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optabs.c (expand_compare_and_swap_loop): Don't clobber old value before comparing it for success.

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* optabs.c (expand_compare_and_swap_loop): Don't clobber old value
        before comparing it for success.

From-SVN: r99525
This commit is contained in:
Richard Henderson 2005-05-10 09:24:41 -07:00 committed by Richard Henderson
parent 8173eefc35
commit 81ba4f39ee
2 changed files with 22 additions and 9 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2005-05-10 Richard Henderson <rth@redhat.com>
* optabs.c (expand_compare_and_swap_loop): Don't clobber old value
before comparing it for success.
2005-05-10 Richard Henderson <rth@redhat.com>
* config/ia64/sync.md (sync_add<I48MODE>): Fix arguments for

26
gcc/optabs.c
View File

@ -5625,24 +5625,27 @@ expand_compare_and_swap_loop (rtx mem, rtx old_reg, rtx new_reg, rtx seq)
{
enum machine_mode mode = GET_MODE (mem);
enum insn_code icode;
rtx label, subtarget;
rtx label, cmp_reg, subtarget;
/* The loop we want to generate looks like
old_reg = mem;
cmp_reg = mem;
label:
old_reg = cmp_reg;
seq;
old_reg = compare-and-swap(mem, old_reg, new_reg)
if (old_reg != new_reg)
cmp_reg = compare-and-swap(mem, old_reg, new_reg)
if (cmp_reg != old_reg)
goto label;
Note that we only do the plain load from memory once. Subsequent
iterations use the value loaded by the compare-and-swap pattern. */
label = gen_label_rtx ();
cmp_reg = gen_reg_rtx (mode);
emit_move_insn (old_reg, mem);
emit_move_insn (cmp_reg, mem);
emit_label (label);
emit_move_insn (old_reg, cmp_reg);
if (seq)
emit_insn (seq);
@ -5654,9 +5657,12 @@ expand_compare_and_swap_loop (rtx mem, rtx old_reg, rtx new_reg, rtx seq)
{
default:
subtarget = expand_val_compare_and_swap_1 (mem, old_reg, new_reg,
old_reg, icode);
cmp_reg, icode);
if (subtarget != NULL_RTX)
break;
{
gcc_assert (subtarget == cmp_reg);
break;
}
/* FALLTHRU */
case CODE_FOR_nothing:
@ -5665,11 +5671,13 @@ expand_compare_and_swap_loop (rtx mem, rtx old_reg, rtx new_reg, rtx seq)
return false;
subtarget = expand_val_compare_and_swap_1 (mem, old_reg, new_reg,
old_reg, icode);
cmp_reg, icode);
if (subtarget == NULL_RTX)
return false;
if (subtarget != cmp_reg)
emit_move_insn (cmp_reg, subtarget);
emit_cmp_insn (subtarget, old_reg, EQ, const0_rtx, mode, true);
emit_cmp_insn (cmp_reg, old_reg, EQ, const0_rtx, mode, true);
}
/* ??? Mark this jump predicted not taken? */