https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110215
Bug ID: 110215
Summary: RA fails to allocate register when loop invariant
lives through EH region
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: wwwhhhyyy333 at gmail dot com
Target Milestone: ---
Created attachment 55305
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55305&action=edit
A Testcase
Compiled with -Ofast, The innermost loop is
.L41:
movups (%rax), %xmm3
movaps (%rsp), %xmm0
addq $16, %rax
subps %xmm3, %xmm0
andps %xmm2, %xmm0
movups %xmm0, -16(%rax)
addps %xmm0, %xmm1
cmpq %rax, %rdx
jne .L41
While for Clang it produces
.LBB0_14: # Parent Loop BB0_3 Depth=1
movups (%rbp,%rax), %xmm1
movaps %xmm3, %xmm2
subps %xmm1, %xmm2
andps %xmm4, %xmm2
movups %xmm2, (%rbp,%rax)
addps %xmm2, %xmm0
addq $16, %rax
cmpq %rax, %r12
jne .LBB0_14
The loop invariant `base` was spilled to stack in GCC, but for clang it can
directly use a sse register.
Godbolt: https://godbolt.org/z/TTvG8M6E8
