367 lines
9.6 KiB
C
367 lines
9.6 KiB
C
/* Instruction scheduling pass.
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Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998,
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1999, 2000, 2001, 2002 Free Software Foundation, Inc.
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Contributed by Michael Tiemann (tiemann@cygnus.com) Enhanced by,
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and currently maintained by, Jim Wilson (wilson@cygnus.com)
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 2, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING. If not, write to the Free
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Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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02111-1307, USA. */
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#include "config.h"
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#include "system.h"
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#include "toplev.h"
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#include "rtl.h"
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#include "tm_p.h"
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#include "hard-reg-set.h"
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#include "basic-block.h"
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#include "regs.h"
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#include "function.h"
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#include "flags.h"
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#include "insn-config.h"
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#include "insn-attr.h"
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#include "except.h"
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#include "toplev.h"
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#include "recog.h"
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#include "cfglayout.h"
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#include "sched-int.h"
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/* The number of insns to be scheduled in total. */
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static int target_n_insns;
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/* The number of insns scheduled so far. */
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static int sched_n_insns;
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/* Implementations of the sched_info functions for region scheduling. */
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static void init_ready_list PARAMS ((struct ready_list *));
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static int can_schedule_ready_p PARAMS ((rtx));
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static int new_ready PARAMS ((rtx));
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static int schedule_more_p PARAMS ((void));
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static const char *ebb_print_insn PARAMS ((rtx, int));
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static int rank PARAMS ((rtx, rtx));
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static int contributes_to_priority PARAMS ((rtx, rtx));
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static void compute_jump_reg_dependencies PARAMS ((rtx, regset, regset,
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regset));
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static void schedule_ebb PARAMS ((rtx, rtx));
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/* Return nonzero if there are more insns that should be scheduled. */
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static int
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schedule_more_p ()
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{
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return sched_n_insns < target_n_insns;
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}
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/* Add all insns that are initially ready to the ready list READY. Called
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once before scheduling a set of insns. */
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static void
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init_ready_list (ready)
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struct ready_list *ready;
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{
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rtx prev_head = current_sched_info->prev_head;
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rtx next_tail = current_sched_info->next_tail;
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rtx insn;
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target_n_insns = 0;
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sched_n_insns = 0;
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#if 0
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/* Print debugging information. */
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if (sched_verbose >= 5)
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debug_dependencies ();
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#endif
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/* Initialize ready list with all 'ready' insns in target block.
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Count number of insns in the target block being scheduled. */
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for (insn = NEXT_INSN (prev_head); insn != next_tail; insn = NEXT_INSN (insn))
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{
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rtx next;
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if (! INSN_P (insn))
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continue;
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next = NEXT_INSN (insn);
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if (INSN_DEP_COUNT (insn) == 0
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&& (! INSN_P (next) || SCHED_GROUP_P (next) == 0))
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ready_add (ready, insn);
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if (!(SCHED_GROUP_P (insn)))
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target_n_insns++;
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}
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}
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/* Called after taking INSN from the ready list. Returns nonzero if this
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insn can be scheduled, nonzero if we should silently discard it. */
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static int
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can_schedule_ready_p (insn)
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rtx insn ATTRIBUTE_UNUSED;
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{
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sched_n_insns++;
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return 1;
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}
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/* Called after INSN has all its dependencies resolved. Return nonzero
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if it should be moved to the ready list or the queue, or zero if we
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should silently discard it. */
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static int
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new_ready (next)
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rtx next ATTRIBUTE_UNUSED;
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{
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return 1;
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}
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/* Return a string that contains the insn uid and optionally anything else
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necessary to identify this insn in an output. It's valid to use a
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static buffer for this. The ALIGNED parameter should cause the string
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to be formatted so that multiple output lines will line up nicely. */
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static const char *
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ebb_print_insn (insn, aligned)
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rtx insn;
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int aligned ATTRIBUTE_UNUSED;
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{
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static char tmp[80];
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sprintf (tmp, "%4d", INSN_UID (insn));
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return tmp;
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}
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/* Compare priority of two insns. Return a positive number if the second
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insn is to be preferred for scheduling, and a negative one if the first
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is to be preferred. Zero if they are equally good. */
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static int
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rank (insn1, insn2)
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rtx insn1 ATTRIBUTE_UNUSED, insn2 ATTRIBUTE_UNUSED;
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{
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return 0;
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}
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/* NEXT is an instruction that depends on INSN (a backward dependence);
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return nonzero if we should include this dependence in priority
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calculations. */
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static int
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contributes_to_priority (next, insn)
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rtx next ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED;
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{
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return 1;
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}
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/* INSN is a JUMP_INSN, COND_SET is the set of registers that are
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conditionally set before INSN. Store the set of registers that
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must be considered as used by this jump in USED and that of
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registers that must be considered as set in SET. */
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static void
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compute_jump_reg_dependencies (insn, cond_set, used, set)
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rtx insn;
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regset cond_set, used, set;
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{
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basic_block b = BLOCK_FOR_INSN (insn);
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edge e;
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for (e = b->succ; e; e = e->succ_next)
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if (e->flags & EDGE_FALLTHRU)
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/* The jump may be a by-product of a branch that has been merged
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in the main codepath after being conditionalized. Therefore
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it may guard the fallthrough block from using a value that has
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conditionally overwritten that of the main codepath. So we
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consider that it restores the value of the main codepath. */
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bitmap_operation (set, e->dest->global_live_at_start, cond_set,
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BITMAP_AND);
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else
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bitmap_operation (used, used, e->dest->global_live_at_start,
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BITMAP_IOR);
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}
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/* Used in schedule_insns to initialize current_sched_info for scheduling
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regions (or single basic blocks). */
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static struct sched_info ebb_sched_info =
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{
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init_ready_list,
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can_schedule_ready_p,
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schedule_more_p,
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new_ready,
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rank,
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ebb_print_insn,
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contributes_to_priority,
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compute_jump_reg_dependencies,
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NULL, NULL,
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NULL, NULL,
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0, 1
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};
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/* Schedule a single extended basic block, defined by the boundaries HEAD
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and TAIL. */
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static void
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schedule_ebb (head, tail)
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rtx head, tail;
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{
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int n_insns;
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struct deps tmp_deps;
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if (no_real_insns_p (head, tail))
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return;
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init_deps_global ();
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/* Compute LOG_LINKS. */
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init_deps (&tmp_deps);
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sched_analyze (&tmp_deps, head, tail);
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free_deps (&tmp_deps);
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/* Compute INSN_DEPEND. */
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compute_forward_dependences (head, tail);
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/* Set priorities. */
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n_insns = set_priorities (head, tail);
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current_sched_info->prev_head = PREV_INSN (head);
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current_sched_info->next_tail = NEXT_INSN (tail);
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if (write_symbols != NO_DEBUG)
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{
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save_line_notes (0, head, tail);
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rm_line_notes (head, tail);
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}
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/* rm_other_notes only removes notes which are _inside_ the
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block---that is, it won't remove notes before the first real insn
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or after the last real insn of the block. So if the first insn
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has a REG_SAVE_NOTE which would otherwise be emitted before the
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insn, it is redundant with the note before the start of the
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block, and so we have to take it out. */
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if (INSN_P (head))
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{
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rtx note;
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for (note = REG_NOTES (head); note; note = XEXP (note, 1))
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if (REG_NOTE_KIND (note) == REG_SAVE_NOTE)
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{
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remove_note (head, note);
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note = XEXP (note, 1);
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remove_note (head, note);
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}
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}
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/* Remove remaining note insns from the block, save them in
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note_list. These notes are restored at the end of
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schedule_block (). */
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rm_other_notes (head, tail);
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current_sched_info->queue_must_finish_empty = 1;
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schedule_block (-1, n_insns);
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/* Sanity check: verify that all region insns were scheduled. */
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if (sched_n_insns != n_insns)
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abort ();
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head = current_sched_info->head;
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tail = current_sched_info->tail;
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if (write_symbols != NO_DEBUG)
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restore_line_notes (head, tail);
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finish_deps_global ();
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}
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/* The one entry point in this file. DUMP_FILE is the dump file for
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this pass. */
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void
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schedule_ebbs (dump_file)
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FILE *dump_file;
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{
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basic_block bb;
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/* Taking care of this degenerate case makes the rest of
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this code simpler. */
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if (n_basic_blocks == 0)
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return;
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sched_init (dump_file);
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current_sched_info = &ebb_sched_info;
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allocate_reg_life_data ();
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compute_bb_for_insn ();
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/* Schedule every region in the subroutine. */
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FOR_EACH_BB (bb)
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{
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rtx head = bb->head;
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rtx tail;
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for (;;)
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{
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edge e;
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tail = bb->end;
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if (bb->next_bb == EXIT_BLOCK_PTR
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|| GET_CODE (bb->next_bb->head) == CODE_LABEL)
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break;
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for (e = bb->succ; e; e = e->succ_next)
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if ((e->flags & EDGE_FALLTHRU) != 0)
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break;
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if (! e)
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break;
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if (GET_CODE (tail) == JUMP_INSN)
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{
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rtx x = find_reg_note (tail, REG_BR_PROB, 0);
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if (x)
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{
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int pred_val = INTVAL (XEXP (x, 0));
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if (pred_val > REG_BR_PROB_BASE / 2)
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break;
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}
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}
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bb = bb->next_bb;
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}
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/* Blah. We should fix the rest of the code not to get confused by
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a note or two. */
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while (head != tail)
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{
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if (GET_CODE (head) == NOTE)
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head = NEXT_INSN (head);
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else if (GET_CODE (tail) == NOTE)
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tail = PREV_INSN (tail);
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else if (GET_CODE (head) == CODE_LABEL)
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head = NEXT_INSN (head);
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else
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break;
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}
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schedule_ebb (head, tail);
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}
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/* It doesn't make much sense to try and update life information here - we
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probably messed up even the flow graph. */
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/* Reposition the prologue and epilogue notes in case we moved the
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prologue/epilogue insns. */
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if (reload_completed)
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reposition_prologue_and_epilogue_notes (get_insns ());
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if (write_symbols != NO_DEBUG)
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rm_redundant_line_notes ();
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sched_finish ();
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}
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