https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93696
Bug ID: 93696
Summary: AVX512VPOPCNTDQ writemask intrinsics produce incorrect
results
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: crazylht at gmail dot com
Target Milestone: ---
Target: i386, x86-64
The writemask (mask) forms of the AVX512VPOPCNTDQ intrinsics generate incorrect
results. When the mask bit is not set, it appears the GCC implementation is
copying from the third parameter, whereas it should be copying from the first
parameter.
testcase:
cat test.c
#include<immintrin.h>
__m128i foo (__m128i dst, __mmask8 m, __m128i src)
{
return _mm_mask_popcnt_epi64 (dst, m, src);
}
gcc10_trunk -O2 -mavx512vpopcntdq -mavx512vl -S
foo(long long __vector(2), unsigned char, long long __vector(2)):
kmovw %edi, %k1
vpopcntq %xmm0, %xmm1{%k1}
vmovdqa64 %xmm1, %xmm0
ret
which is incorrect, it should be
foo(__m128i, unsigned char, __m128i):
kmovw %edi, %k1 #4.10
vpopcntq %xmm1, %xmm0{%k1} #4.10
ret #4.10
Refer to https://godbolt.org/z/EK12b0
Affected intrinsics
_mm256_mask_popcnt_epi64
_mm_mask_popcnt_epi64
_mm256_mask_popcnt_epi32
_mm_mask_popcnt_epi32
_mm512_mask_popcnt_epi32
_mm512_mask_popcnt_epi64
_mm512_mask_popcnt_epi16
_mm256_mask_popcnt_epi16
_mm_mask_popcnt_epi16
_mm512_mask_popcnt_epi8
_mm256_mask_popcnt_epi8
_mm_mask_popcnt_epi8
