https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100165
Bug ID: 100165 Summary: fmov could be used to zero out the upper bits instead of movi/zip or movi/ins with __builtin_shuffle and zero vector Product: gcc Version: 11.0 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: typedef double V __attribute__((vector_size(16))); typedef long long VI __attribute__((vector_size(16))); V foo (V x) { return __builtin_shuffle (x, (V) { 0, 0, }, (VI) {0, 3}); } ----- CUT ---- Or typedef float V __attribute__((vector_size(16))); typedef int VI __attribute__((vector_size(16))); V foo (V x) { return __builtin_shuffle (x, (V) { 0, 0, 0, 0 }, (VI) {0, 1, 4, 5}); } ---- CUT ---- Both should just produce: fmov d0, d0 ret ---- CUT ---- The x86_64 specific version of this was PR 94680 which I just confirmed today.