https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80885
Bug ID: 80885
Summary: Do not use the opaque _mm256_cmp_ps to produce -1
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: glisse at gcc dot gnu.org
Target Milestone: ---
Target: x86_64-*-*
Hello,
in avx2intrin.h, I see a lot of
__v8sf __src = _mm256_setzero_ps ();
__v8sf __mask = _mm256_cmp_ps (__src, __src, _CMP_EQ_OQ);
(and variants with double)
Where gcc knows nothing about _mm256_cmp_ps and blindly generates the insn. It
seems to me that it would be better to use some way to let gcc know the
constant (for instance generate it as __v8si then cast), even if in the end it
might decide to generate the constant this way.
Macros (for the -O0 case) have the rather suspicious
(__v4df)_mm256_set1_pd((double)(long long int) -1)
