https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88570
--- Comment #6 from Hongtao.liu <crazylht at gmail dot com> ---
1. knot should be cheaper than vector compare to mask register.
2. for test2, we failed to eliminate
vcmppd k1, ymm1, ymm2, 1
which is exactlt the same as
vcmppd k1, ymm2, ymm1, 14
Note: pass_combine failed to generate zero-maskig since zero vector is still
used by the condition n1[n] > 0(0.0), if we change condition to a non-zero
constant, then zero-masking will be generated.
void test1(int*__restrict n1, int*__restrict n2,
int*__restrict n3, int*__restrict n4)
{
for (int n = 0; n < 8; ++n)
{
if (n1[n] > 1) --- change from 0 -> 1.
n2[n] = n3[n];
else
n2[n] = n4[n];
}
}
test1:
vmovdqu ymm1, YMMWORD PTR [rdi]
mov eax, 1
vpbroadcastd ymm0, eax
vpcmpd k1, ymm1, ymm0, 6
vpcmpd k2, ymm1, ymm0, 2
vmovdqu32 ymm2{k1}{z}, YMMWORD PTR [rdx]
vmovdqu32 ymm0{k2}{z}, YMMWORD PTR [rcx]
vmovdqa32 ymm0{k1}, ymm2
vmovdqu YMMWORD PTR [rsi], ymm0
vzeroupper
ret
