Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 841 insertions, 0 deletions

diff --git a/build/build-clang/build-clang.py b/build/build-clang/build-clang.py
new file mode 100755
index 0000000000..5345b0a3cb
--- /dev/null
+++ b/build/build-clang/build-clang.py
@@ -0,0 +1,841 @@
+#!/usr/bin/python3
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Only necessary for flake8 to be happy...
+import argparse
+import errno
+import fnmatch
+import glob
+import json
+import os
+import os.path
+import platform
+import re
+import shutil
+import subprocess
+import sys
+import tarfile
+from contextlib import contextmanager
+from shutil import which
+
+import zstandard
+
+
+def is_llvm_toolchain(cc, cxx):
+    return "clang" in cc and "clang" in cxx
+
+
+def check_run(args):
+    print(" ".join(args), file=sys.stderr, flush=True)
+    if args[0] == "cmake":
+        # CMake `message(STATUS)` messages, as appearing in failed source code
+        # compiles, appear on stdout, so we only capture that.
+        p = subprocess.Popen(args, stdout=subprocess.PIPE)
+        lines = []
+        for line in p.stdout:
+            lines.append(line)
+            sys.stdout.write(line.decode())
+            sys.stdout.flush()
+        r = p.wait()
+        if r != 0 and os.environ.get("UPLOAD_DIR"):
+            cmake_output_re = re.compile(b'See also "(.*/CMakeOutput.log)"')
+            cmake_error_re = re.compile(b'See also "(.*/CMakeError.log)"')
+
+            def find_first_match(re):
+                for l in lines:
+                    match = re.search(l)
+                    if match:
+                        return match
+
+            output_match = find_first_match(cmake_output_re)
+            error_match = find_first_match(cmake_error_re)
+
+            upload_dir = os.environ["UPLOAD_DIR"].encode("utf-8")
+            if output_match or error_match:
+                mkdir_p(upload_dir)
+            if output_match:
+                shutil.copy2(output_match.group(1), upload_dir)
+            if error_match:
+                shutil.copy2(error_match.group(1), upload_dir)
+    else:
+        r = subprocess.call(args)
+    assert r == 0
+
+
+def run_in(path, args):
+    with chdir(path):
+        check_run(args)
+
+
+@contextmanager
+def chdir(path):
+    d = os.getcwd()
+    print('cd "%s"' % path, file=sys.stderr)
+    os.chdir(path)
+    try:
+        yield
+    finally:
+        print('cd "%s"' % d, file=sys.stderr)
+        os.chdir(d)
+
+
+def patch(patch, srcdir):
+    patch = os.path.realpath(patch)
+    check_run(["patch", "-d", srcdir, "-p1", "-i", patch, "--fuzz=0", "-s"])
+
+
+def import_clang_tidy(source_dir, build_clang_tidy_alpha, build_clang_tidy_external):
+    clang_plugin_path = os.path.join(os.path.dirname(sys.argv[0]), "..", "clang-plugin")
+    clang_tidy_path = os.path.join(source_dir, "clang-tools-extra/clang-tidy")
+    sys.path.append(clang_plugin_path)
+    from import_mozilla_checks import do_import
+
+    import_options = {
+        "alpha": build_clang_tidy_alpha,
+        "external": build_clang_tidy_external,
+    }
+    do_import(clang_plugin_path, clang_tidy_path, import_options)
+
+
+def build_package(package_build_dir, cmake_args):
+    if not os.path.exists(package_build_dir):
+        os.mkdir(package_build_dir)
+    # If CMake has already been run, it may have been run with different
+    # arguments, so we need to re-run it.  Make sure the cached copy of the
+    # previous CMake run is cleared before running it again.
+    if os.path.exists(package_build_dir + "/CMakeCache.txt"):
+        os.remove(package_build_dir + "/CMakeCache.txt")
+    if os.path.exists(package_build_dir + "/CMakeFiles"):
+        shutil.rmtree(package_build_dir + "/CMakeFiles")
+
+    run_in(package_build_dir, ["cmake"] + cmake_args)
+    run_in(package_build_dir, ["ninja", "install", "-v"])
+
+
+@contextmanager
+def updated_env(env):
+    old_env = os.environ.copy()
+    os.environ.update(env)
+    yield
+    os.environ.clear()
+    os.environ.update(old_env)
+
+
+def build_tar_package(name, base, directory):
+    name = os.path.realpath(name)
+    print("tarring {} from {}/{}".format(name, base, directory), file=sys.stderr)
+    assert name.endswith(".tar.zst")
+
+    cctx = zstandard.ZstdCompressor()
+    with open(name, "wb") as f, cctx.stream_writer(f) as z:
+        with tarfile.open(mode="w|", fileobj=z) as tf:
+            with chdir(base):
+                tf.add(directory)
+
+
+def mkdir_p(path):
+    try:
+        os.makedirs(path)
+    except OSError as e:
+        if e.errno != errno.EEXIST or not os.path.isdir(path):
+            raise
+
+
+def delete(path):
+    if os.path.isdir(path):
+        shutil.rmtree(path)
+    else:
+        try:
+            os.unlink(path)
+        except Exception:
+            pass
+
+
+def install_import_library(build_dir, clang_dir):
+    shutil.copy2(
+        os.path.join(build_dir, "lib", "clang.lib"), os.path.join(clang_dir, "lib")
+    )
+
+
+def is_darwin():
+    return platform.system() == "Darwin"
+
+
+def is_linux():
+    return platform.system() == "Linux"
+
+
+def is_windows():
+    return platform.system() == "Windows"
+
+
+def build_one_stage(
+    cc,
+    cxx,
+    asm,
+    ar,
+    ranlib,
+    libtool,
+    ldflags,
+    src_dir,
+    stage_dir,
+    package_name,
+    osx_cross_compile,
+    build_type,
+    assertions,
+    targets,
+    is_final_stage=False,
+    profile=None,
+):
+    if not os.path.exists(stage_dir):
+        os.mkdir(stage_dir)
+
+    build_dir = stage_dir + "/build"
+    inst_dir = stage_dir + "/" + package_name
+
+    # cmake doesn't deal well with backslashes in paths.
+    def slashify_path(path):
+        return path.replace("\\", "/")
+
+    def cmake_base_args(cc, cxx, asm, ar, ranlib, libtool, ldflags, inst_dir):
+        machine_targets = targets if is_final_stage and targets else "X86"
+
+        cmake_args = [
+            "-GNinja",
+            "-DCMAKE_C_COMPILER=%s" % slashify_path(cc[0]),
+            "-DCMAKE_CXX_COMPILER=%s" % slashify_path(cxx[0]),
+            "-DCMAKE_ASM_COMPILER=%s" % slashify_path(asm[0]),
+            "-DCMAKE_AR=%s" % slashify_path(ar),
+            "-DCMAKE_C_FLAGS=%s" % " ".join(cc[1:]),
+            "-DCMAKE_CXX_FLAGS=%s" % " ".join(cxx[1:]),
+            "-DCMAKE_ASM_FLAGS=%s" % " ".join(asm[1:]),
+            "-DCMAKE_EXE_LINKER_FLAGS=%s" % " ".join(ldflags),
+            "-DCMAKE_SHARED_LINKER_FLAGS=%s" % " ".join(ldflags),
+            "-DCMAKE_BUILD_TYPE=%s" % build_type,
+            "-DCMAKE_INSTALL_PREFIX=%s" % inst_dir,
+            "-DLLVM_TARGETS_TO_BUILD=%s" % machine_targets,
+            "-DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF",
+            "-DLLVM_ENABLE_ASSERTIONS=%s" % ("ON" if assertions else "OFF"),
+            "-DLLVM_ENABLE_BINDINGS=OFF",
+            "-DLLVM_ENABLE_CURL=OFF",
+            "-DLLVM_INCLUDE_TESTS=OFF",
+        ]
+        if is_llvm_toolchain(cc[0], cxx[0]):
+            cmake_args += ["-DLLVM_ENABLE_LLD=ON"]
+
+        if "TASK_ID" in os.environ:
+            cmake_args += [
+                "-DCLANG_REPOSITORY_STRING=taskcluster-%s" % os.environ["TASK_ID"],
+            ]
+        projects = ["clang", "lld"]
+        if is_final_stage:
+            projects.append("clang-tools-extra")
+        else:
+            cmake_args.append("-DLLVM_TOOL_LLI_BUILD=OFF")
+
+        cmake_args.append("-DLLVM_ENABLE_PROJECTS=%s" % ";".join(projects))
+
+        # There is no libxml2 on Windows except if we build one ourselves.
+        # libxml2 is only necessary for llvm-mt, but Windows can just use the
+        # native MT tool.
+        if not is_windows() and is_final_stage:
+            cmake_args += ["-DLLVM_ENABLE_LIBXML2=FORCE_ON"]
+        if is_linux() and not osx_cross_compile and is_final_stage:
+            sysroot = os.path.join(os.environ.get("MOZ_FETCHES_DIR", ""), "sysroot")
+            if os.path.exists(sysroot):
+                cmake_args += ["-DLLVM_BINUTILS_INCDIR=/usr/include"]
+                cmake_args += ["-DCMAKE_SYSROOT=%s" % sysroot]
+                # Work around the LLVM build system not building the i386 compiler-rt
+                # because it doesn't allow to use a sysroot for that during the cmake
+                # checks.
+                cmake_args += ["-DCAN_TARGET_i386=1"]
+        if is_windows():
+            cmake_args.insert(-1, "-DLLVM_EXPORT_SYMBOLS_FOR_PLUGINS=ON")
+            cmake_args.insert(-1, "-DLLVM_USE_CRT_RELEASE=MT")
+        else:
+            # libllvm as a shared library is not supported on Windows
+            cmake_args += ["-DLLVM_LINK_LLVM_DYLIB=ON"]
+        if ranlib is not None:
+            cmake_args += ["-DCMAKE_RANLIB=%s" % slashify_path(ranlib)]
+        if libtool is not None:
+            cmake_args += ["-DCMAKE_LIBTOOL=%s" % slashify_path(libtool)]
+        if osx_cross_compile:
+            arch = "arm64" if os.environ.get("OSX_ARCH") == "arm64" else "x86_64"
+            target_cpu = (
+                "aarch64" if os.environ.get("OSX_ARCH") == "arm64" else "x86_64"
+            )
+            cmake_args += [
+                "-DCMAKE_SYSTEM_NAME=Darwin",
+                "-DCMAKE_SYSTEM_VERSION=%s" % os.environ["MACOSX_DEPLOYMENT_TARGET"],
+                "-DCMAKE_OSX_SYSROOT=%s" % slashify_path(os.getenv("CROSS_SYSROOT")),
+                "-DCMAKE_FIND_ROOT_PATH=%s" % slashify_path(os.getenv("CROSS_SYSROOT")),
+                "-DCMAKE_FIND_ROOT_PATH_MODE_PROGRAM=NEVER",
+                "-DCMAKE_FIND_ROOT_PATH_MODE_LIBRARY=ONLY",
+                "-DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE=ONLY",
+                "-DCMAKE_MACOSX_RPATH=ON",
+                "-DCMAKE_OSX_ARCHITECTURES=%s" % arch,
+                "-DDARWIN_osx_ARCHS=%s" % arch,
+                "-DDARWIN_osx_SYSROOT=%s" % slashify_path(os.getenv("CROSS_SYSROOT")),
+                "-DLLVM_DEFAULT_TARGET_TRIPLE=%s-apple-darwin" % target_cpu,
+                "-DCMAKE_C_COMPILER_TARGET=%s-apple-darwin" % target_cpu,
+                "-DCMAKE_CXX_COMPILER_TARGET=%s-apple-darwin" % target_cpu,
+                "-DCMAKE_ASM_COMPILER_TARGET=%s-apple-darwin" % target_cpu,
+            ]
+            if os.environ.get("OSX_ARCH") == "arm64":
+                cmake_args += [
+                    "-DDARWIN_osx_BUILTIN_ARCHS=arm64",
+                ]
+            # Starting in LLVM 11 (which requires SDK 10.12) the build tries to
+            # detect the SDK version by calling xcrun. Cross-compiles don't have
+            # an xcrun, so we have to set the version explicitly.
+            cmake_args += [
+                "-DDARWIN_macosx_OVERRIDE_SDK_VERSION=%s"
+                % os.environ["MACOSX_DEPLOYMENT_TARGET"],
+            ]
+        if profile == "gen":
+            # Per https://releases.llvm.org/10.0.0/docs/HowToBuildWithPGO.html
+            cmake_args += [
+                "-DLLVM_BUILD_INSTRUMENTED=IR",
+                "-DLLVM_BUILD_RUNTIME=No",
+            ]
+        elif profile:
+            cmake_args += [
+                "-DLLVM_PROFDATA_FILE=%s" % profile,
+            ]
+        return cmake_args
+
+    cmake_args = []
+    cmake_args += cmake_base_args(cc, cxx, asm, ar, ranlib, libtool, ldflags, inst_dir)
+    cmake_args += [src_dir]
+    build_package(build_dir, cmake_args)
+
+    # For some reasons the import library clang.lib of clang.exe is not
+    # installed, so we copy it by ourselves.
+    if is_windows() and is_final_stage:
+        install_import_library(build_dir, inst_dir)
+
+
+# Return the absolute path of a build tool.  We first look to see if the
+# variable is defined in the config file, and if so we make sure it's an
+# absolute path to an existing tool, otherwise we look for a program in
+# $PATH named "key".
+#
+# This expects the name of the key in the config file to match the name of
+# the tool in the default toolchain on the system (for example, "ld" on Unix
+# and "link" on Windows).
+def get_tool(config, key):
+    f = None
+    if key in config:
+        f = config[key].format(**os.environ)
+        if os.path.isabs(f):
+            if not os.path.exists(f):
+                raise ValueError("%s must point to an existing path" % key)
+            return f
+
+    # Assume that we have the name of some program that should be on PATH.
+    tool = which(f) if f else which(key)
+    if not tool:
+        raise ValueError("%s not found on PATH" % (f or key))
+    return tool
+
+
+# This function is intended to be called on the final build directory when
+# building clang-tidy. Also clang-format binaries are included that can be used
+# in conjunction with clang-tidy.
+# As a separate binary we also ship clangd for the language server protocol that
+# can be used as a plugin in `vscode`.
+# Its job is to remove all of the files which won't be used for clang-tidy or
+# clang-format to reduce the download size.  Currently when this function
+# finishes its job, it will leave final_dir with a layout like this:
+#
+# clang/
+#   bin/
+#     clang-apply-replacements
+#     clang-format
+#     clang-tidy
+#     clangd
+#     run-clang-tidy
+#   include/
+#     * (nothing will be deleted here)
+#   lib/
+#     clang/
+#       4.0.0/
+#         include/
+#           * (nothing will be deleted here)
+#   share/
+#     clang/
+#       clang-format-diff.py
+#       clang-tidy-diff.py
+#       run-clang-tidy.py
+def prune_final_dir_for_clang_tidy(final_dir, osx_cross_compile):
+    # Make sure we only have what we expect.
+    dirs = [
+        "bin",
+        "include",
+        "lib",
+        "lib32",
+        "libexec",
+        "msbuild-bin",
+        "share",
+        "tools",
+    ]
+    if is_linux():
+        dirs.append("x86_64-unknown-linux-gnu")
+    for f in glob.glob("%s/*" % final_dir):
+        if os.path.basename(f) not in dirs:
+            raise Exception("Found unknown file %s in the final directory" % f)
+        if not os.path.isdir(f):
+            raise Exception("Expected %s to be a directory" % f)
+
+    kept_binaries = [
+        "clang-apply-replacements",
+        "clang-format",
+        "clang-tidy",
+        "clangd",
+        "clang-query",
+        "run-clang-tidy",
+    ]
+    re_clang_tidy = re.compile(r"^(" + "|".join(kept_binaries) + r")(\.exe)?$", re.I)
+    for f in glob.glob("%s/bin/*" % final_dir):
+        if re_clang_tidy.search(os.path.basename(f)) is None:
+            delete(f)
+
+    # Keep include/ intact.
+
+    # Remove the target-specific files.
+    if is_linux():
+        if os.path.exists(os.path.join(final_dir, "x86_64-unknown-linux-gnu")):
+            shutil.rmtree(os.path.join(final_dir, "x86_64-unknown-linux-gnu"))
+
+    # In lib/, only keep lib/clang/N.M.O/include and the LLVM shared library.
+    re_ver_num = re.compile(r"^\d+\.\d+\.\d+$", re.I)
+    for f in glob.glob("%s/lib/*" % final_dir):
+        name = os.path.basename(f)
+        if name == "clang":
+            continue
+        if osx_cross_compile and name in ["libLLVM.dylib", "libclang-cpp.dylib"]:
+            continue
+        if is_linux() and (
+            fnmatch.fnmatch(name, "libLLVM*.so")
+            or fnmatch.fnmatch(name, "libclang-cpp.so*")
+        ):
+            continue
+        delete(f)
+    for f in glob.glob("%s/lib/clang/*" % final_dir):
+        if re_ver_num.search(os.path.basename(f)) is None:
+            delete(f)
+    for f in glob.glob("%s/lib/clang/*/*" % final_dir):
+        if os.path.basename(f) != "include":
+            delete(f)
+
+    # Completely remove libexec/, msbuild-bin and tools, if it exists.
+    shutil.rmtree(os.path.join(final_dir, "libexec"))
+    for d in ("msbuild-bin", "tools"):
+        d = os.path.join(final_dir, d)
+        if os.path.exists(d):
+            shutil.rmtree(d)
+
+    # In share/, only keep share/clang/*tidy*
+    re_clang_tidy = re.compile(r"format|tidy", re.I)
+    for f in glob.glob("%s/share/*" % final_dir):
+        if os.path.basename(f) != "clang":
+            delete(f)
+    for f in glob.glob("%s/share/clang/*" % final_dir):
+        if re_clang_tidy.search(os.path.basename(f)) is None:
+            delete(f)
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "-c",
+        "--config",
+        action="append",
+        required=True,
+        type=argparse.FileType("r"),
+        help="Clang configuration file",
+    )
+    parser.add_argument(
+        "--clean", required=False, action="store_true", help="Clean the build directory"
+    )
+    parser.add_argument(
+        "--skip-tar",
+        required=False,
+        action="store_true",
+        help="Skip tar packaging stage",
+    )
+    parser.add_argument(
+        "--skip-patch",
+        required=False,
+        action="store_true",
+        help="Do not patch source",
+    )
+
+    args = parser.parse_args()
+
+    if not os.path.exists("llvm/README.txt"):
+        raise Exception(
+            "The script must be run from the root directory of the llvm-project tree"
+        )
+    source_dir = os.getcwd()
+    build_dir = source_dir + "/build"
+
+    if args.clean:
+        shutil.rmtree(build_dir)
+        os.sys.exit(0)
+
+    llvm_source_dir = source_dir + "/llvm"
+
+    exe_ext = ""
+    if is_windows():
+        exe_ext = ".exe"
+
+    cc_name = "clang"
+    cxx_name = "clang++"
+    if is_windows():
+        cc_name = "clang-cl"
+        cxx_name = "clang-cl"
+
+    config = {}
+    # Merge all the configs we got from the command line.
+    for c in args.config:
+        this_config_dir = os.path.dirname(c.name)
+        this_config = json.load(c)
+        patches = this_config.get("patches")
+        if patches:
+            this_config["patches"] = [os.path.join(this_config_dir, p) for p in patches]
+        for key, value in this_config.items():
+            old_value = config.get(key)
+            if old_value is None:
+                config[key] = value
+            elif value is None:
+                if key in config:
+                    del config[key]
+            elif type(old_value) != type(value):
+                raise Exception(
+                    "{} is overriding `{}` with a value of the wrong type".format(
+                        c.name, key
+                    )
+                )
+            elif isinstance(old_value, list):
+                for v in value:
+                    if v not in old_value:
+                        old_value.append(v)
+            elif isinstance(old_value, dict):
+                raise Exception("{} is setting `{}` to a dict?".format(c.name, key))
+            else:
+                config[key] = value
+
+    stages = 2
+    if "stages" in config:
+        stages = int(config["stages"])
+        if stages not in (1, 2, 3, 4):
+            raise ValueError("We only know how to build 1, 2, 3, or 4 stages.")
+    skip_stages = 0
+    if "skip_stages" in config:
+        # The assumption here is that the compiler given in `cc` and other configs
+        # is the result of the last skip stage, built somewhere else.
+        skip_stages = int(config["skip_stages"])
+        if skip_stages >= stages:
+            raise ValueError("Cannot skip more stages than are built.")
+    pgo = False
+    if "pgo" in config:
+        pgo = config["pgo"]
+        if pgo not in (True, False):
+            raise ValueError("Only boolean values are accepted for pgo.")
+    build_type = "Release"
+    if "build_type" in config:
+        build_type = config["build_type"]
+        if build_type not in ("Release", "Debug", "RelWithDebInfo", "MinSizeRel"):
+            raise ValueError(
+                "We only know how to do Release, Debug, RelWithDebInfo or "
+                "MinSizeRel builds"
+            )
+    targets = config.get("targets")
+    build_clang_tidy = False
+    if "build_clang_tidy" in config:
+        build_clang_tidy = config["build_clang_tidy"]
+        if build_clang_tidy not in (True, False):
+            raise ValueError("Only boolean values are accepted for build_clang_tidy.")
+    build_clang_tidy_alpha = False
+    # check for build_clang_tidy_alpha only if build_clang_tidy is true
+    if build_clang_tidy and "build_clang_tidy_alpha" in config:
+        build_clang_tidy_alpha = config["build_clang_tidy_alpha"]
+        if build_clang_tidy_alpha not in (True, False):
+            raise ValueError(
+                "Only boolean values are accepted for build_clang_tidy_alpha."
+            )
+    build_clang_tidy_external = False
+    # check for build_clang_tidy_external only if build_clang_tidy is true
+    if build_clang_tidy and "build_clang_tidy_external" in config:
+        build_clang_tidy_external = config["build_clang_tidy_external"]
+        if build_clang_tidy_external not in (True, False):
+            raise ValueError(
+                "Only boolean values are accepted for build_clang_tidy_external."
+            )
+    osx_cross_compile = False
+    if "osx_cross_compile" in config:
+        osx_cross_compile = config["osx_cross_compile"]
+        if osx_cross_compile not in (True, False):
+            raise ValueError("Only boolean values are accepted for osx_cross_compile.")
+        if osx_cross_compile and not is_linux():
+            raise ValueError("osx_cross_compile can only be used on Linux.")
+    assertions = False
+    if "assertions" in config:
+        assertions = config["assertions"]
+        if assertions not in (True, False):
+            raise ValueError("Only boolean values are accepted for assertions.")
+
+    if is_darwin() or osx_cross_compile:
+        os.environ["MACOSX_DEPLOYMENT_TARGET"] = (
+            "11.0" if os.environ.get("OSX_ARCH") == "arm64" else "10.12"
+        )
+
+    cc = get_tool(config, "cc")
+    cxx = get_tool(config, "cxx")
+    asm = get_tool(config, "ml" if is_windows() else "as")
+    # Not using lld here as default here because it's not in PATH. But clang
+    # knows how to find it when they are installed alongside each others.
+    ar = get_tool(config, "lib" if is_windows() else "ar")
+    ranlib = None if is_windows() else get_tool(config, "ranlib")
+    libtool = None
+    if "libtool" in config:
+        libtool = get_tool(config, "libtool")
+
+    if not os.path.exists(source_dir):
+        os.makedirs(source_dir)
+
+    if not args.skip_patch:
+        for p in config.get("patches", []):
+            patch(p, source_dir)
+
+    package_name = "clang"
+    if build_clang_tidy:
+        package_name = "clang-tidy"
+        if not args.skip_patch:
+            import_clang_tidy(
+                source_dir, build_clang_tidy_alpha, build_clang_tidy_external
+            )
+
+    if not os.path.exists(build_dir):
+        os.makedirs(build_dir)
+
+    stage1_dir = build_dir + "/stage1"
+    stage1_inst_dir = stage1_dir + "/" + package_name
+
+    final_stage_dir = stage1_dir
+
+    if is_darwin():
+        extra_cflags = []
+        extra_cxxflags = []
+        extra_cflags2 = []
+        extra_cxxflags2 = []
+        extra_asmflags = []
+        extra_ldflags = []
+    elif is_linux():
+        extra_cflags = []
+        extra_cxxflags = []
+        extra_cflags2 = ["-fPIC"]
+        # Silence clang's warnings about arguments not being used in compilation.
+        extra_cxxflags2 = [
+            "-fPIC",
+            "-Qunused-arguments",
+        ]
+        extra_asmflags = []
+        # Avoid libLLVM internal function calls going through the PLT.
+        extra_ldflags = ["-Wl,-Bsymbolic-functions"]
+        # For whatever reason, LLVM's build system will set things up to turn
+        # on -ffunction-sections and -fdata-sections, but won't turn on the
+        # corresponding option to strip unused sections.  We do it explicitly
+        # here.  LLVM's build system is also picky about turning on ICF, so
+        # we do that explicitly here, too.
+
+        # It's unfortunately required to specify the linker used here because
+        # the linker flags are used in LLVM's configure step before
+        # -DLLVM_ENABLE_LLD is actually processed.
+        if is_llvm_toolchain(cc, cxx):
+            extra_ldflags += ["-fuse-ld=lld", "-Wl,--icf=safe"]
+        extra_ldflags += ["-Wl,--gc-sections"]
+    elif is_windows():
+        extra_cflags = []
+        extra_cxxflags = []
+        # clang-cl would like to figure out what it's supposed to be emulating
+        # by looking at an MSVC install, but we don't really have that here.
+        # Force things on based on WinMsvc.cmake.
+        # Ideally, we'd just use WinMsvc.cmake as a toolchain file, but it only
+        # really works for cross-compiles, which this is not.
+        with open(os.path.join(llvm_source_dir, "cmake/platforms/WinMsvc.cmake")) as f:
+            compat = [
+                item
+                for line in f
+                for item in line.split()
+                if "-fms-compatibility-version=" in item
+            ][0]
+        extra_cflags2 = [compat]
+        extra_cxxflags2 = [compat]
+        extra_asmflags = []
+        extra_ldflags = []
+
+    if osx_cross_compile:
+        # undo the damage done in the is_linux() block above, and also simulate
+        # the is_darwin() block above.
+        extra_cflags = []
+        extra_cxxflags = []
+        extra_cxxflags2 = []
+
+        extra_flags = [
+            "-mlinker-version=137",
+            "-B",
+            "%s/bin" % os.getenv("CROSS_CCTOOLS_PATH"),
+            "-isysroot",
+            os.getenv("CROSS_SYSROOT"),
+            # technically the sysroot flag there should be enough to deduce this,
+            # but clang needs some help to figure this out.
+            "-I%s/usr/include" % os.getenv("CROSS_SYSROOT"),
+            "-iframework",
+            "%s/System/Library/Frameworks" % os.getenv("CROSS_SYSROOT"),
+        ]
+        extra_cflags += extra_flags
+        extra_cxxflags += extra_flags
+        extra_cflags2 += extra_flags
+        extra_cxxflags2 += extra_flags
+        extra_asmflags += extra_flags
+        extra_ldflags = [
+            "-Wl,-syslibroot,%s" % os.getenv("CROSS_SYSROOT"),
+            "-Wl,-dead_strip",
+        ]
+
+    upload_dir = os.getenv("UPLOAD_DIR")
+    if assertions and upload_dir:
+        extra_cflags2 += ["-fcrash-diagnostics-dir=%s" % upload_dir]
+        extra_cxxflags2 += ["-fcrash-diagnostics-dir=%s" % upload_dir]
+
+    if skip_stages < 1:
+        build_one_stage(
+            [cc] + extra_cflags,
+            [cxx] + extra_cxxflags,
+            [asm] + extra_asmflags,
+            ar,
+            ranlib,
+            libtool,
+            extra_ldflags,
+            llvm_source_dir,
+            stage1_dir,
+            package_name,
+            osx_cross_compile,
+            build_type,
+            assertions,
+            targets,
+            is_final_stage=(stages == 1),
+        )
+
+    if stages >= 2 and skip_stages < 2:
+        stage2_dir = build_dir + "/stage2"
+        stage2_inst_dir = stage2_dir + "/" + package_name
+        final_stage_dir = stage2_dir
+        if skip_stages < 1:
+            cc = stage1_inst_dir + "/bin/%s%s" % (cc_name, exe_ext)
+            cxx = stage1_inst_dir + "/bin/%s%s" % (cxx_name, exe_ext)
+            asm = stage1_inst_dir + "/bin/%s%s" % (cc_name, exe_ext)
+        build_one_stage(
+            [cc] + extra_cflags2,
+            [cxx] + extra_cxxflags2,
+            [asm] + extra_asmflags,
+            ar,
+            ranlib,
+            libtool,
+            extra_ldflags,
+            llvm_source_dir,
+            stage2_dir,
+            package_name,
+            osx_cross_compile,
+            build_type,
+            assertions,
+            targets,
+            is_final_stage=(stages == 2),
+            profile="gen" if pgo else None,
+        )
+
+    if stages >= 3 and skip_stages < 3:
+        stage3_dir = build_dir + "/stage3"
+        stage3_inst_dir = stage3_dir + "/" + package_name
+        final_stage_dir = stage3_dir
+        if skip_stages < 2:
+            cc = stage2_inst_dir + "/bin/%s%s" % (cc_name, exe_ext)
+            cxx = stage2_inst_dir + "/bin/%s%s" % (cxx_name, exe_ext)
+            asm = stage2_inst_dir + "/bin/%s%s" % (cc_name, exe_ext)
+        build_one_stage(
+            [cc] + extra_cflags2,
+            [cxx] + extra_cxxflags2,
+            [asm] + extra_asmflags,
+            ar,
+            ranlib,
+            libtool,
+            extra_ldflags,
+            llvm_source_dir,
+            stage3_dir,
+            package_name,
+            osx_cross_compile,
+            build_type,
+            assertions,
+            targets,
+            (stages == 3),
+        )
+        if pgo:
+            llvm_profdata = stage2_inst_dir + "/bin/llvm-profdata%s" % exe_ext
+            merge_cmd = [llvm_profdata, "merge", "-o", "merged.profdata"]
+            profraw_files = glob.glob(
+                os.path.join(stage2_dir, "build", "profiles", "*.profraw")
+            )
+            run_in(stage3_dir, merge_cmd + profraw_files)
+            if stages == 3:
+                mkdir_p(upload_dir)
+                shutil.copy2(os.path.join(stage3_dir, "merged.profdata"), upload_dir)
+                return
+
+    if stages >= 4 and skip_stages < 4:
+        stage4_dir = build_dir + "/stage4"
+        final_stage_dir = stage4_dir
+        profile = None
+        if pgo:
+            if skip_stages == 3:
+                profile_dir = os.environ.get("MOZ_FETCHES_DIR", "")
+            else:
+                profile_dir = stage3_dir
+            profile = os.path.join(profile_dir, "merged.profdata")
+        if skip_stages < 3:
+            cc = stage3_inst_dir + "/bin/%s%s" % (cc_name, exe_ext)
+            cxx = stage3_inst_dir + "/bin/%s%s" % (cxx_name, exe_ext)
+            asm = stage3_inst_dir + "/bin/%s%s" % (cc_name, exe_ext)
+        build_one_stage(
+            [cc] + extra_cflags2,
+            [cxx] + extra_cxxflags2,
+            [asm] + extra_asmflags,
+            ar,
+            ranlib,
+            libtool,
+            extra_ldflags,
+            llvm_source_dir,
+            stage4_dir,
+            package_name,
+            osx_cross_compile,
+            build_type,
+            assertions,
+            targets,
+            (stages == 4),
+            profile=profile,
+        )
+
+    if build_clang_tidy:
+        prune_final_dir_for_clang_tidy(
+            os.path.join(final_stage_dir, package_name), osx_cross_compile
+        )
+
+    if not args.skip_tar:
+        build_tar_package("%s.tar.zst" % package_name, final_stage_dir, package_name)
+
+
+if __name__ == "__main__":
+    main()