| /* Combine stack adjustments. |
| Copyright (C) 1987-2021 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 3, 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 COPYING3. If not see |
| <http://www.gnu.org/licenses/>. */ |
| |
| /* 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| (a) no longer valid because we've exceeded their range, (b) a |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 "backend.h" |
| #include "rtl.h" |
| #include "df.h" |
| #include "insn-config.h" |
| #include "memmodel.h" |
| #include "emit-rtl.h" |
| #include "recog.h" |
| #include "cfgrtl.h" |
| #include "tree-pass.h" |
| #include "rtl-iter.h" |
| |
| |
| /* This structure records two kinds of stack references between stack |
| adjusting instructions: stack references in memory addresses for |
| regular insns and all stack references for debug insns. */ |
| |
| struct csa_reflist |
| { |
| HOST_WIDE_INT sp_offset; |
| rtx_insn *insn; |
| rtx *ref; |
| struct csa_reflist *next; |
| }; |
| |
| static int stack_memref_p (rtx); |
| static rtx single_set_for_csa (rtx_insn *); |
| static void free_csa_reflist (struct csa_reflist *); |
| static struct csa_reflist *record_one_stack_ref (rtx_insn *, rtx *, |
| struct csa_reflist *); |
| static bool try_apply_stack_adjustment (rtx_insn *, struct csa_reflist *, |
| HOST_WIDE_INT, HOST_WIDE_INT, |
| bitmap, rtx_insn *); |
| static void combine_stack_adjustments_for_block (basic_block, bitmap); |
| |
| |
| /* Main entry point for stack adjustment combination. */ |
| |
| static void |
| combine_stack_adjustments (void) |
| { |
| basic_block bb; |
| bitmap live = BITMAP_ALLOC (®_obstack); |
| |
| FOR_EACH_BB_FN (bb, cfun) |
| combine_stack_adjustments_for_block (bb, live); |
| |
| BITMAP_FREE (live); |
| } |
| |
| /* 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 |
| && CONST_INT_P (XEXP (x, 1))) |
| 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 *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_rtx = XVECEXP (tmp, 0, i); |
| |
| /* The special case is allowing a no-op set. */ |
| if (GET_CODE (this_rtx) == SET |
| && SET_SRC (this_rtx) == SET_DEST (this_rtx)) |
| ; |
| else if (GET_CODE (this_rtx) != CLOBBER |
| && GET_CODE (this_rtx) != USE) |
| return NULL_RTX; |
| } |
| |
| return XVECEXP (tmp, 0, 0); |
| } |
| |
| /* Free the list of csa_reflist nodes. */ |
| |
| static void |
| free_csa_reflist (struct csa_reflist *reflist) |
| { |
| struct csa_reflist *next; |
| for (; reflist ; reflist = next) |
| { |
| next = reflist->next; |
| free (reflist); |
| } |
| } |
| |
| /* Create a new csa_reflist node from the given stack reference. |
| It is already known that the reference is either a MEM satisfying the |
| predicate stack_memref_p or a REG representing the stack pointer. */ |
| |
| static struct csa_reflist * |
| record_one_stack_ref (rtx_insn *insn, rtx *ref, struct csa_reflist *next_reflist) |
| { |
| struct csa_reflist *ml; |
| |
| ml = XNEW (struct csa_reflist); |
| |
| if (REG_P (*ref) || XEXP (*ref, 0) == stack_pointer_rtx) |
| ml->sp_offset = 0; |
| else |
| ml->sp_offset = INTVAL (XEXP (XEXP (*ref, 0), 1)); |
| |
| ml->insn = insn; |
| ml->ref = ref; |
| ml->next = next_reflist; |
| |
| return ml; |
| } |
| |
| /* We only know how to adjust the CFA; no other frame-related changes |
| may appear in any insn to be deleted. */ |
| |
| static bool |
| no_unhandled_cfa (rtx_insn *insn) |
| { |
| if (!RTX_FRAME_RELATED_P (insn)) |
| return true; |
| |
| /* No CFA notes at all is a legacy interpretation like |
| FRAME_RELATED_EXPR, and is context sensitive within |
| the prologue state machine. We can't handle that here. */ |
| bool has_cfa_adjust = false; |
| |
| for (rtx link = REG_NOTES (insn); link; link = XEXP (link, 1)) |
| switch (REG_NOTE_KIND (link)) |
| { |
| default: |
| break; |
| case REG_CFA_ADJUST_CFA: |
| has_cfa_adjust = true; |
| break; |
| |
| case REG_FRAME_RELATED_EXPR: |
| case REG_CFA_DEF_CFA: |
| case REG_CFA_OFFSET: |
| case REG_CFA_REGISTER: |
| case REG_CFA_EXPRESSION: |
| case REG_CFA_RESTORE: |
| case REG_CFA_SET_VDRAP: |
| case REG_CFA_WINDOW_SAVE: |
| case REG_CFA_FLUSH_QUEUE: |
| case REG_CFA_TOGGLE_RA_MANGLE: |
| return false; |
| } |
| |
| return has_cfa_adjust; |
| } |
| |
| /* Attempt to apply ADJUST to the stack adjusting insn INSN, as well |
| as each of the memories and stack references in REFLIST. Return true |
| on success. */ |
| |
| static bool |
| try_apply_stack_adjustment (rtx_insn *insn, struct csa_reflist *reflist, |
| HOST_WIDE_INT new_adjust, HOST_WIDE_INT delta, |
| bitmap live, rtx_insn *other_insn) |
| { |
| struct csa_reflist *ml; |
| rtx set; |
| bool remove_equal = false; |
| |
| set = single_set_for_csa (insn); |
| if (MEM_P (SET_DEST (set))) |
| validate_change (insn, &SET_DEST (set), |
| replace_equiv_address (SET_DEST (set), stack_pointer_rtx), |
| 1); |
| else if (REG_P (SET_SRC (set))) |
| { |
| if (other_insn == NULL_RTX || live == NULL) |
| return false; |
| rtx other_set = single_set_for_csa (other_insn); |
| if (SET_DEST (other_set) != stack_pointer_rtx |
| || GET_CODE (SET_SRC (other_set)) != PLUS |
| || XEXP (SET_SRC (other_set), 0) != stack_pointer_rtx |
| || !CONST_INT_P (XEXP (SET_SRC (other_set), 1))) |
| return false; |
| if (PATTERN (other_insn) != other_set) |
| { |
| if (GET_CODE (PATTERN (other_insn)) != PARALLEL) |
| return false; |
| int i; |
| rtx p = PATTERN (other_insn); |
| for (i = 0; i < XVECLEN (p, 0); ++i) |
| { |
| rtx this_rtx = XVECEXP (p, 0, i); |
| if (this_rtx == other_set) |
| continue; |
| if (GET_CODE (this_rtx) != CLOBBER) |
| return false; |
| if (!REG_P (XEXP (this_rtx, 0)) |
| || !HARD_REGISTER_P (XEXP (this_rtx, 0))) |
| return false; |
| unsigned int end_regno = END_REGNO (XEXP (this_rtx, 0)); |
| for (unsigned int regno = REGNO (XEXP (this_rtx, 0)); |
| regno < end_regno; ++regno) |
| if (bitmap_bit_p (live, regno)) |
| return false; |
| } |
| } |
| validate_change (insn, &PATTERN (insn), copy_rtx (PATTERN (other_insn)), |
| 1); |
| set = single_set_for_csa (insn); |
| validate_change (insn, &XEXP (SET_SRC (set), 1), GEN_INT (new_adjust), |
| 1); |
| remove_equal = true; |
| } |
| else |
| validate_change (insn, &XEXP (SET_SRC (set), 1), GEN_INT (new_adjust), 1); |
| |
| for (ml = reflist; ml ; ml = ml->next) |
| { |
| rtx new_addr = plus_constant (Pmode, stack_pointer_rtx, |
| ml->sp_offset - delta); |
| rtx new_val; |
| |
| if (MEM_P (*ml->ref)) |
| new_val = replace_equiv_address_nv (*ml->ref, new_addr); |
| else if (GET_MODE (*ml->ref) == GET_MODE (stack_pointer_rtx)) |
| new_val = new_addr; |
| else |
| new_val = lowpart_subreg (GET_MODE (*ml->ref), new_addr, |
| GET_MODE (new_addr)); |
| validate_change (ml->insn, ml->ref, new_val, 1); |
| } |
| |
| if (apply_change_group ()) |
| { |
| /* Succeeded. Update our knowledge of the stack references. */ |
| for (ml = reflist; ml ; ml = ml->next) |
| ml->sp_offset -= delta; |
| |
| if (remove_equal) |
| remove_reg_equal_equiv_notes (insn); |
| return true; |
| } |
| else |
| return false; |
| } |
| |
| /* For non-debug insns, record all stack memory references in INSN |
| and return true if there were no other (unrecorded) references to the |
| stack pointer. For debug insns, record all stack references regardless |
| of context and unconditionally return true. */ |
| |
| static bool |
| record_stack_refs (rtx_insn *insn, struct csa_reflist **reflist) |
| { |
| subrtx_ptr_iterator::array_type array; |
| FOR_EACH_SUBRTX_PTR (iter, array, &PATTERN (insn), NONCONST) |
| { |
| rtx *loc = *iter; |
| rtx x = *loc; |
| switch (GET_CODE (x)) |
| { |
| case MEM: |
| if (!reg_mentioned_p (stack_pointer_rtx, x)) |
| iter.skip_subrtxes (); |
| /* We are not able to handle correctly all possible memrefs |
| containing stack pointer, so this check is necessary. */ |
| else if (stack_memref_p (x)) |
| { |
| *reflist = record_one_stack_ref (insn, loc, *reflist); |
| iter.skip_subrtxes (); |
| } |
| /* Try harder for DEBUG_INSNs, handle e.g. |
| (mem (mem (sp + 16) + 4). */ |
| else if (!DEBUG_INSN_P (insn)) |
| return false; |
| break; |
| |
| 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. |
| |
| In DEBUG_INSNs, we want to replace all occurrences, otherwise |
| they will cause -fcompare-debug failures. */ |
| if (REGNO (x) == STACK_POINTER_REGNUM) |
| { |
| if (!DEBUG_INSN_P (insn)) |
| return false; |
| *reflist = record_one_stack_ref (insn, loc, *reflist); |
| } |
| break; |
| |
| default: |
| break; |
| } |
| } |
| return true; |
| } |
| |
| /* If INSN has a REG_ARGS_SIZE note, move it to LAST. |
| AFTER is true iff LAST follows INSN in the instruction stream. */ |
| |
| static void |
| maybe_move_args_size_note (rtx_insn *last, rtx_insn *insn, bool after) |
| { |
| rtx note, last_note; |
| |
| note = find_reg_note (insn, REG_ARGS_SIZE, NULL_RTX); |
| if (note == NULL) |
| return; |
| |
| last_note = find_reg_note (last, REG_ARGS_SIZE, NULL_RTX); |
| if (last_note) |
| { |
| /* The ARGS_SIZE notes are *not* cumulative. They represent an |
| absolute value, and the "most recent" note wins. */ |
| if (!after) |
| XEXP (last_note, 0) = XEXP (note, 0); |
| } |
| else |
| add_reg_note (last, REG_ARGS_SIZE, XEXP (note, 0)); |
| } |
| |
| /* Merge any REG_CFA_ADJUST_CFA note from SRC into DST. |
| AFTER is true iff DST follows SRC in the instruction stream. */ |
| |
| static void |
| maybe_merge_cfa_adjust (rtx_insn *dst, rtx_insn *src, bool after) |
| { |
| rtx snote = NULL, dnote = NULL; |
| rtx sexp, dexp; |
| rtx exp1, exp2; |
| |
| if (RTX_FRAME_RELATED_P (src)) |
| snote = find_reg_note (src, REG_CFA_ADJUST_CFA, NULL_RTX); |
| if (snote == NULL) |
| return; |
| sexp = XEXP (snote, 0); |
| |
| if (RTX_FRAME_RELATED_P (dst)) |
| dnote = find_reg_note (dst, REG_CFA_ADJUST_CFA, NULL_RTX); |
| if (dnote == NULL) |
| { |
| add_reg_note (dst, REG_CFA_ADJUST_CFA, sexp); |
| return; |
| } |
| dexp = XEXP (dnote, 0); |
| |
| gcc_assert (GET_CODE (sexp) == SET); |
| gcc_assert (GET_CODE (dexp) == SET); |
| |
| if (after) |
| exp1 = dexp, exp2 = sexp; |
| else |
| exp1 = sexp, exp2 = dexp; |
| |
| SET_SRC (exp1) = simplify_replace_rtx (SET_SRC (exp1), SET_DEST (exp2), |
| SET_SRC (exp2)); |
| XEXP (dnote, 0) = exp1; |
| } |
| |
| /* Return the next (or previous) active insn within BB. */ |
| |
| static rtx_insn * |
| prev_active_insn_bb (basic_block bb, rtx_insn *insn) |
| { |
| for (insn = PREV_INSN (insn); |
| insn != PREV_INSN (BB_HEAD (bb)); |
| insn = PREV_INSN (insn)) |
| if (active_insn_p (insn)) |
| return insn; |
| return NULL; |
| } |
| |
| static rtx_insn * |
| next_active_insn_bb (basic_block bb, rtx_insn *insn) |
| { |
| for (insn = NEXT_INSN (insn); |
| insn != NEXT_INSN (BB_END (bb)); |
| insn = NEXT_INSN (insn)) |
| if (active_insn_p (insn)) |
| return insn; |
| return NULL; |
| } |
| |
| /* If INSN has a REG_ARGS_SIZE note, if possible move it to PREV. Otherwise |
| search for a nearby candidate within BB where we can stick the note. */ |
| |
| static void |
| force_move_args_size_note (basic_block bb, rtx_insn *prev, rtx_insn *insn) |
| { |
| rtx note; |
| rtx_insn *test, *next_candidate, *prev_candidate; |
| |
| /* If PREV exists, tail-call to the logic in the other function. */ |
| if (prev) |
| { |
| maybe_move_args_size_note (prev, insn, false); |
| return; |
| } |
| |
| /* First, make sure there's anything that needs doing. */ |
| note = find_reg_note (insn, REG_ARGS_SIZE, NULL_RTX); |
| if (note == NULL) |
| return; |
| |
| /* We need to find a spot between the previous and next exception points |
| where we can place the note and "properly" deallocate the arguments. */ |
| next_candidate = prev_candidate = NULL; |
| |
| /* It is often the case that we have insns in the order: |
| call |
| add sp (previous deallocation) |
| sub sp (align for next arglist) |
| push arg |
| and the add/sub cancel. Therefore we begin by searching forward. */ |
| |
| test = insn; |
| while ((test = next_active_insn_bb (bb, test)) != NULL) |
| { |
| /* Found an existing note: nothing to do. */ |
| if (find_reg_note (test, REG_ARGS_SIZE, NULL_RTX)) |
| return; |
| /* Found something that affects unwinding. Stop searching. */ |
| if (CALL_P (test) || !insn_nothrow_p (test)) |
| break; |
| if (next_candidate == NULL) |
| next_candidate = test; |
| } |
| |
| test = insn; |
| while ((test = prev_active_insn_bb (bb, test)) != NULL) |
| { |
| rtx tnote; |
| /* Found a place that seems logical to adjust the stack. */ |
| tnote = find_reg_note (test, REG_ARGS_SIZE, NULL_RTX); |
| if (tnote) |
| { |
| XEXP (tnote, 0) = XEXP (note, 0); |
| return; |
| } |
| if (prev_candidate == NULL) |
| prev_candidate = test; |
| /* Found something that affects unwinding. Stop searching. */ |
| if (CALL_P (test) || !insn_nothrow_p (test)) |
| break; |
| } |
| |
| if (prev_candidate) |
| test = prev_candidate; |
| else if (next_candidate) |
| test = next_candidate; |
| else |
| { |
| /* ??? We *must* have a place, lest we ICE on the lost adjustment. |
| Options are: dummy clobber insn, nop, or prevent the removal of |
| the sp += 0 insn. */ |
| /* TODO: Find another way to indicate to the dwarf2 code that we |
| have not in fact lost an adjustment. */ |
| test = emit_insn_before (gen_rtx_CLOBBER (VOIDmode, const0_rtx), insn); |
| } |
| add_reg_note (test, REG_ARGS_SIZE, XEXP (note, 0)); |
| } |
| |
| /* Subroutine of combine_stack_adjustments, called for each basic block. */ |
| |
| static void |
| combine_stack_adjustments_for_block (basic_block bb, bitmap live) |
| { |
| HOST_WIDE_INT last_sp_adjust = 0; |
| rtx_insn *last_sp_set = NULL; |
| rtx_insn *last2_sp_set = NULL; |
| bitmap last_sp_live = NULL; |
| struct csa_reflist *reflist = NULL; |
| bitmap copy = NULL; |
| rtx_insn *insn, *next; |
| rtx set; |
| bool end_of_block = false; |
| |
| bitmap_copy (live, DF_LR_IN (bb)); |
| df_simulate_initialize_forwards (bb, live); |
| |
| 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 && find_reg_note (insn, REG_STACK_CHECK, NULL_RTX)) |
| set = NULL_RTX; |
| if (set) |
| { |
| rtx dest = SET_DEST (set); |
| rtx src = SET_SRC (set); |
| HOST_WIDE_INT this_adjust = 0; |
| |
| /* Find constant additions to the stack pointer. */ |
| if (dest == stack_pointer_rtx |
| && GET_CODE (src) == PLUS |
| && XEXP (src, 0) == stack_pointer_rtx |
| && CONST_INT_P (XEXP (src, 1))) |
| this_adjust = INTVAL (XEXP (src, 1)); |
| /* Or such additions turned by postreload into a store of |
| equivalent register. */ |
| else if (dest == stack_pointer_rtx |
| && REG_P (src) |
| && REGNO (src) != STACK_POINTER_REGNUM) |
| if (rtx equal = find_reg_note (insn, REG_EQUAL, NULL_RTX)) |
| if (GET_CODE (XEXP (equal, 0)) == PLUS |
| && XEXP (XEXP (equal, 0), 0) == stack_pointer_rtx |
| && CONST_INT_P (XEXP (XEXP (equal, 0), 1))) |
| this_adjust = INTVAL (XEXP (XEXP (equal, 0), 1)); |
| |
| if (this_adjust) |
| { |
| /* 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; |
| if (REG_P (src)) |
| { |
| if (copy == NULL) |
| copy = BITMAP_ALLOC (®_obstack); |
| last_sp_live = copy; |
| bitmap_copy (last_sp_live, live); |
| } |
| else |
| last_sp_live = NULL; |
| df_simulate_one_insn_forwards (bb, insn, live); |
| continue; |
| } |
| |
| /* If not all recorded refs 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 cannot |
| 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 (no_unhandled_cfa (insn) |
| && try_apply_stack_adjustment (last_sp_set, reflist, |
| last_sp_adjust |
| + this_adjust, |
| this_adjust, |
| last_sp_live, |
| insn)) |
| { |
| /* It worked! */ |
| maybe_move_args_size_note (last_sp_set, insn, false); |
| maybe_merge_cfa_adjust (last_sp_set, insn, false); |
| delete_insn (insn); |
| last_sp_adjust += this_adjust; |
| last_sp_live = NULL; |
| 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 (no_unhandled_cfa (last_sp_set) |
| && !REG_P (src) |
| && try_apply_stack_adjustment (insn, reflist, |
| last_sp_adjust |
| + this_adjust, |
| -last_sp_adjust, |
| NULL, NULL)) |
| { |
| /* It worked! */ |
| maybe_move_args_size_note (insn, last_sp_set, true); |
| maybe_merge_cfa_adjust (insn, last_sp_set, true); |
| delete_insn (last_sp_set); |
| last_sp_set = insn; |
| last_sp_adjust += this_adjust; |
| last_sp_live = NULL; |
| free_csa_reflist (reflist); |
| reflist = NULL; |
| df_simulate_one_insn_forwards (bb, insn, live); |
| continue; |
| } |
| } |
| |
| /* Combination failed. Restart processing from here. If |
| deallocation+allocation conspired to cancel, we can |
| delete the old deallocation insn. */ |
| if (last_sp_set) |
| { |
| if (last_sp_adjust == 0 && no_unhandled_cfa (last_sp_set)) |
| { |
| maybe_move_args_size_note (insn, last_sp_set, true); |
| maybe_merge_cfa_adjust (insn, last_sp_set, true); |
| delete_insn (last_sp_set); |
| } |
| else |
| last2_sp_set = last_sp_set; |
| } |
| free_csa_reflist (reflist); |
| reflist = NULL; |
| last_sp_set = insn; |
| last_sp_adjust = this_adjust; |
| if (REG_P (src)) |
| { |
| if (copy == NULL) |
| copy = BITMAP_ALLOC (®_obstack); |
| last_sp_live = copy; |
| bitmap_copy (last_sp_live, live); |
| } |
| else |
| last_sp_live = NULL; |
| df_simulate_one_insn_forwards (bb, insn, live); |
| continue; |
| } |
| |
| /* Find a store with pre-(dec|inc)rement or pre-modify of exactly |
| the previous adjustment and turn it into a simple store. This |
| is equivalent to anticipating the stack adjustment so this must |
| be an allocation. */ |
| if (MEM_P (dest) |
| && ((STACK_GROWS_DOWNWARD |
| ? (GET_CODE (XEXP (dest, 0)) == PRE_DEC |
| && known_eq (last_sp_adjust, |
| GET_MODE_SIZE (GET_MODE (dest)))) |
| : (GET_CODE (XEXP (dest, 0)) == PRE_INC |
| && known_eq (-last_sp_adjust, |
| GET_MODE_SIZE (GET_MODE (dest))))) |
| || ((STACK_GROWS_DOWNWARD |
| ? last_sp_adjust >= 0 : last_sp_adjust <= 0) |
| && 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) |
| && try_apply_stack_adjustment (insn, reflist, 0, |
| -last_sp_adjust, |
| NULL, NULL)) |
| { |
| if (last2_sp_set) |
| maybe_move_args_size_note (last2_sp_set, last_sp_set, false); |
| else |
| maybe_move_args_size_note (insn, last_sp_set, true); |
| delete_insn (last_sp_set); |
| free_csa_reflist (reflist); |
| reflist = NULL; |
| last_sp_set = NULL; |
| last_sp_adjust = 0; |
| last_sp_live = NULL; |
| df_simulate_one_insn_forwards (bb, insn, live); |
| continue; |
| } |
| } |
| |
| if (!CALL_P (insn) && last_sp_set && record_stack_refs (insn, &reflist)) |
| { |
| df_simulate_one_insn_forwards (bb, insn, live); |
| continue; |
| } |
| |
| /* 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) |
| { |
| force_move_args_size_note (bb, last2_sp_set, last_sp_set); |
| delete_insn (last_sp_set); |
| } |
| free_csa_reflist (reflist); |
| reflist = NULL; |
| last2_sp_set = NULL; |
| last_sp_set = NULL; |
| last_sp_adjust = 0; |
| last_sp_live = NULL; |
| } |
| |
| df_simulate_one_insn_forwards (bb, insn, live); |
| } |
| |
| if (last_sp_set && last_sp_adjust == 0) |
| { |
| force_move_args_size_note (bb, last2_sp_set, last_sp_set); |
| delete_insn (last_sp_set); |
| } |
| |
| if (reflist) |
| free_csa_reflist (reflist); |
| if (copy) |
| BITMAP_FREE (copy); |
| } |
| |
| static unsigned int |
| rest_of_handle_stack_adjustments (void) |
| { |
| df_note_add_problem (); |
| df_analyze (); |
| combine_stack_adjustments (); |
| return 0; |
| } |
| |
| namespace { |
| |
| const pass_data pass_data_stack_adjustments = |
| { |
| RTL_PASS, /* type */ |
| "csa", /* name */ |
| OPTGROUP_NONE, /* optinfo_flags */ |
| TV_COMBINE_STACK_ADJUST, /* tv_id */ |
| 0, /* properties_required */ |
| 0, /* properties_provided */ |
| 0, /* properties_destroyed */ |
| 0, /* todo_flags_start */ |
| TODO_df_finish, /* todo_flags_finish */ |
| }; |
| |
| class pass_stack_adjustments : public rtl_opt_pass |
| { |
| public: |
| pass_stack_adjustments (gcc::context *ctxt) |
| : rtl_opt_pass (pass_data_stack_adjustments, ctxt) |
| {} |
| |
| /* opt_pass methods: */ |
| virtual bool gate (function *); |
| virtual unsigned int execute (function *) |
| { |
| return rest_of_handle_stack_adjustments (); |
| } |
| |
| }; // class pass_stack_adjustments |
| |
| bool |
| pass_stack_adjustments::gate (function *) |
| { |
| /* This is kind of a heuristic. We need to run combine_stack_adjustments |
| even for machines with possibly nonzero TARGET_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) |
| return false; |
| #endif |
| return flag_combine_stack_adjustments; |
| } |
| |
| } // anon namespace |
| |
| rtl_opt_pass * |
| make_pass_stack_adjustments (gcc::context *ctxt) |
| { |
| return new pass_stack_adjustments (ctxt); |
| } |