|author||Nico Weber <email@example.com>||Thu Nov 07 13:14:37 2019 -0500|
|committer||Commit Bot <firstname.lastname@example.org>||Thu Nov 07 19:51:09 2019 +0000|
win: Only use ICF and LTO if explicitly opted in. The bots pass --use-icf and --use-lto, so it doesn't affect them. Makes the Windows build more like the non-Windows build, and makes incremental build times (== local dev) in the default build config 20x faster. (It also makes it possible to set CC/CXX to clang-cl without getting warnings about /GL, but that's not my motivation here. But I might want to use goma to build gn in the future, at least on my laptop, and then that'll come in handy.) Also add /Zc:inline to cflags in release builds on Windows. Also change non-Win to use LTO only in release builds -- LTO in debug builds doesn't make much sense. Release build times (always `ninja -C out`, i.e. linking both gn.exe and gn_unittests.exe): With this patch: Full: 4m25s Touch just src\gn\command_analyze.cc: 3.8s Size of out\: 844 MB Peak memory use during build: 250 MB With this patch but no /Zc:inline: Full: 4m25s Touch just src\gn\command_analyze.cc: 4.8s Size of out\: 1.05 GB Peak memory use during build: 345 MB Without this patch (== this patch with --use-icf --use-lto; /Zc:inline seems to have no effect when used with /GL): Full: 4m33s Touch just src\gn\command_analyze.cc: 1m55s (!) Size of out\: 1.52 GB Peak memory use during build: 678 MB Change-Id: Idd87389c7537828fe6523a64de6031f9cbbc0fc6 Reviewed-on: https://gn-review.googlesource.com/c/gn/+/6442 Reviewed-by: Scott Graham <email@example.com> Commit-Queue: Nico Weber <firstname.lastname@example.org>
GN is a meta-build system that generates build files for Ninja.
Alternatively, you can build GN from source:
git clone https://gn.googlesource.com/gn cd gn python build/gen.py ninja -C out # To run tests: out/gn_unittests
On Windows, it is expected that
lib.exe can be found in
PATH, so you'll want to run from a Visual Studio command prompt, or similar.
On Linux and Mac, the default compiler is
clang++, a recent version is expected to be found in
PATH. This can be overridden by setting
There is a simple example in examples/simple_build directory that is a good place to get started with the minimal configuration.
For a maximal configuration see the Chromium setup:
and the Fuchsia setup:
If you find a bug, you can see if it is known or report it in the bug database.
GN uses Gerrit for code review. The short version of how to patch is:
Register at https://gn-review.googlesource.com. ... edit code ... ninja -C out && out/gn_unittests
Then, to upload a change for review:
git commit git cl upload --gerrit
When revising a change, use:
git commit --amend git cl upload --gerrit
which will add the new changes to the existing code review, rather than creating a new one.
We ask that all contributors sign Google's Contributor License Agreement (either individual or corporate as appropriate, select ‘any other Google project’).
You may ask questions and follow along with GN‘s development on Chromium’s gn-dev@ Google Group.