https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66726
Bug ID: 66726 Summary: missed optimization, factor conversion out of COND_EXPR Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: law at redhat dot com Target Milestone: --- Given something like this: n = (short unsigned int) mode_size[(unsigned int) mode] * 8 <= 64 ? (int) ((short unsigned int) mode_size[(unsigned int) mode] * 8) : 64; Note the (int) cast on the true arm of the COND_EXPR. As a result of that cast, the transformations to turn a COND_EXPR into a MIN/MAX expression in fold-const.c will not trigger. This could be fixed by a patch to match.pd, but the pattern would only really be applicable to GENERIC and thus isn't considered a good design match for match.pd. We could extend fold-const.c to catch this case, but that would really only help GENERIC as well. The best option it seems would be to catch this in phi-opt which would also take us a step closer to handling pr45397. Testcase: /* { dg-do compile } */ /* { dg-options "-O2 -fdump-tree-original" } */ extern unsigned short mode_size[]; int oof (int mode) { return (64 < mode_size[mode] ? 64 : mode_size[mode]); } /* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "original" } } */