# -*- Mode: python; 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/.
# PGO
# ==============================================================
llvm_profdata = check_prog(
"LLVM_PROFDATA", ["llvm-profdata"], allow_missing=True, paths=clang_search_path
)
@depends_if(llvm_profdata)
@checking("whether llvm-profdata supports 'order' subcommand")
def llvm_profdata_order(profdata):
retcode, _, _ = get_cmd_output(profdata, "order", "--help")
return retcode == 0
option(
"--enable-profile-generate",
env="MOZ_PROFILE_GENERATE",
nargs="?",
choices=("cross",),
help="Build a PGO instrumented binary",
)
enable_profile_generate = depends_if("--enable-profile-generate")(lambda _: True)
imply_option("MOZ_PGO", enable_profile_generate)
set_config("MOZ_PROFILE_GENERATE", enable_profile_generate)
set_define("MOZ_PROFILE_GENERATE", enable_profile_generate)
option(
"--enable-profile-use",
env="MOZ_PROFILE_USE",
nargs="?",
choices=("cross",),
help="Use a generated profile during the build",
)
enable_profile_use = depends_if("--enable-profile-use")(lambda _: True)
imply_option("MOZ_PGO", enable_profile_use)
set_config("MOZ_PROFILE_USE", enable_profile_use)
option(
"--with-pgo-profile-path",
help="Path to the directory with unmerged profile data to use during the build"
", or to a merged profdata file",
nargs=1,
)
@depends(
"--with-pgo-profile-path",
"--enable-profile-use",
llvm_profdata,
build_environment,
)
@imports("os")
def pgo_profile_path(path, pgo_use, profdata, build_env):
topobjdir = build_env.topobjdir
if topobjdir.endswith("/js/src"):
topobjdir = topobjdir[:-7]
if not path:
return os.path.join(topobjdir, "instrumented", "merged.profdata")
if path and not pgo_use:
die("Pass --enable-profile-use to use --with-pgo-profile-path.")
if path and not profdata:
die("LLVM_PROFDATA must be set to process the pgo profile.")
if not os.path.isfile(path[0]):
die("Argument to --with-pgo-profile-path must be a file.")
if not os.path.isabs(path[0]):
die("Argument to --with-pgo-profile-path must be an absolute path.")
return path[0]
set_config("PGO_PROFILE_PATH", pgo_profile_path)
@depends(
"--enable-profile-use",
pgo_profile_path,
llvm_profdata,
llvm_profdata_order,
build_environment,
)
def orderfile_path(profile_use, path, profdata, profdata_order, build_env):
if not profile_use:
return None
if not profdata_order:
return None
topobjdir = build_env.topobjdir
orderfile = os.path.join(topobjdir, "orderfile.txt")
check_cmd_output(profdata, "order", path, "-o", orderfile)
return orderfile
pgo_temporal = c_compiler.try_compile(
flags=["-fprofile-generate", "-mllvm", "-pgo-temporal-instrumentation"],
check_msg="whether the C compiler supports temporal instrumentation",
when="--enable-profile-generate",
)
@depends(
c_compiler,
select_linker,
target,
pgo_profile_path,
orderfile_path,
target_is_windows,
pgo_temporal,
)
@imports("multiprocessing")
def pgo_flags(
compiler, linker, target, profdata, orderfile, target_is_windows, pgo_temporal
):
if compiler.type == "gcc":
return namespace(
gen_cflags=["-fprofile-generate"],
gen_ldflags=["-fprofile-generate"],
use_cflags=["-fprofile-use", "-fprofile-correction", "-Wcoverage-mismatch"],
use_ldflags=["-fprofile-use"],
)
if compiler.type in ("clang-cl", "clang"):
prefix = ""
if compiler.type == "clang-cl":
prefix = "/clang:"
gen_ldflags = None
else:
gen_ldflags = ["-fprofile-generate"]
use_ldflags = []
if orderfile:
if compiler.type == "clang-cl":
use_ldflags += [
"-ORDER:@" + orderfile,
"/ignore:4037", # Disable warn missing order symbol
]
elif linker.KIND == "ld64" or (linker.KIND == "lld" and target.os == "OSX"):
use_ldflags += ["-Wl,-order_file", orderfile]
elif linker.KIND == "lld":
use_ldflags += [
"-Wl,--symbol-ordering-file",
orderfile,
"-Wl,--no-warn-symbol-ordering",
]
if use_ldflags:
log.info("Activating PGO-based orderfile")
gen_cflags = [prefix + "-fprofile-generate"]
if pgo_temporal:
gen_cflags += ["-mllvm", "-pgo-temporal-instrumentation"]
if target_is_windows:
# native llvm-profdata.exe on Windows can't read profile data
# if name compression is enabled (which cross-compiling enables
# by default)
gen_cflags += ["-mllvm", "-enable-name-compression=false"]
return namespace(
gen_cflags=gen_cflags,
gen_ldflags=gen_ldflags,
use_cflags=[
prefix + "-fprofile-use=%s" % profdata,
# Some error messages about mismatched profile data
# come in via -Wbackend-plugin, so disable those too.
"-Wno-error=backend-plugin",
],
use_ldflags=use_ldflags,
)
set_config("PROFILE_GEN_CFLAGS", pgo_flags.gen_cflags)
set_config("PROFILE_GEN_LDFLAGS", pgo_flags.gen_ldflags)
set_config("PROFILE_USE_CFLAGS", pgo_flags.use_cflags)
set_config("PROFILE_USE_LDFLAGS", pgo_flags.use_ldflags)
option(
"--with-pgo-jarlog",
help="Use the provided jarlog file when packaging during a profile-use " "build",
nargs=1,
)
set_config("PGO_JARLOG_PATH", depends_if("--with-pgo-jarlog")(lambda p: p))
@depends("MOZ_PGO", "--enable-profile-use", "--enable-profile-generate", c_compiler
)
def moz_pgo_rust(pgo, profile_use, profile_generate, c_compiler):
if not pgo:
return
# Enabling PGO through MOZ_PGO only and not --enable* flags.
if not profile_use and not profile_generate:
return
if profile_use and profile_generate:
die("Cannot build with --enable-profile-use and --enable-profile-generate.")
want_cross = (len(profile_use) and profile_use[0] == "cross") or (
len(profile_generate) and profile_generate[0] == "cross"
)
if not want_cross:
return
if c_compiler.type == "gcc":
die("Cannot use cross-language PGO with GCC.")
return True
set_config("MOZ_PGO_RUST", moz_pgo_rust)
# LTO
# ==============================================================
option(
"--enable-lto",
env="MOZ_LTO",
nargs="*",
choices=("full", "thin", "cross"),
help="Enable LTO",
)
option(
env="MOZ_LD64_KNOWN_GOOD",
nargs=1,
help="Indicate that ld64 is free of symbol aliasing bugs",
)
imply_option("MOZ_LD64_KNOWN_GOOD", depends_if("MOZ_AUTOMATION")(lambda _: True))
@depends(
"--enable-lto",
c_compiler,
select_linker,
"MOZ_LD64_KNOWN_GOOD",
target,
"--enable-profile-generate",
pass_manager.enabled,
"--enable-profile-use",
"MOZ_AUTOMATION",
)
@imports("multiprocessing")
def lto(
values,
c_compiler,
select_linker,
ld64_known_good,
target,
instrumented_build,
pass_manager,
pgo_build,
moz_automation,
):
cflags = []
ldflags = []
enabled = None
rust_lto = False
if not values:
return
# Sanitize LTO modes.
if "full" in values and "thin" in values:
die("incompatible --enable-lto choices 'full' and 'thin'")
# If a value was given to --enable-lto, use that. Otherwise, make the lto
# mode explicit, using full with gcc, and full or thin with clang depending
# on the performance benefit.
# Defaulting to full LTO is costly in terms of compilation time, so we only
# default to it if MOZ_AUTOMATION and PGO are on, and for some platforms.
# Based on speedometer3 scores, full lto + pgo is beneficial for Linux and
# Windows for x86_64 targets.
if values == () or values == ("cross",):
if c_compiler.type == "gcc":
values += ("full",)
elif (
pgo_build
and moz_automation
and target.os in ("WINNT", "GNU")
and target.cpu == "x86_64"
):
values += ("full",)
else:
values += ("thin",)
if instrumented_build:
log.warning("Disabling LTO because --enable-profile-generate is specified")
return
if c_compiler.type == "gcc":
if "cross" in values:
die("Cross-language LTO is not supported with GCC.")
if "thin" in values:
die(
"gcc does not support thin LTO. Use `--enable-lto` "
"to enable full LTO for gcc."
)
if (
target.kernel == "Darwin"
and "cross" in values
and select_linker.KIND == "ld64"
and not ld64_known_good
):
die(
"The Mac linker is known to have a bug that affects cross-language "
"LTO. If you know that your linker is free from this bug, please "
"set the environment variable `MOZ_LD64_KNOWN_GOOD=1` and re-run "
"configure."
)
if c_compiler.type == "clang":
if "full" in values:
cflags.append("-flto")
ldflags.append("-flto")
else:
cflags.append("-flto=thin")
ldflags.append("-flto=thin")
if target.os == "Android" and "cross" in values:
# Work around https://github.com/rust-lang/rust/issues/90088
# by enabling the highest level of SSE the rust targets default
# to.
# https://github.com/rust-lang/rust/blob/bdfcb88e8b6203ccb46a2fb6649979b773efc8ac/compiler/rustc_target/src/spec/i686_linux_android.rs#L13
# https://github.com/rust-lang/rust/blob/8d1083e319841624f64400e1524805a40d725439/compiler/rustc_target/src/spec/x86_64_linux_android.rs#L7
if target.cpu == "x86":
ldflags.append("-Wl,-plugin-opt=-mattr=+ssse3")
elif target.cpu == "x86_64":
ldflags.append("-Wl,-plugin-opt=-mattr=+sse4.2")
elif c_compiler.type == "clang-cl":
if "full" in values:
cflags.append("-flto")
else:
cflags.append("-flto=thin")
# With clang-cl, -flto can only be used with -c or -fuse-ld=lld.
# AC_TRY_LINKs during configure don't have -c, so pass -fuse-ld=lld.
cflags.append("-fuse-ld=lld")
# Explicitly set the CPU to optimize for so the linker doesn't
# choose a poor default. Rust compilation by default uses the
# pentium4 CPU on x86:
#
# https://github.com/rust-lang/rust/blob/049a49b91151a88c95fa0d62a53fd0a0ac2c3af9/compiler/rustc_target/src/spec/i686_pc_windows_msvc.rs#L5
#
# which specifically supports "long" (multi-byte) nops. See
# https://bugzilla.mozilla.org/show_bug.cgi?id=1568450#c8 for details.
#
# The pentium4 seems like kind of a weird CPU to optimize for, but
# it seems to have worked out OK thus far. LLVM does not seem to
# specifically schedule code for the pentium4's deep pipeline, so
# that probably contributes to it being an OK default for our
# purposes.
if target.cpu == "x86":
ldflags.append("-mllvm:-mcpu=pentium4")
# This is also the CPU that Rust uses. The LLVM source code
# recommends this as the "generic 64-bit specific x86 processor model":
#
# https://github.com/llvm/llvm-project/blob/e7694f34ab6a12b8bb480cbfcb396d0a64fe965f/llvm/lib/Target/X86/X86.td#L1165-L1187
if target.cpu == "x86_64":
ldflags.append("-mllvm:-mcpu=x86-64")
# We do not need special flags for arm64. Hooray for fixed-length
# instruction sets.
else:
num_cores = multiprocessing.cpu_count()
cflags.append("-flto")
cflags.append("-flifetime-dse=1")
ldflags.append("-flto=%s" % num_cores)
ldflags.append("-flifetime-dse=1")
# Tell LTO not to inline functions above a certain size, to mitigate
# binary size growth while still getting good performance.
# (For hot functions, PGO will put a multiplier on this limit.)
if target.os == "WINNT":
ldflags.append("-mllvm:-import-instr-limit=10")
elif target.kernel == "Darwin":
ldflags.append("-Wl,-mllvm,-import-instr-limit=10")
elif c_compiler.type == "clang":
ldflags.append("-Wl,-plugin-opt=-import-instr-limit=10")
# If we're using the new pass manager, we can also enable the new PM
# during LTO. Further we can use the resulting size savings to increase
# the import limit in hot functions.
if pass_manager:
if target.os == "WINNT":
if c_compiler.version >= "12.0.0" and c_compiler.version < "13.0.0":
ldflags.append("-opt:ltonewpassmanager")
if c_compiler.version >= "12.0.0":
ldflags.append("-mllvm:-import-hot-multiplier=30")
elif target.kernel == "Darwin":
ldflags.append("-Wl,-mllvm,-import-hot-multiplier=30")
else:
if c_compiler.version < "13.0.0":
ldflags.append("-Wl,-plugin-opt=new-pass-manager")
ldflags.append("-Wl,-plugin-opt=-import-hot-multiplier=30")
# Pick Rust LTO mode in case of cross lTO. Thin is the default.
if "cross" in values:
rust_lto = "full" if "full" in values else "thin"
else:
rust_lto = ""
return namespace(
enabled=True,
cflags=cflags,
ldflags=ldflags,
rust_lto=rust_lto,
)
@depends(
dso_flags,
when=building_with_gnu_compatible_cc
& gcc_use_gnu_ld
& ~developer_options
& ~enable_profile_generate,
)
def remove_dead_symbols(dso_flags):
dso_flags.ldopts.append("-Wl,--gc-sections")
set_config("MOZ_LTO", lto.enabled)
set_define("MOZ_LTO", lto.enabled)
set_config("MOZ_LTO_CFLAGS", lto.cflags)
set_config("MOZ_LTO_LDFLAGS", lto.ldflags)
set_config("MOZ_LTO_RUST_CROSS", lto.rust_lto)
