From 15c4170060b9f7046db8e8ace6d9d6eebe5c796e Mon Sep 17 00:00:00 2001 From: Eric Christopher Date: Wed, 31 Jan 2018 19:52:58 +0000 Subject: [PATCH] Clarify that optimization levels -O2 and above are recommended for use of PGO. git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@323902 91177308-0d34-0410-b5e6-96231b3b80d8 --- docs/UsersManual.rst | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/docs/UsersManual.rst b/docs/UsersManual.rst index 48ea714304..84dfe9fc3d 100644 --- a/docs/UsersManual.rst +++ b/docs/UsersManual.rst @@ -1375,7 +1375,8 @@ Profile Guided Optimization Profile information enables better optimization. For example, knowing that a branch is taken very frequently helps the compiler make better decisions when ordering basic blocks. Knowing that a function ``foo`` is called more -frequently than another function ``bar`` helps the inliner. +frequently than another function ``bar`` helps the inliner. Optimization +levels ``-O2`` and above are recommended for use of profile guided optimization. Clang supports profile guided optimization with two different kinds of profiling. A sampling profiler can generate a profile with very low runtime -- 2.50.1