Chromium/V8 runbook

chromium-v8-runbook.md

Chromium/V8 runbook

XCode:

• Note that you'll need XCode, not just the XCode Mac CLI tools, to build/compile Chromium/V8 on Mac.

• Ensure that you see this:

   $ xcode-select --print-path
   /Applications/Xcode.app/Contents/Developer
  

  and this:

  ls `xcode-select -p`/Platforms/MacOSX.platform/Developer/SDKs
  ... DriverKit, sdk dirs, sdk executables, etc ...
  

  and of course:

  g++ --help
  ... gives us a little manpage like:
  OVERVIEW: clang LLVM compiler
  linkerz loaderz oh my!
  

Contributing:

• Contributing
• See: https://chromium.googlesource.com/chromium/src/+/refs/heads/main/docs/commit_checklist.md
• See https://chromium.googlesource.com/chromium/src/+/master/docs/contributing.md
• Life of a Chromium developer
• Chromium 101 Tutorial, really nice
• • See V8 issues and Chromium first bugs to fix
• Commit checklist

1. Set up repo, build from source

• Building from source
• Check out source code
• Check out source code using depot_tools
  • ensure depot_tools in beginning of PATH
  • in an empty dir, fetch v8
  • Update dependencies: gclient sync
  • git new-branch fix-bug-1234

2. Developer & Commit Workflows (from "Life of a Chromium Developer" by Google)

   • Start work: git pull --rebase && client gsync

   • Code, compile with Ninja and GN tools/dev/gm.py x64.release

   • Compile and test: tools/dev/gm.py x64.release.check ... this takes quite awhile

   • # In the src/ directory:
     $ gn gen out/Default
     
     # Set build arguments (such as debug vs release):
     $ gn args out/Default
     
     # Do a build of the ‘chrome’ target:
     $ autoninja -C out/Default chrome
     # ‘autoninja’ is preferred over ‘ninja’
     # Builds to src/out/ directory, e.g. src/out/Default/chrome
     # For clean build, delete out/ directory (rarely needed)
     

   • Make new branch git checkout -t -b my_new_feature origin/main

   • Iterate on patches:

   • git cl upload

   • git cl try

   • todo git cl land - how is land different than try

3. Request review.

   • Reviews are at: https://chromium-review.googlesource.com/q/status:open+-is:wip
   • Request a review from your V8 workspace, not chromium
   • Add your name to AUTHORS file
   • For push access, you'll need a .netrc file with creds. See https://v8.dev/docs/source-code
   • git cl upload.

For fetching all branches, add the following into your remote configuration in .git/config:

fetch = +refs/branch-heads/*:refs/remotes/branch-heads/*
fetch = +refs/tags/*:refs/tags/*

Running V8 "locally:" Compile the shell sample and run it as a shell!
Per https://stackoverflow.com/questions/1802478/running-v8-javascript-engine-standalone

$> svn co http://v8.googlecode.com/svn/trunk v8-trunk
...
$> cd v8-trunk
$> scons
$> g++ ./samples/shell.cc -o v8-shell -I include libv8.a 
Now, we have a standalone binary called v8-shell.

Running the console:

$> ./v8-shell 
V8 version 2.0.2
> var x = 10;
> x
10
> function foo(x) { return x * x; }
> foo
function foo(x) { return x * x; }
> quit()
Executing Javascript from the command line:

$> ./v8-shell -e 'print("10*10 = " + 10*10)'
10*10 = 100

Scons:

https://stackoverflow.com/questions/17475268/c-c-header-file-not-found

See:

https://github.com/danbev/learning-v8#building-v8