On Sat, Feb 11, 2012 at 1:26 AM, Richard Henderson <r...@redhat.com> wrote:
> On 02/09/2012 03:47 PM, Uros Bizjak wrote:
>> 2012-02-10 Uros Bizjak <ubiz...@gmail.com>
>>
>> * compare-elim.c (find_comparisons_in_bb): Eliminate only compares
>> having mode compatible with the mode of previous compare. Substitute
>> compare mode of previous compare with the mode, compatible
>> with eliminated and previous compare.
>
> This patch is ok for 4.8.
>
> For 4.6 and 4.7 I would prefer that we simply not eliminate the compare. I.e.
> For 4.6 and 4.7, there are only two extant users of this pass and neither
> of them use anything besides CCmode before compare-elim.c does its own
> manipulation of the modes later.
Attached patch is what I have committed to 4.6 and 4.7.
2012-02-11 Uros Bizjak <ubiz...@gmail.com>
* compare-elim.c (find_comparisons_in_bb): Eliminate only compares
having the same mode as previous compare.
Bootstrapped and regression tested on x86_64-pc-linux-gnu {,-m32},
together with a target-patch that enables this functionality.
Uros.
Index: compare-elim.c
===================================================================
--- compare-elim.c (revision 184123)
+++ compare-elim.c (working copy)
@@ -297,8 +297,11 @@ find_comparisons_in_bb (struct dom_walk_data *data
src = conforming_compare (insn);
if (src)
{
+ enum machine_mode src_mode = GET_MODE (src);
+
/* Eliminate a compare that's redundant with the previous. */
if (last_cmp_valid
+ && src_mode == last_cmp->orig_mode
&& rtx_equal_p (last_cmp->in_a, XEXP (src, 0))
&& rtx_equal_p (last_cmp->in_b, XEXP (src, 1)))
{
@@ -311,7 +314,7 @@ find_comparisons_in_bb (struct dom_walk_data *data
last_cmp->prev_clobber = last_clobber;
last_cmp->in_a = XEXP (src, 0);
last_cmp->in_b = XEXP (src, 1);
- last_cmp->orig_mode = GET_MODE (SET_DEST (single_set (insn)));
+ last_cmp->orig_mode = src_mode;
VEC_safe_push (comparison_struct_p, heap, all_compares, last_cmp);
/* It's unusual, but be prepared for comparison patterns that
