https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106583
Bug ID: 106583 Summary: Suboptimal immediate generation on aarch64 Product: gcc Version: unknown Status: UNCONFIRMED Keywords: missed-optimization Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: ktkachov at gcc dot gnu.org Target Milestone: --- Target: aarch64 A simple codegen issue: unsigned long long foo (void) { return 0x7efefefefefefeff; } generates at -O2 foo: mov x0, 65279 movk x0, 0xfefe, lsl 16 movk x0, 0xfefe, lsl 32 movk x0, 0x7efe, lsl 48 ret whereas LLVM can do: foo: // @foo mov x0, #-72340172838076674 movk x0, #65279 movk x0, #32510, lsl #48 ret Should be a matter of just making aarch64_internal_mov_immediate in aarch64.cc a bit smarter