https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89984
Bug ID: 89984
Summary: Extra register move
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: hjl.tools at gmail dot com
Target Milestone: ---
Target: x86-64,i386
[hjl@gnu-cfl-1 xxx]$ cat x.i
float
check_f_pos (float x, float y)
{
return x * __builtin_copysignf (1.0f, y);
}
[hjl@gnu-cfl-1 xxx]$ cat x.i
float
check_f_pos (float x, float y)
{
return x * __builtin_copysignf (1.0f, y);
}
[hjl@gnu-cfl-1 xxx]$ make
/export/build/gnu/tools-build/gcc-wip-debug/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/tools-build/gcc-wip-debug/build-x86_64-linux/gcc/ -mavx2
-O2 -S x.i
[hjl@gnu-cfl-1 xxx]$ cat x.s
.file "x.i"
.text
.p2align 4
.globl check_f_pos
.type check_f_pos, @function
check_f_pos:
.LFB0:
.cfi_startproc
vandps .LC0(%rip), %xmm1, %xmm1
vxorps %xmm0, %xmm1, %xmm1
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Why not just do
vxorps %xmm0, %xmm1, %xmm0
vmovaps %xmm1, %xmm0
ret
.cfi_endproc
.LFE0:
.size check_f_pos, .-check_f_pos
.section .rodata.cst16,"aM",@progbits,16
.align 16
.LC0:
.long 2147483648
.long 0
.long 0
.long 0
.ident "GCC: (GNU) 9.0.1 20190403 (experimental)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-cfl-1 xxx]$
