Optimize string escape functions

When generating Chromium's build files, this reduces the number of cycles gn
uses across all threads from 41,325,733,995 to 38,453,104,830 (-7%) indicated by
callgrind.  Runtime is also reduced from 3.45s to 3.43s (-0.6%) measured with
100 samples.  GN is likely bound more by disk IO and exec_script()'s than CPU
cycles, so that would explain why runtime reduction is only 0.6%.  But 0.6% is
still better than 0%.


Change-Id: Ief145407a0bf3ef00b13ce2532df4ff028f05c89
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/4620
Reviewed-by: Brett Wilson <brettw@google.com>
Commit-Queue: Brett Wilson <brettw@google.com>
1 file changed
tree: 9ff71e9a56ad2bed08597fed27d3ce07a9cc0917
  1. .clang-format
  2. .editorconfig
  3. .gitignore
  4. .style.yapf
  8. README.md
  9. base/
  10. build/
  11. docs/
  12. infra/
  13. tools/
  14. util/


GN is a meta-build system that generates build files for Ninja. There is documentation in docs/ and a presentation on it.

Getting started

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

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:

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.

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 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 w/ GN‘s development on Chromium’s gn-dev@ Google Group.