https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96715
Bug ID: 96715 Summary: Failure to optimize copysign of variable by negated variable Product: gcc Version: 11.0 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 __builtin_copysignf(x, -x); } This can be optimized to `return -x;`. This transformation is done by LLVM, but not by GCC.