document --with-optimizations in the README for issue26359.

This commit is contained in:
Gregory P. Smith ext:(%20%5BGoogle%20Inc.%5D) 2016-09-08 18:33:00 +00:00
parent 2b2a9be913
commit 014d52ffc4
1 changed files with 13 additions and 4 deletions

17
README
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@ -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
----------