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llvm-mirror/utils/gn/build/write_vcsrevision.py
Nico Weber 02bc480b15 [gn build] replace llvm_allow_tardy_revision with llvm_append_vc_rev
Previously, the gn build would create VCSRevision.h / VCSVersion.h
files with some LLD_REVISION / LLVM_REVISION / CLANG_REVISION but
by default wouldn't add a dependency on .git/logs/HEAD so that
the step doesn't rerun after every branch switch or every pull.

That's bad for deterministic builds, and having --version print
some arbitrarily old revision isn't great either.

Instead, move to the model that the cmake build (now) uses fairly
consistently: If llvm_append_vc_rev is set, include the revision,
else don't.

Since the GN build is focused on developers, set llvm_append_vc_rev
to false instead of true by default (different from the cmake build),
so that things don't rebuild after every branch switch and every
pull.

While here, also remove some pre-monorepo code.

Differential Revision: https://reviews.llvm.org/D72859
2020-01-16 19:05:07 -05:00

85 lines
3.2 KiB
Python
Executable File

#!/usr/bin/env python
"""Gets the current revision and writes it to VCSRevision.h."""
from __future__ import print_function
import argparse
import os
import subprocess
import sys
THIS_DIR = os.path.abspath(os.path.dirname(__file__))
LLVM_DIR = os.path.dirname(os.path.dirname(os.path.dirname(THIS_DIR)))
def which(program):
# distutils.spawn.which() doesn't find .bat files,
# https://bugs.python.org/issue2200
for path in os.environ["PATH"].split(os.pathsep):
candidate = os.path.join(path, program)
if os.path.isfile(candidate) and os.access(candidate, os.X_OK):
return candidate
return None
def main():
parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument('-d', '--depfile',
help='if set, writes a depfile that causes this script '
'to re-run each time the current revision changes')
parser.add_argument('--write-git-rev', action='store_true',
help='if set, writes git revision, else writes #undef')
parser.add_argument('--name', action='append',
help='if set, writes a depfile that causes this script '
'to re-run each time the current revision changes')
parser.add_argument('vcs_header', help='path to the output file to write')
args = parser.parse_args()
vcsrevision_contents = ''
if args.write_git_rev:
git, use_shell = which('git'), False
if not git: git = which('git.exe')
if not git: git, use_shell = which('git.bat'), True
git_dir = subprocess.check_output(
[git, 'rev-parse', '--git-dir'],
cwd=LLVM_DIR, shell=use_shell).decode().strip()
if not os.path.isdir(git_dir):
print('.git dir not found at "%s"' % git_dir, file=sys.stderr)
return 1
rev = subprocess.check_output(
[git, 'rev-parse', '--short', 'HEAD'],
cwd=git_dir, shell=use_shell).decode().strip()
url = subprocess.check_output(
[git, 'remote', 'get-url', 'origin'],
cwd=git_dir, shell=use_shell).decode().strip()
for name in args.name:
vcsrevision_contents += '#define %s_REVISION "%s"\n' % (name, rev)
vcsrevision_contents += '#define %s_REPOSITORY "%s"\n' % (name, url)
else:
for name in args.name:
vcsrevision_contents += '#undef %s_REVISION\n' % name
vcsrevision_contents += '#undef %s_REPOSITORY\n' % name
# If the output already exists and is identical to what we'd write,
# return to not perturb the existing file's timestamp.
if os.path.exists(args.vcs_header) and \
open(args.vcs_header).read() == vcsrevision_contents:
return 0
# http://neugierig.org/software/blog/2014/11/binary-revisions.html
if args.depfile:
build_dir = os.getcwd()
with open(args.depfile, 'w') as depfile:
depfile.write('%s: %s\n' % (
args.vcs_header,
os.path.relpath(os.path.join(git_dir, 'logs', 'HEAD'),
build_dir)))
open(args.vcs_header, 'w').write(vcsrevision_contents)
if __name__ == '__main__':
sys.exit(main())