https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91154
--- Comment #16 from Richard Biener <rguenth at gcc dot gnu.org> ---
Ah, because x86_64_general_operand allows memory but the v alternative not
and reloading that is appearantly more expensive than not doing that and
reloading the general reg later. Fun. Changing that to
x86_64_nonmemory_operand
makes the whole thing work nearly fully (for this testcase, breaking everything
else of course), there's one gpr op remaining again because we get memory,
this time in the first operand which I kept as nonimmediate_operand.
Not sure how we make RA happier to reload a memory operand for the v,v,v
alternative without doing that elsewhere.
movl $-987654321, %r10d
vmovd (%rdi), %xmm0
leal -1(%r8), %r9d
xorl %eax, %eax
vmovd %r10d, %xmm1
.p2align 4,,10
.p2align 3
.L3:
vmovd (%rdx,%rax,4), %xmm2
vpaddd %xmm2, %xmm0, %xmm0
vmovd %xmm0, 4(%rdi,%rax,4)
movl (%rcx,%rax,4), %r8d
addl (%rsi,%rax,4), %r8d
vmovd %r8d, %xmm3
movq %rax, %r8
vpmaxsd %xmm0, %xmm3, %xmm0
vpmaxsd %xmm1, %xmm0, %xmm0
vmovd %xmm0, 4(%rdi,%rax,4)
addq $1, %rax
cmpq %r9, %r8
jne .L3
