build/ Add --link-lib=LINK_LIB option.

This adds one new command-line option to the build/
script to allow linking the final executable(s) with one or
more extra libraries.

This is mostly useful to link a custom malloc implementation
or a cpu profiling library, like libtcmalloc.a or libprofiler.a
provided by the the gperftools project [1].

For the record, using:

  build/ --use-icf --use-lto --link-lib=/path/to/libtcmalloc.a

Results in a noticeably faster GN executable for both Chromium
(21% faster) and the Fuchsia build (43% faster!)

It is also possible to link against a more recent release of TCMalloc
from [2], but measurements show no noticeable performance difference
with the older release for GN workloads.

    BEFORE:  Done. Made 13124 targets from 2289 files in 3593ms
    AFTER:   Done. Made 13124 targets from 2289 files in 4358ms

    BEFORE: [...] Done. Made 47263 targets from 3819 files in 14263ms
    AFTER:  [...] Done. Made 47263 targets from 3819 files in 9923ms


Change-Id: If21911f13a886eeae09797099a078ed1d4f789dd
Reviewed-by: Scott Graham <>
Commit-Queue: David Turner <>
1 file changed
tree: 0c9be7d4c33e08ca97c6cf4e4599e4fa5b4bec28
  1. build/
  2. docs/
  3. examples/
  4. infra/
  5. misc/
  6. src/
  7. .clang-format
  8. .editorconfig
  9. .gitignore
  10. .style.yapf
  13. OWNERS


GN is a meta-build system that generates build files for Ninja.

Related resources:

Getting a binary

You can download the latest version of GN binary for Linux, macOS and Windows.

Alternatively, you can build GN from source:

git clone
cd gn
python build/
ninja -C out
# To run tests:

On Windows, it is expected that cl.exe, link.exe, and 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 CC, CXX, and AR.


There is a simple example in examples/simple_build directory that is a good place to get started with the minimal configuration.

To build and run the simple example with the default gcc compiler:

cd examples/simple_build
../../out/gn gen -C out
ninja -C out

For a maximal configuration see the Chromium setup:

and the Fuchsia setup:

Reporting bugs

If you find a bug, you can see if it is known or report it in the bug database.

Sending patches

GN uses Gerrit for code review. The short version of how to patch is:

Register at

... edit code ...
ninja -C out && out/gn_unittests

Then, to upload a change for review:

git commit
git push origin HEAD:refs/for/master

The first time you do this you'll get an error from the server about a missing change-ID. Follow the directions in the error message to install the change-ID hook and run git commit --amend to apply the hook to the current commit.

When revising a change, use:

git commit --amend
git push origin HEAD:refs/for/master

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.