https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102224
Bug ID: 102224
Summary: Incorrect compile on `x * copysign(1.0, x)`
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
float f(float x, float y)
{
return x * copysignf(1.0f, x);
}
On latest trunk with -O3 on x86, this compiles to:
f(float):
andps xmm0, XMMWORD PTR .LC0[rip]
xorps xmm0, xmm0
ret
.LC0:
.long -2147483648
.long 0
.long 0
.long 0
This is likely because the XOR_SIGN pattern emitted by
convert_expand_mult_copysign fails to check that x and y are not the same
(note: it can be optimized to ABS_EXPR in that case).
