https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101142
--- Comment #2 from Hongtao.liu <crazylht at gmail dot com> ---
I'm working on a patch which disparages slightly the mask register alternative
for bitwise operations(using "?k" in alternatives). It can prevent mask bitwise
instruction generation when the input is not allocate as mask registers.
Also when allocano cost of GENERAL_REGS is same as MASK_REGS, allocate
MASK_REGS first since it has already been disparaged. This is for testcase like
below where the input is allocated as mask registers, then mask bitwise
instructions should be used here.
#include<immintrin.h>
volatile __mmask8 foo;
void
foo_orb (__m512i a, __m512i b, __m512i c, __m512i d)
{
__mmask8 m1 = _mm512_cmp_epi64_mask (a, b, 2);
__mmask8 m2 = _mm512_cmp_epi64_mask (c, d, 4);
foo = m1 | m2;
}
vpcmpq $2, %zmm1, %zmm0, %k0
vpcmpq $4, %zmm3, %zmm2, %k1
korb %k1, %k0, %k2
kmovb %k2, foo(%rip)
ret
foo:
