diff --git a/gcc/ChangeLog b/gcc/ChangeLog index b8cfa974699..f60049ff6ab 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2007-03-30 Steven Bosscher + + * regmove.c: Move all of pass_stack_adjustments from here... + * combine-stack-adj.c: ...to this new file. + * Makefile.in: Add rules for combine-stack-adj.o. + 2007-03-30 Zdenek Dvorak PR tree-optimization/31383 diff --git a/gcc/Makefile.in b/gcc/Makefile.in index 4c351908270..05fb4ee0be1 100644 --- a/gcc/Makefile.in +++ b/gcc/Makefile.in @@ -969,6 +969,7 @@ OBJS-common = \ cfgloopmanip.o \ cfgrtl.o \ combine.o \ + combine-stack-adj.o \ convert.o \ coverage.o \ cse.o \ @@ -2679,6 +2680,10 @@ regmove.o : regmove.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) \ insn-config.h $(TIMEVAR_H) tree-pass.h \ $(RECOG_H) output.h $(REGS_H) hard-reg-set.h $(FLAGS_H) $(FUNCTION_H) \ $(EXPR_H) $(BASIC_BLOCK_H) toplev.h $(TM_P_H) except.h reload.h +combine-stack-adj.o : combine-stack-adj.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \ + $(TM_H) $(RTL_H) insn-config.h $(TIMEVAR_H) tree-pass.h \ + $(RECOG_H) output.h $(REGS_H) hard-reg-set.h $(FLAGS_H) $(FUNCTION_H) \ + $(EXPR_H) $(BASIC_BLOCK_H) toplev.h $(TM_P_H) except.h reload.h ddg.o : ddg.c $(DDG_H) $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TARGET_H) \ toplev.h $(RTL_H) $(TM_P_H) $(REGS_H) $(FUNCTION_H) \ $(FLAGS_H) insn-config.h $(INSN_ATTR_H) except.h $(RECOG_H) \ diff --git a/gcc/combine-stack-adj.c b/gcc/combine-stack-adj.c new file mode 100644 index 00000000000..fb1480a012d --- /dev/null +++ b/gcc/combine-stack-adj.c @@ -0,0 +1,489 @@ +/* Combine stack adjustments. + Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, + 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc. + +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, 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301, USA. */ + +/* Track stack adjustments and stack memory references. Attempt to + 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 + ACCUMULATE_OUTGOING_ARGS. It is of significantly more value to + targets that define PREFERRED_STACK_BOUNDARY more aligned than + STACK_BOUNDARY (e.g. x86), or if not all registers can be pushed + (e.g. x86 fp regs) which would ordinarily have to be implemented + as a sub/mov pair due to restrictions in calls.c. + + 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. + + Restriction B is based on the assumption that push instructions + are smaller or faster. If a port really wants to remove all + pushes, it should have defined ACCUMULATE_OUTGOING_ARGS. The + one exception that is made is for an add immediately followed + by a push. */ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "tm.h" +#include "rtl.h" +#include "tm_p.h" +#include "insn-config.h" +#include "recog.h" +#include "output.h" +#include "regs.h" +#include "hard-reg-set.h" +#include "flags.h" +#include "function.h" +#include "expr.h" +#include "basic-block.h" +#include "except.h" +#include "toplev.h" +#include "reload.h" +#include "timevar.h" +#include "tree-pass.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 + +/* This structure records stack memory references between stack adjusting + instructions. */ + +struct csa_memlist +{ + HOST_WIDE_INT sp_offset; + rtx insn, *mem; + struct csa_memlist *next; +}; + +static int stack_memref_p (rtx); +static rtx single_set_for_csa (rtx); +static void free_csa_memlist (struct csa_memlist *); +static struct csa_memlist *record_one_stack_memref (rtx, rtx *, + struct csa_memlist *); +static int try_apply_stack_adjustment (rtx, struct csa_memlist *, + HOST_WIDE_INT, HOST_WIDE_INT); +static void combine_stack_adjustments_for_block (basic_block); +static int record_stack_memrefs (rtx *, void *); + + +/* Main entry point for stack adjustment combination. */ + +static void +combine_stack_adjustments (void) +{ + basic_block bb; + + FOR_EACH_BB (bb) + combine_stack_adjustments_for_block (bb); +} + +/* Recognize a MEM of the form (sp) or (plus sp const). */ + +static int +stack_memref_p (rtx x) +{ + if (!MEM_P (x)) + return 0; + x = XEXP (x, 0); + + if (x == stack_pointer_rtx) + return 1; + if (GET_CODE (x) == PLUS + && XEXP (x, 0) == stack_pointer_rtx + && GET_CODE (XEXP (x, 1)) == CONST_INT) + return 1; + + return 0; +} + +/* Recognize either normal single_set or the hack in i386.md for + tying fp and sp adjustments. */ + +static rtx +single_set_for_csa (rtx insn) +{ + int i; + rtx tmp = single_set (insn); + if (tmp) + return tmp; + + if (!NONJUMP_INSN_P (insn) + || GET_CODE (PATTERN (insn)) != PARALLEL) + return NULL_RTX; + + tmp = PATTERN (insn); + if (GET_CODE (XVECEXP (tmp, 0, 0)) != SET) + return NULL_RTX; + + for (i = 1; i < XVECLEN (tmp, 0); ++i) + { + rtx this = XVECEXP (tmp, 0, i); + + /* The special case is allowing a no-op set. */ + if (GET_CODE (this) == SET + && SET_SRC (this) == SET_DEST (this)) + ; + else if (GET_CODE (this) != CLOBBER + && GET_CODE (this) != USE) + return NULL_RTX; + } + + return XVECEXP (tmp, 0, 0); +} + +/* Free the list of csa_memlist nodes. */ + +static void +free_csa_memlist (struct csa_memlist *memlist) +{ + struct csa_memlist *next; + for (; memlist ; memlist = next) + { + next = memlist->next; + free (memlist); + } +} + +/* Create a new csa_memlist node from the given memory reference. + It is already known that the memory is stack_memref_p. */ + +static struct csa_memlist * +record_one_stack_memref (rtx insn, rtx *mem, struct csa_memlist *next_memlist) +{ + struct csa_memlist *ml; + + ml = XNEW (struct csa_memlist); + + if (XEXP (*mem, 0) == stack_pointer_rtx) + ml->sp_offset = 0; + else + ml->sp_offset = INTVAL (XEXP (XEXP (*mem, 0), 1)); + + ml->insn = insn; + ml->mem = mem; + ml->next = next_memlist; + + return ml; +} + +/* Attempt to apply ADJUST to the stack adjusting insn INSN, as well + as each of the memories in MEMLIST. Return true on success. */ + +static int +try_apply_stack_adjustment (rtx insn, struct csa_memlist *memlist, HOST_WIDE_INT new_adjust, + HOST_WIDE_INT delta) +{ + struct csa_memlist *ml; + rtx set; + + 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) + 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 ()) + { + /* Succeeded. Update our knowledge of the memory references. */ + for (ml = memlist; ml ; ml = ml->next) + ml->sp_offset -= delta; + + return 1; + } + else + return 0; +} + +/* Called via for_each_rtx and used to record all stack memory references in + the insn and discard all other stack pointer references. */ +struct record_stack_memrefs_data +{ + rtx insn; + struct csa_memlist *memlist; +}; + +static int +record_stack_memrefs (rtx *xp, void *data) +{ + rtx x = *xp; + struct record_stack_memrefs_data *d = + (struct record_stack_memrefs_data *) data; + if (!x) + return 0; + switch (GET_CODE (x)) + { + case MEM: + 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 necessary. */ + if (stack_memref_p (x)) + { + d->memlist = record_one_stack_memref (d->insn, xp, d->memlist); + return -1; + } + return 1; + case REG: + /* ??? We want be able to handle non-memory stack pointer + references later. For now just discard all insns referring to + stack pointer outside mem expressions. We would probably + want to teach validate_replace to simplify expressions first. + + 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 explicit clobber in an asm statement will + result in a QImode clobber. */ + if (REGNO (x) == STACK_POINTER_REGNUM) + return 1; + break; + default: + break; + } + return 0; +} + +/* Subroutine of combine_stack_adjustments, called for each basic block. */ + +static void +combine_stack_adjustments_for_block (basic_block bb) +{ + HOST_WIDE_INT last_sp_adjust = 0; + rtx last_sp_set = NULL_RTX; + struct csa_memlist *memlist = NULL; + rtx insn, next, set; + struct record_stack_memrefs_data data; + bool end_of_block = false; + + for (insn = BB_HEAD (bb); !end_of_block ; insn = next) + { + end_of_block = insn == BB_END (bb); + next = NEXT_INSN (insn); + + if (! INSN_P (insn)) + continue; + + set = single_set_for_csa (insn); + if (set) + { + rtx dest = SET_DEST (set); + rtx src = SET_SRC (set); + + /* Find constant additions to the stack pointer. */ + if (dest == stack_pointer_rtx + && GET_CODE (src) == PLUS + && XEXP (src, 0) == stack_pointer_rtx + && GET_CODE (XEXP (src, 1)) == CONST_INT) + { + HOST_WIDE_INT this_adjust = INTVAL (XEXP (src, 1)); + + /* If we've not seen an adjustment previously, record + it now and continue. */ + if (! last_sp_set) + { + last_sp_set = insn; + last_sp_adjust = this_adjust; + 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. + + 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) + { + 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; + } + } + + /* 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 (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; + } + } + + /* 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 + turn it into a direct store. Obviously we can't do this if + there were any intervening uses of the stack pointer. */ + if (memlist == NULL + && MEM_P (dest) + && ((GET_CODE (XEXP (dest, 0)) == PRE_DEC + && (last_sp_adjust + == (HOST_WIDE_INT) GET_MODE_SIZE (GET_MODE (dest)))) + || (GET_CODE (XEXP (dest, 0)) == PRE_MODIFY + && GET_CODE (XEXP (XEXP (dest, 0), 1)) == PLUS + && XEXP (XEXP (XEXP (dest, 0), 1), 0) == stack_pointer_rtx + && (GET_CODE (XEXP (XEXP (XEXP (dest, 0), 1), 1)) + == CONST_INT) + && (INTVAL (XEXP (XEXP (XEXP (dest, 0), 1), 1)) + == -last_sp_adjust))) + && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx + && ! reg_mentioned_p (stack_pointer_rtx, src) + && memory_address_p (GET_MODE (dest), stack_pointer_rtx) + && validate_change (insn, &SET_DEST (set), + replace_equiv_address (dest, + stack_pointer_rtx), + 0)) + { + delete_insn (last_sp_set); + free_csa_memlist (memlist); + memlist = NULL; + last_sp_set = NULL_RTX; + last_sp_adjust = 0; + continue; + } + } + + data.insn = insn; + data.memlist = memlist; + if (!CALL_P (insn) && last_sp_set + && !for_each_rtx (&PATTERN (insn), record_stack_memrefs, &data)) + { + memlist = data.memlist; + continue; + } + memlist = data.memlist; + + /* Otherwise, we were not able to process the instruction. + Do not continue collecting data across such a one. */ + if (last_sp_set + && (CALL_P (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; + } + } + + if (last_sp_set && last_sp_adjust == 0) + delete_insn (last_sp_set); + + if (memlist) + free_csa_memlist (memlist); +} + + +static bool +gate_handle_stack_adjustments (void) +{ + return (optimize > 0); +} + +static unsigned int +rest_of_handle_stack_adjustments (void) +{ + life_analysis (PROP_POSTRELOAD); + cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_UPDATE_LIFE + | (flag_crossjumping ? CLEANUP_CROSSJUMP : 0)); + + /* This is kind of a heuristic. We need to run combine_stack_adjustments + even for machines with possibly nonzero RETURN_POPS_ARGS + and ACCUMULATE_OUTGOING_ARGS. We expect that only ports having + push instructions will have popping returns. */ +#ifndef PUSH_ROUNDING + if (!ACCUMULATE_OUTGOING_ARGS) +#endif + combine_stack_adjustments (); + return 0; +} + +struct tree_opt_pass pass_stack_adjustments = +{ + "csa", /* name */ + gate_handle_stack_adjustments, /* gate */ + rest_of_handle_stack_adjustments, /* execute */ + NULL, /* sub */ + NULL, /* next */ + 0, /* static_pass_number */ + 0, /* tv_id */ + 0, /* properties_required */ + 0, /* properties_provided */ + 0, /* properties_destroyed */ + 0, /* todo_flags_start */ + TODO_dump_func | + TODO_ggc_collect, /* todo_flags_finish */ + 0 /* letter */ +}; + diff --git a/gcc/regmove.c b/gcc/regmove.c index 06272e5e770..d874695b9f4 100644 --- a/gcc/regmove.c +++ b/gcc/regmove.c @@ -623,12 +623,11 @@ optimize_reg_copy_2 (rtx insn, rtx dest, rtx src) if (reg_mentioned_p (dest, PATTERN (q))) PATTERN (q) = replace_rtx (PATTERN (q), dest, src); - - if (CALL_P (q)) - { - REG_N_CALLS_CROSSED (dregno)--; - REG_N_CALLS_CROSSED (sregno)++; - } + if (CALL_P (q)) + { + REG_N_CALLS_CROSSED (dregno)--; + REG_N_CALLS_CROSSED (sregno)++; + } } remove_note (p, find_reg_note (p, REG_DEAD, dest)); @@ -644,6 +643,7 @@ optimize_reg_copy_2 (rtx insn, rtx dest, rtx src) break; } } + /* 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 incorporate the zero/sign extension @@ -2083,408 +2083,13 @@ stable_and_no_regs_but_for_p (rtx x, rtx src, rtx dst) } } -/* Track stack adjustments and stack memory references. Attempt to - 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 - ACCUMULATE_OUTGOING_ARGS. It is of significantly more value to - targets that define PREFERRED_STACK_BOUNDARY more aligned than - STACK_BOUNDARY (e.g. x86), or if not all registers can be pushed - (e.g. x86 fp regs) which would ordinarily have to be implemented - as a sub/mov pair due to restrictions in calls.c. - - 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. - - Restriction B is based on the assumption that push instructions - are smaller or faster. If a port really wants to remove all - pushes, it should have defined ACCUMULATE_OUTGOING_ARGS. The - one exception that is made is for an add immediately followed - by a push. */ - -/* This structure records stack memory references between stack adjusting - instructions. */ - -struct csa_memlist -{ - HOST_WIDE_INT sp_offset; - rtx insn, *mem; - struct csa_memlist *next; -}; - -static int stack_memref_p (rtx); -static rtx single_set_for_csa (rtx); -static void free_csa_memlist (struct csa_memlist *); -static struct csa_memlist *record_one_stack_memref (rtx, rtx *, - struct csa_memlist *); -static int try_apply_stack_adjustment (rtx, struct csa_memlist *, - HOST_WIDE_INT, HOST_WIDE_INT); -static void combine_stack_adjustments_for_block (basic_block); -static int record_stack_memrefs (rtx *, void *); - - -/* Main entry point for stack adjustment combination. */ - -static void -combine_stack_adjustments (void) -{ - basic_block bb; - - FOR_EACH_BB (bb) - combine_stack_adjustments_for_block (bb); -} - -/* Recognize a MEM of the form (sp) or (plus sp const). */ - -static int -stack_memref_p (rtx x) -{ - if (!MEM_P (x)) - return 0; - x = XEXP (x, 0); - - if (x == stack_pointer_rtx) - return 1; - if (GET_CODE (x) == PLUS - && XEXP (x, 0) == stack_pointer_rtx - && GET_CODE (XEXP (x, 1)) == CONST_INT) - return 1; - - return 0; -} - -/* Recognize either normal single_set or the hack in i386.md for - tying fp and sp adjustments. */ - -static rtx -single_set_for_csa (rtx insn) -{ - int i; - rtx tmp = single_set (insn); - if (tmp) - return tmp; - - if (!NONJUMP_INSN_P (insn) - || GET_CODE (PATTERN (insn)) != PARALLEL) - return NULL_RTX; - - tmp = PATTERN (insn); - if (GET_CODE (XVECEXP (tmp, 0, 0)) != SET) - return NULL_RTX; - - for (i = 1; i < XVECLEN (tmp, 0); ++i) - { - rtx this = XVECEXP (tmp, 0, i); - - /* The special case is allowing a no-op set. */ - if (GET_CODE (this) == SET - && SET_SRC (this) == SET_DEST (this)) - ; - else if (GET_CODE (this) != CLOBBER - && GET_CODE (this) != USE) - return NULL_RTX; - } - - return XVECEXP (tmp, 0, 0); -} - -/* Free the list of csa_memlist nodes. */ - -static void -free_csa_memlist (struct csa_memlist *memlist) -{ - struct csa_memlist *next; - for (; memlist ; memlist = next) - { - next = memlist->next; - free (memlist); - } -} - -/* Create a new csa_memlist node from the given memory reference. - It is already known that the memory is stack_memref_p. */ - -static struct csa_memlist * -record_one_stack_memref (rtx insn, rtx *mem, struct csa_memlist *next_memlist) -{ - struct csa_memlist *ml; - - ml = XNEW (struct csa_memlist); - - if (XEXP (*mem, 0) == stack_pointer_rtx) - ml->sp_offset = 0; - else - ml->sp_offset = INTVAL (XEXP (XEXP (*mem, 0), 1)); - - ml->insn = insn; - ml->mem = mem; - ml->next = next_memlist; - - return ml; -} - -/* Attempt to apply ADJUST to the stack adjusting insn INSN, as well - as each of the memories in MEMLIST. Return true on success. */ - -static int -try_apply_stack_adjustment (rtx insn, struct csa_memlist *memlist, HOST_WIDE_INT new_adjust, - HOST_WIDE_INT delta) -{ - struct csa_memlist *ml; - rtx set; - - 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) - 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 ()) - { - /* Succeeded. Update our knowledge of the memory references. */ - for (ml = memlist; ml ; ml = ml->next) - ml->sp_offset -= delta; - - return 1; - } - else - return 0; -} - -/* Called via for_each_rtx and used to record all stack memory references in - the insn and discard all other stack pointer references. */ -struct record_stack_memrefs_data -{ - rtx insn; - struct csa_memlist *memlist; -}; - -static int -record_stack_memrefs (rtx *xp, void *data) -{ - rtx x = *xp; - struct record_stack_memrefs_data *d = - (struct record_stack_memrefs_data *) data; - if (!x) - return 0; - switch (GET_CODE (x)) - { - case MEM: - 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 necessary. */ - if (stack_memref_p (x)) - { - d->memlist = record_one_stack_memref (d->insn, xp, d->memlist); - return -1; - } - return 1; - case REG: - /* ??? We want be able to handle non-memory stack pointer - references later. For now just discard all insns referring to - stack pointer outside mem expressions. We would probably - want to teach validate_replace to simplify expressions first. - - 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 explicit clobber in an asm statement will - result in a QImode clobber. */ - if (REGNO (x) == STACK_POINTER_REGNUM) - return 1; - break; - default: - break; - } - return 0; -} - -/* Subroutine of combine_stack_adjustments, called for each basic block. */ - -static void -combine_stack_adjustments_for_block (basic_block bb) -{ - HOST_WIDE_INT last_sp_adjust = 0; - rtx last_sp_set = NULL_RTX; - struct csa_memlist *memlist = NULL; - rtx insn, next, set; - struct record_stack_memrefs_data data; - bool end_of_block = false; - - for (insn = BB_HEAD (bb); !end_of_block ; insn = next) - { - end_of_block = insn == BB_END (bb); - next = NEXT_INSN (insn); - - if (! INSN_P (insn)) - continue; - - set = single_set_for_csa (insn); - if (set) - { - rtx dest = SET_DEST (set); - rtx src = SET_SRC (set); - - /* Find constant additions to the stack pointer. */ - if (dest == stack_pointer_rtx - && GET_CODE (src) == PLUS - && XEXP (src, 0) == stack_pointer_rtx - && GET_CODE (XEXP (src, 1)) == CONST_INT) - { - HOST_WIDE_INT this_adjust = INTVAL (XEXP (src, 1)); - - /* If we've not seen an adjustment previously, record - it now and continue. */ - if (! last_sp_set) - { - last_sp_set = insn; - last_sp_adjust = this_adjust; - 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. - - 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) - { - 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; - } - } - - /* 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 (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; - } - } - - /* 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 - turn it into a direct store. Obviously we can't do this if - there were any intervening uses of the stack pointer. */ - if (memlist == NULL - && MEM_P (dest) - && ((GET_CODE (XEXP (dest, 0)) == PRE_DEC - && (last_sp_adjust - == (HOST_WIDE_INT) GET_MODE_SIZE (GET_MODE (dest)))) - || (GET_CODE (XEXP (dest, 0)) == PRE_MODIFY - && GET_CODE (XEXP (XEXP (dest, 0), 1)) == PLUS - && XEXP (XEXP (XEXP (dest, 0), 1), 0) == stack_pointer_rtx - && (GET_CODE (XEXP (XEXP (XEXP (dest, 0), 1), 1)) - == CONST_INT) - && (INTVAL (XEXP (XEXP (XEXP (dest, 0), 1), 1)) - == -last_sp_adjust))) - && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx - && ! reg_mentioned_p (stack_pointer_rtx, src) - && memory_address_p (GET_MODE (dest), stack_pointer_rtx) - && validate_change (insn, &SET_DEST (set), - replace_equiv_address (dest, - stack_pointer_rtx), - 0)) - { - delete_insn (last_sp_set); - free_csa_memlist (memlist); - memlist = NULL; - last_sp_set = NULL_RTX; - last_sp_adjust = 0; - continue; - } - } - - data.insn = insn; - data.memlist = memlist; - if (!CALL_P (insn) && last_sp_set - && !for_each_rtx (&PATTERN (insn), record_stack_memrefs, &data)) - { - memlist = data.memlist; - continue; - } - memlist = data.memlist; - - /* Otherwise, we were not able to process the instruction. - Do not continue collecting data across such a one. */ - if (last_sp_set - && (CALL_P (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; - } - } - - if (last_sp_set && last_sp_adjust == 0) - delete_insn (last_sp_set); - - if (memlist) - free_csa_memlist (memlist); -} - static bool gate_handle_regmove (void) { return (optimize > 0 && flag_regmove); } - /* Register allocation pre-pass, to reduce number of moves necessary for two-address machines. */ static unsigned int @@ -2513,46 +2118,3 @@ struct tree_opt_pass pass_regmove = 'N' /* letter */ }; - -static bool -gate_handle_stack_adjustments (void) -{ - return (optimize > 0); -} - -static unsigned int -rest_of_handle_stack_adjustments (void) -{ - life_analysis (PROP_POSTRELOAD); - cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_UPDATE_LIFE - | (flag_crossjumping ? CLEANUP_CROSSJUMP : 0)); - - /* This is kind of a heuristic. We need to run combine_stack_adjustments - even for machines with possibly nonzero RETURN_POPS_ARGS - and ACCUMULATE_OUTGOING_ARGS. We expect that only ports having - push instructions will have popping returns. */ -#ifndef PUSH_ROUNDING - if (!ACCUMULATE_OUTGOING_ARGS) -#endif - combine_stack_adjustments (); - return 0; -} - -struct tree_opt_pass pass_stack_adjustments = -{ - "csa", /* name */ - gate_handle_stack_adjustments, /* gate */ - rest_of_handle_stack_adjustments, /* execute */ - NULL, /* sub */ - NULL, /* next */ - 0, /* static_pass_number */ - 0, /* tv_id */ - 0, /* properties_required */ - 0, /* properties_provided */ - 0, /* properties_destroyed */ - 0, /* todo_flags_start */ - TODO_dump_func | - TODO_ggc_collect, /* todo_flags_finish */ - 0 /* letter */ -}; -