https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113857
Bug ID: 113857 Summary: fmov should be used to zero the upper bits of the vector register Product: gcc Version: 14.0 Status: UNCONFIRMED Keywords: missed-optimization Severity: enhancement Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: pinskia at gcc dot gnu.org Target Milestone: --- Target: aarch64 Take: ``` #define vect128 __attribute__((vector_size(16) )) #define vect64 __attribute__((vector_size(8) )) vect64 float f64( float a) { return (vect64 float){a, 0}; } vect128 float f128( float a) { return (vect128 float){a, 0, 0, 0}; } ``` GCC produces fmov for f64 but does not for f128. Note we could the same for: ``` vect64 short s64( short a) { return (vect64 short){a, 0}; } vect128 int i128( int a) { return (vect128 int){a, 0}; } ``` Well s64 can only be done if f16 extensions are enabled.