tools/pgo/generate_profile.py

#!/usr/bin/env python3
# Copyright 2023 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
'''Runs benchmarks as described in docs/pgo.md, and similar to the PGO bots.

You need to build chrome with chrome_pgo_phase=1 (and the args.gn described
in docs/pgo.md for stage 1), and then run this like

    tools/pgo/generate_profile.py -C out/builddir

After that, the final profile will be in out/builddir/profile.profdata.
With that, you can do a second build with:

    is_official_build
    pgo_data_path = "//out/builddir/profile.profdata"

and with chrome_pgo_phase _not_ set. (It defaults to =2 in official builds.)
'''
# TODO(thakis): Make PGO bots actually run this script, crbug.com/1455237

import argparse
import glob
import os
import shutil
import subprocess
import sys

exe_ext = '.exe' if sys.platform == 'win32' else ''

THIS_DIR = os.path.dirname(__file__)
ROOT_DIR = f'{THIS_DIR}/../..'
UPDATE_PY = f'{THIS_DIR}/../clang/scripts/update.py'
LLVM_DIR = f'{ROOT_DIR}/third_party/llvm-build/Release+Asserts'
PROFDATA = f'{LLVM_DIR}/bin/llvm-profdata' + exe_ext


def main():
    if not os.path.exists(PROFDATA):
        print(f'{PROFDATA} does not exist, downloading it')
        subprocess.run([sys.executable, UPDATE_PY, '--package=coverage_tools'],
                       check=True)

    parser = argparse.ArgumentParser(
        epilog=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
    parser.add_argument('-C',
                        help='Path to build directory',
                        required=True,
                        metavar='builddir',
                        dest='builddir')
    parser.add_argument('--keep-temps', help='Whether to keep term files')
    args = parser.parse_args()

    # This is load-bearing:
    # - `open` (used by run_benchmark) needs absolute paths
    # - `open` sets the cwd to `/`, so LLVM_PROFILE_FILE must
    #   be an absolute path
    # Both are based off this variable.
    # See also https://crbug.com/1478279
    builddir = os.path.realpath(args.builddir)
    if sys.platform == 'darwin':
        chrome_path = f'{builddir}/Chromium.app/Contents/MacOS/Chromium'
    else:
        chrome_path = f'{builddir}/chrome' + exe_ext
    profiledir = f'{builddir}/profile'

    def run_benchmark(args):
        '''Puts profdata in {profiledir}/{args[0]}.profdata'''
        name = args[0]
        profraw_path = f'{profiledir}/{name}/raw'
        if os.path.exists(profraw_path):
            shutil.rmtree(profraw_path)
        os.makedirs(profraw_path, exist_ok=True)

        env = os.environ.copy()
        env['LLVM_PROFILE_FILE'] = f'{profraw_path}/default-%2m.profraw'

        subprocess.run(['vpython3', 'tools/perf/run_benchmark'] + args + [
            '--assert-gpu-compositing',
            '--browser=exact',
            f'--browser-executable={chrome_path}',
        ],
                       check=True,
                       env=env,
                       cwd=ROOT_DIR)
        prof_path = f'{profiledir}/{name}.profdata'
        subprocess.run([PROFDATA, 'merge', '-o', prof_path] +
                       glob.glob(f'{profraw_path}/*.profraw'),
                       check=True)

    if os.path.exists(profiledir):
        shutil.rmtree(profiledir)

    run_benchmark(['system_health.common_desktop', '--run-abridged-story-set'])
    run_benchmark(['speedometer2'])
    run_benchmark(['jetstream2'])
    run_benchmark([
        'rendering.desktop', '--also-run-disabled-tests',
        '--story-tag-filter=motionmark_fixed_2_seconds'
    ])

    subprocess.run([PROFDATA, 'merge', '-o', f'{builddir}/profile.profdata'] +
                   glob.glob(f'{profiledir}/*.profdata'),
                   check=True)

    if not args.keep_temps:
        shutil.rmtree(profiledir)


if __name__ == '__main__':
    sys.exit(main())