Re: [PATCH] forwprop: Remove incorrect assertion [PR102897]

["Kewen.Lin" <linkw@linux.ibm.com>]

Hi Richi,

on 2021/10/26 下午3:50, Richard Biener wrote:
> On Tue, Oct 26, 2021 at 5:40 AM Kewen.Lin <linkw@linux.ibm.com> wrote:
>>
>> Hi,
>>
>> As PR102897 shows, there is one incorrect assertion in function
>> simplify_permutation, which is based on the wrong assumption that
>> all cases with op2_type == tgt_type are handled previously, the
>> proposed fix is to remove this wrong assertion.
>>
>> Bootstrapped and regtested on x86_64-redhat-linux,
>> aarch64-linux-gnu and powerpc64{,le}-linux-gnu.
> 
> I think you need to enable optimization in the new testcase, gcc.dg/ only
> runs -O0 by default which wouldn't trigger forwprop?  Please verify the
> testcase ICEs before the fix.
> 

Thanks for catching!  You are right, the optimization option is required,
I just verified it and committed with the additional "-O1" as r12-4705.

> Otherwise OK.
> 

Thanks!

BR,
Kewen

> Thanks,
> Richard,
> 
>> BR,
>> Kewen
>> -----
>> gcc/ChangeLog:
>>
>>         PR tree-optimization/102897
>>         * tree-ssa-forwprop.c (simplify_permutation): Remove a wrong assertion.
>>
>> gcc/testsuite/ChangeLog:
>>
>>         * gcc.dg/pr102897.c: New test.
>> ---
>>  gcc/testsuite/gcc.dg/pr102897.c | 16 ++++++++++++++++
>>  gcc/tree-ssa-forwprop.c         |  2 --
>>  2 files changed, 16 insertions(+), 2 deletions(-)
>>  create mode 100644 gcc/testsuite/gcc.dg/pr102897.c
>>
>> diff --git a/gcc/testsuite/gcc.dg/pr102897.c b/gcc/testsuite/gcc.dg/pr102897.c
>> new file mode 100644
>> index 00000000000..d96b0e48ccc
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/pr102897.c
>> @@ -0,0 +1,16 @@
>> +/* { dg-do compile } */
>> +/* Specify C99 to avoid the warning/error on compound literals.  */
>> +/* { dg-options "-std=c99" } */
>> +
>> +/* Verify that there is no ICE.  */
>> +
>> +typedef __attribute__((vector_size(8))) signed char int8x8_t;
>> +typedef __attribute__((vector_size(8))) unsigned char uint8x8_t;
>> +
>> +int8x8_t fn1 (int8x8_t val20, char tmp)
>> +{
>> +  uint8x8_t __trans_tmp_3;
>> +  __trans_tmp_3 = (uint8x8_t){tmp};
>> +  int8x8_t __a = (int8x8_t) __trans_tmp_3;
>> +  return __builtin_shuffle (__a, val20, (uint8x8_t){0});
>> +}
>> diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c
>> index 5b30d4c1a76..a830bab78ba 100644
>> --- a/gcc/tree-ssa-forwprop.c
>> +++ b/gcc/tree-ssa-forwprop.c
>> @@ -2267,8 +2267,6 @@ simplify_permutation (gimple_stmt_iterator *gsi)
>>           if (!VECTOR_TYPE_P (tgt_type))
>>             return 0;
>>           tree op2_type = TREE_TYPE (op2);
>> -         /* Should have folded this before.  */
>> -         gcc_assert (op2_type != tgt_type);
>>
>>           /* Figure out the shrunk factor.  */
>>           poly_uint64 tgt_units = TYPE_VECTOR_SUBPARTS (tgt_type);
>> --
>> 2.27.0