diff options
| author | Richard Henderson <rth@redhat.com> | 2005-05-10 16:24:41 +0000 |
|---|---|---|
| committer | Richard Henderson <rth@redhat.com> | 2005-05-10 16:24:41 +0000 |
| commit | d672a9b2ff2565dad1325d683bc564b7ba65063e (patch) | |
| tree | 6476d8f67b2ec37727a66a5c5fe4e31209e944c7 /gcc/optabs.c | |
| parent | 79fc9f4b346f957ca051b07231038fee154cc626 (diff) | |
* optabs.c (expand_compare_and_swap_loop): Don't clobber old value
before comparing it for success.
git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@99525 138bc75d-0d04-0410-961f-82ee72b054a4
Diffstat (limited to 'gcc/optabs.c')
| -rw-r--r-- | gcc/optabs.c | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/gcc/optabs.c b/gcc/optabs.c index 3b3250aac3b..2955f7b3ad9 100644 --- a/gcc/optabs.c +++ b/gcc/optabs.c @@ -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? */ |