gn.md

GN

GN stands for Generate Ninja and the executable gn is a bash script that call gn.py.

$ tools/dev/v8gen.py --help

Show all executables

$ gn ls out/x64.release_gcc --type=executable

If you want details of a specific target you can use desc:

$ gn desc out/x64.release_gcc/ //:mksnapshot

//:mksnapshot is a label where // indicates the root directory and then the name of the label. If the label was in a subdirectory that subdirectory would come before the :. This command is useful to see which files are included in an executable.

When gn starts it will search for a .gn file in the current directory. The one V8 in specifies the following:

import("//build/dotfile_settings.gni")                                          

This includes a bunch of gni files from the build directory (the dotfile_settings.gni) that is.

buildconfig = "//build/config/BUILDCONFIG.gn"                                   

This is the master GN build configuration file.

Show all shared_libraries:

$ gn ls out/x64.release_gcc --type=shared_libraries

Edit build arguments:

$ vi out/x64.release_gcc/args.gn
$ gn args out/x64.release_gcc

This will open an editor where you can set configuration options. I've been using the following:

v8_monolithic = true
use_custom_libcxx = false
v8_use_external_startup_data = false
is_debug = true
target_cpu = "x64"
v8_enable_backtrace = true
v8_enable_slow_dchecks = true
v8_optimized_debug = false

List avaiable build arguments:

$ gn args --list out/x64.release

List all available targets:

$ ninja -C out/x64.release/ -t targets all

Building:

$ env CPATH=/usr/include ninja -C out/x64.release_gcc/

Running quickchecks:

$ ./tools/run-tests.py --outdir=out/x64.release --quickcheck

You can use ./tools-run-tests.py -h to list all the options that can be passed to run-tests.