/* Common subexpression elimination for GNU compiler.
- Copyright (C) 1987-2019 Free Software Foundation, Inc.
+ Copyright (C) 1987-2021 Free Software Foundation, Inc.
This file is part of GCC.
static void cse_prescan_path (struct cse_basic_block_data *);
static void invalidate_from_clobbers (rtx_insn *);
static void invalidate_from_sets_and_clobbers (rtx_insn *);
-static rtx cse_process_notes (rtx, rtx, bool *);
static void cse_extended_basic_block (struct cse_basic_block_data *);
extern void dump_class (struct table_elt*);
static void get_cse_reg_info_1 (unsigned int regno);
for (i = 0; i < n_sets; i++)
{
bool repeat = false;
- bool mem_noop_insn = false;
+ bool noop_insn = false;
rtx src, dest;
rtx src_folded;
struct table_elt *elt = 0, *p;
/* Compute SRC's hash code, and also notice if it
should not be recorded at all. In that case,
- prevent any further processing of this assignment. */
- do_not_record = 0;
+ prevent any further processing of this assignment.
+
+ We set DO_NOT_RECORD if the destination has a REG_UNUSED note.
+ This avoids getting the source register into the tables, where it
+ may be invalidated later (via REG_QTY), then trigger an ICE upon
+ re-insertion.
+
+ This is only a problem in multi-set insns. If it were a single
+ set the dead copy would have been removed. If the RHS were anything
+ but a simple REG, then we won't call insert_regs and thus there's
+ no potential for triggering the ICE. */
+ do_not_record = (REG_P (dest)
+ && REG_P (src)
+ && find_reg_note (insn, REG_UNUSED, dest));
hash_arg_in_memory = 0;
sets[i].src = src;
to prefer it. Copy it to src_related. The code below will
then give it a negative cost. */
if (GET_CODE (dest) == code && rtx_equal_p (p->exp, dest))
- src_related = dest;
+ src_related = p->exp;
}
/* Find the cheapest valid equivalent, trying all the available
}
/* Similarly, lots of targets don't allow no-op
- (set (mem x) (mem x)) moves. */
+ (set (mem x) (mem x)) moves. Even (set (reg x) (reg x))
+ might be impossible for certain registers (like CC registers). */
else if (n_sets == 1
- && MEM_P (trial)
- && MEM_P (dest)
+ && !CALL_P (insn)
+ && (MEM_P (trial) || REG_P (trial))
&& rtx_equal_p (trial, dest)
&& !side_effects_p (dest)
&& (cfun->can_delete_dead_exceptions
- || insn_nothrow_p (insn)))
+ || insn_nothrow_p (insn))
+ /* We can only remove the later store if the earlier aliases
+ at least all accesses the later one. */
+ && (!MEM_P (trial)
+ || ((MEM_ALIAS_SET (dest) == MEM_ALIAS_SET (trial)
+ || alias_set_subset_of (MEM_ALIAS_SET (dest),
+ MEM_ALIAS_SET (trial)))
+ && (!MEM_EXPR (trial)
+ || refs_same_for_tbaa_p (MEM_EXPR (trial),
+ MEM_EXPR (dest))))))
{
SET_SRC (sets[i].rtl) = trial;
- mem_noop_insn = true;
+ noop_insn = true;
break;
}
sets[i].rtl = 0;
}
- /* Similarly for no-op MEM moves. */
- else if (mem_noop_insn)
+ /* Similarly for no-op moves. */
+ else if (noop_insn)
{
if (cfun->can_throw_non_call_exceptions && can_throw_internal (insn))
cse_cfg_altered = true;
}
}
\f
-/* Process X, part of the REG_NOTES of an insn. Look at any REG_EQUAL notes
- and replace any registers in them with either an equivalent constant
- or the canonical form of the register. If we are inside an address,
- only do this if the address remains valid.
+static rtx cse_process_note (rtx);
- OBJECT is 0 except when within a MEM in which case it is the MEM.
+/* A simplify_replace_fn_rtx callback for cse_process_note. Process X,
+ part of the REG_NOTES of an insn. Replace any registers with either
+ an equivalent constant or the canonical form of the register.
+ Only replace addresses if the containing MEM remains valid.
- Return the replacement for X. */
+ Return the replacement for X, or null if it should be simplified
+ recursively. */
static rtx
-cse_process_notes_1 (rtx x, rtx object, bool *changed)
+cse_process_note_1 (rtx x, const_rtx, void *)
{
- enum rtx_code code = GET_CODE (x);
- const char *fmt = GET_RTX_FORMAT (code);
- int i;
-
- switch (code)
+ if (MEM_P (x))
{
- case CONST:
- case SYMBOL_REF:
- case LABEL_REF:
- CASE_CONST_ANY:
- case PC:
- case CC0:
- case LO_SUM:
- return x;
-
- case MEM:
- validate_change (x, &XEXP (x, 0),
- cse_process_notes (XEXP (x, 0), x, changed), 0);
- return x;
-
- case EXPR_LIST:
- if (REG_NOTE_KIND (x) == REG_EQUAL)
- XEXP (x, 0) = cse_process_notes (XEXP (x, 0), NULL_RTX, changed);
- /* Fall through. */
-
- case INSN_LIST:
- case INT_LIST:
- if (XEXP (x, 1))
- XEXP (x, 1) = cse_process_notes (XEXP (x, 1), NULL_RTX, changed);
+ validate_change (x, &XEXP (x, 0), cse_process_note (XEXP (x, 0)), false);
return x;
+ }
- case SIGN_EXTEND:
- case ZERO_EXTEND:
- case SUBREG:
- {
- rtx new_rtx = cse_process_notes (XEXP (x, 0), object, changed);
- /* We don't substitute VOIDmode constants into these rtx,
- since they would impede folding. */
- if (GET_MODE (new_rtx) != VOIDmode)
- validate_change (object, &XEXP (x, 0), new_rtx, 0);
- return x;
- }
-
- case UNSIGNED_FLOAT:
- {
- rtx new_rtx = cse_process_notes (XEXP (x, 0), object, changed);
- /* We don't substitute negative VOIDmode constants into these rtx,
- since they would impede folding. */
- if (GET_MODE (new_rtx) != VOIDmode
- || (CONST_INT_P (new_rtx) && INTVAL (new_rtx) >= 0)
- || (CONST_DOUBLE_P (new_rtx) && CONST_DOUBLE_HIGH (new_rtx) >= 0))
- validate_change (object, &XEXP (x, 0), new_rtx, 0);
- return x;
- }
-
- case REG:
- i = REG_QTY (REGNO (x));
+ if (REG_P (x))
+ {
+ int i = REG_QTY (REGNO (x));
/* Return a constant or a constant register. */
if (REGNO_QTY_VALID_P (REGNO (x)))
/* Otherwise, canonicalize this register. */
return canon_reg (x, NULL);
-
- default:
- break;
}
- for (i = 0; i < GET_RTX_LENGTH (code); i++)
- if (fmt[i] == 'e')
- validate_change (object, &XEXP (x, i),
- cse_process_notes (XEXP (x, i), object, changed), 0);
-
- return x;
+ return NULL_RTX;
}
+/* Process X, part of the REG_NOTES of an insn. Replace any registers in it
+ with either an equivalent constant or the canonical form of the register.
+ Only replace addresses if the containing MEM remains valid. */
+
static rtx
-cse_process_notes (rtx x, rtx object, bool *changed)
+cse_process_note (rtx x)
{
- rtx new_rtx = cse_process_notes_1 (x, object, changed);
- if (new_rtx != x)
- *changed = true;
- return new_rtx;
+ return simplify_replace_fn_rtx (x, NULL_RTX, cse_process_note_1, NULL);
}
\f
{
/* Process notes first so we have all notes in canonical forms
when looking for duplicate operations. */
- if (REG_NOTES (insn))
- {
- bool changed = false;
- REG_NOTES (insn) = cse_process_notes (REG_NOTES (insn),
- NULL_RTX, &changed);
- if (changed)
- df_notes_rescan (insn);
- }
+ bool changed = false;
+ for (rtx note = REG_NOTES (insn); note; note = XEXP (note, 1))
+ if (REG_NOTE_KIND (note) == REG_EQUAL)
+ {
+ rtx newval = cse_process_note (XEXP (note, 0));
+ if (newval != XEXP (note, 0))
+ {
+ XEXP (note, 0) = newval;
+ changed = true;
+ }
+ }
+ if (changed)
+ df_notes_rescan (insn);
cse_insn (insn);
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