[Bug testsuite/92127] [10 regression] gcc.dg/vect/costmodel/ppc/costmodel-fast-math-vect-pr29925.c fails after r276645 on power7

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92127

Kewen Lin <linkw at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |linkw at gcc dot gnu.org

--- Comment #3 from Kewen Lin <linkw at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #2)
> I suggest to make the test less dependent on unrolling by placing
> 
> #pragma GCC unroll 0
> 
> before the inner loop which is likely unrolled now.  I wonder whether
> the test tests profitability of outer loop vectorization (likely
> not profitable)?  I see rs6000 adjusts unroll parameters as well.

Confirmed that the inner loop is completely unrolled after the suspected
commit. I checked the dump details, the test is to test the inner loop
profitable or not, the outer loop vectorization fail far ahead of profit
determination.

/home/linkw/gcc/gcc-git-base/gcc/testsuite/gcc.dg/vect/costmodel/ppc/costmodel-fast-math-vect-pr29925.c:18:20:
missed:   versioning for alias required: can't determine dependence between *_7
and *_11
consider run-time aliasing test between *_7 and *_11
/home/linkw/gcc/gcc-git-base/gcc/testsuite/gcc.dg/vect/costmodel/ppc/costmodel-fast-math-vect-pr29925.c:18:20:
missed:   runtime alias check not supported for outer loop.
/home/linkw/gcc/gcc-git-base/gcc/testsuite/gcc.dg/vect/costmodel/ppc/costmodel-fast-math-vect-pr29925.c:13:4:
missed:  bad data dependence.
/home/linkw/gcc/gcc-git-base/gcc/testsuite/gcc.dg/vect/costmodel/ppc/costmodel-fast-math-vect-pr29925.c:13:4:
missed: couldn't vectorize loop