484 lines
16 KiB
Python
Executable File
484 lines
16 KiB
Python
Executable File
#!/usr/bin/env python3
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"""
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This script:
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- Builds clang with user-defined flags
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- Uses that clang to build an instrumented clang, which can be used to collect
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PGO samples
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- Builds a user-defined set of sources (default: clang) to act as a
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"benchmark" to generate a PGO profile
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- Builds clang once more with the PGO profile generated above
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This is a total of four clean builds of clang (by default). This may take a
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while. :)
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This scripts duplicates https://llvm.org/docs/AdvancedBuilds.html#multi-stage-pgo
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Eventually, it will be updated to instead call the cmake cache mentioned there.
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"""
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import argparse
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import collections
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import multiprocessing
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import os
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import shlex
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import shutil
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import subprocess
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import sys
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### User configuration
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# If you want to use a different 'benchmark' than building clang, make this
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# function do what you want. out_dir is the build directory for clang, so all
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# of the clang binaries will live under "${out_dir}/bin/". Using clang in
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# ${out_dir} will magically have the profiles go to the right place.
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#
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# You may assume that out_dir is a freshly-built directory that you can reach
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# in to build more things, if you'd like.
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def _run_benchmark(env, out_dir, include_debug_info):
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"""The 'benchmark' we run to generate profile data."""
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target_dir = env.output_subdir('instrumentation_run')
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# `check-llvm` and `check-clang` are cheap ways to increase coverage. The
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# former lets us touch on the non-x86 backends a bit if configured, and the
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# latter gives us more C to chew on (and will send us through diagnostic
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# paths a fair amount, though the `if (stuff_is_broken) { diag() ... }`
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# branches should still heavily be weighted in the not-taken direction,
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# since we built all of LLVM/etc).
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_build_things_in(env, out_dir, what=['check-llvm', 'check-clang'])
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# Building tblgen gets us coverage; don't skip it. (out_dir may also not
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# have them anyway, but that's less of an issue)
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cmake = _get_cmake_invocation_for_bootstrap_from(
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env, out_dir, skip_tablegens=False)
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if include_debug_info:
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cmake.add_flag('CMAKE_BUILD_TYPE', 'RelWithDebInfo')
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_run_fresh_cmake(env, cmake, target_dir)
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# Just build all the things. The more data we have, the better.
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_build_things_in(env, target_dir, what=['all'])
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### Script
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class CmakeInvocation:
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_cflags = ['CMAKE_C_FLAGS', 'CMAKE_CXX_FLAGS']
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_ldflags = [
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'CMAKE_EXE_LINKER_FLAGS',
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'CMAKE_MODULE_LINKER_FLAGS',
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'CMAKE_SHARED_LINKER_FLAGS',
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]
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def __init__(self, cmake, maker, cmake_dir):
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self._prefix = [cmake, '-G', maker, cmake_dir]
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# Map of str -> (list|str).
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self._flags = {}
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for flag in CmakeInvocation._cflags + CmakeInvocation._ldflags:
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self._flags[flag] = []
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def add_new_flag(self, key, value):
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self.add_flag(key, value, allow_overwrites=False)
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def add_flag(self, key, value, allow_overwrites=True):
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if key not in self._flags:
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self._flags[key] = value
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return
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existing_value = self._flags[key]
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if isinstance(existing_value, list):
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existing_value.append(value)
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return
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if not allow_overwrites:
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raise ValueError('Invalid overwrite of %s requested' % key)
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self._flags[key] = value
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def add_cflags(self, flags):
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# No, I didn't intend to append ['-', 'O', '2'] to my flags, thanks :)
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assert not isinstance(flags, str)
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for f in CmakeInvocation._cflags:
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self._flags[f].extend(flags)
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def add_ldflags(self, flags):
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assert not isinstance(flags, str)
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for f in CmakeInvocation._ldflags:
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self._flags[f].extend(flags)
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def to_args(self):
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args = self._prefix.copy()
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for key, value in sorted(self._flags.items()):
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if isinstance(value, list):
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# We preload all of the list-y values (cflags, ...). If we've
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# nothing to add, don't.
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if not value:
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continue
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value = ' '.join(value)
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arg = '-D' + key
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if value != '':
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arg += '=' + value
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args.append(arg)
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return args
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class Env:
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def __init__(self, llvm_dir, use_make, output_dir, default_cmake_args,
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dry_run):
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self.llvm_dir = llvm_dir
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self.use_make = use_make
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self.output_dir = output_dir
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self.default_cmake_args = default_cmake_args.copy()
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self.dry_run = dry_run
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def get_default_cmake_args_kv(self):
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return self.default_cmake_args.items()
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def get_cmake_maker(self):
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return 'Ninja' if not self.use_make else 'Unix Makefiles'
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def get_make_command(self):
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if self.use_make:
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return ['make', '-j{}'.format(multiprocessing.cpu_count())]
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return ['ninja']
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def output_subdir(self, name):
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return os.path.join(self.output_dir, name)
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def has_llvm_subproject(self, name):
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if name == 'compiler-rt':
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subdir = '../compiler-rt'
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elif name == 'clang':
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subdir = '../clang'
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else:
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raise ValueError('Unknown subproject: %s' % name)
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return os.path.isdir(os.path.join(self.llvm_dir, subdir))
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# Note that we don't allow capturing stdout/stderr. This works quite nicely
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# with dry_run.
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def run_command(self,
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cmd,
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cwd=None,
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check=False,
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silent_unless_error=False):
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print(
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'Running `%s` in %s' % (cmd, shlex.quote(cwd or os.getcwd())))
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if self.dry_run:
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return
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if silent_unless_error:
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stdout, stderr = subprocess.PIPE, subprocess.STDOUT
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else:
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stdout, stderr = None, None
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# Don't use subprocess.run because it's >= py3.5 only, and it's not too
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# much extra effort to get what it gives us anyway.
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popen = subprocess.Popen(
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cmd,
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stdin=subprocess.DEVNULL,
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stdout=stdout,
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stderr=stderr,
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cwd=cwd)
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stdout, _ = popen.communicate()
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return_code = popen.wait(timeout=0)
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if not return_code:
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return
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if silent_unless_error:
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print(stdout.decode('utf-8', 'ignore'))
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if check:
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raise subprocess.CalledProcessError(
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returncode=return_code, cmd=cmd, output=stdout, stderr=None)
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def _get_default_cmake_invocation(env):
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inv = CmakeInvocation(
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cmake='cmake', maker=env.get_cmake_maker(), cmake_dir=env.llvm_dir)
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for key, value in env.get_default_cmake_args_kv():
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inv.add_new_flag(key, value)
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return inv
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def _get_cmake_invocation_for_bootstrap_from(env, out_dir,
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skip_tablegens=True):
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clang = os.path.join(out_dir, 'bin', 'clang')
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cmake = _get_default_cmake_invocation(env)
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cmake.add_new_flag('CMAKE_C_COMPILER', clang)
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cmake.add_new_flag('CMAKE_CXX_COMPILER', clang + '++')
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# We often get no value out of building new tblgens; the previous build
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# should have them. It's still correct to build them, just slower.
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def add_tablegen(key, binary):
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path = os.path.join(out_dir, 'bin', binary)
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# Check that this exists, since the user's allowed to specify their own
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# stage1 directory (which is generally where we'll source everything
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# from). Dry runs should hope for the best from our user, as well.
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if env.dry_run or os.path.exists(path):
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cmake.add_new_flag(key, path)
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if skip_tablegens:
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add_tablegen('LLVM_TABLEGEN', 'llvm-tblgen')
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add_tablegen('CLANG_TABLEGEN', 'clang-tblgen')
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return cmake
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def _build_things_in(env, target_dir, what):
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cmd = env.get_make_command() + what
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env.run_command(cmd, cwd=target_dir, check=True)
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def _run_fresh_cmake(env, cmake, target_dir):
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if not env.dry_run:
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try:
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shutil.rmtree(target_dir)
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except FileNotFoundError:
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pass
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os.makedirs(target_dir, mode=0o755)
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cmake_args = cmake.to_args()
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env.run_command(
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cmake_args, cwd=target_dir, check=True, silent_unless_error=True)
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def _build_stage1_clang(env):
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target_dir = env.output_subdir('stage1')
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cmake = _get_default_cmake_invocation(env)
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_run_fresh_cmake(env, cmake, target_dir)
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_build_things_in(env, target_dir, what=['clang', 'llvm-profdata', 'profile'])
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return target_dir
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def _generate_instrumented_clang_profile(env, stage1_dir, profile_dir,
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output_file):
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llvm_profdata = os.path.join(stage1_dir, 'bin', 'llvm-profdata')
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if env.dry_run:
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profiles = [os.path.join(profile_dir, '*.profraw')]
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else:
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profiles = [
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os.path.join(profile_dir, f) for f in os.listdir(profile_dir)
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if f.endswith('.profraw')
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]
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cmd = [llvm_profdata, 'merge', '-output=' + output_file] + profiles
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env.run_command(cmd, check=True)
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def _build_instrumented_clang(env, stage1_dir):
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assert os.path.isabs(stage1_dir)
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target_dir = os.path.join(env.output_dir, 'instrumented')
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cmake = _get_cmake_invocation_for_bootstrap_from(env, stage1_dir)
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cmake.add_new_flag('LLVM_BUILD_INSTRUMENTED', 'IR')
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# libcxx's configure step messes with our link order: we'll link
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# libclang_rt.profile after libgcc, and the former requires atexit from the
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# latter. So, configure checks fail.
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#
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# Since we don't need libcxx or compiler-rt anyway, just disable them.
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cmake.add_new_flag('LLVM_BUILD_RUNTIME', 'No')
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_run_fresh_cmake(env, cmake, target_dir)
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_build_things_in(env, target_dir, what=['clang', 'lld'])
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profiles_dir = os.path.join(target_dir, 'profiles')
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return target_dir, profiles_dir
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def _build_optimized_clang(env, stage1_dir, profdata_file):
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if not env.dry_run and not os.path.exists(profdata_file):
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raise ValueError('Looks like the profdata file at %s doesn\'t exist' %
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profdata_file)
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target_dir = os.path.join(env.output_dir, 'optimized')
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cmake = _get_cmake_invocation_for_bootstrap_from(env, stage1_dir)
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cmake.add_new_flag('LLVM_PROFDATA_FILE', os.path.abspath(profdata_file))
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# We'll get complaints about hash mismatches in `main` in tools/etc. Ignore
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# it.
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cmake.add_cflags(['-Wno-backend-plugin'])
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_run_fresh_cmake(env, cmake, target_dir)
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_build_things_in(env, target_dir, what=['clang'])
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return target_dir
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Args = collections.namedtuple('Args', [
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'do_optimized_build',
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'include_debug_info',
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'profile_location',
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'stage1_dir',
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])
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def _parse_args():
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parser = argparse.ArgumentParser(
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description='Builds LLVM and Clang with instrumentation, collects '
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'instrumentation profiles for them, and (optionally) builds things'
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'with these PGO profiles. By default, it\'s assumed that you\'re '
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'running this from your LLVM root, and all build artifacts will be '
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'saved to $PWD/out.')
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parser.add_argument(
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'--cmake-extra-arg',
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action='append',
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default=[],
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help='an extra arg to pass to all cmake invocations. Note that this '
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'is interpreted as a -D argument, e.g. --cmake-extra-arg FOO=BAR will '
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'be passed as -DFOO=BAR. This may be specified multiple times.')
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parser.add_argument(
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'--dry-run',
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action='store_true',
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help='print commands instead of running them')
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parser.add_argument(
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'--llvm-dir',
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default='.',
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help='directory containing an LLVM checkout (default: $PWD)')
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parser.add_argument(
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'--no-optimized-build',
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action='store_true',
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help='disable the final, PGO-optimized build')
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parser.add_argument(
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'--out-dir',
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help='directory to write artifacts to (default: $llvm_dir/out)')
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parser.add_argument(
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'--profile-output',
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help='where to output the profile (default is $out/pgo_profile.prof)')
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parser.add_argument(
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'--stage1-dir',
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help='instead of having an initial build of everything, use the given '
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'directory. It is expected that this directory will have clang, '
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'llvm-profdata, and the appropriate libclang_rt.profile already built')
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parser.add_argument(
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'--use-debug-info-in-benchmark',
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action='store_true',
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help='use a regular build instead of RelWithDebInfo in the benchmark. '
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'This increases benchmark execution time and disk space requirements, '
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'but gives more coverage over debuginfo bits in LLVM and clang.')
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parser.add_argument(
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'--use-make',
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action='store_true',
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default=shutil.which('ninja') is None,
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help='use Makefiles instead of ninja')
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args = parser.parse_args()
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llvm_dir = os.path.abspath(args.llvm_dir)
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if args.out_dir is None:
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output_dir = os.path.join(llvm_dir, 'out')
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else:
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output_dir = os.path.abspath(args.out_dir)
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extra_args = {'CMAKE_BUILD_TYPE': 'Release',
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'LLVM_ENABLE_PROJECTS': 'clang;compiler-rt;lld'}
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for arg in args.cmake_extra_arg:
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if arg.startswith('-D'):
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arg = arg[2:]
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elif arg.startswith('-'):
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raise ValueError('Unknown not- -D arg encountered; you may need '
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'to tweak the source...')
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split = arg.split('=', 1)
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if len(split) == 1:
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key, val = split[0], ''
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else:
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key, val = split
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extra_args[key] = val
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env = Env(
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default_cmake_args=extra_args,
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dry_run=args.dry_run,
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llvm_dir=llvm_dir,
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output_dir=output_dir,
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use_make=args.use_make,
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)
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if args.profile_output is not None:
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profile_location = args.profile_output
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else:
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profile_location = os.path.join(env.output_dir, 'pgo_profile.prof')
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result_args = Args(
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do_optimized_build=not args.no_optimized_build,
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include_debug_info=args.use_debug_info_in_benchmark,
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profile_location=profile_location,
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stage1_dir=args.stage1_dir,
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)
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return env, result_args
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def _looks_like_llvm_dir(directory):
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"""Arbitrary set of heuristics to determine if `directory` is an llvm dir.
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Errs on the side of false-positives."""
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contents = set(os.listdir(directory))
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expected_contents = [
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'CODE_OWNERS.TXT',
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'cmake',
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'docs',
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'include',
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'utils',
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]
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if not all(c in contents for c in expected_contents):
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return False
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try:
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include_listing = os.listdir(os.path.join(directory, 'include'))
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except NotADirectoryError:
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return False
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return 'llvm' in include_listing
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def _die(*args, **kwargs):
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kwargs['file'] = sys.stderr
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print(*args, **kwargs)
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sys.exit(1)
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def _main():
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env, args = _parse_args()
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if not _looks_like_llvm_dir(env.llvm_dir):
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_die('Looks like %s isn\'t an LLVM directory; please see --help' %
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env.llvm_dir)
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if not env.has_llvm_subproject('clang'):
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_die('Need a clang checkout at tools/clang')
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if not env.has_llvm_subproject('compiler-rt'):
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_die('Need a compiler-rt checkout at projects/compiler-rt')
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def status(*args):
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print(*args, file=sys.stderr)
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if args.stage1_dir is None:
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status('*** Building stage1 clang...')
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stage1_out = _build_stage1_clang(env)
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else:
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stage1_out = args.stage1_dir
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status('*** Building instrumented clang...')
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instrumented_out, profile_dir = _build_instrumented_clang(env, stage1_out)
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status('*** Running profdata benchmarks...')
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_run_benchmark(env, instrumented_out, args.include_debug_info)
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status('*** Generating profile...')
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_generate_instrumented_clang_profile(env, stage1_out, profile_dir,
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args.profile_location)
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print('Final profile:', args.profile_location)
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if args.do_optimized_build:
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status('*** Building PGO-optimized binaries...')
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optimized_out = _build_optimized_clang(env, stage1_out,
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args.profile_location)
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print('Final build directory:', optimized_out)
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if __name__ == '__main__':
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_main()
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