This function is used to validate REG_EQUIV notes generated by ira,
and to validate potential insn combines performed by ira. The two
conditions are not exactly the same, with reload being more
restrictive. Separate them so more combines/moves can occur.
For example, this sequence from cfgexpand.c:expand_gimple_cond
callq _Z18update_bb_for_insnP15basic_block_def
mov 0x10(%rbx),%rdi
mov 0x0(%rip),%rbp # x_rtl+0x34
callq _Z9safe_as_aIP8rtx_insn7rtx_defET_PT0_
mov %r13,%rdx
mov %rbp,%rsi
mov %rax,%rdi
callq _Z18create_basic_blockP7rtx_defS0_P15basic_block_def
becomes
callq _Z18update_bb_for_insnP15basic_block_def
mov 0x10(%rbx),%rdi
callq _Z9safe_as_aIP8rtx_insn7rtx_defET_PT0_
mov 0x0(%rip),%rsi # x_rtl+0x34
mov %r13,%rdx
mov %rax,%rdi
callq _Z18create_basic_blockP7rtx_defS0_P15basic_block_def
* ira.c (enum valid_equiv): New.
(validate_equiv_mem): Return enum.
(update_equiv_mem): Create replacement in more cases.
(add_store_equivs): Update validate_equiv_mem call.
diff --git a/gcc/ira.c b/gcc/ira.c
index aa721fa..ff0b941 100644
--- a/gcc/ira.c
+++ b/gcc/ira.c
@@ -2951,23 +2951,28 @@ validate_equiv_mem_from_store (rtx dest, const_rtx set
ATTRIBUTE_UNUSED,
info->equiv_mem_modified = true;
}
+enum valid_equiv { valid_none, valid_combine, valid_reload };
+
/* Verify that no store between START and the death of REG invalidates
MEMREF. MEMREF is invalidated by modifying a register used in MEMREF,
by storing into an overlapping memory location, or with a non-const
CALL_INSN.
- Return 1 if MEMREF remains valid. */
-static int
+ Return VALID_RELOAD if MEMREF remains valid for reload,
+ VALID_COMBINE if valid for combine_and_move_insns, and
+ VALID_NONE otherwise. */
+static enum valid_equiv
validate_equiv_mem (rtx_insn *start, rtx reg, rtx memref)
{
rtx_insn *insn;
rtx note;
struct equiv_mem_data info = { memref, false };
+ enum valid_equiv ret = valid_reload;
/* If the memory reference has side effects or is volatile, it isn't a
valid equivalence. */
if (side_effects_p (memref))
- return 0;
+ return valid_none;
for (insn = start; insn; insn = NEXT_INSN (insn))
{
@@ -2975,19 +2980,27 @@ validate_equiv_mem (rtx_insn *start, rtx reg, rtx
memref)
continue;
if (find_reg_note (insn, REG_DEAD, reg))
- return 1;
+ return ret;
- /* This used to ignore readonly memory and const/pure calls. The problem
- is the equivalent form may reference a pseudo which gets assigned a
- call clobbered hard reg. When we later replace REG with its
- equivalent form, the value in the call-clobbered reg has been
- changed and all hell breaks loose. */
if (CALL_P (insn))
- return 0;
+ {
+ /* We can combine a reg def from one insn into a reg use in
+ another over a call if the memory is readonly or the call
+ const/pure. However, we can't set reg_equiv notes up for
+ reload over any call. The problem is the equivalent form
+ may reference a pseudo which gets assigned a call
+ clobbered hard reg. When we later replace REG with its
+ equivalent form, the value in the call-clobbered reg has
+ been changed and all hell breaks loose. */
+ ret = valid_combine;
+ if (! MEM_READONLY_P (memref)
+ && ! RTL_CONST_OR_PURE_CALL_P (insn))
+ return valid_none;
+ }
note_stores (PATTERN (insn), validate_equiv_mem_from_store, &info);
if (info.equiv_mem_modified)
- return 0;
+ return valid_none;
/* If a register mentioned in MEMREF is modified via an
auto-increment, we lose the equivalence. Do the same if one
@@ -2999,10 +3012,10 @@ validate_equiv_mem (rtx_insn *start, rtx reg, rtx
memref)
|| REG_NOTE_KIND (note) == REG_DEAD)
&& REG_P (XEXP (note, 0))
&& reg_overlap_mentioned_p (XEXP (note, 0), memref))
- return 0;
+ return valid_none;
}
- return 0;
+ return valid_none;
}
/* Returns zero if X is known to be invariant. */
@@ -3510,24 +3523,32 @@ update_equiv_regs (void)
note. */
note = find_reg_note (insn, REG_EQUIV, NULL_RTX);
- if (note == NULL_RTX && REG_BASIC_BLOCK (regno) >= NUM_FIXED_BLOCKS
- && MEM_P (SET_SRC (set))
- && validate_equiv_mem (insn, dest, SET_SRC (set)))
- note = set_unique_reg_note (insn, REG_EQUIV, copy_rtx (SET_SRC
(set)));
-
+ rtx replacement = NULL_RTX;
if (note)
+ replacement = XEXP (note, 0);
+ else if (REG_BASIC_BLOCK (regno) >= NUM_FIXED_BLOCKS
+ && MEM_P (SET_SRC (set)))
{
- int regno = REGNO (dest);
- rtx x = XEXP (note, 0);
+ enum valid_equiv validity;
+ validity = validate_equiv_mem (insn, dest, SET_SRC (set));
+ if (validity != valid_none)
+ {
+ replacement = copy_rtx (SET_SRC (set));
+ if (validity == valid_reload)
+ note = set_unique_reg_note (insn, REG_EQUIV, replacement);
+ }
+ }
- /* If we haven't done so, record for reload that this is an
- equivalencing insn. */
- if (!reg_equiv[regno].is_arg_equivalence)
- ira_reg_equiv[regno].init_insns
- = gen_rtx_INSN_LIST (VOIDmode, insn,
- ira_reg_equiv[regno].init_insns);
+ /* If we haven't done so, record for reload that this is an
+ equivalencing insn. */
+ if (note && !reg_equiv[regno].is_arg_equivalence)
+ ira_reg_equiv[regno].init_insns
+ = gen_rtx_INSN_LIST (VOIDmode, insn,
+ ira_reg_equiv[regno].init_insns);
- reg_equiv[regno].replacement = x;
+ if (replacement)
+ {
+ reg_equiv[regno].replacement = replacement;
reg_equiv[regno].src_p = &SET_SRC (set);
reg_equiv[regno].loop_depth = (short) loop_depth;
@@ -3536,7 +3557,8 @@ update_equiv_regs (void)
{
/* Note that the statement below does not affect the priority
in local-alloc! */
- REG_LIVE_LENGTH (regno) *= 2;
+ if (note)
+ REG_LIVE_LENGTH (regno) *= 2;
/* If the register is referenced exactly twice, meaning it is
set once and used once, indicate that the reference may be
@@ -3548,7 +3570,7 @@ update_equiv_regs (void)
calls. */
if (REG_N_REFS (regno) == 2
- && (rtx_equal_p (x, src)
+ && (rtx_equal_p (replacement, src)
|| ! equiv_init_varies_p (src))
&& NONJUMP_INSN_P (insn)
&& equiv_init_movable_p (PATTERN (insn), regno))
@@ -3598,7 +3620,7 @@ add_store_equivs (void)
For all other cases the luids should be valid. */
&& DF_INSN_LUID (init_insn) < DF_INSN_LUID (insn)
&& ! find_reg_note (init_insn, REG_EQUIV, NULL_RTX)
- && validate_equiv_mem (init_insn, src, dest)
+ && validate_equiv_mem (init_insn, src, dest) == valid_reload
&& ! memref_used_between_p (dest, init_insn, insn)
/* Attaching a REG_EQUIV note will fail if INIT_INSN has
multiple sets. */
--
Alan Modra
Australia Development Lab, IBM
