From 014d52ffc4586e30a1fa4cbedc1532419a5916a1 Mon Sep 17 00:00:00 2001 From: "Gregory P. Smith ext:(%20%5BGoogle%20Inc.%5D)" Date: Thu, 8 Sep 2016 18:33:00 +0000 Subject: [PATCH] document --with-optimizations in the README for issue26359. --- README | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/README b/README index 7d8eeccc687..6dfbd8c3024 100644 --- a/README +++ b/README @@ -46,16 +46,17 @@ For example: (This will fail if you *also* built at the top-level directory. You should do a "make clean" at the toplevel first.) -If you need an optimized version of Python, you type "make profile-opt" in the -top level directory. This will rebuild the interpreter executable using Profile -Guided Optimization (PGO). For more details, see the section bellow. +To get an optimized build of Python, "configure --with-optimizations" before +you run make. This sets the default make targets up to enable Profile Guided +Optimization (PGO) and Link Time Optimization (LTO) on most platforms. +For more details, see the sections bellow. Profile Guided Optimization --------------------------- PGO takes advantage of recent versions of the GCC or Clang compilers. -If ran, the "profile-opt" rule will do several steps. +If ran, "make profile-opt" will do several steps. First, the entire Python directory is cleaned of temporary files that may have resulted in a previous compilation. @@ -75,6 +76,14 @@ collected in the previous one. The end result will be a Python binary that is optimized and suitable for distribution or production installation. +Link Time Optimization +---------------------- + +LTO takes advantages of recent compiler toolchains ability to optimize across +the otherwise arbitrary .o file boundary when building final executables or +shared libraries for additional performance gains. + + What's New ----------