https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104610
--- Comment #21 from Uroš Bizjak <ubizjak at gmail dot com> ---
Just before the patch from Comment #20, the compiler creates (-O2 -mavx):
--cut here--
vmovdqa .LC1(%rip), %xmm0
vmovdqa %xmm0, -24(%rsp)
vmovdqu (%rdi), %xmm0
vpxor .LC0(%rip), %xmm0, %xmm0
vptest %xmm0, %xmm0
je .L5
.L2:
movl $1, %eax
testl %eax, %eax
sete %al
ret
.L5:
vmovdqu 16(%rdi), %xmm0
vpxor -24(%rsp), %xmm0, %xmm0
vptest %xmm0, %xmm0
jne .L2
xorl %eax, %eax
testl %eax, %eax
sete %al
ret
--cut here--
Please note the creative way of returning 0 and 1 ... :
movl $1, %eax
testl %eax, %eax
sete %al
ret
Even the new code (From comment #20) is unnecessarily convoluted:
.L2: movl $1, %eax
xorl $1, %eax
ret
.L5: xorl %eax, %eax
xorl $1, %eax
ret
