https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98647
Bug ID: 98647
Summary: Failure to optimize out convertion from float to
vector type
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
float f(float val)
{
return _mm_cvtss_f32(_mm_and_ps(_mm_set_ss(val),
_mm_castsi128_ps(_mm_set1_epi32(0x7fffffff))));
}
This can be optimized to avoid the conversions in the emitted assembly code.
This optimization is done by LLVM, but not by GCC.
LLVM code generation :
.LCPI1_0:
.long 0x7fffffff # float NaN
.long 0x7fffffff # float NaN
.long 0x7fffffff # float NaN
.long 0x7fffffff # float NaN
f(float): # @f(float)
andps xmm0, xmmword ptr [rip + .LCPI1_0]
ret
GCC code generation :
f(float):
pxor xmm1, xmm1
movss xmm1, xmm0
movaps xmm0, XMMWORD PTR .LC1[rip]
andps xmm0, xmm1
ret
.LC1:
.long 2147483647
.long 2147483647
.long 2147483647
.long 2147483647
