https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101754
Bug ID: 101754 Summary: Missed fold for a/b*b Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: llvm at rifkin dot dev Target Milestone: --- GCC is not optimizing the following (contrived) divisibility check https://godbolt.org/z/1rEhYa8Ts. bool foo(int a, int b) { return a/b*b == a; } bool bar(int a, int b) { return a%b == 0; } If GCC can fold a/b*b into a-a%b, it will be able to optimize properly the rest of the way.