diff --git a/clang/docs/CommandGuide/clang.rst b/clang/docs/CommandGuide/clang.rst index 663aca1f6ddcb..a0c2594d06c61 100644 --- a/clang/docs/CommandGuide/clang.rst +++ b/clang/docs/CommandGuide/clang.rst @@ -429,8 +429,12 @@ Code Generation Options :option:`-Ofast` Enables all the optimizations from :option:`-O3` along with other aggressive optimizations that may violate strict compliance with - language standards. This is deprecated in favor of :option:`-O3` - in combination with :option:`-ffast-math`. + language standards. This is deprecated in Clang 19 and a warning is emitted + that :option:`-O3` in combination with :option:`-ffast-math` should be used + instead if the request for non-standard math behavior is intended. There + is no timeline yet for removal; the aim is to discourage use of + :option:`-Ofast` due to the surprising behavior of an optimization flag + changing the observable behavior of correct code. :option:`-Os` Like :option:`-O2` with extra optimizations to reduce code size.