Hi,
On 9/4/2022 上午 3:36, Segher Boessenkool wrote:
> Hi!
>
> On Mon, Feb 28, 2022 at 11:17:27AM +0800, HAO CHEN GUI wrote:
>> This patch corrects the match pattern in pr56605.c. The former pattern
>> is wrong and test case fails with GCC11. It should match following insn on
>> each subtarget after mode promotion is disabled. The patch need to be
>> backported to GCC11.
>>
>> //gimple
>> _17 = (unsigned int) _20;
>> prolog_loop_niters.4_23 = _17 & 3;
>>
>> //rtl
>> (insn 19 18 20 2 (parallel [
>> (set (reg:CC 208)
>> (compare:CC (and:SI (subreg:SI (reg:DI 207) 0)
>> (const_int 3 [0x3]))
>> (const_int 0 [0])))
>> (set (reg:SI 129 [ prolog_loop_niters.5 ])
>> (and:SI (subreg:SI (reg:DI 207) 0)
>> (const_int 3 [0x3])))
>> ]) 197 {*andsi3_imm_mask_dot2}
>>
>>
>> Bootstrapped and tested on powerpc64-linux BE/LE and AIX with no
>> regressions.
>> Is this okay for trunk and GCC11? Any recommendations? Thanks a lot.
>>
>> ChangeLog
>> 2022-02-28 Haochen Gui <guih...@linux.ibm.com>
>>
>> gcc/testsuite/
>> PR target/102146
>> * gcc.target/powerpc/pr56605.c: Correct match pattern in combine pass.
>>
>>
>> patch.diff
>> diff --git a/gcc/testsuite/gcc.target/powerpc/pr56605.c
>> b/gcc/testsuite/gcc.target/powerpc/pr56605.c
>> index fdedbfc573d..231d808aa99 100644
>> --- a/gcc/testsuite/gcc.target/powerpc/pr56605.c
>> +++ b/gcc/testsuite/gcc.target/powerpc/pr56605.c
>> @@ -11,5 +11,5 @@ void foo (short* __restrict sb, int* __restrict ia)
>> ia[i] = (int) sb[i];
>> }
>>
>> -/* { dg-final { scan-rtl-dump-times {\(compare:CC
>> \((?:and|zero_extend):(?:DI) \((?:sub)?reg:[SD]I} 1 "combine" } } */
>> +/* { dg-final { scan-rtl-dump-times {\(compare:CC \(and:SI \(subreg:SI
>> \(reg:DI} 1 "combine" } } */
>
> The old pattern uses non-capturing braces here, which are required for
> ...-times to work correctly. The zero_extend alternative is required as
> well, as is making the subreg optional (we have an actual reg in one of
> the cases currently). What do you consider wrong about the old pattern,
> what in the generated code is different from what you expect?
>
> It works correctly on p7 etc. btw; where do you see it fail? p10?
>
>
I saw it failed with GCC11.
FAIL: gcc.target/powerpc/pr56605.c scan-rtl-dump-times combine "\\(compare:CC
\\((?:and|zero_extend):(?:DI) \\((?:sub)?reg:[SD]I" 1
On ppc64le with GCC11, it should match following insn.
(compare:CC (and:SI (subreg:SI (reg:DI 208) 0)
With GCC12, it should match following insn.
(compare:CC (and:SI (subreg:SI (reg:DI 207) 0)
With GCC12 the pattern actually matches:
(compare:CC (and:DI (subreg:DI (reg:SI 136 [ niters.6 ]) 0)
So GCC12 doesn't fail the case. But it actually match wrong insn.
There is no such insn in GCC11 combine dump. So GCC11 hits the problem.
Thanks.
> Segher
