/* Move registers around to reduce number of move instructions needed.
Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
- 1999, 2000, 2001 Free Software Foundation, Inc.
+ 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
-This file is part of GNU CC.
+This file is part of GCC.
-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.
+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.
-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.
+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 GNU CC; see the file COPYING. If not, write to
-the Free Software Foundation, 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA. */
+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. */
/* This module looks for cases where matching constraints would force
#include "config.h"
#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
#include "rtl.h" /* stdio.h must precede rtl.h for FFS. */
#include "tm_p.h"
#include "insn-config.h"
#include "toplev.h"
#include "reload.h"
+
+/* Turn STACK_GROWS_DOWNWARD into a boolean. */
+#ifdef STACK_GROWS_DOWNWARD
+#undef STACK_GROWS_DOWNWARD
+#define STACK_GROWS_DOWNWARD 1
+#else
+#define STACK_GROWS_DOWNWARD 0
+#endif
+
static int perhaps_ends_bb_p PARAMS ((rtx));
static int optimize_reg_copy_1 PARAMS ((rtx, rtx, rtx));
static void optimize_reg_copy_2 PARAMS ((rtx, rtx, rtx));
static void optimize_reg_copy_3 PARAMS ((rtx, rtx, rtx));
-static rtx gen_add3_insn PARAMS ((rtx, rtx, rtx));
static void copy_src_to_dest PARAMS ((rtx, rtx, rtx, int));
static int *regmove_bb_head;
static int try_auto_increment PARAMS ((rtx, rtx, rtx, rtx, HOST_WIDE_INT, int));
static int find_matches PARAMS ((rtx, struct match *));
-static void replace_in_call_usage PARAMS ((rtx *, int, rtx, rtx));
+static void replace_in_call_usage PARAMS ((rtx *, unsigned int, rtx, rtx));
static int fixup_match_1 PARAMS ((rtx, rtx, rtx, rtx, rtx, int, int, int, FILE *))
;
static int reg_is_remote_constant_p PARAMS ((rtx, rtx, rtx));
static int replacement_quality PARAMS ((rtx));
static int fixup_match_2 PARAMS ((rtx, rtx, rtx, rtx, FILE *));
-/* Return non-zero if registers with CLASS1 and CLASS2 can be merged without
+/* Return nonzero if registers with CLASS1 and CLASS2 can be merged without
causing too much register allocation problems. */
static int
regclass_compatible_p (class0, class1)
&& ! CLASS_LIKELY_SPILLED_P (class1)));
}
-/* Generate and return an insn body to add r1 and c,
- storing the result in r0. */
-static rtx
-gen_add3_insn (r0, r1, c)
- rtx r0, r1, c;
-{
- int icode = (int) add_optab->handlers[(int) GET_MODE (r0)].insn_code;
-
- if (icode == CODE_FOR_nothing
- || ! ((*insn_data[icode].operand[0].predicate)
- (r0, insn_data[icode].operand[0].mode))
- || ! ((*insn_data[icode].operand[1].predicate)
- (r1, insn_data[icode].operand[1].mode))
- || ! ((*insn_data[icode].operand[2].predicate)
- (c, insn_data[icode].operand[2].mode)))
- return NULL_RTX;
-
- return (GEN_FCN (icode) (r0, r1, c));
-}
-
-
/* INC_INSN is an instruction that adds INCREMENT to REG.
Try to fold INC_INSN as a post/pre in/decrement into INSN.
Iff INC_INSN_SET is nonzero, inc_insn has a destination different from src.
/* Can't use the size of SET_SRC, we might have something like
(sign_extend:SI (mem:QI ... */
rtx use = find_use_as_address (pset, reg, 0);
- if (use != 0 && use != (rtx) 1)
+ if (use != 0 && use != (rtx) (size_t) 1)
{
int size = GET_MODE_SIZE (GET_MODE (use));
if (0
= gen_rtx_EXPR_LIST (REG_INC,
reg, REG_NOTES (insn));
if (! inc_insn_set)
- {
- PUT_CODE (inc_insn, NOTE);
- NOTE_LINE_NUMBER (inc_insn) = NOTE_INSN_DELETED;
- NOTE_SOURCE_FILE (inc_insn) = 0;
- }
+ delete_insn (inc_insn);
return 1;
}
}
{
int flags_regno;
int flags_nregs;
- int block;
+ basic_block block;
#ifdef HAVE_cc0
/* If we found a flags register on a cc0 host, bail. */
{
enum machine_mode mode = (flags ? HImode : VOIDmode);
rtx insn;
- for (insn = get_insns(); insn; insn = NEXT_INSN (insn))
+ for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
PUT_MODE (insn, mode);
return;
}
flags_set_1_rtx = flags;
/* Process each basic block. */
- for (block = n_basic_blocks - 1; block >= 0; block--)
+ FOR_EACH_BB_REVERSE (block)
{
rtx insn, end;
int live;
- insn = BLOCK_HEAD (block);
- end = BLOCK_END (block);
+ insn = block->head;
+ end = block->end;
/* Look out for the (unlikely) case of flags being live across
basic block boundaries. */
{
int i;
for (i = 0; i < flags_nregs; ++i)
- live |= REGNO_REG_SET_P (BASIC_BLOCK (block)->global_live_at_start,
+ live |= REGNO_REG_SET_P (block->global_live_at_start,
flags_regno + i);
}
#endif
a candidate for tying to a hard register, since the output might in
turn be a candidate to be tied to a different hard register. */
static int
-replacement_quality(reg)
+replacement_quality (reg)
rtx reg;
{
int src_regno;
int sregno = REGNO (src);
int dregno = REGNO (dest);
- /* We don't want to mess with hard regs if register classes are small. */
+ /* We don't want to mess with hard regs if register classes are small. */
if (sregno == dregno
|| (SMALL_REGISTER_CLASSES
&& (sregno < FIRST_PSEUDO_REGISTER
}
/* INSN is a ZERO_EXTEND or SIGN_EXTEND of SRC to DEST.
Look if SRC dies there, and if it is only set once, by loading
- it from memory. If so, try to encorporate the zero/sign extension
+ it from memory. If so, try to incorporate the zero/sign extension
into the memory read, change SRC to the mode of DEST, and alter
the remaining accesses to use the appropriate SUBREG. This allows
SRC and DEST to be tied later. */
if (src_no < FIRST_PSEUDO_REGISTER
|| dst_no < FIRST_PSEUDO_REGISTER
|| ! find_reg_note (insn, REG_DEAD, src_reg)
+ || REG_N_DEATHS (src_no) != 1
|| REG_N_SETS (src_no) != 1)
return;
for (p = PREV_INSN (insn); p && ! reg_set_p (src_reg, p); p = PREV_INSN (p))
if (! (set = single_set (p))
|| GET_CODE (SET_SRC (set)) != MEM
+ /* If there's a REG_EQUIV note, this must be an insn that loads an
+ argument. Prefer keeping the note over doing this optimization. */
+ || find_reg_note (p, REG_EQUIV, NULL_RTX)
|| SET_DEST (set) != src_reg)
return;
- /* Be conserative: although this optimization is also valid for
+ /* Be conservative: although this optimization is also valid for
volatile memory references, that could cause trouble in later passes. */
if (MEM_VOLATILE_P (SET_SRC (set)))
return;
PUT_MODE (src_reg, old_mode);
XEXP (src, 0) = src_reg;
}
+ else
+ {
+ rtx note = find_reg_note (p, REG_EQUAL, NULL_RTX);
+ if (note)
+ remove_note (p, note);
+ }
}
\f
/* Generate the src->dest move. */
start_sequence ();
emit_move_insn (dest, src);
- seq = gen_sequence ();
+ seq = get_insns ();
end_sequence ();
/* If this sequence uses new registers, we may not use it. */
if (old_num_regs != reg_rtx_no
p_move_notes = ®_NOTES (move_insn);
p_insn_notes = ®_NOTES (insn);
- /* Move any notes mentioning src to the move instruction */
+ /* Move any notes mentioning src to the move instruction. */
for (link = REG_NOTES (insn); link != NULL_RTX; link = next)
{
next = XEXP (link, 1);
*p_move_notes = NULL_RTX;
*p_insn_notes = NULL_RTX;
- /* Is the insn the head of a basic block? If so extend it */
+ /* Is the insn the head of a basic block? If so extend it. */
insn_uid = INSN_UID (insn);
move_uid = INSN_UID (move_insn);
if (insn_uid < old_max_uid)
rtx insn;
rtx first;
{
- register rtx p;
+ rtx p;
if (REG_N_SETS (REGNO (reg)) != 1)
return 0;
(set (reg100) (plus reg100 offset2-offset1)) */
/* ??? What does this comment mean? */
-/* cse disrupts preincrement / postdecrement squences when it finds a
+/* cse disrupts preincrement / postdecrement sequences when it finds a
hard register as ultimate source, like the frame pointer. */
static int
if (perhaps_ends_bb_p (p))
break;
else if (! INSN_P (p))
- continue;
+ continue;
if (find_regno_note (p, REG_DEAD, REGNO (dst)))
dst_death = p;
&& GET_CODE (SET_SRC (pset)) == PLUS
&& XEXP (SET_SRC (pset), 0) == src
&& GET_CODE (XEXP (SET_SRC (pset), 1)) == CONST_INT)
- {
+ {
HOST_WIDE_INT newconst
= INTVAL (offset) - INTVAL (XEXP (SET_SRC (pset), 1));
rtx add = gen_add3_insn (dst, dst, GEN_INT (newconst));
#endif
return 1;
}
- }
+ }
if (reg_set_p (dst, PATTERN (p)))
- break;
+ break;
/* If we have passed a call instruction, and the
pseudo-reg SRC is not already live across a call,
hard regs are clobbered. Thus, we only use it for src for
non-call insns. */
if (GET_CODE (p) == CALL_INSN)
- {
+ {
if (! dst_death)
num_calls++;
- if (REG_N_CALLS_CROSSED (REGNO (src)) == 0)
- break;
+ if (REG_N_CALLS_CROSSED (REGNO (src)) == 0)
+ break;
if (call_used_regs [REGNO (dst)]
|| find_reg_fusage (p, CLOBBER, dst))
break;
- }
+ }
else if (reg_set_p (src, PATTERN (p)))
- break;
+ break;
}
return 0;
}
+/* Main entry for the register move optimization.
+ F is the first instruction.
+ NREGS is one plus the highest pseudo-reg number used in the instruction.
+ REGMOVE_DUMP_FILE is a stream for output of a trace of actions taken
+ (or 0 if none should be output). */
+
void
regmove_optimize (f, nregs, regmove_dump_file)
rtx f;
int pass;
int i;
rtx copy_src, copy_dst;
+ basic_block bb;
/* ??? Hack. Regmove doesn't examine the CFG, and gets mightily
confused by non-call exceptions ending blocks. */
return;
/* Find out where a potential flags register is live, and so that we
- can supress some optimizations in those zones. */
+ can suppress some optimizations in those zones. */
mark_flags_life_zones (discover_flags_reg ());
regno_src_regno = (int *) xmalloc (sizeof *regno_src_regno * nregs);
regmove_bb_head = (int *) xmalloc (sizeof (int) * (old_max_uid + 1));
for (i = old_max_uid; i >= 0; i--) regmove_bb_head[i] = -1;
- for (i = 0; i < n_basic_blocks; i++)
- regmove_bb_head[INSN_UID (BLOCK_HEAD (i))] = i;
+ FOR_EACH_BB (bb)
+ regmove_bb_head[INSN_UID (bb->head)] = bb->index;
/* A forward/backward pass. Replace output operands with input operands. */
&& (GET_CODE (SET_SRC (set)) == SIGN_EXTEND
|| GET_CODE (SET_SRC (set)) == ZERO_EXTEND)
&& GET_CODE (XEXP (SET_SRC (set), 0)) == REG
- && GET_CODE (SET_DEST(set)) == REG)
+ && GET_CODE (SET_DEST (set)) == REG)
optimize_reg_copy_3 (insn, SET_DEST (set), SET_SRC (set));
if (flag_expensive_optimizations && ! pass
&& GET_CODE (SET_SRC (set)) == REG
- && GET_CODE (SET_DEST(set)) == REG)
+ && GET_CODE (SET_DEST (set)) == REG)
{
/* If this is a register-register copy where SRC is not dead,
see if we can optimize it. If this optimization succeeds,
if (regno_src_regno[REGNO (SET_DEST (set))] < 0
&& SET_SRC (set) != SET_DEST (set))
{
- int srcregno = REGNO (SET_SRC(set));
+ int srcregno = REGNO (SET_SRC (set));
if (regno_src_regno[srcregno] >= 0)
srcregno = regno_src_regno[srcregno];
regno_src_regno[REGNO (SET_DEST (set))] = srcregno;
}
}
}
- if (! flag_regmove)
- continue;
+ if (! flag_regmove)
+ continue;
if (! find_matches (insn, &match))
continue;
if (recog_data.operand[match_no] != SET_DEST (set))
continue;
- /* If the operands already match, then there is nothing to do. */
+ /* If the operands already match, then there is nothing to do. */
if (operands_match_p (src, dst))
continue;
if (! regclass_compatible_p (src_class, dst_class))
continue;
+ if (GET_MODE (src) != GET_MODE (dst))
+ continue;
+
if (fixup_match_1 (insn, set, src, src_subreg, dst, pass,
op_no, match_no,
regmove_dump_file))
if (GET_CODE (dst) != REG
|| REGNO (dst) < FIRST_PSEUDO_REGISTER
- || REG_LIVE_LENGTH (REGNO (dst)) < 0)
+ || REG_LIVE_LENGTH (REGNO (dst)) < 0
+ || RTX_UNCHANGING_P (dst))
continue;
- /* If the operands already match, then there is nothing to do. */
+ /* If the operands already match, then there is nothing to do. */
if (operands_match_p (src, dst))
continue;
if (! set)
continue;
+ /* Note that single_set ignores parts of a parallel set for
+ which one of the destinations is REG_UNUSED. We can't
+ handle that here, since we can wind up rewriting things
+ such that a single register is set twice within a single
+ parallel. */
+ if (reg_set_p (src, insn))
+ continue;
+
/* match_no/dst must be a write-only operand, and
operand_operand/src must be a read-only operand. */
if (match.use[op_no] != READ
}
src_class = reg_preferred_class (REGNO (src));
dst_class = reg_preferred_class (REGNO (dst));
- if (! regclass_compatible_p (src_class, dst_class))
+
+ if (! (src_note = find_reg_note (insn, REG_DEAD, src)))
{
- if (!copy_src)
- {
- copy_src = src;
- copy_dst = dst;
- }
+ /* We used to force the copy here like in other cases, but
+ it produces worse code, as it eliminates no copy
+ instructions and the copy emitted will be produced by
+ reload anyway. On patterns with multiple alternatives,
+ there may be better solution available.
+
+ In particular this change produced slower code for numeric
+ i387 programs. */
+
continue;
}
- /* Can not modify an earlier insn to set dst if this insn
- uses an old value in the source. */
- if (reg_overlap_mentioned_p (dst, SET_SRC (set)))
+ if (! regclass_compatible_p (src_class, dst_class))
{
if (!copy_src)
{
continue;
}
- if (! (src_note = find_reg_note (insn, REG_DEAD, src)))
+ /* Can not modify an earlier insn to set dst if this insn
+ uses an old value in the source. */
+ if (reg_overlap_mentioned_p (dst, SET_SRC (set)))
{
if (!copy_src)
{
continue;
}
-
/* If src is set once in a different basic block,
and is set equal to a constant, then do not use
it for this optimization, as this would make it
no longer equivalent to a constant. */
- if (reg_is_remote_constant_p (src, insn, f))
+ if (reg_is_remote_constant_p (src, insn, f))
{
if (!copy_src)
{
}
/* If we weren't able to replace any of the alternatives, try an
- alternative appoach of copying the source to the destination. */
+ alternative approach of copying the source to the destination. */
if (!success && copy_src != NULL_RTX)
copy_src_to_dest (insn, copy_src, copy_dst, old_max_uid);
/* In fixup_match_1, some insns may have been inserted after basic block
ends. Fix that here. */
- for (i = 0; i < n_basic_blocks; i++)
+ FOR_EACH_BB (bb)
{
- rtx end = BLOCK_END (i);
+ rtx end = bb->end;
rtx new = end;
rtx next = NEXT_INSN (new);
while (next != 0 && INSN_UID (next) >= old_max_uid
- && (i == n_basic_blocks - 1 || BLOCK_HEAD (i + 1) != next))
+ && (bb->next_bb == EXIT_BLOCK_PTR || bb->next_bb->head != next))
new = next, next = NEXT_INSN (new);
- BLOCK_END (i) = new;
+ bb->end = new;
}
done:
if (*p == ',')
i++;
- while ((c = *p++) != '\0' && c != ',')
- switch (c)
- {
- case '=':
- break;
- case '+':
- break;
- case '&':
- matchp->early_clobber[op_no] = 1;
- break;
- case '%':
- matchp->commutative[op_no] = op_no + 1;
- matchp->commutative[op_no + 1] = op_no;
- break;
- case '0': case '1': case '2': case '3': case '4':
- case '5': case '6': case '7': case '8': case '9':
- c -= '0';
- if (c < op_no && likely_spilled[(unsigned char) c])
+ while ((c = *p) != '\0' && c != ',')
+ {
+ switch (c)
+ {
+ case '=':
break;
- matchp->with[op_no] = c;
- any_matches = 1;
- if (matchp->commutative[op_no] >= 0)
- matchp->with[matchp->commutative[op_no]] = c;
- break;
+ case '+':
+ break;
+ case '&':
+ matchp->early_clobber[op_no] = 1;
+ break;
+ case '%':
+ matchp->commutative[op_no] = op_no + 1;
+ matchp->commutative[op_no + 1] = op_no;
+ break;
+
+ case '0': case '1': case '2': case '3': case '4':
+ case '5': case '6': case '7': case '8': case '9':
+ {
+ char *end;
+ unsigned long match_ul = strtoul (p, &end, 10);
+ int match = match_ul;
+
+ p = end;
+
+ if (match < op_no && likely_spilled[match])
+ continue;
+ matchp->with[op_no] = match;
+ any_matches = 1;
+ if (matchp->commutative[op_no] >= 0)
+ matchp->with[matchp->commutative[op_no]] = match;
+ }
+ continue;
+
case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': case 'h':
case 'j': case 'k': case 'l': case 'p': case 'q': case 't': case 'u':
case 'v': case 'w': case 'x': case 'y': case 'z': case 'A': case 'B':
case 'C': case 'D': case 'W': case 'Y': case 'Z':
- if (CLASS_LIKELY_SPILLED_P (REG_CLASS_FROM_LETTER ((unsigned char)c)))
+ if (CLASS_LIKELY_SPILLED_P (REG_CLASS_FROM_CONSTRAINT ((unsigned char) c, p) ))
likely_spilled[op_no] = 1;
break;
}
+ p += CONSTRAINT_LEN (c, p);
+ }
}
return any_matches;
}
static void
replace_in_call_usage (loc, dst_reg, src, insn)
rtx *loc;
- int dst_reg;
+ unsigned int dst_reg;
rtx src;
rtx insn;
{
int success = 0;
int num_calls = 0, s_num_calls = 0;
enum rtx_code code = NOTE;
- HOST_WIDE_INT insn_const = 0, newconst;
+ HOST_WIDE_INT insn_const = 0, newconst = 0;
rtx overlap = 0; /* need to move insn ? */
rtx src_note = find_reg_note (insn, REG_DEAD, src), dst_note = NULL_RTX;
int length, s_length;
rtx notes = REG_NOTES (insn);
emit_insn_after_with_line_notes (pat, PREV_INSN (p), insn);
- PUT_CODE (insn, NOTE);
- NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
- NOTE_SOURCE_FILE (insn) = 0;
+ delete_insn (insn);
/* emit_insn_after_with_line_notes has no
return value, so search for the new insn. */
insn = p;
if (note && CONSTANT_P (XEXP (note, 0)))
{
- for (q = PREV_INSN (insn); q; q = PREV_INSN(q))
+ for (q = PREV_INSN (insn); q; q = PREV_INSN (q))
{
/* ??? We can't scan past the end of a basic block without
updating the register lifetime info
if (q && set2 && SET_DEST (set2) == src && CONSTANT_P (SET_SRC (set2))
&& validate_change (insn, &SET_SRC (set), XEXP (note, 0), 0))
{
- PUT_CODE (q, NOTE);
- NOTE_LINE_NUMBER (q) = NOTE_INSN_DELETED;
- NOTE_SOURCE_FILE (q) = 0;
+ delete_insn (q);
REG_N_SETS (REGNO (src))--;
REG_N_CALLS_CROSSED (REGNO (src)) -= num_calls2;
REG_LIVE_LENGTH (REGNO (src)) -= s_length2;
{
/* ??? We can't scan past the end of a basic block without updating
the register lifetime info
- (REG_DEAD/basic_block_live_at_start). */
+ (REG_DEAD/basic_block_live_at_start). */
if (perhaps_ends_bb_p (q))
break;
else if (! INSN_P (q))
}
\f
/* Track stack adjustments and stack memory references. Attempt to
- reduce the number of stack adjustments by back-propogating across
+ reduce the number of stack adjustments by back-propagating across
the memory references.
This is intended primarily for use with targets that do not define
(e.g. x86 fp regs) which would ordinarily have to be implemented
as a sub/mov pair due to restrictions in calls.c.
- Propogation stops when any of the insns that need adjusting are
+ Propagation stops when any of the insns that need adjusting are
(a) no longer valid because we've exceeded their range, (b) a
non-trivial push instruction, or (c) a call instruction.
void
combine_stack_adjustments ()
{
- int i;
+ basic_block bb;
- for (i = 0; i < n_basic_blocks; ++i)
- combine_stack_adjustments_for_block (BASIC_BLOCK (i));
+ FOR_EACH_BB (bb)
+ combine_stack_adjustments_for_block (bb);
}
/* Recognize a MEM of the form (sp) or (plus sp const). */
struct csa_memlist *ml;
rtx set;
- /* We know INSN matches single_set_for_csa, because that's what we
- recognized earlier. However, if INSN is not single_set, it is
- doing double duty as a barrier for frame pointer memory accesses,
- which we are not recording. Therefore, an adjust insn that is not
- single_set may not have a positive delta applied. */
-
- if (delta > 0 && ! single_set (insn))
- return 0;
set = single_set_for_csa (insn);
validate_change (insn, &XEXP (SET_SRC (set), 1), GEN_INT (new_adjust), 1);
for (ml = memlist; ml ; ml = ml->next)
- {
- HOST_WIDE_INT c = ml->sp_offset - delta;
- rtx new = gen_rtx_MEM (GET_MODE (*ml->mem),
- plus_constant (stack_pointer_rtx, c));
-
- /* Don't reference memory below the stack pointer. */
- if (c < 0)
- {
- cancel_changes (0);
- return 0;
- }
-
- MEM_COPY_ATTRIBUTES (new, *ml->mem);
- validate_change (ml->insn, ml->mem, new, 1);
- }
+ validate_change
+ (ml->insn, ml->mem,
+ replace_equiv_address_nv (*ml->mem,
+ plus_constant (stack_pointer_rtx,
+ ml->sp_offset - delta)), 1);
if (apply_change_group ())
{
if (!reg_mentioned_p (stack_pointer_rtx, x))
return -1;
/* We are not able to handle correctly all possible memrefs containing
- stack pointer, so this check is neccesary. */
+ stack pointer, so this check is necessary. */
if (stack_memref_p (x))
{
d->memlist = record_one_stack_memref (d->insn, xp, d->memlist);
We can't just compare with STACK_POINTER_RTX because the
reference to the stack pointer might be in some other mode.
- In particular, an explict clobber in an asm statement will
+ In particular, an explicit clobber in an asm statement will
result in a QImode clober. */
if (REGNO (x) == STACK_POINTER_REGNUM)
return 1;
HOST_WIDE_INT last_sp_adjust = 0;
rtx last_sp_set = NULL_RTX;
struct csa_memlist *memlist = NULL;
- rtx pending_delete;
- rtx insn, next;
+ rtx insn, next, set;
struct record_stack_memrefs_data data;
+ bool end_of_block = false;
- for (insn = bb->head; ; insn = next)
+ for (insn = bb->head; !end_of_block ; insn = next)
{
- rtx set;
-
- pending_delete = NULL_RTX;
+ end_of_block = insn == bb->end;
next = NEXT_INSN (insn);
if (! INSN_P (insn))
- goto processed;
+ continue;
set = single_set_for_csa (insn);
if (set)
{
last_sp_set = insn;
last_sp_adjust = this_adjust;
- goto processed;
+ continue;
}
/* If not all recorded memrefs can be adjusted, or the
adjustment is now too large for a constant addition,
- we cannot merge the two stack adjustments. */
- if (! try_apply_stack_adjustment (last_sp_set, memlist,
- last_sp_adjust + this_adjust,
- this_adjust))
+ we cannot merge the two stack adjustments.
+
+ Also we need to be careful to not move stack pointer
+ such that we create stack accesses outside the allocated
+ area. We can combine an allocation into the first insn,
+ or a deallocation into the second insn. We can not
+ combine an allocation followed by a deallocation.
+
+ The only somewhat frequent occurrence of the later is when
+ a function allocates a stack frame but does not use it.
+ For this case, we would need to analyze rtl stream to be
+ sure that allocated area is really unused. This means not
+ only checking the memory references, but also all registers
+ or global memory references possibly containing a stack
+ frame address.
+
+ Perhaps the best way to address this problem is to teach
+ gcc not to allocate stack for objects never used. */
+
+ /* Combine an allocation into the first instruction. */
+ if (STACK_GROWS_DOWNWARD ? this_adjust <= 0 : this_adjust >= 0)
{
- free_csa_memlist (memlist);
- memlist = NULL;
- last_sp_set = insn;
- last_sp_adjust = this_adjust;
- goto processed;
+ if (try_apply_stack_adjustment (last_sp_set, memlist,
+ last_sp_adjust + this_adjust,
+ this_adjust))
+ {
+ /* It worked! */
+ delete_insn (insn);
+ last_sp_adjust += this_adjust;
+ continue;
+ }
}
- /* It worked! */
- pending_delete = insn;
- last_sp_adjust += this_adjust;
-
- /* If, by some accident, the adjustments cancel out,
- delete both insns and start from scratch. */
- if (last_sp_adjust == 0)
+ /* Otherwise we have a deallocation. Do not combine with
+ a previous allocation. Combine into the second insn. */
+ else if (STACK_GROWS_DOWNWARD
+ ? last_sp_adjust >= 0 : last_sp_adjust <= 0)
{
- if (last_sp_set == bb->head)
- bb->head = NEXT_INSN (last_sp_set);
- flow_delete_insn (last_sp_set);
-
- free_csa_memlist (memlist);
- memlist = NULL;
- last_sp_set = NULL_RTX;
+ if (try_apply_stack_adjustment (insn, memlist,
+ last_sp_adjust + this_adjust,
+ -last_sp_adjust))
+ {
+ /* It worked! */
+ delete_insn (last_sp_set);
+ last_sp_set = insn;
+ last_sp_adjust += this_adjust;
+ free_csa_memlist (memlist);
+ memlist = NULL;
+ continue;
+ }
}
- goto processed;
+ /* Combination failed. Restart processing from here. If
+ deallocation+allocation conspired to cancel, we can
+ delete the old deallocation insn. */
+ if (last_sp_set && last_sp_adjust == 0)
+ delete_insn (insn);
+ free_csa_memlist (memlist);
+ memlist = NULL;
+ last_sp_set = insn;
+ last_sp_adjust = this_adjust;
+ continue;
}
/* Find a predecrement of exactly the previous adjustment and
&& ! reg_mentioned_p (stack_pointer_rtx, src)
&& memory_address_p (GET_MODE (dest), stack_pointer_rtx)
&& validate_change (insn, &SET_DEST (set),
- change_address (dest, VOIDmode,
- stack_pointer_rtx), 0))
+ replace_equiv_address (dest,
+ stack_pointer_rtx),
+ 0))
{
- if (last_sp_set == bb->head)
- bb->head = NEXT_INSN (last_sp_set);
- flow_delete_insn (last_sp_set);
-
+ delete_insn (last_sp_set);
free_csa_memlist (memlist);
memlist = NULL;
last_sp_set = NULL_RTX;
last_sp_adjust = 0;
- goto processed;
+ continue;
}
}
&& !for_each_rtx (&PATTERN (insn), record_stack_memrefs, &data))
{
memlist = data.memlist;
- goto processed;
+ continue;
}
memlist = data.memlist;
&& (GET_CODE (insn) == CALL_INSN
|| reg_mentioned_p (stack_pointer_rtx, PATTERN (insn))))
{
+ if (last_sp_set && last_sp_adjust == 0)
+ delete_insn (last_sp_set);
free_csa_memlist (memlist);
memlist = NULL;
last_sp_set = NULL_RTX;
last_sp_adjust = 0;
}
-
- processed:
- if (insn == bb->end)
- break;
-
- if (pending_delete)
- flow_delete_insn (pending_delete);
}
- if (pending_delete)
- {
- bb->end = PREV_INSN (pending_delete);
- flow_delete_insn (pending_delete);
- }
+ if (last_sp_set && last_sp_adjust == 0)
+ delete_insn (last_sp_set);
}
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