flags.configure

# -*- Mode: python; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 40 -*-
# vim: set filetype=python:
# 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/.

# We support C++14, but we don't want to enable the sized deallocation
# facilities in C++14 yet.
check_and_add_flag("-fno-sized-deallocation", compiler=cxx_compiler)
# Likewise for C++17 and aligned allocation.  It's not immediately obvious
# from the clang and GCC documentation, but they both support this.
check_and_add_flag("-fno-aligned-new", compiler=cxx_compiler)

# Please keep these last in this file.
add_old_configure_assignment("_COMPILATION_CFLAGS", compilation_flags.cflags)
add_old_configure_assignment("_COMPILATION_CXXFLAGS", compilation_flags.cxxflags)
add_old_configure_assignment("_COMPILATION_HOST_CFLAGS", compilation_flags.host_cflags)
add_old_configure_assignment(
    "_COMPILATION_HOST_CXXFLAGS", compilation_flags.host_cxxflags
)


option(
    "--disable-new-pass-manager",
    help="Use the legacy LLVM pass manager in clang builds",
)


@depends(
    "--enable-new-pass-manager",
    c_compiler,
    host,
    target,
    "MOZ_PGO",
    enable_fuzzing,
    ubsan,
)
def pass_manager(enabled, compiler, host, target, pgo, enable_fuzzing, ubsan):
    if compiler.type not in ("clang", "clang-cl"):
        return None

    # As of clang 13, the default pass manager is the new one.
    if compiler.version >= "13.0.0":
        if enabled:
            return namespace(flags=None, enabled=True)
        if compiler.type == "clang":
            return namespace(flags=["-flegacy-pass-manager"], enabled=False)
        if compiler.type == "clang-cl":
            return namespace(flags=["-Xclang", "-flegacy-pass-manager"], enabled=False)

    if not enabled:
        if compiler.version >= "15.0.0":
            die("--disable-new-pass-manager is only supported with clang < 15")
        return None
    if compiler.version < "9.0.0":
        if enabled.origin != "default":
            die("--enable-new-pass-manager is only supported with clang >= 9")
        return None

    if host.os == "OSX":
        # Some native Mac builds hang with the new pass manager. Given the
        # inability to test in CI, don't take the risk of further breakage.
        if enabled.origin != "default":
            die(
                "--enable-new-pass-manager causes problems on mac hosts with clang < 13"
            )
        return None
    if target.os == "OSX" and not pgo:
        # Also disable when cross-compiling to Mac, because plain-ish opt
        # builds hang. Variants like asan and ccov work fine, but it would be
        # too tedious to test them all here. PGO is the only thing that matters
        # enough to make an exception for.
        if enabled.origin != "default":
            die(
                "--enable-new-pass-manager causes problems on mac builds with clang < 13"
            )
        return None
    if enable_fuzzing and compiler.version < "10.0.0":
        # Clang 9 does not seem to play well with libFuzzer
        if enabled.origin != "default":
            die(
                "--enable-new-pass-manager causes problems on fuzzing builds with clang < 10"
            )
        return None
    if ubsan and compiler.version == "10.0.0":
        # Clang 10.0.0 hangs with some ubsan-inserted code constructs.
        # This was fixed in 10.0.1 (https://llvm.org/pr45835)
        if enabled.origin != "default":
            die(
                "--enable-new-pass-manager causes problems with ubsan builds with clang 10.0.0"
            )
        return None
    if compiler.type == "clang":
        return namespace(flags=["-fexperimental-new-pass-manager"], enabled=True)
    elif compiler.type == "clang-cl":
        return namespace(
            flags=["-Xclang", "-fexperimental-new-pass-manager"], enabled=True
        )


set_config("MOZ_PASS_MANAGER_FLAGS", pass_manager.flags)


# Try to make builds more reproducible and allow sharing built artifacts across
# source and object directories by using -ffile-prefix-map and friends.  To
# "unwind" the prefix maps, use:
#
# (gdb) set substitute-path /topsrcdir/ $topsrcdir/
#
# (lldb) settings set target.source-map /topobjdir/ $topobjdir/
#
# See, for example, https://lldb.llvm.org/use/map.html.
@depends(
    path_remapping,
    path_remappings,
    c_compiler,
)
@imports(_from="os", _import="sep")
def file_prefix_map_flags(path_remapping, path_remappings, compiler):
    if "c" not in path_remapping:
        return []

    if (compiler.type == "gcc" and compiler.version < "8.1") or (
        compiler.type in ("clang", "clang-cl") and compiler.version < "10.0.0"
    ):
        die(
            f"Compiler of type {compiler.type} and version {compiler.version} "
            "does not support --enable-path-remapping."
        )

    flags = []
    for old, new in path_remappings:
        # We would prefer to use just -ffile-prefix-map, but clang-cl doesn't
        # seem to recognize it.
        for flag in ("-fdebug-prefix-map", "-fmacro-prefix-map"):
            flag = f"{flag}={old}={new}"
            if compiler.type in ("gcc", "clang"):
                flags.append(flag)
            elif compiler.type == "clang-cl":
                flags.extend(["-Xclang", flag])

    return flags


set_config("MOZ_FILE_PREFIX_MAP_FLAGS", file_prefix_map_flags)