https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95488
Bug ID: 95488
Summary: Suboptimal multiplication codegen for v16qi
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: crazylht at gmail dot com
Target Milestone: ---
Target: x86_64-*-* i?86-*-*
cat test.c
---
typedef unsigned char v16qi __attribute__ ((vector_size (16)));
v16qi
foo (v16qi a, v16qi b)
{
return a*b;
}
---
gcc -O2 -march=skylake-avx512
---
foo(unsigned char __vector(16), unsigned char __vector(16)):
vpunpcklbw xmm3, xmm0, xmm0
vpunpcklbw xmm2, xmm1, xmm1
vpunpckhbw xmm0, xmm0, xmm0
vpunpckhbw xmm1, xmm1, xmm1
vpmullw xmm2, xmm2, xmm3
vpmullw xmm1, xmm1, xmm0
vmovdqa xmm3, XMMWORD PTR .LC0[rip]
vpand xmm0, xmm3, xmm2
vpand xmm3, xmm3, xmm1
vpackuswb xmm0, xmm0, xmm3
ret
.LC0:
.value 255
.value 255
.value 255
.value 255
.value 255
.value 255
.value 255
.value 255
---
icc generate
---
foo(unsigned char __vector(16), unsigned char __vector(16)):
vpmovzxbw ymm2, xmm0 #5.15
vpmovzxbw ymm3, xmm1 #5.15
vpmullw ymm4, ymm2, ymm3 #5.15
vpmovwb xmm0, ymm4 #5.15
vzeroupper #5.15
ret #5.15
---
we can do better in ix86_expand_vecop_qihi, problem is how can i get sign info
for an rtx operand.
