/* Combine stack adjustments.
- Copyright (C) 1987-2014 Free Software Foundation, Inc.
+ Copyright (C) 1987-2019 Free Software Foundation, Inc.
This file is part of GCC.
#include "config.h"
#include "system.h"
#include "coretypes.h"
-#include "tm.h"
+#include "backend.h"
#include "rtl.h"
-#include "tm_p.h"
+#include "df.h"
#include "insn-config.h"
+#include "memmodel.h"
+#include "emit-rtl.h"
#include "recog.h"
-#include "regs.h"
-#include "hard-reg-set.h"
-#include "flags.h"
-#include "function.h"
-#include "expr.h"
-#include "basic-block.h"
-#include "df.h"
-#include "except.h"
-#include "reload.h"
+#include "cfgrtl.h"
#include "tree-pass.h"
+#include "rtl-iter.h"
\f
-/* 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 two kinds of stack references between stack
adjusting instructions: stack references in memory addresses for
regular insns and all stack references for debug insns. */
static int try_apply_stack_adjustment (rtx_insn *, struct csa_reflist *,
HOST_WIDE_INT, HOST_WIDE_INT);
static void combine_stack_adjustments_for_block (basic_block);
-static int record_stack_refs (rtx *, void *);
/* Main entry point for stack adjustment combination. */
&& SET_SRC (this_rtx) == SET_DEST (this_rtx))
;
else if (GET_CODE (this_rtx) != CLOBBER
+ && GET_CODE (this_rtx) != CLOBBER_HIGH
&& GET_CODE (this_rtx) != USE)
return NULL_RTX;
}
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. */
return 0;
}
-/* Called via for_each_rtx and used to record all stack memory and other
- references in the insn and discard all other stack pointer references. */
-struct record_stack_refs_data
-{
- rtx_insn *insn;
- struct csa_reflist *reflist;
-};
+/* 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 int
-record_stack_refs (rtx *xp, void *data)
+static bool
+record_stack_refs (rtx_insn *insn, struct csa_reflist **reflist)
{
- rtx x = *xp;
- struct record_stack_refs_data *d =
- (struct record_stack_refs_data *) data;
- if (!x)
- return 0;
- switch (GET_CODE (x))
+ subrtx_ptr_iterator::array_type array;
+ FOR_EACH_SUBRTX_PTR (iter, array, &PATTERN (insn), NONCONST)
{
- 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->reflist = record_one_stack_ref (d->insn, xp, d->reflist);
- return -1;
- }
- /* Try harder for DEBUG_INSNs, handle e.g. (mem (mem (sp + 16) + 4). */
- return !DEBUG_INSN_P (d->insn);
- 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)
+ rtx *loc = *iter;
+ rtx x = *loc;
+ switch (GET_CODE (x))
{
- if (!DEBUG_INSN_P (d->insn))
- return 1;
- d->reflist = record_one_stack_ref (d->insn, xp, d->reflist);
- return -1;
+ 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;
}
- break;
- default:
- break;
}
- return 0;
+ return true;
}
/* If INSN has a REG_ARGS_SIZE note, move it to LAST.
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 *
struct csa_reflist *reflist = NULL;
rtx_insn *insn, *next;
rtx set;
- struct record_stack_refs_data data;
bool end_of_block = false;
for (insn = BB_HEAD (bb); !end_of_block ; insn = next)
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);
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
+ 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
/* 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, reflist,
- last_sp_adjust + this_adjust,
- this_adjust))
+ if (no_unhandled_cfa (insn)
+ && try_apply_stack_adjustment (last_sp_set, reflist,
+ last_sp_adjust
+ + this_adjust,
+ this_adjust))
{
/* 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;
continue;
else if (STACK_GROWS_DOWNWARD
? last_sp_adjust >= 0 : last_sp_adjust <= 0)
{
- if (try_apply_stack_adjustment (insn, reflist,
- last_sp_adjust + this_adjust,
- -last_sp_adjust))
+ if (no_unhandled_cfa (last_sp_set)
+ && try_apply_stack_adjustment (insn, reflist,
+ last_sp_adjust
+ + this_adjust,
+ -last_sp_adjust))
{
/* 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;
delete the old deallocation insn. */
if (last_sp_set)
{
- if (last_sp_adjust == 0)
+ 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
if (MEM_P (dest)
&& ((STACK_GROWS_DOWNWARD
? (GET_CODE (XEXP (dest, 0)) == PRE_DEC
- && last_sp_adjust
- == (HOST_WIDE_INT) GET_MODE_SIZE (GET_MODE (dest)))
+ && known_eq (last_sp_adjust,
+ GET_MODE_SIZE (GET_MODE (dest))))
: (GET_CODE (XEXP (dest, 0)) == PRE_INC
- && last_sp_adjust
- == -(HOST_WIDE_INT) GET_MODE_SIZE (GET_MODE (dest))))
+ && 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
}
}
- data.insn = insn;
- data.reflist = reflist;
if (!CALL_P (insn) && last_sp_set
- && !for_each_rtx (&PATTERN (insn), record_stack_refs, &data))
- {
- reflist = data.reflist;
- continue;
- }
- reflist = data.reflist;
+ && record_stack_refs (insn, &reflist))
+ continue;
/* Otherwise, we were not able to process the instruction.
Do not continue collecting data across such a one. */
projects / gcc.git / blobdiff