https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87678
Bug ID: 87678
Summary: Redundant vmovss with -fPIC
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: hjl.tools at gmail dot com
CC: ubizjak at gmail dot com
Target Milestone: ---
Target: i386
[hjl@gnu-efi-2 broadcast-1]$ cat y.c
#include <immintrin.h>
float
foo (__m128 x)
{
return ((__v4sf) x)[0] * 2.387f;
}
[hjl@gnu-efi-2 broadcast-1]$ gcc -O2 y.c -mfpmath=sse -fpic -m32 -S -mavx
c[hjl@gnu-efi-2 broadcast-1]$ cat y.s
.file "y.c"
.text
.p2align 4,,15
.globl foo
.type foo, @function
foo:
.LFB5086:
.cfi_startproc
call __x86.get_pc_thunk.ax
addl $_GLOBAL_OFFSET_TABLE_, %eax
subl $28, %esp
.cfi_def_cfa_offset 32
vmovss .LC0@GOTOFF(%eax), %xmm1
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This isn't needed.
vmulss %xmm1, %xmm0, %xmm0
vmovss %xmm0, 12(%esp)
flds 12(%esp)
addl $28, %esp
.cfi_def_cfa_offset 4
ret
.cfi_endproc
.LFE5086:
.size foo, .-foo
We should replace
vmovss .LC0@GOTOFF(%eax), %xmm1
vmulss %xmm1, %xmm0, %xmm0
with
vmulss .LC0@GOTOFF(%eax), %xmm0, %xmm0
