
cc0_live = 0;
|
||
last_mem_set = 0;
|
||
|
||
/* Include any notes at the end of the block in the scan.
|
||
This is in case the block ends with a call to setjmp. */
|
||
|
||
while (NEXT_INSN (last) != 0 && GET_CODE (NEXT_INSN (last)) == NOTE)
|
||
{
|
||
/* Look for loop boundaries, we are going forward here. */
|
||
last = NEXT_INSN (last);
|
||
if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_BEG)
|
||
loop_depth++;
|
||
else if (NOTE_LINE_NUMBER (last) == NOTE_INSN_LOOP_END)
|
||
loop_depth--;
|
||
}
|
||
|
||
if (final)
|
||
{
|
||
register int i, offset;
|
||
REGSET_ELT_TYPE bit;
|
||
|
||
num_scratch = 0;
|
||
maxlive = (regset) alloca (regset_bytes);
|
||
bcopy ((char *) old, (char *) maxlive, regset_bytes);
|
||
regs_sometimes_live
|
||
= (struct sometimes *) alloca (max_regno * sizeof (struct sometimes));
|
||
|
||
/* Process the regs live at the end of the block.
|
||
Enter them in MAXLIVE and REGS_SOMETIMES_LIVE.
|
||
Also mark them as not local to any one basic block. */
|
||
|
||
for (offset = 0, i = 0; offset < regset_size; offset++)
|
||
for (bit = 1; bit; bit <<= 1, i++)
|
||
{
|
||
if (i == max_regno)
|
||
break;
|
||
if (old[offset] & bit)
|
||
{
|
||
reg_basic_block[i] = REG_BLOCK_GLOBAL;
|
||
regs_sometimes_live[sometimes_max].offset = offset;
|
||
regs_sometimes_live[sometimes_max].bit = i % REGSET_ELT_BITS;
|
||
sometimes_max++;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Scan the block an insn at a time from end to beginning. */
|
||
|
||
for (insn = last; ; insn = prev)
|
||
{
|
||
prev = PREV_INSN (insn);
|
||
|
||
if (GET_CODE (insn) == NOTE)
|
||
{
|
||
/* Look for loop boundaries, remembering that we are going
|
||
backwards. */
|
||
if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
|
||
loop_depth++;
|
||
else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
|
||
loop_depth--;
|
||
|
||
/* If we have LOOP_DEPTH == 0, there has been a bookkeeping error.
|
||
Abort now rather than setting register status incorrectly. */
|
||
if (loop_depth == 0)
|
||
abort ();
|
||
|
||
/* If this is a call to `setjmp' et al,
|
||
warn if any non-volatile datum is live. */
|
||
|
||
if (final && NOTE_LINE_NUMBER (insn) == NOTE_INSN_SETJMP)
|
||
{
|
||
int i;
|
||
for (i = 0; i < regset_size; i++)
|
||
regs_live_at_setjmp[i] |= old[i];
|
||
}
|
||
}
|
||
|
||
/* Update the life-status of regs for this insn.
|
||
First DEAD gets which regs are set in this insn
|
||
then LIVE gets which regs are used in this insn.
|
||
Then the regs live before the insn
|
||
are those live after, with DEAD regs turned off,
|
||
and then LIVE regs turned on. */
|
||
|
||
else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
|
||
{
|
||
register int i;
|
||
rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
|
||
int insn_is_dead
|
||
= (insn_dead_p (PATTERN (insn), old, 0)
|
||
/* Don't delete something that refers to volatile storage! */
|
||
&& ! INSN_VOLATILE (insn));
|
||
int libcall_is_dead
|
||
= (insn_is_dead && note != 0
|
||
&& libcall_dead_p (PATTERN (insn), old, note, insn));
|
||
|
||
/* If an instruction consists of just dead store(s) on final pass,
|
||
"delete" it by turning it into a NOTE of type NOTE_INSN_DELETED.
|
||
We could really delete it with delete_insn, but that
|
||
can cause trouble for first or last insn in a basic block. */
|
||
if (final && insn_is_dead)
|
||
{
|
||
PUT_CODE (insn, NOTE);
|
||
NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
|
||
NOTE_SOURCE_FILE (insn) = 0;
|
||
|
||
/* CC0 is now known to be dead. Either this insn used it,
|
||
in which case it doesn't anymore, or clobbered it,
|
||
so the next insn can't use it. */
|
||
cc0_live = 0;
|
||
|
||
/* If this insn is copying the return value from a library call,
|
||
delete the entire library call. */
|
||
if (libcall_is_dead)
|
||
{
|
||
rtx first = XEXP (note, 0);
|
||
rtx p = insn;
|
||
while (INSN_DELETED_P (first))
|
||
first = NEXT_INSN (first);
|
||
while (p != first)
|
||
{
|
||
p = PREV_INSN (p);
|
||
PUT_CODE (p, NOTE);
|
||
NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
|
||
NOTE_SOURCE_FILE (p) = 0;
|
||
}
|
||
}
|
||
goto flushed;
|
||
}
|
||
|
||
for (i = 0; i < regset_size; i++)
|
||
{
|
||
dead[i] = 0; /* Faster than bzero here */
|
||
live[i] = 0; /* since regset_size is usually small */
|
||
}
|
||
|
||
/* See if this is an increment or decrement that can be
|
||
merged into a following memory address. */
|
||
#ifdef AUTO_INC_DEC
|
||
{
|
||
register rtx x = PATTERN (insn);
|
||
/* Does this instruction increment or decrement a register? */
|
||
if (final && GET_CODE (x) == SET
|
||
&& GET_CODE (SET_DEST (x)) == REG
|
||
&& (GET_CODE (SET_SRC (x)) == PLUS
|
||
|| GET_CODE (SET_SRC (x)) == MINUS)
|
||
&& XEXP (SET_SRC (x), 0) == SET_DEST (x)
|
||
&& GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
|
||
/* Ok, look for a following memory ref we can combine with.
|
||
If one is found, change the memory ref to a PRE_INC
|
||
or PRE_DEC, cancel this insn, and return 1.
|
||
Return 0 if nothing has been done. */
|
||
&& try_pre_increment_1 (insn))
|
||
goto flushed;
|
||
}
|
||
#endif /* AUTO_INC_DEC */
|
||
|
||
/* If this is not the final pass, and this insn is copying the
|
||
value of a library call and it's dead, don't scan the
|
||
insns that perform the library call, so that the call's
|
||
arguments are not marked live. */
|
||
if (libcall_is_dead)
|
||
{
|
||
/* Mark the dest reg as `significant'. */
|
||
mark_set_regs (old, dead, PATTERN (insn), NULL_RTX, significant);
|
||
|
||
insn = XEXP (note, 0);
|
||
prev = PREV_INSN (insn);
|
||
}
|
||
else if (GET_CODE (PATTERN (insn)) == SET
|
||
&& SET_DEST (PATTERN (insn)) == stack_pointer_rtx
|
||
&& GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
|
||
&& XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
|
||
&& GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
|
||
/* We have an insn to pop a constant amount off the stack.
|
||
(Such insns use PLUS regardless of the direction of the stack,
|
||
and any insn to adjust the stack by a constant is always a pop.)
|
||
These insns, if not dead stores, have no effect on life. */
|
||
;
|
||
else
|
||
{
|
||
/* LIVE gets the regs used in INSN;
|
||
DEAD gets those set by it. Dead insns don't make anything
|
||
live. */
|
||
|
||
mark_set_regs (old, dead, PATTERN (insn),
|
||
final ? insn : NULL_RTX, significant);
|
||
|
||
/* If an insn doesn't use CC0, it becomes dead since we
|
||
assume that every insn clobbers it. So show it dead here;
|
||
mark_used_regs will set it live if it is referenced. */
|
||
cc0_live = 0;
|
||
|
||
if (! insn_is_dead)
|
||
mark_used_regs (old, live, PATTERN (insn), final, insn);
|
||
|
||
/* Sometimes we may have inserted something before INSN (such as
|
||
a move) when we make an auto-inc. So ensure we will scan
|
||
those insns. */
|
||
#ifdef AUTO_INC_DEC
|
||
prev = PREV_INSN (insn);
|
||
#endif
|
||
|
||
if (! insn_is_dead && GET_CODE (insn) == CALL_INSN)
|
||
{
|
||
register int i;
|
||
|
||
rtx note;
|
||
|
||
for (note = CALL_INSN_FUNCTION_USAGE (insn);
|
||
note;
|
||
note = XEXP (note, 1))
|
||
if (GET_CODE (XEXP (note, 0)) == USE)
|
||
mark_used_regs (old, live, SET_DEST (XEXP (note, 0)),
|
||
final, insn);
|
||
|
||
/* Each call clobbers all call-clobbered regs that are not
|
||
global. Note that the function-value reg is a
|
||
call-clobbered reg, and mark_set_regs has already had
|
||
a chance to handle it. */
|
||
|
||
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
|
||
if (call_used_regs[i] && ! global_regs[i])
|
||
dead[i / REGSET_ELT_BITS]
|
||
|= ((REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS));
|
||
|
||
/* The stack ptr is used (honorarily) by a CALL insn. */
|
||
live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
|
||
|= ((REGSET_ELT_TYPE) 1
|
||
<< (STACK_POINTER_REGNUM % REGSET_ELT_BITS));
|
||
|
||
/* Calls may also reference any of the global registers,
|
||
so they are made live. */
|
||
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
|
||
if (global_regs[i])
|
||
mark_used_regs (old, live,
|
||
gen_rtx (REG, reg_raw_mode[i], i),
|
||
final, insn);
|
||
|
||
/* Calls also clobber memory. */
|
||
last_mem_set = 0;
|
||
}
|
||
|
||
/* Update OLD for the registers used or set. */
|
||
for (i = 0; i < regset_size; i++)
|
||
{
|
||
old[i] &= ~dead[i];
|
||
old[i] |= live[i];
|
||
}
|
||
|
||
if (GET_CODE (insn) == CALL_INSN && final)
|
||
{
|
||
/* Any regs live at the time of a call instruction
|
||
must not go in a register clobbered by calls.
|
||
Find all regs now live and record this for them. */
|
||
|
||
register struct sometimes *p = regs_sometimes_live;
|
||
|
||
for (i = 0; i < sometimes_max; i++, p++)
|
||
if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
|
||
reg_n_calls_crossed[p->offset * REGSET_ELT_BITS + p->bit]+= 1;
|
||
}
|
||
}
|
||
|
||
/* On final pass, add any additional sometimes-live regs
|
||
into MAXLIVE and REGS_SOMETIMES_LIVE.
|
||
Also update counts of how many insns each reg is live at. */
|
||
|
||
if (final)
|
||
{
|
||
for (i = 0; i < regset_size; i++)
|
||
{
|
||
register REGSET_ELT_TYPE diff = live[i] & ~maxlive[i];
|
||
|
||
if (diff)
|
||
{
|
||
register int regno;
|
||
maxlive[i] |= diff;
|
||
for (regno = 0; diff && regno < REGSET_ELT_BITS; regno++)
|
||
if (diff & ((REGSET_ELT_TYPE) 1 << regno))
|
||
{
|
||
regs_sometimes_live[sometimes_max].offset = i;
|
||
regs_sometimes_live[sometimes_max].bit = regno;
|
||
diff &= ~ ((REGSET_ELT_TYPE) 1 << regno);
|
||
sometimes_max++;
|
||
}
|
||
}
|
||
}
|
||
|
||
{
|
||
register struct sometimes *p = regs_sometimes_live;
|
||
for (i = 0; i < sometimes_max; i++, p++)
|
||
{
|
||
if (old[p->offset] & ((REGSET_ELT_TYPE) 1 << p->bit))
|
||
reg_live_length[p->offset * REGSET_ELT_BITS + p->bit]++;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
flushed: ;
|
||
if (insn == first)
|
||
break;
|
||
}
|
||
|
||
if (num_scratch > max_scratch)
|
||
max_scratch = num_scratch;
|
||
}
|
||
|
||
/* Return 1 if X (the body of an insn, or part of it) is just dead stores
|
||
(SET expressions whose destinations are registers dead after the insn).
|
||
NEEDED is the regset that says which regs are alive after the insn.
|
||
|
||
Unless CALL_OK is non-zero, an insn is needed if it contains a CALL. */
|
||
|
||
static int
|
||
insn_dead_p (x, needed, call_ok)
|
||
rtx x;
|
||
regset needed;
|
||
int call_ok;
|
||
{
|
||
register RTX_CODE code = GET_CODE (x);
|
||
/* If setting something that's a reg or part of one,
|
||
see if that register's altered value will be live. */
|
||
|
||
if (code == SET)
|
||
{
|
||
register rtx r = SET_DEST (x);
|
||
/* A SET that is a subroutine call cannot be dead. */
|
||
if (! call_ok && GET_CODE (SET_SRC (x)) == CALL)
|
||
return 0;
|
||
|
||
#ifdef HAVE_cc0
|
||
if (GET_CODE (r) == CC0)
|
||
return ! cc0_live;
|
||
#endif
|
||
|
||
if (GET_CODE (r) == MEM && last_mem_set && ! MEM_VOLATILE_P (r)
|
||
&& rtx_equal_p (r, last_mem_set))
|
||
return 1;
|
||
|
||
while (GET_CODE (r) == SUBREG
|
||
|| GET_CODE (r) == STRICT_LOW_PART
|
||
|| GET_CODE (r) == ZERO_EXTRACT
|
||
|| GET_CODE (r) == SIGN_EXTRACT)
|
||
r = SUBREG_REG (r);
|
||
|
||
if (GET_CODE (r) == REG)
|
||
{
|
||
register int regno = REGNO (r);
|
||
register int offset = regno / REGSET_ELT_BITS;
|
||
register REGSET_ELT_TYPE bit
|
||
= (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
|
||
|
||
/* Don't delete insns to set global regs. */
|
||
if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
|
||
/* Make sure insns to set frame pointer aren't deleted. */
|
||
|| regno == FRAME_POINTER_REGNUM
|
||
#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
|
||
|| regno == HARD_FRAME_POINTER_REGNUM
|
||
#endif
|
||
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
|
||
/* Make sure insns to set arg pointer are never deleted
|
||
(if the arg pointer isn't fixed, there will be a USE for
|
||
it, so we can treat it normally). */
|
||
|| (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
|
||
#endif
|
||
|| (needed[offset] & bit) != 0)
|
||
return 0;
|
||
|
||
/* If this is a hard register, verify that subsequent words are
|
||
not needed. */
|
||
if (regno < FIRST_PSEUDO_REGISTER)
|
||
{
|
||
int n = HARD_REGNO_NREGS (regno, GET_MODE (r));
|
||
|
||
while (--n > 0)
|
||
if ((needed[(regno + n) / REGSET_ELT_BITS]
|
||
& ((REGSET_ELT_TYPE) 1
|
||
<< ((regno + n) % REGSET_ELT_BITS))) != 0)
|
||
return 0;
|
||
}
|
||
|
||
return 1;
|
||
}
|
||
}
|
||
/* If performing several activities,
|
||
insn is dead if each activity is individually dead.
|
||
Also, CLOBBERs and USEs can be ignored; a CLOBBER or USE
|
||
that's inside a PARALLEL doesn't make the insn worth keeping. */
|
||
else if (code == PARALLEL)
|
||
{
|
||
register int i = XVECLEN (x, 0);
|
||
for (i--; i >= 0; i--)
|
||
{
|
||
rtx elt = XVECEXP (x, 0, i);
|
||
if (!insn_dead_p (elt, needed, call_ok)
|
||
&& GET_CODE (elt) != CLOBBER
|
||
&& GET_CODE (elt) != USE)
|
||
return 0;
|
||
}
|
||
return 1;
|
||
}
|
||
/* We do not check CLOBBER or USE here.
|
||
An insn consisting of just a CLOBBER or just a USE
|
||
should not be deleted. */
|
||
return 0;
|
||
}
|
||
|
||
/* If X is the pattern of the last insn in a libcall, and assuming X is dead,
|
||
return 1 if the entire library call is dead.
|
||
This is true if X copies a register (hard or pseudo)
|
||
and if the hard return reg of the call insn is dead.
|
||
(The caller should have tested the destination of X already for death.)
|
||
|
||
If this insn doesn't just copy a register, then we don't
|
||
have an ordinary libcall. In that case, cse could not have
|
||
managed to substitute the source for the dest later on,
|
||
so we can assume the libcall is dead.
|
||
|
||
NEEDED is the bit vector of pseudoregs live before this insn.
|
||
NOTE is the REG_RETVAL note of the insn. INSN is the insn itself. */
|
||
|
||
static int
|
||
libcall_dead_p (x, needed, note, insn)
|
||
rtx x;
|
||
regset needed;
|
||
rtx note;
|
||
rtx insn;
|
||
{
|
||
register RTX_CODE code = GET_CODE (x);
|
||
|
||
if (code == SET)
|
||
{
|
||
register rtx r = SET_SRC (x);
|
||
if (GET_CODE (r) == REG)
|
||
{
|
||
rtx call = XEXP (note, 0);
|
||
register int i;
|
||
|
||
/* Find the call insn. */
|
||
while (call != insn && GET_CODE (call) != CALL_INSN)
|
||
call = NEXT_INSN (call);
|
||
|
||
/* If there is none, do nothing special,
|
||
since ordinary death handling can understand these insns. */
|
||
if (call == insn)
|
||
return 0;
|
||
|
||
/* See if the hard reg holding the value is dead.
|
||
If this is a PARALLEL, find the call within it. */
|
||
call = PATTERN (call);
|
||
if (GET_CODE (call) == PARALLEL)
|
||
{
|
||
for (i = XVECLEN (call, 0) - 1; i >= 0; i--)
|
||
if (GET_CODE (XVECEXP (call, 0, i)) == SET
|
||
&& GET_CODE (SET_SRC (XVECEXP (call, 0, i))) == CALL)
|
||
break;
|
||
|
||
/* This may be a library call that is returning a value
|
||
via invisible pointer. Do nothing special, since
|
||
ordinary death handling can understand these insns. */
|
||
if (i < 0)
|
||
return 0;
|
||
|
||
call = XVECEXP (call, 0, i);
|
||
}
|
||
|
||
return insn_dead_p (call, needed, 1);
|
||
}
|
||
}
|
||
return 1;
|
||
}
|
||
|
||
/* Return 1 if register REGNO was used before it was set.
|
||
In other words, if it is live at function entry.
|
||
Don't count global register variables, though. */
|
||
|
||
int
|
||
regno_uninitialized (regno)
|
||
int regno;
|
||
{
|
||
if (n_basic_blocks == 0
|
||
|| (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
|
||
return 0;
|
||
|
||
return (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
|
||
& ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS)));
|
||
}
|
||
|
||
/* 1 if register REGNO was alive at a place where `setjmp' was called
|
||
and was set more than once or is an argument.
|
||
Such regs may be clobbered by `longjmp'. */
|
||
|
||
int
|
||
regno_clobbered_at_setjmp (regno)
|
||
int regno;
|
||
{
|
||
if (n_basic_blocks == 0)
|
||
return 0;
|
||
|
||
return ((reg_n_sets[regno] > 1
|
||
|| (basic_block_live_at_start[0][regno / REGSET_ELT_BITS]
|
||
& ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))))
|
||
&& (regs_live_at_setjmp[regno / REGSET_ELT_BITS]
|
||
& ((REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS))));
|
||
}
|
||
|
||
/* Process the registers that are set within X.
|
||
Their bits are set to 1 in the regset DEAD,
|
||
because they are dead prior to this insn.
|
||
|
||
If INSN is nonzero, it is the insn being processed
|
||
and the fact that it is nonzero implies this is the FINAL pass
|
||
in propagate_block. In this case, various info about register
|
||
usage is stored, LOG_LINKS fields of insns are set up. */
|
||
|
||
static void
|
||
mark_set_regs (needed, dead, x, insn, significant)
|
||
regset needed;
|
||
regset dead;
|
||
rtx x;
|
||
rtx insn;
|
||
regset significant;
|
||
{
|
||
register RTX_CODE code = GET_CODE (x);
|
||
|
||
if (code == SET || code == CLOBBER)
|
||
mark_set_1 (needed, dead, x, insn, significant);
|
||
else if (code == PARALLEL)
|
||
{
|
||
register int i;
|
||
for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
|
||
{
|
||
code = GET_CODE (XVECEXP (x, 0, i));
|
||
if (code == SET || code == CLOBBER)
|
||
mark_set_1 (needed, dead, XVECEXP (x, 0, i), insn, significant);
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Process a single SET rtx, X. */
|
||
|
||
static void
|
||
mark_set_1 (needed, dead, x, insn, significant)
|
||
regset needed;
|
||
regset dead;
|
||
rtx x;
|
||
rtx insn;
|
||
regset significant;
|
||
{
|
||
register int regno;
|
||
register rtx reg = SET_DEST (x);
|
||
|
||
/* Modifying just one hardware register of a multi-reg value
|
||
or just a byte field of a register
|
||
does not mean the value from before this insn is now dead.
|
||
But it does mean liveness of that register at the end of the block
|
||
is significant.
|
||
|
||
Within mark_set_1, however, we treat it as if the register is
|
||
indeed modified. mark_used_regs will, however, also treat this
|
||
register as being used. Thus, we treat these insns as setting a
|
||
new value for the register as a function of its old value. This
|
||
cases LOG_LINKS to be made appropriately and this will help combine. */
|
||
|
||
while (GET_CODE (reg) == SUBREG || GET_CODE (reg) == ZERO_EXTRACT
|
||
|| GET_CODE (reg) == SIGN_EXTRACT
|
||
|| GET_CODE (reg) == STRICT_LOW_PART)
|
||
reg = XEXP (reg, 0);
|
||
|
||
/* If we are writing into memory or into a register mentioned in the
|
||
address of the last thing stored into memory, show we don't know
|
||
what the last store was. If we are writing memory, save the address
|
||
unless it is volatile. */
|
||
if (GET_CODE (reg) == MEM
|
||
|| (GET_CODE (reg) == REG
|
||
&& last_mem_set != 0 && reg_overlap_mentioned_p (reg, last_mem_set)))
|
||
last_mem_set = 0;
|
||
|
||
if (GET_CODE (reg) == MEM && ! side_effects_p (reg)
|
||
/* There are no REG_INC notes for SP, so we can't assume we'll see
|
||
everything that invalidates it. To be safe, don't eliminate any
|
||
stores though SP; none of them should be redundant anyway. */
|
||
&& ! reg_mentioned_p (stack_pointer_rtx, reg))
|
||
last_mem_set = reg;
|
||
|
||
if (GET_CODE (reg) == REG
|
||
&& (regno = REGNO (reg), regno != FRAME_POINTER_REGNUM)
|
||
#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
|
||
&& regno != HARD_FRAME_POINTER_REGNUM
|
||
#endif
|
||
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
|
||
&& ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
|
||
#endif
|
||
&& ! (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]))
|
||
/* && regno != STACK_POINTER_REGNUM) -- let's try without this. */
|
||
{
|
||
register int offset = regno / REGSET_ELT_BITS;
|
||
register REGSET_ELT_TYPE bit
|
||
= (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
|
||
REGSET_ELT_TYPE all_needed = (needed[offset] & bit);
|
||
REGSET_ELT_TYPE some_needed = (needed[offset] & bit);
|
||
|
||
/* Mark it as a significant register for this basic block. */
|
||
if (significant)
|
||
significant[offset] |= bit;
|
||
|
||
/* Mark it as as dead before this insn. */
|
||
dead[offset] |= bit;
|
||
|
||
/* A hard reg in a wide mode may really be multiple registers.
|
||
If so, mark all of them just like the first. */
|
||
if (regno < FIRST_PSEUDO_REGISTER)
|
||
{
|
||
int n;
|
||
|
||
/* Nothing below is needed for the stack pointer; get out asap.
|
||
Eg, log links aren't needed, since combine won't use them. */
|
||
if (regno == STACK_POINTER_REGNUM)
|
||
return;
|
||
|
||
n = HARD_REGNO_NREGS (regno, GET_MODE (reg));
|
||
while (--n > 0)
|
||
{
|
||
if (significant)
|
||
significant[(regno + n) / REGSET_ELT_BITS]
|
||
|= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
|
||
dead[(regno + n) / REGSET_ELT_BITS]
|
||
|= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
|
||
some_needed
|
||
|= (needed[(regno + n) / REGSET_ELT_BITS]
|
||
& (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
|
||
all_needed
|
||
&= (needed[(regno + n) / REGSET_ELT_BITS]
|
||
& (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
|
||
}
|
||
}
|
||
/* Additional data to record if this is the final pass. */
|
||
if (insn)
|
||
{
|
||
register rtx y = reg_next_use[regno];
|
||
register int blocknum = BLOCK_NUM (insn);
|
||
|
||
/* If this is a hard reg, record this function uses the reg. */
|
||
|
||
if (regno < FIRST_PSEUDO_REGISTER)
|
||
{
|
||
register int i;
|
||
int endregno = regno + HARD_REGNO_NREGS (regno, GET_MODE (reg));
|
||
|
||
for (i = regno; i < endregno; i++)
|
||
{
|
||
/* The next use is no longer "next", since a store
|
||
intervenes. */
|
||
reg_next_use[i] = 0;
|
||
|
||
regs_ever_live[i] = 1;
|
||
reg_n_sets[i]++;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
/* The next use is no longer "next", since a store
|
||
intervenes. */
|
||
reg_next_use[regno] = 0;
|
||
|
||
/* Keep track of which basic blocks each reg appears in. */
|
||
|
||
if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
|
||
reg_basic_block[regno] = blocknum;
|
||
else if (reg_basic_block[regno] != blocknum)
|
||
reg_basic_block[regno] = REG_BLOCK_GLOBAL;
|
||
|
||
/* Count (weighted) references, stores, etc. This counts a
|
||
register twice if it is modified, but that is correct. */
|
||
reg_n_sets[regno]++;
|
||
|
||
reg_n_refs[regno] += loop_depth;
|
||
|
||
/* The insns where a reg is live are normally counted
|
||
elsewhere, but we want the count to include the insn
|
||
where the reg is set, and the normal counting mechanism
|
||
would not count it. */
|
||
reg_live_length[regno]++;
|
||
}
|
||
|
||
if (all_needed)
|
||
{
|
||
/* Make a logical link from the next following insn
|
||
that uses this register, back to this insn.
|
||
The following insns have already been processed.
|
||
|
||
We don't build a LOG_LINK for hard registers containing
|
||
in ASM_OPERANDs. If these registers get replaced,
|
||
we might wind up changing the semantics of the insn,
|
||
even if reload can make what appear to be valid assignments
|
||
later. */
|
||
if (y && (BLOCK_NUM (y) == blocknum)
|
||
&& (regno >= FIRST_PSEUDO_REGISTER
|
||
|| asm_noperands (PATTERN (y)) < 0))
|
||
LOG_LINKS (y)
|
||
= gen_rtx (INSN_LIST, VOIDmode, insn, LOG_LINKS (y));
|
||
}
|
||
else if (! some_needed)
|
||
{
|
||
/* Note that dead stores have already been deleted when possible
|
||
If we get here, we have found a dead store that cannot
|
||
be eliminated (because the same insn does something useful).
|
||
Indicate this by marking the reg being set as dying here. */
|
||
REG_NOTES (insn)
|
||
= gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
|
||
reg_n_deaths[REGNO (reg)]++;
|
||
}
|
||
else
|
||
{
|
||
/* This is a case where we have a multi-word hard register
|
||
and some, but not all, of the words of the register are
|
||
needed in subsequent insns. Write REG_UNUSED notes
|
||
for those parts that were not needed. This case should
|
||
be rare. */
|
||
|
||
int i;
|
||
|
||
for (i = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1;
|
||
i >= 0; i--)
|
||
if ((needed[(regno + i) / REGSET_ELT_BITS]
|
||
& ((REGSET_ELT_TYPE) 1
|
||
<< ((regno + i) % REGSET_ELT_BITS))) == 0)
|
||
REG_NOTES (insn)
|
||
= gen_rtx (EXPR_LIST, REG_UNUSED,
|
||
gen_rtx (REG, reg_raw_mode[regno + i],
|
||
regno + i),
|
||
REG_NOTES (insn));
|
||
}
|
||
}
|
||
}
|
||
else if (GET_CODE (reg) == REG)
|
||
reg_next_use[regno] = 0;
|
||
|
||
/* If this is the last pass and this is a SCRATCH, show it will be dying
|
||
here and count it. */
|
||
else if (GET_CODE (reg) == SCRATCH && insn != 0)
|
||
{
|
||
REG_NOTES (insn)
|
||
= gen_rtx (EXPR_LIST, REG_UNUSED, reg, REG_NOTES (insn));
|
||
num_scratch++;
|
||
}
|
||
}
|
||
|
||
#ifdef AUTO_INC_DEC
|
||
|
||
/* X is a MEM found in INSN. See if we can convert it into an auto-increment
|
||
reference. */
|
||
|
||
static void
|
||
find_auto_inc (needed, x, insn)
|
||
regset needed;
|
||
rtx x;
|
||
rtx insn;
|
||
{
|
||
rtx addr = XEXP (x, 0);
|
||
HOST_WIDE_INT offset = 0;
|
||
rtx set;
|
||
|
||
/* Here we detect use of an index register which might be good for
|
||
postincrement, postdecrement, preincrement, or predecrement. */
|
||
|
||
if (GET_CODE (addr) == PLUS && GET_CODE (XEXP (addr, 1)) == CONST_INT)
|
||
offset = INTVAL (XEXP (addr, 1)), addr = XEXP (addr, 0);
|
||
|
||
if (GET_CODE (addr) == REG)
|
||
{
|
||
register rtx y;
|
||
register int size = GET_MODE_SIZE (GET_MODE (x));
|
||
rtx use;
|
||
rtx incr;
|
||
int regno = REGNO (addr);
|
||
|
||
/* Is the next use an increment that might make auto-increment? */
|
||
if ((incr = reg_next_use[regno]) != 0
|
||
&& (set = single_set (incr)) != 0
|
||
&& GET_CODE (set) == SET
|
||
&& BLOCK_NUM (incr) == BLOCK_NUM (insn)
|
||
/* Can't add side effects to jumps; if reg is spilled and
|
||
reloaded, there's no way to store back the altered value. */
|
||
&& GET_CODE (insn) != JUMP_INSN
|
||
&& (y = SET_SRC (set), GET_CODE (y) == PLUS)
|
||
&& XEXP (y, 0) == addr
|
||
&& GET_CODE (XEXP (y, 1)) == CONST_INT
|
||
&& (0
|
||
#ifdef HAVE_POST_INCREMENT
|
||
|| (INTVAL (XEXP (y, 1)) == size && offset == 0)
|
||
#endif
|
||
#ifdef HAVE_POST_DECREMENT
|
||
|| (INTVAL (XEXP (y, 1)) == - size && offset == 0)
|
||
#endif
|
||
#ifdef HAVE_PRE_INCREMENT
|
||
|| (INTVAL (XEXP (y, 1)) == size && offset == size)
|
||
#endif
|
||
#ifdef HAVE_PRE_DECREMENT
|
||
|| (INTVAL (XEXP (y, 1)) == - size && offset == - size)
|
||
#endif
|
||
)
|
||
/* Make sure this reg appears only once in this insn. */
|
||
&& (use = find_use_as_address (PATTERN (insn), addr, offset),
|
||
use != 0 && use != (rtx) 1))
|
||
{
|
||
rtx q = SET_DEST (set);
|
||
enum rtx_code inc_code = (INTVAL (XEXP (y, 1)) == size
|
||
? (offset ? PRE_INC : POST_INC)
|
||
: (offset ? PRE_DEC : POST_DEC));
|
||
|
||
if (dead_or_set_p (incr, addr))
|
||
{
|
||
/* This is the simple case. Try to make the auto-inc. If
|
||
we can't, we are done. Otherwise, we will do any
|
||
needed updates below. */
|
||
if (! validate_change (insn, &XEXP (x, 0),
|
||
gen_rtx (inc_code, Pmode, addr),
|
||
0))
|
||
return;
|
||
}
|
||
else if (GET_CODE (q) == REG
|
||
/* PREV_INSN used here to check the semi-open interval
|
||
[insn,incr). */
|
||
&& ! reg_used_between_p (q, PREV_INSN (insn), incr))
|
||
{
|
||
/* We have *p followed sometime later by q = p+size.
|
||
Both p and q must be live afterward,
|
||
and q is not used between INSN and it's assignment.
|
||
Change it to q = p, ...*q..., q = q+size.
|
||
Then fall into the usual case. */
|
||
rtx insns, temp;
|
||
|
||
start_sequence ();
|
||
emit_move_insn (q, addr);
|
||
insns = get_insns ();
|
||
end_sequence ();
|
||
|
||
/* If anything in INSNS have UID's that don't fit within the
|
||
extra space we allocate earlier, we can't make this auto-inc.
|
||
This should never happen. */
|
||
for (temp = insns; temp; temp = NEXT_INSN (temp))
|
||
{
|
||
if (INSN_UID (temp) > max_uid_for_flow)
|
||
return;
|
||
BLOCK_NUM (temp) = BLOCK_NUM (insn);
|
||
}
|
||
|
||
/* If we can't make the auto-inc, or can't make the
|
||
replacement into Y, exit. There's no point in making
|
||
the change below if we can't do the auto-inc and doing
|
||
so is not correct in the pre-inc case. */
|
||
|
||
validate_change (insn, &XEXP (x, 0),
|
||
gen_rtx (inc_code, Pmode, q),
|
||
1);
|
||
validate_change (incr, &XEXP (y, 0), q, 1);
|
||
if (! apply_change_group ())
|
||
return;
|
||
|
||
/* We now know we'll be doing this change, so emit the
|
||
new insn(s) and do the updates. */
|
||
emit_insns_before (insns, insn);
|
||
|
||
if (basic_block_head[BLOCK_NUM (insn)] == insn)
|
||
basic_block_head[BLOCK_NUM (insn)] = insns;
|
||
|
||
/* INCR will become a NOTE and INSN won't contain a
|
||
use of ADDR. If a use of ADDR was just placed in
|
||
the insn before INSN, make that the next use.
|
||
Otherwise, invalidate it. */
|
||
if (GET_CODE (PREV_INSN (insn)) == INSN
|
||
&& GET_CODE (PATTERN (PREV_INSN (insn))) == SET
|
||
&& SET_SRC (PATTERN (PREV_INSN (insn))) == addr)
|
||
reg_next_use[regno] = PREV_INSN (insn);
|
||
else
|
||
reg_next_use[regno] = 0;
|
||
|
||
addr = q;
|
||
regno = REGNO (q);
|
||
|
||
/* REGNO is now used in INCR which is below INSN, but
|
||
it previously wasn't live here. If we don't mark
|
||
it as needed, we'll put a REG_DEAD note for it
|
||
on this insn, which is incorrect. */
|
||
needed[regno / REGSET_ELT_BITS]
|
||
|= (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
|
||
|
||
/* If there are any calls between INSN and INCR, show
|
||
that REGNO now crosses them. */
|
||
for (temp = insn; temp != incr; temp = NEXT_INSN (temp))
|
||
if (GET_CODE (temp) == CALL_INSN)
|
||
reg_n_calls_crossed[regno]++;
|
||
}
|
||
else
|
||
return;
|
||
|
||
/* If we haven't returned, it means we were able to make the
|
||
auto-inc, so update the status. First, record that this insn
|
||
has an implicit side effect. */
|
||
|
||
REG_NOTES (insn)
|
||
= gen_rtx (EXPR_LIST, REG_INC, addr, REG_NOTES (insn));
|
||
|
||
/* Modify the old increment-insn to simply copy
|
||
the already-incremented value of our register. */
|
||
if (! validate_change (incr, &SET_SRC (set), addr, 0))
|
||
abort ();
|
||
|
||
/* If that makes it a no-op (copying the register into itself) delete
|
||
it so it won't appear to be a "use" and a "set" of this
|
||
register. */
|
||
if (SET_DEST (set) == addr)
|
||
{
|
||
PUT_CODE (incr, NOTE);
|
||
NOTE_LINE_NUMBER (incr) = NOTE_INSN_DELETED;
|
||
NOTE_SOURCE_FILE (incr) = 0;
|
||
}
|
||
|
||
if (regno >= FIRST_PSEUDO_REGISTER)
|
||
{
|
||
/* Count an extra reference to the reg. When a reg is
|
||
incremented, spilling it is worse, so we want to make
|
||
that less likely. */
|
||
reg_n_refs[regno] += loop_depth;
|
||
|
||
/* Count the increment as a setting of the register,
|
||
even though it isn't a SET in rtl. */
|
||
reg_n_sets[regno]++;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
#endif /* AUTO_INC_DEC */
|
||
|
||
/* Scan expression X and store a 1-bit in LIVE for each reg it uses.
|
||
This is done assuming the registers needed from X
|
||
are those that have 1-bits in NEEDED.
|
||
|
||
On the final pass, FINAL is 1. This means try for autoincrement
|
||
and count the uses and deaths of each pseudo-reg.
|
||
|
||
INSN is the containing instruction. If INSN is dead, this function is not
|
||
called. */
|
||
|
||
static void
|
||
mark_used_regs (needed, live, x, final, insn)
|
||
regset needed;
|
||
regset live;
|
||
rtx x;
|
||
int final;
|
||
rtx insn;
|
||
{
|
||
register RTX_CODE code;
|
||
register int regno;
|
||
int i;
|
||
|
||
retry:
|
||
code = GET_CODE (x);
|
||
switch (code)
|
||
{
|
||
case LABEL_REF:
|
||
case SYMBOL_REF:
|
||
case CONST_INT:
|
||
case CONST:
|
||
case CONST_DOUBLE:
|
||
case PC:
|
||
case ADDR_VEC:
|
||
case ADDR_DIFF_VEC:
|
||
case ASM_INPUT:
|
||
return;
|
||
|
||
#ifdef HAVE_cc0
|
||
case CC0:
|
||
cc0_live = 1;
|
||
return;
|
||
#endif
|
||
|
||
case CLOBBER:
|
||
/* If we are clobbering a MEM, mark any registers inside the address
|
||
as being used. */
|
||
if (GET_CODE (XEXP (x, 0)) == MEM)
|
||
mark_used_regs (needed, live, XEXP (XEXP (x, 0), 0), final, insn);
|
||
return;
|
||
|
||
case MEM:
|
||
/* Invalidate the data for the last MEM stored. We could do this only
|
||
if the addresses conflict, but this doesn't seem worthwhile. */
|
||
last_mem_set = 0;
|
||
|
||
#ifdef AUTO_INC_DEC
|
||
if (final)
|
||
find_auto_inc (needed, x, insn);
|
||
#endif
|
||
break;
|
||
|
||
case SUBREG:
|
||
if (GET_CODE (SUBREG_REG (x)) == REG
|
||
&& REGNO (SUBREG_REG (x)) >= FIRST_PSEUDO_REGISTER
|
||
&& (GET_MODE_SIZE (GET_MODE (x))
|
||
!= GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)))))
|
||
reg_changes_size[REGNO (SUBREG_REG (x))] = 1;
|
||
|
||
/* While we're here, optimize this case. */
|
||
x = SUBREG_REG (x);
|
||
|
||
/* In case the SUBREG is not of a register, don't optimize */
|
||
if (GET_CODE (x) != REG)
|
||
{
|
||
mark_used_regs (needed, live, x, final, insn);
|
||
return;
|
||
}
|
||
|
||
/* ... fall through ... */
|
||
|
||
case REG:
|
||
/* See a register other than being set
|
||
=> mark it as needed. */
|
||
|
||
regno = REGNO (x);
|
||
{
|
||
register int offset = regno / REGSET_ELT_BITS;
|
||
register REGSET_ELT_TYPE bit
|
||
= (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
|
||
REGSET_ELT_TYPE all_needed = needed[offset] & bit;
|
||
REGSET_ELT_TYPE some_needed = needed[offset] & bit;
|
||
|
||
live[offset] |= bit;
|
||
/* A hard reg in a wide mode may really be multiple registers.
|
||
If so, mark all of them just like the first. */
|
||
if (regno < FIRST_PSEUDO_REGISTER)
|
||
{
|
||
int n;
|
||
|
||
/* For stack ptr or fixed arg pointer,
|
||
nothing below can be necessary, so waste no more time. */
|
||
if (regno == STACK_POINTER_REGNUM
|
||
#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
|
||
|| regno == HARD_FRAME_POINTER_REGNUM
|
||
#endif
|
||
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
|
||
|| (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
|
||
#endif
|
||
|| regno == FRAME_POINTER_REGNUM)
|
||
{
|
||
/* If this is a register we are going to try to eliminate,
|
||
don't mark it live here. If we are successful in
|
||
eliminating it, it need not be live unless it is used for
|
||
pseudos, in which case it will have been set live when
|
||
it was allocated to the pseudos. If the register will not
|
||
be eliminated, reload will set it live at that point. */
|
||
|
||
if (! TEST_HARD_REG_BIT (elim_reg_set, regno))
|
||
regs_ever_live[regno] = 1;
|
||
return;
|
||
}
|
||
/* No death notes for global register variables;
|
||
their values are live after this function exits. */
|
||
if (global_regs[regno])
|
||
{
|
||
if (final)
|
||
reg_next_use[regno] = insn;
|
||
return;
|
||
}
|
||
|
||
n = HARD_REGNO_NREGS (regno, GET_MODE (x));
|
||
while (--n > 0)
|
||
{
|
||
live[(regno + n) / REGSET_ELT_BITS]
|
||
|= (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS);
|
||
some_needed
|
||
|= (needed[(regno + n) / REGSET_ELT_BITS]
|
||
& (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
|
||
all_needed
|
||
&= (needed[(regno + n) / REGSET_ELT_BITS]
|
||
& (REGSET_ELT_TYPE) 1 << ((regno + n) % REGSET_ELT_BITS));
|
||
}
|
||
}
|
||
if (final)
|
||
{
|
||
/* Record where each reg is used, so when the reg
|
||
is set we know the next insn that uses it. */
|
||
|
||
reg_next_use[regno] = insn;
|
||
|
||
if (regno < FIRST_PSEUDO_REGISTER)
|
||
{
|
||
/* If a hard reg is being used,
|
||
record that this function does use it. */
|
||
|
||
i = HARD_REGNO_NREGS (regno, GET_MODE (x));
|
||
if (i == 0)
|
||
i = 1;
|
||
do
|
||
regs_ever_live[regno + --i] = 1;
|
||
while (i > 0);
|
||
}
|
||
else
|
||
{
|
||
/* Keep track of which basic block each reg appears in. */
|
||
|
||
register int blocknum = BLOCK_NUM (insn);
|
||
|
||
if (reg_basic_block[regno] == REG_BLOCK_UNKNOWN)
|
||
reg_basic_block[regno] = blocknum;
|
||
else if (reg_basic_block[regno] != blocknum)
|
||
reg_basic_block[regno] = REG_BLOCK_GLOBAL;
|
||
|
||
/* Count (weighted) number of uses of each reg. */
|
||
|
||
reg_n_refs[regno] += loop_depth;
|
||
}
|
||
|
||
/* Record and count the insns in which a reg dies.
|
||
If it is used in this insn and was dead below the insn
|
||
then it dies in this insn. If it was set in this insn,
|
||
we do not make a REG_DEAD note; likewise if we already
|
||
made such a note. */
|
||
|
||
if (! all_needed
|
||
&& ! dead_or_set_p (insn, x)
|
||
#if 0
|
||
&& (regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno])
|
||
#endif
|
||
)
|
||
{
|
||
/* Check for the case where the register dying partially
|
||
overlaps the register set by this insn. */
|
||
if (regno < FIRST_PSEUDO_REGISTER
|
||
&& HARD_REGNO_NREGS (regno, GET_MODE (x)) > 1)
|
||
{
|
||
int n = HARD_REGNO_NREGS (regno, GET_MODE (x));
|
||
while (--n >= 0)
|
||
some_needed |= dead_or_set_regno_p (insn, regno + n);
|
||
}
|
||
|
||
/* If none of the words in X is needed, make a REG_DEAD
|
||
note. Otherwise, we must make partial REG_DEAD notes. */
|
||
if (! some_needed)
|
||
{
|
||
REG_NOTES (insn)
|
||
= gen_rtx (EXPR_LIST, REG_DEAD, x, REG_NOTES (insn));
|
||
reg_n_deaths[regno]++;
|
||
}
|
||
else
|
||
{
|
||
int i;
|
||
|
||
/* Don't make a REG_DEAD note for a part of a register
|
||
that is set in the insn. */
|
||
|
||
for (i = HARD_REGNO_NREGS (regno, GET_MODE (x)) - 1;
|
||
i >= 0; i--)
|
||
if ((needed[(regno + i) / REGSET_ELT_BITS]
|
||
& ((REGSET_ELT_TYPE) 1
|
||
<< ((regno + i) % REGSET_ELT_BITS))) == 0
|
||
&& ! dead_or_set_regno_p (insn, regno + i))
|
||
REG_NOTES (insn)
|
||
= gen_rtx (EXPR_LIST, REG_DEAD,
|
||
gen_rtx (REG, reg_raw_mode[regno + i],
|
||
regno + i),
|
||
REG_NOTES (insn));
|
||
}
|
||
}
|
||
}
|
||
}
|
||
return;
|
||
|
||
case SET:
|
||
{
|
||
register rtx testreg = SET_DEST (x);
|
||
int mark_dest = 0;
|
||
|
||
/* If storing into MEM, don't show it as being used. But do
|
||
show the address as being used. */
|
||
if (GET_CODE (testreg) == MEM)
|
||
{
|
||
#ifdef AUTO_INC_DEC
|
||
if (final)
|
||
find_auto_inc (needed, testreg, insn);
|
||
#endif
|
||
mark_used_regs (needed, live, XEXP (testreg, 0), final, insn);
|
||
mark_used_regs (needed, live, SET_SRC (x), final, insn);
|
||
return;
|
||
}
|
||
|
||
/* Storing in STRICT_LOW_PART is like storing in a reg
|
||
in that this SET might be dead, so ignore it in TESTREG.
|
||
but in some other ways it is like using the reg.
|
||
|
||
Storing in a SUBREG or a bit field is like storing the entire
|
||
register in that if the register's value is not used
|
||
then this SET is not needed. */
|
||
while (GET_CODE (testreg) == STRICT_LOW_PART
|
||
|| GET_CODE (testreg) == ZERO_EXTRACT
|
||
|| GET_CODE (testreg) == SIGN_EXTRACT
|
||
|| GET_CODE (testreg) == SUBREG)
|
||
{
|
||
if (GET_CODE (testreg) == SUBREG
|
||
&& GET_CODE (SUBREG_REG (testreg)) == REG
|
||
&& REGNO (SUBREG_REG (testreg)) >= FIRST_PSEUDO_REGISTER
|
||
&& (GET_MODE_SIZE (GET_MODE (testreg))
|
||
!= GET_MODE_SIZE (GET_MODE (SUBREG_REG (testreg)))))
|
||
reg_changes_size[REGNO (SUBREG_REG (testreg))] = 1;
|
||
|
||
/* Modifying a single register in an alternate mode
|
||
does not use any of the old value. But these other
|
||
ways of storing in a register do use the old value. */
|
||
if (GET_CODE (testreg) == SUBREG
|
||
&& !(REG_SIZE (SUBREG_REG (testreg)) > REG_SIZE (testreg)))
|
||
;
|
||
else
|
||
mark_dest = 1;
|
||
|
||
testreg = XEXP (testreg, 0);
|
||
}
|
||
|
||
/* If this is a store into a register,
|
||
recursively scan the value being stored. */
|
||
|
||
if (GET_CODE (testreg) == REG
|
||
&& (regno = REGNO (testreg), regno != FRAME_POINTER_REGNUM)
|
||
#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
|
||
&& regno != HARD_FRAME_POINTER_REGNUM
|
||
#endif
|
||
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
|
||
&& ! (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
|
||
#endif
|
||
)
|
||
/* We used to exclude global_regs here, but that seems wrong.
|
||
Storing in them is like storing in mem. */
|
||
{
|
||
mark_used_regs (needed, live, SET_SRC (x), final, insn);
|
||
if (mark_dest)
|
||
mark_used_regs (needed, live, SET_DEST (x), final, insn);
|
||
return;
|
||
}
|
||
}
|
||
break;
|
||
|
||
case RETURN:
|
||
/* If exiting needs the right stack value, consider this insn as
|
||
using the stack pointer. In any event, consider it as using
|
||
all global registers. */
|
||
|
||
#ifdef EXIT_IGNORE_STACK
|
||
if (! EXIT_IGNORE_STACK
|
||
|| (! FRAME_POINTER_REQUIRED && flag_omit_frame_pointer))
|
||
#endif
|
||
live[STACK_POINTER_REGNUM / REGSET_ELT_BITS]
|
||
|= (REGSET_ELT_TYPE) 1 << (STACK_POINTER_REGNUM % REGSET_ELT_BITS);
|
||
|
||
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
|
||
if (global_regs[i])
|
||
live[i / REGSET_ELT_BITS]
|
||
|= (REGSET_ELT_TYPE) 1 << (i % REGSET_ELT_BITS);
|
||
break;
|
||
}
|
||
|
||
/* Recursively scan the operands of this expression. */
|
||
|
||
{
|
||
register char *fmt = GET_RTX_FORMAT (code);
|
||
register int i;
|
||
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
{
|
||
/* Tail recursive case: save a function call level. */
|
||
if (i == 0)
|
||
{
|
||
x = XEXP (x, 0);
|
||
goto retry;
|
||
}
|
||
mark_used_regs (needed, live, XEXP (x, i), final, insn);
|
||
}
|
||
else if (fmt[i] == 'E')
|
||
{
|
||
register int j;
|
||
for (j = 0; j < XVECLEN (x, i); j++)
|
||
mark_used_regs (needed, live, XVECEXP (x, i, j), final, insn);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
#ifdef AUTO_INC_DEC
|
||
|
||
static int
|
||
try_pre_increment_1 (insn)
|
||
rtx insn;
|
||
{
|
||
/* Find the next use of this reg. If in same basic block,
|
||
make it do pre-increment or pre-decrement if appropriate. */
|
||
rtx x = PATTERN (insn);
|
||
HOST_WIDE_INT amount = ((GET_CODE (SET_SRC (x)) == PLUS ? 1 : -1)
|
||
* INTVAL (XEXP (SET_SRC (x), 1)));
|
||
int regno = REGNO (SET_DEST (x));
|
||
rtx y = reg_next_use[regno];
|
||
if (y != 0
|
||
&& BLOCK_NUM (y) == BLOCK_NUM (insn)
|
||
/* Don't do this if the reg dies, or gets set in y; a standard addressing
|
||
mode would be better. */
|
||
&& ! dead_or_set_p (y, SET_DEST (x))
|
||
&& try_pre_increment (y, SET_DEST (PATTERN (insn)),
|
||
amount))
|
||
{
|
||
/* We have found a suitable auto-increment
|
||
and already changed insn Y to do it.
|
||
So flush this increment-instruction. */
|
||
PUT_CODE (insn, NOTE);
|
||
NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
|
||
NOTE_SOURCE_FILE (insn) = 0;
|
||
/* Count a reference to this reg for the increment
|
||
insn we are deleting. When a reg is incremented.
|
||
spilling it is worse, so we want to make that
|
||
less likely. */
|
||
if (regno >= FIRST_PSEUDO_REGISTER)
|
||
{
|
||
reg_n_refs[regno] += loop_depth;
|
||
reg_n_sets[regno]++;
|
||
}
|
||
return 1;
|
||
}
|
||
return 0;
|
||
}
|
||
|
||
/* Try to change INSN so that it does pre-increment or pre-decrement
|
||
addressing on register REG in order to add AMOUNT to REG.
|
||
AMOUNT is negative for pre-decrement.
|
||
Returns 1 if the change could be made.
|
||
This checks all about the validity of the result of modifying INSN. */
|
||
|
||
static int
|
||
try_pre_increment (insn, reg, amount)
|
||
rtx insn, reg;
|
||
HOST_WIDE_INT amount;
|
||
{
|
||
register rtx use;
|
||
|
||
/* Nonzero if we can try to make a pre-increment or pre-decrement.
|
||
For example, addl $4,r1; movl (r1),... can become movl +(r1),... */
|
||
int pre_ok = 0;
|
||
/* Nonzero if we can try to make a post-increment or post-decrement.
|
||
For example, addl $4,r1; movl -4(r1),... can become movl (r1)+,...
|
||
It is possible for both PRE_OK and POST_OK to be nonzero if the machine
|
||
supports both pre-inc and post-inc, or both pre-dec and post-dec. */
|
||
int post_ok = 0;
|
||
|
||
/* Nonzero if the opportunity actually requires post-inc or post-dec. */
|
||
int do_post = 0;
|
||
|
||
/* From the sign of increment, see which possibilities are conceivable
|
||
on this target machine. */
|
||
#ifdef HAVE_PRE_INCREMENT
|
||
if (amount > 0)
|
||
pre_ok = 1;
|
||
#endif
|
||
#ifdef HAVE_POST_INCREMENT
|
||
if (amount > 0)
|
||
post_ok = 1;
|
||
#endif
|
||
|
||
#ifdef HAVE_PRE_DECREMENT
|
||
if (amount < 0)
|
||
pre_ok = 1;
|
||
#endif
|
||
#ifdef HAVE_POST_DECREMENT
|
||
if (amount < 0)
|
||
post_ok = 1;
|
||
#endif
|
||
|
||
if (! (pre_ok || post_ok))
|
||
return 0;
|
||
|
||
/* It is not safe to add a side effect to a jump insn
|
||
because if the incremented register is spilled and must be reloaded
|
||
there would be no way to store the incremented value back in memory. */
|
||
|
||
if (GET_CODE (insn) == JUMP_INSN)
|
||
return 0;
|
||
|
||
use = 0;
|
||
if (pre_ok)
|
||
use = find_use_as_address (PATTERN (insn), reg, 0);
|
||
if (post_ok && (use == 0 || use == (rtx) 1))
|
||
{
|
||
use = find_use_as_address (PATTERN (insn), reg, -amount);
|
||
do_post = 1;
|
||
}
|
||
|
||
if (use == 0 || use == (rtx) 1)
|
||
return 0;
|
||
|
||
if (GET_MODE_SIZE (GET_MODE (use)) != (amount > 0 ? amount : - amount))
|
||
return 0;
|
||
|
||
/* See if this combination of instruction and addressing mode exists. */
|
||
if (! validate_change (insn, &XEXP (use, 0),
|
||
gen_rtx (amount > 0
|
||
? (do_post ? POST_INC : PRE_INC)
|
||
: (do_post ? POST_DEC : PRE_DEC),
|
||
Pmode, reg), 0))
|
||
return 0;
|
||
|
||
/* Record that this insn now has an implicit side effect on X. */
|
||
REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_INC, reg, REG_NOTES (insn));
|
||
return 1;
|
||
}
|
||
|
||
#endif /* AUTO_INC_DEC */
|
||
|
||
/* Find the place in the rtx X where REG is used as a memory address.
|
||
Return the MEM rtx that so uses it.
|
||
If PLUSCONST is nonzero, search instead for a memory address equivalent to
|
||
(plus REG (const_int PLUSCONST)).
|
||
|
||
If such an address does not appear, return 0.
|
||
If REG appears more than once, or is used other than in such an address,
|
||
return (rtx)1. */
|
||
|
||
static rtx
|
||
find_use_as_address (x, reg, plusconst)
|
||
register rtx x;
|
||
rtx reg;
|
||
HOST_WIDE_INT plusconst;
|
||
{
|
||
enum rtx_code code = GET_CODE (x);
|
||
char *fmt = GET_RTX_FORMAT (code);
|
||
register int i;
|
||
register rtx value = 0;
|
||
register rtx tem;
|
||
|
||
if (code == MEM && XEXP (x, 0) == reg && plusconst == 0)
|
||
return x;
|
||
|
||
if (code == MEM && GET_CODE (XEXP (x, 0)) == PLUS
|
||
&& XEXP (XEXP (x, 0), 0) == reg
|
||
&& GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT
|
||
&& INTVAL (XEXP (XEXP (x, 0), 1)) == plusconst)
|
||
return x;
|
||
|
||
if (code == SIGN_EXTRACT || code == ZERO_EXTRACT)
|
||
{
|
||
/* If REG occurs inside a MEM used in a bit-field reference,
|
||
that is unacceptable. */
|
||
if (find_use_as_address (XEXP (x, 0), reg, 0) != 0)
|
||
return (rtx) (HOST_WIDE_INT) 1;
|
||
}
|
||
|
||
if (x == reg)
|
||
return (rtx) (HOST_WIDE_INT) 1;
|
||
|
||
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
|
||
{
|
||
if (fmt[i] == 'e')
|
||
{
|
||
tem = find_use_as_address (XEXP (x, i), reg, plusconst);
|
||
if (value == 0)
|
||
value = tem;
|
||
else if (tem != 0)
|
||
return (rtx) (HOST_WIDE_INT) 1;
|
||
}
|
||
if (fmt[i] == 'E')
|
||
{
|
||
register int j;
|
||
for (j = XVECLEN (x, i) - 1; j >= 0; j--)
|
||
{
|
||
tem = find_use_as_address (XVECEXP (x, i, j), reg, plusconst);
|
||
if (value == 0)
|
||
value = tem;
|
||
else if (tem != 0)
|
||
return (rtx) (HOST_WIDE_INT) 1;
|
||
}
|
||
}
|
||
}
|
||
|
||
return value;
|
||
}
|
||
|
||
/* Write information about registers and basic blocks into FILE.
|
||
This is part of making a debugging dump. */
|
||
|
||
void
|
||
dump_flow_info (file)
|
||
FILE *file;
|
||
{
|
||
register int i;
|
||
static char *reg_class_names[] = REG_CLASS_NAMES;
|
||
|
||
fprintf (file, "%d registers.\n", max_regno);
|
||
|
||
for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
|
||
if (reg_n_refs[i])
|
||
{
|
||
enum reg_class class, altclass;
|
||
fprintf (file, "\nRegister %d used %d times across %d insns",
|
||
i, reg_n_refs[i], reg_live_length[i]);
|
||
if (reg_basic_block[i] >= 0)
|
||
fprintf (file, " in block %d", reg_basic_block[i]);
|
||
if (reg_n_deaths[i] != 1)
|
||
fprintf (file, "; dies in %d places", reg_n_deaths[i]);
|
||
if (reg_n_calls_crossed[i] == 1)
|
||
fprintf (file, "; crosses 1 call");
|
||
else if (reg_n_calls_crossed[i])
|
||
fprintf (file, "; crosses %d calls", reg_n_calls_crossed[i]);
|
||
if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
|
||
fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
|
||
class = reg_preferred_class (i);
|
||
altclass = reg_alternate_class (i);
|
||
if (class != GENERAL_REGS || altclass != ALL_REGS)
|
||
{
|
||
if (altclass == ALL_REGS || class == ALL_REGS)
|
||
fprintf (file, "; pref %s", reg_class_names[(int) class]);
|
||
else if (altclass == NO_REGS)
|
||
fprintf (file, "; %s or none", reg_class_names[(int) class]);
|
||
else
|
||
fprintf (file, "; pref %s, else %s",
|
||
reg_class_names[(int) class],
|
||
reg_class_names[(int) altclass]);
|
||
}
|
||
if (REGNO_POINTER_FLAG (i))
|
||
fprintf (file, "; pointer");
|
||
fprintf (file, ".\n");
|
||
}
|
||
fprintf (file, "\n%d basic blocks.\n", n_basic_blocks);
|
||
for (i = 0; i < n_basic_blocks; i++)
|
||
{
|
||
register rtx head, jump;
|
||
register int regno;
|
||
fprintf (file, "\nBasic block %d: first insn %d, last %d.\n",
|
||
i,
|
||
INSN_UID (basic_block_head[i]),
|
||
INSN_UID (basic_block_end[i]));
|
||
/* The control flow graph's storage is freed
|
||
now when flow_analysis returns.
|
||
Don't try to print it if it is gone. */
|
||
if (basic_block_drops_in)
|
||
{
|
||
fprintf (file, "Reached from blocks: ");
|
||
head = basic_block_head[i];
|
||
if (GET_CODE (head) == CODE_LABEL)
|
||
for (jump = LABEL_REFS (head);
|
||
jump != head;
|
||
jump = LABEL_NEXTREF (jump))
|
||
{
|
||
register int from_block = BLOCK_NUM (CONTAINING_INSN (jump));
|
||
fprintf (file, " %d", from_block);
|
||
}
|
||
if (basic_block_drops_in[i])
|
||
fprintf (file, " previous");
|
||
}
|
||
fprintf (file, "\nRegisters live at start:");
|
||
for (regno = 0; regno < max_regno; regno++)
|
||
{
|
||
register int offset = regno / REGSET_ELT_BITS;
|
||
register REGSET_ELT_TYPE bit
|
||
= (REGSET_ELT_TYPE) 1 << (regno % REGSET_ELT_BITS);
|
||
if (basic_block_live_at_start[i][offset] & bit)
|
||
fprintf (file, " %d", regno);
|
||
}
|
||
fprintf (file, "\n");
|
||
}
|
||
fprintf (file, "\n");
|
||
}
|