freebsd-src/contrib/gcc/sched-ebb.c
David E. O'Brien 1952e2e1c1 Enlist the FreeBSD-CURRENT users as testers of what is to become Gcc 3.1.0.
These bits are taken from the FSF anoncvs repo on 1-Feb-2002 08:20 PST.
2002-02-01 18:16:02 +00:00

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/* Instruction scheduling pass.
Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998,
1999, 2000, 2001 Free Software Foundation, Inc.
Contributed by Michael Tiemann (tiemann@cygnus.com) Enhanced by,
and currently maintained by, Jim Wilson (wilson@cygnus.com)
This file is part of GCC.
GCC 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.
GCC 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 GCC; see the file COPYING. If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA. */
#include "config.h"
#include "system.h"
#include "toplev.h"
#include "rtl.h"
#include "tm_p.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "regs.h"
#include "function.h"
#include "flags.h"
#include "insn-config.h"
#include "insn-attr.h"
#include "except.h"
#include "toplev.h"
#include "recog.h"
#include "cfglayout.h"
#include "sched-int.h"
/* The number of insns to be scheduled in total. */
static int target_n_insns;
/* The number of insns scheduled so far. */
static int sched_n_insns;
/* Implementations of the sched_info functions for region scheduling. */
static void init_ready_list PARAMS ((struct ready_list *));
static int can_schedule_ready_p PARAMS ((rtx));
static int new_ready PARAMS ((rtx));
static int schedule_more_p PARAMS ((void));
static const char *print_insn PARAMS ((rtx, int));
static int rank PARAMS ((rtx, rtx));
static int contributes_to_priority PARAMS ((rtx, rtx));
static void compute_jump_reg_dependencies PARAMS ((rtx, regset));
static void schedule_ebb PARAMS ((rtx, rtx));
/* Return nonzero if there are more insns that should be scheduled. */
static int
schedule_more_p ()
{
return sched_n_insns < target_n_insns;
}
/* Add all insns that are initially ready to the ready list READY. Called
once before scheduling a set of insns. */
static void
init_ready_list (ready)
struct ready_list *ready;
{
rtx prev_head = current_sched_info->prev_head;
rtx next_tail = current_sched_info->next_tail;
rtx insn;
target_n_insns = 0;
sched_n_insns = 0;
#if 0
/* Print debugging information. */
if (sched_verbose >= 5)
debug_dependencies ();
#endif
/* Initialize ready list with all 'ready' insns in target block.
Count number of insns in the target block being scheduled. */
for (insn = NEXT_INSN (prev_head); insn != next_tail; insn = NEXT_INSN (insn))
{
rtx next;
if (! INSN_P (insn))
continue;
next = NEXT_INSN (insn);
if (INSN_DEP_COUNT (insn) == 0
&& (SCHED_GROUP_P (next) == 0 || ! INSN_P (next)))
ready_add (ready, insn);
if (!(SCHED_GROUP_P (insn)))
target_n_insns++;
}
}
/* Called after taking INSN from the ready list. Returns nonzero if this
insn can be scheduled, nonzero if we should silently discard it. */
static int
can_schedule_ready_p (insn)
rtx insn ATTRIBUTE_UNUSED;
{
sched_n_insns++;
return 1;
}
/* Called after INSN has all its dependencies resolved. Return nonzero
if it should be moved to the ready list or the queue, or zero if we
should silently discard it. */
static int
new_ready (next)
rtx next ATTRIBUTE_UNUSED;
{
return 1;
}
/* Return a string that contains the insn uid and optionally anything else
necessary to identify this insn in an output. It's valid to use a
static buffer for this. The ALIGNED parameter should cause the string
to be formatted so that multiple output lines will line up nicely. */
static const char *
print_insn (insn, aligned)
rtx insn;
int aligned ATTRIBUTE_UNUSED;
{
static char tmp[80];
sprintf (tmp, "%4d", INSN_UID (insn));
return tmp;
}
/* Compare priority of two insns. Return a positive number if the second
insn is to be preferred for scheduling, and a negative one if the first
is to be preferred. Zero if they are equally good. */
static int
rank (insn1, insn2)
rtx insn1 ATTRIBUTE_UNUSED, insn2 ATTRIBUTE_UNUSED;
{
return 0;
}
/* NEXT is an instruction that depends on INSN (a backward dependence);
return nonzero if we should include this dependence in priority
calculations. */
static int
contributes_to_priority (next, insn)
rtx next ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED;
{
return 1;
}
/* INSN is a JUMP_INSN. Store the set of registers that must be considered
to be set by this jump in SET. */
static void
compute_jump_reg_dependencies (insn, set)
rtx insn;
regset set;
{
basic_block b = BLOCK_FOR_INSN (insn);
edge e;
for (e = b->succ; e; e = e->succ_next)
if ((e->flags & EDGE_FALLTHRU) == 0)
{
bitmap_operation (set, set, e->dest->global_live_at_start,
BITMAP_IOR);
}
}
/* Used in schedule_insns to initialize current_sched_info for scheduling
regions (or single basic blocks). */
static struct sched_info ebb_sched_info =
{
init_ready_list,
can_schedule_ready_p,
schedule_more_p,
new_ready,
rank,
print_insn,
contributes_to_priority,
compute_jump_reg_dependencies,
NULL, NULL,
NULL, NULL,
0, 1
};
/* Schedule a single extended basic block, defined by the boundaries HEAD
and TAIL. */
static void
schedule_ebb (head, tail)
rtx head, tail;
{
int n_insns;
struct deps tmp_deps;
if (no_real_insns_p (head, tail))
return;
init_deps_global ();
/* Compute LOG_LINKS. */
init_deps (&tmp_deps);
sched_analyze (&tmp_deps, head, tail);
free_deps (&tmp_deps);
/* Compute INSN_DEPEND. */
compute_forward_dependences (head, tail);
/* Set priorities. */
n_insns = set_priorities (head, tail);
current_sched_info->prev_head = PREV_INSN (head);
current_sched_info->next_tail = NEXT_INSN (tail);
if (write_symbols != NO_DEBUG)
{
save_line_notes (0, head, tail);
rm_line_notes (head, tail);
}
/* rm_other_notes only removes notes which are _inside_ the
block---that is, it won't remove notes before the first real insn
or after the last real insn of the block. So if the first insn
has a REG_SAVE_NOTE which would otherwise be emitted before the
insn, it is redundant with the note before the start of the
block, and so we have to take it out. */
if (INSN_P (head))
{
rtx note;
for (note = REG_NOTES (head); note; note = XEXP (note, 1))
if (REG_NOTE_KIND (note) == REG_SAVE_NOTE)
{
remove_note (head, note);
note = XEXP (note, 1);
remove_note (head, note);
}
}
/* Remove remaining note insns from the block, save them in
note_list. These notes are restored at the end of
schedule_block (). */
rm_other_notes (head, tail);
current_sched_info->queue_must_finish_empty = 1;
schedule_block (-1, n_insns);
/* Sanity check: verify that all region insns were scheduled. */
if (sched_n_insns != n_insns)
abort ();
head = current_sched_info->head;
tail = current_sched_info->tail;
if (write_symbols != NO_DEBUG)
restore_line_notes (head, tail);
finish_deps_global ();
}
/* The one entry point in this file. DUMP_FILE is the dump file for
this pass. */
void
schedule_ebbs (dump_file)
FILE *dump_file;
{
int i;
/* Taking care of this degenerate case makes the rest of
this code simpler. */
if (n_basic_blocks == 0)
return;
scope_to_insns_initialize ();
sched_init (dump_file);
current_sched_info = &ebb_sched_info;
allocate_reg_life_data ();
compute_bb_for_insn (get_max_uid ());
/* Schedule every region in the subroutine. */
for (i = 0; i < n_basic_blocks; i++)
{
rtx head = BASIC_BLOCK (i)->head;
rtx tail;
for (;;)
{
basic_block b = BASIC_BLOCK (i);
edge e;
tail = b->end;
if (i + 1 == n_basic_blocks
|| GET_CODE (BLOCK_HEAD (i + 1)) == CODE_LABEL)
break;
for (e = b->succ; e; e = e->succ_next)
if ((e->flags & EDGE_FALLTHRU) != 0)
break;
if (! e)
break;
if (GET_CODE (tail) == JUMP_INSN)
{
rtx x = find_reg_note (tail, REG_BR_PROB, 0);
if (x)
{
int pred_val = INTVAL (XEXP (x, 0));
if (pred_val > REG_BR_PROB_BASE / 2)
break;
}
}
i++;
}
/* Blah. We should fix the rest of the code not to get confused by
a note or two. */
while (head != tail)
{
if (GET_CODE (head) == NOTE)
head = NEXT_INSN (head);
else if (GET_CODE (tail) == NOTE)
tail = PREV_INSN (tail);
else if (GET_CODE (head) == CODE_LABEL)
head = NEXT_INSN (head);
else
break;
}
schedule_ebb (head, tail);
}
/* It doesn't make much sense to try and update life information here - we
probably messed up even the flow graph. */
/* Reposition the prologue and epilogue notes in case we moved the
prologue/epilogue insns. */
if (reload_completed)
reposition_prologue_and_epilogue_notes (get_insns ());
if (write_symbols != NO_DEBUG)
rm_redundant_line_notes ();
scope_to_insns_finalize ();
sched_finish ();
}