# Copyright 2013 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import("//build/buildflag_header.gni")
import("//build/config/android/config.gni")
import("//build/config/c++/c++.gni")
import("//build/config/chrome_build.gni")
import("//build/config/chromeos/args.gni")
import("//build/config/chromeos/ui_mode.gni")
import("//build/config/clang/clang.gni")
import("//build/config/compiler/compiler.gni")
import("//build/config/coverage/coverage.gni")
import("//build/config/dcheck_always_on.gni")
import("//build/config/gclient_args.gni")
import("//build/config/host_byteorder.gni")
import("//build/config/rust.gni")
import("//build/config/sanitizers/sanitizers.gni")
import("//build/config/ui.gni")
import("//build/config/unwind.gni")
import("//build/toolchain/cc_wrapper.gni")
import("//build/toolchain/goma.gni")
import("//build/toolchain/rbe.gni")
import("//build/toolchain/toolchain.gni")
import("//build_overrides/build.gni")
if (current_cpu == "arm" || current_cpu == "arm64") {
import("//build/config/arm.gni")
}
if (current_cpu == "mipsel" || current_cpu == "mips64el" ||
current_cpu == "mips" || current_cpu == "mips64") {
import("//build/config/mips.gni")
}
if (is_mac) {
import("//build/config/apple/symbols.gni")
}
if (is_ios) {
import("//build/config/ios/ios_sdk.gni")
}
if (is_nacl) {
# To keep NaCl variables out of builds that don't include NaCl, all
# variables defined in nacl/config.gni referenced here should be protected by
# is_nacl conditions.
import("//build/config/nacl/config.gni")
}
lld_path = ""
if (!is_clang) {
declare_args() {
# This allows overriding the location of lld.
lld_path = rebase_path("$clang_base_path/bin", root_build_dir)
}
} else {
# clang looks for lld next to it, no need for -B.
lld_path = ""
}
declare_args() {
# Normally, Android builds are lightly optimized, even for debug builds, to
# keep binary size down. Setting this flag to true disables such optimization
android_full_debug = false
# Compile in such a way as to make it possible for the profiler to unwind full
# stack frames. Setting this flag has a large effect on the performance of the
# generated code than just setting profiling, but gives the profiler more
# information to analyze.
# Requires profiling to be set to true.
enable_full_stack_frames_for_profiling = false
# When we are going to use gold we need to find it.
# This is initialized below, after use_gold might have been overridden.
gold_path = ""
# Enable fatal linker warnings. Building Chromium with certain versions
# of binutils can cause linker warning.
fatal_linker_warnings = true
# Build with C++ RTTI enabled. Chromium builds without RTTI by default,
# but some sanitizers are known to require it, like CFI diagnostics
# and UBsan variants.
use_rtti = use_cfi_diag || is_ubsan_vptr || is_ubsan_security
# AFDO (Automatic Feedback Directed Optimizer) is a form of profile-guided
# optimization that GCC supports. It used by ChromeOS in their official
# builds. To use it, set auto_profile_path to the path to a file containing
# the needed gcov profiling data.
auto_profile_path = ""
# Path to an AFDO profile to use while building with clang, if any. Empty
# implies none.
clang_sample_profile_path = ""
# Some configurations have default sample profiles. If this is true and
# clang_sample_profile_path is empty, we'll fall back to the default.
#
# We currently only have default profiles for Chromium in-tree, so we disable
# this by default for all downstream projects, since these profiles are likely
# nonsensical for said projects.
clang_use_default_sample_profile =
chrome_pgo_phase == 0 && build_with_chromium && is_official_build &&
(is_android || chromeos_is_browser_only)
# This configuration is used to select a default profile in Chrome OS based on
# the microarchitectures we are using. This is only used if
# clang_use_default_sample_profile is true and clang_sample_profile_path is
# empty.
chromeos_afdo_platform = "atom"
# Emit debug information for profiling wile building with clang.
# Only enable this for ChromeOS official builds for AFDO.
clang_emit_debug_info_for_profiling = is_chromeos_device && is_official_build
# Turn this on to have the compiler output extra timing information.
compiler_timing = false
# Turn this on to use ghash feature of lld for faster debug link on Windows.
# http://blog.llvm.org/2018/01/improving-link-time-on-windows-with.html
use_ghash = true
# Whether to enable ThinLTO optimizations. Turning ThinLTO optimizations on
# can substantially increase link time and binary size, but they generally
# also make binaries a fair bit faster.
#
# TODO(gbiv): We disable optimizations by default on most platforms because
# the space overhead is too great. We should use some mixture of profiles and
# optimization settings to better tune the size increase.
thin_lto_enable_optimizations =
(is_chromeos || is_android || is_win || is_linux || is_mac ||
(is_ios && use_lld)) && is_official_build
# Initialize all local variables with a pattern. This flag will fill
# uninitialized floating-point types (and 32-bit pointers) with 0xFF and the
# rest with 0xAA. This makes behavior of uninitialized memory bugs consistent,
# recognizable in the debugger, and crashes on memory accesses through
# uninitialized pointers.
#
# TODO(crbug.com/1131993): This regresses binary size by ~1MB on Android and
# needs to be evaluated before enabling it there as well.
init_stack_vars = !(is_android && is_official_build)
# Zero init has favorable performance/size tradeoffs for Chrome OS
# but was not evaluated for other platforms.
init_stack_vars_zero = is_chromeos
# This argument is to control whether enabling text section splitting in the
# final binary. When enabled, the separated text sections with prefix
# '.text.hot', '.text.unlikely', '.text.startup' and '.text.exit' will not be
# merged to '.text' section. This allows us to identify the hot code section
# ('.text.hot') in the binary, which allows our data collection pipelines to
# more easily identify code that we assume to be hot/cold that doesn't turn
# out to be such in the field.
use_text_section_splitting = is_chromeos
# Enable DWARF v5.
use_dwarf5 = false
# Override this to put full paths to PDBs in Windows PE files. This helps
# windbg and Windows Performance Analyzer with finding the PDBs in some local-
# build scenarios. This is never needed for bots or official builds. Because
# this puts the output directory in the DLLs/EXEs it breaks build determinism.
# Bugs have been reported to the windbg/WPA teams and this workaround will be
# removed when they are fixed.
use_full_pdb_paths = false
# Enable -H, which prints the include tree during compilation.
# For use by tools/clang/scripts/analyze_includes.py
show_includes = false
# Enable Profi algorithm. Profi can infer block and edge counts.
# https://clang.llvm.org/docs/UsersManual.html#using-sampling-profilers
# TODO(crbug.com/1375958i:) Possibly enable this for Android too.
use_profi = is_chromeos
# If true, linker crashes will be rerun with `--reproduce` which causes
# a reproducer file to be saved.
save_reproducers_on_lld_crash = false
# Enable ShadowCallStack for compiled binaries. SCS stores a pointer to a
# shadow call stack in register x18. Hence, x18 must not be used by the OS
# or libraries. We assume that to be the case for high end Android
# configurations. For more details see
# https://clang.llvm.org/docs/ShadowCallStack.html
enable_shadow_call_stack = false
# Use DWARF simple template names, with the following exceptions:
#
# * Windows is not supported as it doesn't use DWARF.
# * Apple platforms (e.g. MacOS, iPhone, iPad) aren't supported because xcode
# lldb doesn't have the needed changes yet.
# TODO(crbug.com/1379070): Remove if the upstream default ever changes.
#
# This greatly reduces the size of debug builds, at the cost of
# debugging information which is required by some specialized
# debugging tools.
simple_template_names = is_clang && !is_nacl && !is_win && !is_apple
}
declare_args() {
# Set to true to use icf, Identical Code Folding.
#
# icf=all is broken in older golds, see
# https://sourceware.org/bugzilla/show_bug.cgi?id=17704
# chromeos binutils has been patched with the fix, so always use icf there.
# The bug only affects x86 and x64, so we can still use ICF when targeting
# other architectures.
#
# lld doesn't have the bug.
use_icf = (is_posix || is_fuchsia) && !is_debug && !using_sanitizer &&
!use_clang_coverage && current_os != "zos" &&
!(is_android && use_order_profiling) &&
(use_lld || (use_gold && (is_chromeos || !(current_cpu == "x86" ||
current_cpu == "x64"))))
}
if (is_android) {
# Set the path to use orderfile for linking Chrome
# Note that this is for using only one orderfile for linking
# the Chrome binary/library.
declare_args() {
chrome_orderfile_path = ""
if (defined(default_chrome_orderfile)) {
# Allow downstream tools to set orderfile path with
# another variable.
chrome_orderfile_path = default_chrome_orderfile
}
}
}
declare_args() {
# Turn off the --call-graph-profile-sort flag for lld by default. Enable
# selectively for targets where it's beneficial.
enable_call_graph_profile_sort =
chrome_pgo_phase == 2 ||
(is_chromeos &&
(clang_use_default_sample_profile || clang_sample_profile_path != ""))
}
assert(!(llvm_force_head_revision && use_goma),
"can't use goma with trunk clang")
assert(!(llvm_force_head_revision && use_remoteexec),
"can't use rbe with trunk clang")
# default_include_dirs ---------------------------------------------------------
#
# This is a separate config so that third_party code (which would not use the
# source root and might have conflicting versions of some headers) can remove
# this and specify their own include paths.
config("default_include_dirs") {
include_dirs = [
"//",
root_gen_dir,
]
}
# Compiler instrumentation can introduce dependencies in DSOs to symbols in
# the executable they are loaded into, so they are unresolved at link-time.
config("no_unresolved_symbols") {
if (!using_sanitizer &&
(is_linux || is_chromeos || is_android || is_fuchsia)) {
ldflags = [
"-Wl,-z,defs",
"-Wl,--as-needed",
]
}
}
# compiler ---------------------------------------------------------------------
#
# Base compiler configuration.
#
# See also "runtime_library" below for related stuff and a discussion about
# where stuff should go. Put warning related stuff in the "warnings" config.
config("compiler") {
asmflags = []
cflags = []
cflags_c = []
cflags_cc = []
cflags_objc = []
cflags_objcc = []
rustflags = []
ldflags = []
defines = []
configs = []
rustflags = []
# System-specific flags. If your compiler flags apply to one of the
# categories here, add it to the associated file to keep this shared config
# smaller.
if (is_win) {
configs += [ "//build/config/win:compiler" ]
} else if (is_android) {
configs += [ "//build/config/android:compiler" ]
} else if (is_linux || is_chromeos) {
configs += [ "//build/config/linux:compiler" ]
} else if (is_nacl) {
configs += [ "//build/config/nacl:compiler" ]
} else if (is_mac) {
configs += [ "//build/config/mac:compiler" ]
} else if (is_ios) {
configs += [ "//build/config/ios:compiler" ]
} else if (is_fuchsia) {
configs += [ "//build/config/fuchsia:compiler" ]
} else if (current_os == "aix") {
configs += [ "//build/config/aix:compiler" ]
} else if (current_os == "zos") {
configs += [ "//build/config/zos:compiler" ]
}
configs += [
# See the definitions below.
":clang_revision",
":rustc_revision",
":compiler_cpu_abi",
":compiler_codegen",
":compiler_deterministic",
]
# Here we enable -fno-delete-null-pointer-checks, which makes various nullptr
# operations (e.g. dereferencing) into defined behavior. This avoids deletion
# of some security-critical code: see https://crbug.com/1139129.
# Nacl does not support the flag. And, we still want UBSAN to catch undefined
# behavior related to nullptrs, so do not add this flag if UBSAN is enabled.
# GCC seems to have some bugs compiling constexpr code when this is defined,
# so only enable it if using_clang. See: https://gcc.gnu.org/PR97913
# TODO(mpdenton): remove is_clang once GCC bug is fixed.
if (!is_nacl && !is_ubsan && is_clang) {
cflags += [ "-fno-delete-null-pointer-checks" ]
}
# Don't emit the GCC version ident directives, they just end up in the
# .comment section or debug info taking up binary size, and makes comparing
# .o files built with different compiler versions harder.
if (!is_win || is_clang) {
cflags += [ "-fno-ident" ]
}
# In general, Windows is totally different, but all the other builds share
# some common compiler and linker configuration.
if (!is_win) {
# Common POSIX compiler flags setup.
# --------------------------------
cflags += [ "-fno-strict-aliasing" ] # See http://crbug.com/32204
# Stack protection. ShadowCallStack and Stack protector address the same
# problems. Therefore, we only enable one or the other. Clang advertises SCS as
# a stronger alternative to StackProtector, so we give SCS precedence over SP.
if (enable_shadow_call_stack) {
# On Aarch64, SCS requires the x18 register to be unused because it will hold
# a pointer to the shadow stack. For Android we know that Clang doesn't use
# x18 by default. On other OSs adding "-ffixed-x18" might be required.
assert(is_android)
scs_parameters = [
"-fsanitize=shadow-call-stack",
"-fno-stack-protector",
]
cflags += scs_parameters
ldflags += scs_parameters
} else {
if (is_apple) {
# The strong variant of the stack protector significantly increases
# binary size, so only enable it in debug mode.
if (is_debug) {
cflags += [ "-fstack-protector-strong" ]
} else {
cflags += [ "-fstack-protector" ]
}
} else if ((is_posix && !is_chromeos && !is_nacl) || is_fuchsia) {
# TODO(phajdan.jr): Use -fstack-protector-strong when our gcc supports it.
# See also https://crbug.com/533294
# The x86 toolchain currently has problems with stack-protector.
if (is_android && current_cpu == "x86") {
cflags += [ "-fno-stack-protector" ]
} else if (current_os != "aix") {
# Not available on aix.
cflags += [ "-fstack-protector" ]
}
}
}
if (use_lld) {
ldflags += [ "-fuse-ld=lld" ]
if (lld_path != "") {
ldflags += [ "-B$lld_path" ]
}
}
# Linker warnings.
if (fatal_linker_warnings && !is_apple && current_os != "aix" &&
current_os != "zos") {
ldflags += [ "-Wl,--fatal-warnings" ]
}
if (fatal_linker_warnings && is_apple) {
ldflags += [ "-Wl,-fatal_warnings" ]
}
}
if (is_clang && is_debug) {
# Allow comparing the address of references and 'this' against 0
# in debug builds. Technically, these can never be null in
# well-defined C/C++ and Clang can optimize such checks away in
# release builds, but they may be used in asserts in debug builds.
cflags_cc += [
"-Wno-undefined-bool-conversion",
"-Wno-tautological-undefined-compare",
]
}
# Non-Apple Posix and Fuchsia compiler flags setup.
# -----------------------------------
if ((is_posix && !is_apple) || is_fuchsia) {
if (enable_profiling) {
if (!is_debug) {
cflags += [ "-g" ]
if (enable_full_stack_frames_for_profiling) {
cflags += [
"-fno-inline",
"-fno-optimize-sibling-calls",
]
}
}
}
# Explicitly pass --build-id to ld. Compilers used to always pass this
# implicitly but don't any more (in particular clang when built without
# ENABLE_LINKER_BUILD_ID=ON).
if (is_official_build) {
# The sha1 build id has lower risk of collision but is more expensive to
# compute, so only use it in the official build to avoid slowing down
# links.
ldflags += [ "-Wl,--build-id=sha1" ]
} else if (current_os != "aix" && current_os != "zos") {
ldflags += [ "-Wl,--build-id" ]
}
if (!is_android) {
defines += [
# _FILE_OFFSET_BITS=64 should not be set on Android in order to maintain
# the behavior of the Android NDK from earlier versions.
# See https://android-developers.googleblog.com/2017/09/introducing-android-native-development.html
"_FILE_OFFSET_BITS=64",
"_LARGEFILE_SOURCE",
"_LARGEFILE64_SOURCE",
]
}
if (!is_nacl) {
if (exclude_unwind_tables) {
cflags += [
"-fno-unwind-tables",
"-fno-asynchronous-unwind-tables",
]
rustflags += [ "-Cforce-unwind-tables=no" ]
defines += [ "NO_UNWIND_TABLES" ]
} else {
cflags += [ "-funwind-tables" ]
rustflags += [ "-Cforce-unwind-tables=yes" ]
}
}
}
# Apple compiler flags setup.
# ---------------------------------
if (is_apple) {
# On Intel, clang emits both Apple's "compact unwind" information and
# DWARF eh_frame unwind information by default, for compatibility reasons.
# This flag limits emission of eh_frame information to functions
# whose unwind information can't be expressed in the compact unwind format
# (which in practice means almost everything gets only compact unwind
# entries). This reduces object file size a bit and makes linking a bit
# faster.
# On arm64, this is already the default behavior.
if (current_cpu == "x64") {
asmflags += [ "-femit-dwarf-unwind=no-compact-unwind" ]
cflags += [ "-femit-dwarf-unwind=no-compact-unwind" ]
}
}
# Linux/Android/Fuchsia common flags setup.
# ---------------------------------
if (is_linux || is_chromeos || is_android || is_fuchsia) {
asmflags += [ "-fPIC" ]
cflags += [ "-fPIC" ]
ldflags += [ "-fPIC" ]
rustflags += [ "-Crelocation-model=pic" ]
if (!is_clang) {
# Use pipes for communicating between sub-processes. Faster.
# (This flag doesn't do anything with Clang.)
cflags += [ "-pipe" ]
}
ldflags += [
"-Wl,-z,noexecstack",
"-Wl,-z,relro",
]
if (!is_component_build) {
ldflags += [ "-Wl,-z,now" ]
}
}
# Linux-specific compiler flags setup.
# ------------------------------------
if (use_gold) {
ldflags += [ "-fuse-ld=gold" ]
if (!is_android) {
# On Android, this isn't needed. gcc in the NDK knows to look next to
# it with -fuse-ld=gold, and clang gets a --gcc-toolchain flag passed
# above.
if (gold_path != "") {
ldflags += [ "-B$gold_path" ]
}
ldflags += [
# Experimentation found that using four linking threads
# saved ~20% of link time.
# https://groups.google.com/a/chromium.org/group/chromium-dev/browse_thread/thread/281527606915bb36
# Only apply this to the target linker, since the host
# linker might not be gold, but isn't used much anyway.
"-Wl,--threads",
"-Wl,--thread-count=4",
]
}
# TODO(thestig): Make this flag work with GN.
#if (!is_official_build && !is_chromeos && !(is_asan || is_lsan || is_tsan || is_msan)) {
# ldflags += [
# "-Wl,--detect-odr-violations",
# ]
#}
}
if (use_icf && (!is_apple || use_lld)) {
ldflags += [ "-Wl,--icf=all" ]
}
if (is_linux || is_chromeos) {
cflags += [ "-pthread" ]
# Do not use the -pthread ldflag here since it becomes a no-op
# when using -nodefaultlibs, which would cause an unused argument
# error. "-lpthread" is added in //build/config:default_libs.
}
# Clang-specific compiler flags setup.
# ------------------------------------
if (is_clang) {
cflags += [ "-fcolor-diagnostics" ]
# Enable -fmerge-all-constants. This used to be the default in clang
# for over a decade. It makes clang non-conforming, but is fairly safe
# in practice and saves some binary size. We might want to consider
# disabling this (https://bugs.llvm.org/show_bug.cgi?id=18538#c13),
# but for now it looks like our build might rely on it
# (https://crbug.com/829795).
cflags += [ "-fmerge-all-constants" ]
}
if (use_lld) {
# TODO(thakis): Make the driver pass --color-diagnostics to the linker
# if -fcolor-diagnostics is passed to it, and pass -fcolor-diagnostics
# in ldflags instead.
if (is_win) {
# On Windows, we call the linker directly, instead of calling it through
# the driver.
ldflags += [ "--color-diagnostics" ]
} else {
ldflags += [ "-Wl,--color-diagnostics" ]
}
}
# Enable text section splitting only on linux when using lld for now. Other
# platforms can be added later if needed.
if ((is_linux || is_chromeos) && use_lld && use_text_section_splitting) {
ldflags += [ "-Wl,-z,keep-text-section-prefix" ]
}
if (is_clang && !is_nacl && current_os != "zos") {
cflags += [ "-fcrash-diagnostics-dir=" + clang_diagnostic_dir ]
if (save_reproducers_on_lld_crash && use_lld) {
ldflags += [
"-fcrash-diagnostics=all",
"-fcrash-diagnostics-dir=" + clang_diagnostic_dir,
]
}
# TODO(hans): Remove this once Clang generates better optimized debug info
# by default. https://crbug.com/765793
cflags += [
"-mllvm",
"-instcombine-lower-dbg-declare=0",
]
if (!is_debug && use_thin_lto && is_a_target_toolchain) {
if (is_win) {
ldflags += [ "-mllvm:-instcombine-lower-dbg-declare=0" ]
} else {
ldflags += [ "-Wl,-mllvm,-instcombine-lower-dbg-declare=0" ]
}
}
# TODO(crbug.com/1235145): Investigate why/if this should be needed.
if (is_win) {
cflags += [ "/clang:-ffp-contract=off" ]
} else {
cflags += [ "-ffp-contract=off" ]
}
}
# C11/C++11 compiler flags setup.
# ---------------------------
if (is_linux || is_chromeos || is_android || (is_nacl && is_clang) ||
current_os == "aix") {
if (is_clang) {
standard_prefix = "c"
# Since we build with -std=c* and not -std=gnu*, _GNU_SOURCE will not be
# defined by the compiler. However, lots of code relies on the
# non-standard features that _GNU_SOURCE enables, so define it manually.
defines += [ "_GNU_SOURCE" ]
if (is_nacl) {
# Undefine __STRICT_ANSI__ to get non-standard features which would
# otherwise not be enabled by NaCl's sysroots.
cflags += [ "-U__STRICT_ANSI__" ]
}
} else {
# Gcc does not support ##__VA_ARGS__ when in standards-conforming mode,
# but we use this feature in several places in Chromium.
# TODO(thomasanderson): Replace usages of ##__VA_ARGS__ with the
# standard-compliant __VA_OPT__ added by C++20, and switch the gcc build
# to -std=c*.
standard_prefix = "gnu"
}
cflags_c += [ "-std=${standard_prefix}11" ]
if (is_nacl && !is_nacl_saigo) {
# This is for the pnacl_newlib toolchain. It's only used to build
# a few independent ppapi test files that don't pull in any other
# dependencies.
cflags_cc += [ "-std=${standard_prefix}++14" ]
if (is_clang) {
cflags_cc += [ "-fno-trigraphs" ]
}
} else if (is_clang) {
if (defined(use_cxx17) && use_cxx17) {
cflags_cc += [ "-std=${standard_prefix}++17" ]
} else {
cflags_cc += [ "-std=${standard_prefix}++20" ]
}
} else {
# The gcc bots are currently using GCC 9, which is not new enough to
# support "c++20"/"gnu++20".
cflags_cc += [ "-std=${standard_prefix}++2a" ]
}
} else if (is_win) {
cflags_c += [ "/std:c11" ]
if ((defined(use_cxx17) && use_cxx17) ||
(!is_clang && defined(msvc_use_cxx17) && msvc_use_cxx17)) {
cflags_cc += [ "/std:c++17" ]
} else {
cflags_cc += [ "/std:c++20" ]
}
} else if (!is_nacl) {
# TODO(mcgrathr) - the NaCl GCC toolchain doesn't support either
# gnu11/gnu++11 or c11/c++11; we technically don't need this toolchain any
# more, but there are still a few buildbots using it, so until those are
# turned off we need the !is_nacl clause and the (is_nacl && is_clang)
# clause, above.
cflags_c += [ "-std=c11" ]
if (defined(use_cxx17) && use_cxx17) {
cflags_cc += [ "-std=c++17" ]
} else {
cflags_cc += [ "-std=c++20" ]
}
}
if (is_clang && current_os != "zos") {
# C++17 removes trigraph support, but clang still warns that it ignores
# them when seeing them. Don't.
cflags_cc += [ "-Wno-trigraphs" ]
}
if (use_relative_vtables_abi) {
cflags_cc += [ "-fexperimental-relative-c++-abi-vtables" ]
ldflags += [ "-fexperimental-relative-c++-abi-vtables" ]
}
# Add flags for link-time optimization. These flags enable
# optimizations/transformations that require whole-program visibility at link
# time, so they need to be applied to all translation units, and we may end up
# with miscompiles if only part of the program is compiled with LTO flags. For
# that reason, we cannot allow targets to enable or disable these flags, for
# example by disabling the optimize configuration.
# TODO(pcc): Make this conditional on is_official_build rather than on gn
# flags for specific features.
if (!is_debug && use_thin_lto && is_a_target_toolchain) {
assert(use_lld, "LTO is only supported with lld")
cflags += [
"-flto=thin",
"-fsplit-lto-unit",
]
# Limit the size of the ThinLTO cache to the lesser of 10% of
# available disk space, 40GB and 100000 files.
cache_policy = "cache_size=10%:cache_size_bytes=40g:cache_size_files=100000"
# An import limit of 30 has better performance (per speedometer) and lower
# binary size than the default setting of 100.
# TODO(gbiv): We ideally shouldn't need to specify this; ThinLTO
# should be able to better manage binary size increases on its own.
import_instr_limit = 30
if (is_win) {
ldflags += [
"/opt:lldltojobs=all",
"-mllvm:-import-instr-limit=$import_instr_limit",
"/lldltocache:" +
rebase_path("$root_out_dir/thinlto-cache", root_build_dir),
"/lldltocachepolicy:$cache_policy",
"-mllvm:-disable-auto-upgrade-debug-info",
]
} else {
ldflags += [ "-flto=thin" ]
# Enabling ThinLTO on Chrome OS too, in an effort to reduce the memory
# usage in crbug.com/1038040. Note this will increase build time in
# Chrome OS.
# In ThinLTO builds, we run at most one link process at a time,
# and let it use all cores.
# TODO(thakis): Check if '=0' (that is, number of cores, instead
# of "all" which means number of hardware threads) is faster.
ldflags += [ "-Wl,--thinlto-jobs=all" ]
if (is_apple) {
ldflags += [
"-Wl,-cache_path_lto," +
rebase_path("$root_out_dir/thinlto-cache", root_build_dir),
"-Wcrl,object_path_lto",
]
} else {
ldflags +=
[ "-Wl,--thinlto-cache-dir=" +
rebase_path("$root_out_dir/thinlto-cache", root_build_dir) ]
}
ldflags += [ "-Wl,--thinlto-cache-policy=$cache_policy" ]
if (is_chromeos) {
# ARM was originally set lower than x86 to keep the size
# bloat of ThinLTO to <10%, but that's potentially no longer true.
# FIXME(inglorion): maybe tune these?
# TODO(b/271459198): Revert limit on amd64 to 30 when fixed.
import_instr_limit = 20
} else if (is_android) {
# TODO(crbug.com/1308318): Investigate if we can get the > 6% perf win
# of import_instr_limit 30 with a binary size hit smaller than ~2 MiB.
import_instr_limit = 5
}
ldflags += [ "-Wl,-mllvm,-import-instr-limit=$import_instr_limit" ]
if (!is_chromeos) {
# TODO(https://crbug.com/972449): turn on for ChromeOS when that
# toolchain has this flag.
# We only use one version of LLVM within a build so there's no need to
# upgrade debug info, which can be expensive since it runs the verifier.
ldflags += [ "-Wl,-mllvm,-disable-auto-upgrade-debug-info" ]
}
}
# TODO(https://crbug.com/1211155): investigate why this isn't effective on
# arm32.
if (!is_android || current_cpu == "arm64") {
cflags += [ "-fwhole-program-vtables" ]
if (toolchain_supports_rust_thin_lto) {
# whole-program-vtables implies -fsplit-lto-unit, and Rust needs to match
# behaviour. Rust needs to know the linker will be doing LTO in this case
# or it rejects the Zsplit-lto-unit flag.
rustflags += [
"-Zsplit-lto-unit",
"-Clinker-plugin-lto=yes",
]
} else {
# Don't include bitcode if it won't be used.
rustflags += [ "-Cembed-bitcode=no" ]
}
if (!is_win) {
ldflags += [ "-fwhole-program-vtables" ]
}
}
# This flag causes LTO to create an .ARM.attributes section with the correct
# architecture. This is necessary because LLD will refuse to link a program
# unless the architecture revision in .ARM.attributes is sufficiently new.
# TODO(pcc): The contents of .ARM.attributes should be based on the
# -march flag passed at compile time (see llvm.org/pr36291).
if (current_cpu == "arm") {
ldflags += [ "-march=$arm_arch" ]
}
}
if (compiler_timing) {
if (is_clang && !is_nacl) {
cflags += [ "-ftime-trace" ]
} else if (is_win) {
cflags += [
# "Documented" here:
# http://aras-p.info/blog/2017/10/23/Best-unknown-MSVC-flag-d2cgsummary/
"/d2cgsummary",
]
}
}
# Pass flag to LLD so Android builds can allow debuggerd to properly symbolize
# stack crashes (http://crbug.com/919499).
if (use_lld && is_android) {
ldflags += [ "-Wl,--no-rosegment" ]
}
# TODO(crbug.com/1374347): Cleanup undefined symbol errors caught by
# --no-undefined-version.
if (use_lld && !is_win && !is_mac && !is_ios) {
ldflags += [ "-Wl,--undefined-version" ]
}
if (use_lld && is_apple) {
ldflags += [ "-Wl,--strict-auto-link" ]
}
# LLD does call-graph-sorted binary layout by default when profile data is
# present. On Android this increases binary size due to more thinks for long
# jumps. Turn it off by default and enable selectively for targets where it's
# beneficial.
if (use_lld && !enable_call_graph_profile_sort) {
if (is_win) {
ldflags += [ "/call-graph-profile-sort:no" ]
} else {
ldflags += [ "-Wl,--no-call-graph-profile-sort" ]
}
}
if (is_clang && !is_nacl && show_includes) {
if (is_win) {
# TODO(crbug.com/1223741): Goma mixes the -H and /showIncludes output.
assert(!use_goma, "show_includes on Windows is not reliable with goma")
cflags += [
"/clang:-H",
"/clang:-fshow-skipped-includes",
]
} else {
cflags += [
"-H",
"-fshow-skipped-includes",
]
}
}
# This flag enforces that member pointer base types are complete. It helps
# prevent us from running into problems in the Microsoft C++ ABI (see
# https://crbug.com/847724).
if (is_clang && !is_nacl && target_os != "chromeos" &&
(is_win || use_custom_libcxx)) {
cflags += [ "-fcomplete-member-pointers" ]
}
# Use DWARF simple template names.
if (simple_template_names) {
cflags_cc += [ "-gsimple-template-names" ]
}
# MLGO specific flags. These flags enable an ML-based inliner trained on
# Chrome on Android (arm32) with ThinLTO enabled, optimizing for size.
# The "release" ML model is embedded into clang as part of its build.
# Currently, the ML inliner is only enabled when targeting Android due to:
# a) Android is where size matters the most.
# b) MLGO presently has the limitation of only being able to embed one model
# at a time; It is unclear if the embedded model is beneficial for
# non-Android targets.
# MLGO is only officially supported on linux.
if (use_ml_inliner && is_a_target_toolchain) {
assert(
is_android && host_os == "linux",
"MLGO is currently only supported for targeting Android on a linux host")
if (use_thin_lto) {
ldflags += [ "-Wl,-mllvm,-enable-ml-inliner=release" ]
}
}
if (clang_embed_bitcode) {
assert(!use_thin_lto,
"clang_embed_bitcode is only supported in non-ThinLTO builds")
cflags += [
"-Xclang",
"-fembed-bitcode=all",
]
}
if (lld_emit_indexes_and_imports) {
assert(use_thin_lto,
"lld_emit_indexes_and_imports is only supported with ThinLTO builds")
ldflags += [
"-Wl,--save-temps=import",
"-Wl,--thinlto-emit-index-files",
]
}
# Pass the same C/C++ flags to the objective C/C++ compiler.
cflags_objc += cflags_c
cflags_objcc += cflags_cc
# Assign any flags set for the C compiler to asmflags so that they are sent
# to the assembler. The Windows assembler takes different types of flags
# so only do so for posix platforms.
if (is_posix || is_fuchsia) {
asmflags += cflags
asmflags += cflags_c
}
if (is_chromeos_device && !is_nacl) {
# On ChromeOS devices, we want to ensure we're using Chrome's allocator
# symbols for all C++ new/delete operator overloads. PartitionAlloc
# and other local allocators should always take precedence over system or
# preloaded allocators. These are the mangled symbol names.
# See b/280115910 for details.
ldflags += [
"-Wl,--export-dynamic-symbol=_ZdaPv,-u,_ZdaPv",
"-Wl,--export-dynamic-symbol=_ZdaPvRKSt9nothrow_t,-u,_ZdaPvRKSt9nothrow_t",
"-Wl,--export-dynamic-symbol=_ZdlPv,-u,_ZdlPv",
"-Wl,--export-dynamic-symbol=_ZdlPvm,-u,_ZdlPvm",
"-Wl,--export-dynamic-symbol=_ZdlPvRKSt9nothrow_t,-u,_ZdlPvRKSt9nothrow_t",
"-Wl,--export-dynamic-symbol=_Znam,-u,_Znam",
"-Wl,--export-dynamic-symbol=_ZnamRKSt9nothrow_t,-u,_ZnamRKSt9nothrow_t",
"-Wl,--export-dynamic-symbol=_Znwm,-u,_Znwm",
"-Wl,--export-dynamic-symbol=_ZnwmRKSt9nothrow_t,-u,_ZnwmRKSt9nothrow_t",
"-Wl,--export-dynamic-symbol=_ZdaPvmSt11align_val_t,-u,_ZdaPvmSt11align_val_t",
"-Wl,--export-dynamic-symbol=_ZdaPvSt11align_val_t,-u,_ZdaPvSt11align_val_t",
"-Wl,--export-dynamic-symbol=_ZdaPvSt11align_val_tRKSt9nothrow_t,-u,_ZdaPvSt11align_val_tRKSt9nothrow_t",
"-Wl,--export-dynamic-symbol=_ZdlPvmSt11align_val_t,-u,_ZdlPvmSt11align_val_t",
"-Wl,--export-dynamic-symbol=_ZdlPvSt11align_val_t,-u,_ZdlPvSt11align_val_t",
"-Wl,--export-dynamic-symbol=_ZdlPvSt11align_val_tRKSt9nothrow_t,-u,_ZdlPvSt11align_val_tRKSt9nothrow_t",
"-Wl,--export-dynamic-symbol=_ZnamSt11align_val_t,-u,_ZnamSt11align_val_t",
"-Wl,--export-dynamic-symbol=_ZnamSt11align_val_tRKSt9nothrow_t,-u,_ZnamSt11align_val_tRKSt9nothrow_t",
"-Wl,--export-dynamic-symbol=_ZnwmSt11align_val_t,-u,_ZnwmSt11align_val_t",
"-Wl,--export-dynamic-symbol=_ZnwmSt11align_val_tRKSt9nothrow_t,-u,_ZnwmSt11align_val_tRKSt9nothrow_t",
]
}
# Rust compiler flags setup.
# ---------------------------
rustflags += [
# Overflow checks are optional in Rust, but even if switched
# off they do not cause undefined behavior (the overflowing
# behavior is defined). Because containers are bounds-checked
# in safe Rust, they also can't provoke buffer overflows.
# As such these checks may be less important in Rust than C++.
# But in (simplistic) testing they have negligible performance
# overhead, and this helps to provide consistent behavior
# between different configurations, so we'll keep them on until
# we discover a reason to turn them off.
"-Coverflow-checks=on",
# By default Rust passes `-nodefaultlibs` to the linker, however this
# conflicts with our `--unwind=none` flag for Android dylibs, as the latter
# is then unused and produces a warning/error. So this removes the
# `-nodefaultlibs` from the linker invocation from Rust, which would be used
# to compile dylibs on Android, such as for constructing unit test APKs.
"-Cdefault-linker-libraries",
# To make Rust .d files compatible with ninja
"-Zdep-info-omit-d-target",
# If a macro panics during compilation, show which macro and where it is
# defined.
"-Zmacro-backtrace",
# For deterministic builds, keep the local machine's current working
# directory from appearing in build outputs.
"-Zremap-cwd-prefix=.",
]
if (!is_win || force_rustc_color_output) {
# Colorize error output. The analogous flag is passed for clang. This must
# be platform-gated since rustc will unconditionally output ANSI escape
# sequences, ignoring the platform, when stderr is not a terminal.
rustflags += [ "--color=always" ]
}
if (rust_abi_target != "") {
rustflags += [ "--target=$rust_abi_target" ]
}
if (!use_thin_lto) {
# Don't include bitcode if it won't be used.
rustflags += [ "-Cembed-bitcode=no" ]
}
if (is_official_build) {
rustflags += [ "-Ccodegen-units=1" ]
}
if (!rust_prebuilt_stdlib) {
# When building against the Chromium Rust stdlib (which we compile) always
# abort instead of unwinding when panic occurs. In official builds, panics
# abort immediately (this is configured in the stdlib) to keep binary size
# down. So we unconditionally match behaviour in unofficial too.
rustflags += [
"-Cpanic=abort",
"-Zpanic_abort_tests",
]
}
# Normally, this would be defined in the `runtime_library` config but NaCl
# saigo libc++ does not use the custom hermetic libc++. Unfortunately, there
# isn't really a better config to add this define for the define to
# consistently apply in both Chromium and non-Chromium code *and* non-NaCl
# and NaCl code.
#
# TODO(https://crbug.com/702997): Move this back to the `runtime_library`
# config when NaCl is removed.
if (use_safe_libcxx) {
# TODO(https://crbug.com/1465186): Switch saigo to hardened mode once
# it's rolled in.
if (is_nacl_saigo) {
defines += [ "_LIBCPP_ENABLE_ASSERTIONS=1" ]
} else {
defines += [ "_LIBCPP_ENABLE_SAFE_MODE=1" ]
}
}
}
# The BUILDCONFIG file sets this config on targets by default, which means when
# building with ThinLTO, no optimization is performed in the link step.
config("thinlto_optimize_default") {
if (!is_debug && use_thin_lto && is_a_target_toolchain) {
lto_opt_level = 0
if (is_win) {
ldflags = [ "/opt:lldlto=" + lto_opt_level ]
} else {
ldflags = [ "-Wl,--lto-O" + lto_opt_level ]
}
if (toolchain_supports_rust_thin_lto) {
# We always point Rust to a linker that performs LTO, so we don't want Rust
# to preemptively do so during compilation too or they conflict. But we do
# want Rust to generate LTO metadata in order for the linker to do its job.
rustflags = [ "-Clinker-plugin-lto=yes" ]
} else {
# Don't include bitcode if it won't be used.
rustflags = [ "-Cembed-bitcode=no" ]
}
}
}
# Use this to enable optimization in the ThinLTO link step for select targets
# when thin_lto_enable_optimizations is set by doing:
#
# configs -= [ "//build/config/compiler:thinlto_optimize_default" ]
# configs += [ "//build/config/compiler:thinlto_optimize_max" ]
#
# Since it makes linking significantly slower and more resource intensive, only
# use it on important targets such as the main browser executable or dll.
config("thinlto_optimize_max") {
if (!is_debug && use_thin_lto && is_a_target_toolchain) {
if (thin_lto_enable_optimizations) {
lto_opt_level = 2
} else {
lto_opt_level = 0
}
if (is_win) {
ldflags = [ "/opt:lldlto=" + lto_opt_level ]
} else {
ldflags = [ "-Wl,--lto-O" + lto_opt_level ]
}
if (toolchain_supports_rust_thin_lto) {
# We always point Rust to a linker that performs LTO, so we don't want Rust
# to preemptively do so during compilation too or they conflict. But we do
# want Rust to generate LTO metadata in order for the linker to do its job.
rustflags = [ "-Clinker-plugin-lto=yes" ]
} else {
# Don't include bitcode if it won't be used.
rustflags = [ "-Cembed-bitcode=no" ]
}
}
}
# This provides the basic options to select the target CPU and ABI.
# It is factored out of "compiler" so that special cases can use this
# without using everything that "compiler" brings in. Options that
# tweak code generation for a particular CPU do not belong here!
# See "compiler_codegen", below.
config("compiler_cpu_abi") {
cflags = []
ldflags = []
defines = []
configs = []
if (is_chromeos) {
configs += [ "//build/config/chromeos:compiler_cpu_abi" ]
}
# TODO(https://crbug.com/1383873): Remove this once figured out.
if (is_apple && current_cpu == "arm64") {
cflags += [ "-fno-global-isel" ]
ldflags += [ "-fno-global-isel" ]
}
if ((is_posix && !is_apple) || is_fuchsia) {
# CPU architecture. We may or may not be doing a cross compile now, so for
# simplicity we always explicitly set the architecture.
if (current_cpu == "x64") {
cflags += [
"-m64",
"-msse3",
]
ldflags += [ "-m64" ]
} else if (current_cpu == "x86") {
cflags += [ "-m32" ]
ldflags += [ "-m32" ]
if (!is_nacl) {
cflags += [
"-mfpmath=sse",
"-msse3",
]
}
} else if (current_cpu == "arm") {
if (is_clang && !is_android && !is_nacl &&
!(is_chromeos_lacros && is_chromeos_device)) {
cflags += [ "--target=arm-linux-gnueabihf" ]
ldflags += [ "--target=arm-linux-gnueabihf" ]
}
if (!is_nacl) {
cflags += [
"-march=$arm_arch",
"-mfloat-abi=$arm_float_abi",
]
}
if (arm_tune != "") {
cflags += [ "-mtune=$arm_tune" ]
}
} else if (current_cpu == "arm64") {
if (is_clang && !is_android && !is_nacl && !is_fuchsia &&
!(is_chromeos_lacros && is_chromeos_device)) {
cflags += [ "--target=aarch64-linux-gnu" ]
ldflags += [ "--target=aarch64-linux-gnu" ]
}
} else if (current_cpu == "mipsel" && !is_nacl) {
ldflags += [ "-Wl,--hash-style=sysv" ]
if (custom_toolchain == "") {
if (is_clang) {
if (is_android) {
cflags += [ "--target=mipsel-linux-android" ]
ldflags += [ "--target=mipsel-linux-android" ]
} else {
cflags += [ "--target=mipsel-linux-gnu" ]
ldflags += [ "--target=mipsel-linux-gnu" ]
}
} else {
cflags += [ "-EL" ]
ldflags += [ "-EL" ]
}
}
if (mips_arch_variant == "r6") {
cflags += [ "-mno-odd-spreg" ]
ldflags += [ "-mips32r6" ]
if (is_clang) {
cflags += [
"-march=mipsel",
"-mcpu=mips32r6",
]
} else {
cflags += [
"-mips32r6",
"-Wa,-mips32r6",
]
if (is_android) {
ldflags += [ "-Wl,-melf32ltsmip" ]
}
}
if (mips_use_msa == true) {
cflags += [
"-mmsa",
"-mfp64",
]
}
} else if (mips_arch_variant == "r2") {
ldflags += [ "-mips32r2" ]
if (is_clang) {
cflags += [
"-march=mipsel",
"-mcpu=mips32r2",
]
} else {
cflags += [
"-mips32r2",
"-Wa,-mips32r2",
]
if (mips_float_abi == "hard" && mips_fpu_mode != "") {
cflags += [ "-m$mips_fpu_mode" ]
}
}
} else if (mips_arch_variant == "r1") {
ldflags += [ "-mips32" ]
if (is_clang) {
cflags += [
"-march=mipsel",
"-mcpu=mips32",
]
} else {
cflags += [
"-mips32",
"-Wa,-mips32",
]
}
} else if (mips_arch_variant == "loongson3") {
defines += [ "_MIPS_ARCH_LOONGSON" ]
cflags += [
"-march=loongson3a",
"-mno-branch-likely",
"-Wa,-march=loongson3a",
]
}
if (mips_dsp_rev == 1) {
cflags += [ "-mdsp" ]
} else if (mips_dsp_rev == 2) {
cflags += [ "-mdspr2" ]
}
cflags += [ "-m${mips_float_abi}-float" ]
} else if (current_cpu == "mips" && !is_nacl) {
ldflags += [ "-Wl,--hash-style=sysv" ]
if (custom_toolchain == "") {
if (is_clang) {
cflags += [ "--target=mips-linux-gnu" ]
ldflags += [ "--target=mips-linux-gnu" ]
} else {
cflags += [ "-EB" ]
ldflags += [ "-EB" ]
}
}
if (mips_arch_variant == "r6") {
cflags += [
"-mips32r6",
"-Wa,-mips32r6",
]
if (mips_use_msa == true) {
cflags += [
"-mmsa",
"-mfp64",
]
}
} else if (mips_arch_variant == "r2") {
cflags += [
"-mips32r2",
"-Wa,-mips32r2",
]
if (mips_float_abi == "hard" && mips_fpu_mode != "") {
cflags += [ "-m$mips_fpu_mode" ]
}
} else if (mips_arch_variant == "r1") {
cflags += [
"-mips32",
"-Wa,-mips32",
]
}
if (mips_dsp_rev == 1) {
cflags += [ "-mdsp" ]
} else if (mips_dsp_rev == 2) {
cflags += [ "-mdspr2" ]
}
cflags += [ "-m${mips_float_abi}-float" ]
} else if (current_cpu == "mips64el") {
cflags += [ "-D__SANE_USERSPACE_TYPES__" ]
ldflags += [ "-Wl,--hash-style=sysv" ]
if (custom_toolchain == "") {
if (is_clang) {
if (is_android) {
cflags += [ "--target=mips64el-linux-android" ]
ldflags += [ "--target=mips64el-linux-android" ]
} else {
cflags += [ "--target=mips64el-linux-gnuabi64" ]
ldflags += [ "--target=mips64el-linux-gnuabi64" ]
}
} else {
cflags += [
"-EL",
"-mabi=64",
]
ldflags += [
"-EL",
"-mabi=64",
]
}
}
if (mips_arch_variant == "r6") {
if (is_clang) {
cflags += [
"-march=mips64el",
"-mcpu=mips64r6",
]
} else {
cflags += [
"-mips64r6",
"-Wa,-mips64r6",
]
ldflags += [ "-mips64r6" ]
}
if (mips_use_msa == true) {
cflags += [
"-mmsa",
"-mfp64",
]
}
} else if (mips_arch_variant == "r2") {
ldflags += [ "-mips64r2" ]
if (is_clang) {
cflags += [
"-march=mips64el",
"-mcpu=mips64r2",
]
} else {
cflags += [
"-mips64r2",
"-Wa,-mips64r2",
]
}
} else if (mips_arch_variant == "loongson3") {
defines += [ "_MIPS_ARCH_LOONGSON" ]
cflags += [
"-march=loongson3a",
"-mno-branch-likely",
"-Wa,-march=loongson3a",
]
}
} else if (current_cpu == "mips64") {
ldflags += [ "-Wl,--hash-style=sysv" ]
if (custom_toolchain == "") {
if (is_clang) {
cflags += [ "--target=mips64-linux-gnuabi64" ]
ldflags += [ "--target=mips64-linux-gnuabi64" ]
} else {
cflags += [
"-EB",
"-mabi=64",
]
ldflags += [
"-EB",
"-mabi=64",
]
}
}
if (mips_arch_variant == "r6") {
cflags += [
"-mips64r6",
"-Wa,-mips64r6",
]
ldflags += [ "-mips64r6" ]
if (mips_use_msa == true) {
cflags += [
"-mmsa",
"-mfp64",
]
}
} else if (mips_arch_variant == "r2") {
cflags += [
"-mips64r2",
"-Wa,-mips64r2",
]
ldflags += [ "-mips64r2" ]
}
} else if (current_cpu == "ppc64") {
if (current_os == "aix") {
cflags += [ "-maix64" ]
ldflags += [ "-maix64" ]
} else {
cflags += [ "-m64" ]
ldflags += [ "-m64" ]
}
} else if (current_cpu == "riscv64") {
if (is_clang && !is_android) {
cflags += [ "--target=riscv64-linux-gnu" ]
ldflags += [ "--target=riscv64-linux-gnu" ]
}
cflags += [ "-mabi=lp64d" ]
} else if (current_cpu == "loong64") {
if (is_clang) {
cflags += [ "--target=loongarch64-linux-gnu" ]
ldflags += [ "--target=loongarch64-linux-gnu" ]
}
cflags += [
"-mabi=lp64d",
"-mcmodel=medium",
]
} else if (current_cpu == "s390x") {
cflags += [ "-m64" ]
ldflags += [ "-m64" ]
}
}
asmflags = cflags
}
# This provides options to tweak code generation that are necessary
# for particular Chromium code or for working around particular
# compiler bugs (or the combination of the two).
config("compiler_codegen") {
configs = []
cflags = []
ldflags = []
if (is_nacl) {
configs += [ "//build/config/nacl:compiler_codegen" ]
}
if (current_cpu == "arm64" && !is_win && is_clang) {
# Disable outlining everywhere on arm64 except Win. For more information see
# crbug.com/931297 for Android and crbug.com/1410297 for iOS.
# TODO(crbug.com/1411363): Enable this on Windows if possible.
cflags += [ "-mno-outline" ]
# This can be removed once https://bugs.llvm.org/show_bug.cgi?id=40348
# has been resolved, and -mno-outline is obeyed by the linker during
# ThinLTO.
ldflags += [ "-Wl,-mllvm,-enable-machine-outliner=never" ]
}
asmflags = cflags
}
# This provides options that make the build deterministic, so that the same
# revision produces the same output, independent of the name of the build
# directory and of the computer the build is done on.
# The relative path from build dir to source dir makes it into the build
# outputs, so it's recommended that you use a build dir two levels deep
# (e.g. "out/Release") so that you get the same "../.." path as all the bots
# in your build outputs.
config("compiler_deterministic") {
cflags = []
ldflags = []
swiftflags = []
# Eliminate build metadata (__DATE__, __TIME__ and __TIMESTAMP__) for
# deterministic build. See https://crbug.com/314403
if (!is_official_build) {
if (is_win && !is_clang) {
cflags += [
"/wd4117", # Trying to define or undefine a predefined macro.
"/D__DATE__=",
"/D__TIME__=",
"/D__TIMESTAMP__=",
]
} else {
cflags += [
"-Wno-builtin-macro-redefined",
"-D__DATE__=",
"-D__TIME__=",
"-D__TIMESTAMP__=",
]
}
}
# Makes builds independent of absolute file path.
if (is_clang && strip_absolute_paths_from_debug_symbols) {
# If debug option is given, clang includes $cwd in debug info by default.
# For such build, this flag generates reproducible obj files even we use
# different build directory like "out/feature_a" and "out/feature_b" if
# we build same files with same compile flag.
# Other paths are already given in relative, no need to normalize them.
if (is_nacl) {
# TODO(https://crbug.com/1231236): Use -ffile-compilation-dir= here.
cflags += [
"-Xclang",
"-fdebug-compilation-dir",
"-Xclang",
".",
]
} else {
# -ffile-compilation-dir is an alias for both -fdebug-compilation-dir=
# and -fcoverage-compilation-dir=.
cflags += [ "-ffile-compilation-dir=." ]
swiftflags += [ "-file-compilation-dir=." ]
}
if (!is_win) {
# We don't use clang -cc1as on Windows (yet? https://crbug.com/762167)
asmflags = [ "-Wa,-fdebug-compilation-dir,." ]
}
if (is_win && use_lld) {
if (symbol_level == 2 || (is_clang && using_sanitizer)) {
# Absolutize source file paths for PDB. Pass the real build directory
# if the pdb contains source-level debug information and if linker
# reproducibility is not critical.
ldflags += [ "/PDBSourcePath:" + rebase_path(root_build_dir) ]
} else {
# Use a fake fixed base directory for paths in the pdb to make the pdb
# output fully deterministic and independent of the build directory.
ldflags += [ "/PDBSourcePath:o:\fake\prefix" ]
}
}
}
# Tells the compiler not to use absolute paths when passing the default
# paths to the tools it invokes. We don't want this because we don't
# really need it and it can mess up the goma cache entries.
if (is_clang && (!is_nacl || is_nacl_saigo)) {
cflags += [ "-no-canonical-prefixes" ]
# Same for links: Let the compiler driver invoke the linker
# with a relative path and pass relative paths to built-in
# libraries. Not needed on Windows because we call the linker
# directly there, not through the compiler driver.
# We don't link on goma, so this change is just for cleaner
# internal linker invocations, for people who work on the build.
if (!is_win) {
ldflags += [ "-no-canonical-prefixes" ]
}
}
}
config("clang_revision") {
if (is_clang && clang_base_path == default_clang_base_path) {
update_args = [
"--print-revision",
"--verify-version=$clang_version",
]
if (llvm_force_head_revision) {
update_args += [ "--llvm-force-head-revision" ]
}
clang_revision = exec_script("//tools/clang/scripts/update.py",
update_args,
"trim string")
# This is here so that all files get recompiled after a clang roll and
# when turning clang on or off. (defines are passed via the command line,
# and build system rebuild things when their commandline changes). Nothing
# should ever read this define.
defines = [ "CR_CLANG_REVISION=\"$clang_revision\"" ]
}
}
config("rustc_revision") {
if (rustc_revision != "") {
# Similar to the above config, this is here so that all files get recompiled
# after a rustc roll. Nothing should ever read this cfg. This will not be
# set if a custom toolchain is used.
rustflags = [
"--cfg",
"cr_rustc_revision=\"$rustc_revision\"",
]
}
}
config("compiler_arm_fpu") {
if (current_cpu == "arm" && !is_ios && !is_nacl) {
cflags = [ "-mfpu=$arm_fpu" ]
if (!arm_use_thumb) {
cflags += [ "-marm" ]
}
asmflags = cflags
}
}
config("compiler_arm_thumb") {
if (current_cpu == "arm" && arm_use_thumb && is_posix &&
!(is_apple || is_nacl)) {
cflags = [ "-mthumb" ]
}
}
config("compiler_arm") {
if (current_cpu == "arm" && is_chromeos) {
# arm is normally the default mode for clang, but on chromeos a wrapper
# is used to pass -mthumb, and therefor change the default.
cflags = [ "-marm" ]
}
}
# runtime_library -------------------------------------------------------------
#
# Sets the runtime library and associated options.
#
# How do you determine what should go in here vs. "compiler" above? Consider if
# a target might choose to use a different runtime library (ignore for a moment
# if this is possible or reasonable on your system). If such a target would want
# to change or remove your option, put it in the runtime_library config. If a
# target wants the option regardless, put it in the compiler config.
config("runtime_library") {
configs = []
# The order of this config is important: it must appear before
# android:runtime_library. This is to ensure libc++ appears before
# libandroid_support in the -isystem include order. Otherwise, there will be
# build errors related to symbols declared in math.h.
if (use_custom_libcxx) {
configs += [ "//build/config/c++:runtime_library" ]
}
# Rust and C++ both provide intrinsics for LLVM to call for math operations. We
# want to use the C++ intrinsics, not the ones in the Rust compiler_builtins
# library. The Rust symbols are marked as weak, so that they can be replaced by
# the C++ symbols. This config ensures the C++ symbols exist and are strong in
# order to cause that replacement to occur by explicitly linking in clang's
# compiler-rt library.
if (is_clang && toolchain_has_rust) {
configs += [ "//build/config/clang:compiler_builtins" ]
}
# TODO(crbug.com/830987): Come up with a better name for is POSIX + Fuchsia
# configuration.
if (is_posix || is_fuchsia) {
configs += [ "//build/config/posix:runtime_library" ]
if (use_custom_libunwind) {
# Instead of using an unwind lib from the toolchain,
# buildtools/third_party/libunwind will be built and used directly.
ldflags = [ "--unwindlib=none" ]
}
}
# System-specific flags. If your compiler flags apply to one of the
# categories here, add it to the associated file to keep this shared config
# smaller.
if (is_win) {
configs += [ "//build/config/win:runtime_library" ]
} else if (is_linux || is_chromeos) {
configs += [ "//build/config/linux:runtime_library" ]
if (is_chromeos) {
configs += [ "//build/config/chromeos:runtime_library" ]
}
} else if (is_ios) {
configs += [ "//build/config/ios:runtime_library" ]
} else if (is_mac) {
configs += [ "//build/config/mac:runtime_library" ]
} else if (is_android) {
configs += [ "//build/config/android:runtime_library" ]
}
if (is_component_build) {
defines = [ "COMPONENT_BUILD" ]
}
}
# treat_warnings_as_errors ----------------------------------------------------
#
# Adding this config causes the compiler to treat warnings as fatal errors.
# This is used as a subconfig of both chromium_code and no_chromium_code, and
# is broken out separately so nocompile tests can force-enable this setting
# independently of the default warning flags.
config("treat_warnings_as_errors") {
if (is_win) {
cflags = [ "/WX" ]
} else {
cflags = [ "-Werror" ]
# The compiler driver can sometimes (rarely) emit warnings before calling
# the actual linker. Make sure these warnings are treated as errors as
# well.
ldflags = [ "-Werror" ]
}
# Turn rustc warnings into the "deny" lint level, which produce compiler
# errors. The equivalent of -Werror for clang/gcc.
#
# Note we apply the actual lint flags in config("compiler"). All warnings
# are suppressed in third-party crates.
rustflags = [ "-Dwarnings" ]
}
# default_warnings ------------------------------------------------------------
#
# Collects all warning flags that are used by default. This is used as a
# subconfig of both chromium_code and no_chromium_code. This way these
# flags are guaranteed to appear on the compile command line after -Wall.
config("default_warnings") {
cflags = []
cflags_c = []
cflags_cc = []
ldflags = []
configs = []
if (is_win) {
if (fatal_linker_warnings) {
arflags = [ "/WX" ]
ldflags = [ "/WX" ]
}
defines = [
# Without this, Windows headers warn that functions like wcsnicmp
# should be spelled _wcsnicmp. But all other platforms keep spelling
# it wcsnicmp, making this warning unhelpful. We don't want it.
"_CRT_NONSTDC_NO_WARNINGS",
# TODO(thakis): winsock wants us to use getaddrinfo instead of
# gethostbyname. Fires mostly in non-Chromium code. We probably
# want to remove this define eventually.
"_WINSOCK_DEPRECATED_NO_WARNINGS",
]
if (!is_clang) {
# TODO(thakis): Remove this once
# https://swiftshader-review.googlesource.com/c/SwiftShader/+/57968 has
# rolled into angle.
cflags += [ "/wd4244" ]
}
} else {
if (is_apple && !is_nacl) {
# When compiling Objective-C, warns if a method is used whose
# availability is newer than the deployment target.
cflags += [ "-Wunguarded-availability" ]
}
if (is_ios) {
# When compiling Objective-C, warns if a selector named via @selector has
# not been defined in any visible interface.
cflags += [ "-Wundeclared-selector" ]
}
# Suppress warnings about ABI changes on ARM (Clang doesn't give this
# warning).
if (current_cpu == "arm" && !is_clang) {
cflags += [ "-Wno-psabi" ]
}
if (!is_clang) {
cflags_cc += [
# See comment for -Wno-c++11-narrowing.
"-Wno-narrowing",
]
# -Wno-class-memaccess warns about hash table and vector in blink.
# But the violation is intentional.
if (!is_nacl) {
cflags_cc += [ "-Wno-class-memaccess" ]
}
# -Wunused-local-typedefs is broken in gcc,
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63872
cflags += [ "-Wno-unused-local-typedefs" ]
# Don't warn about "maybe" uninitialized. Clang doesn't include this
# in -Wall but gcc does, and it gives false positives.
cflags += [ "-Wno-maybe-uninitialized" ]
cflags += [ "-Wno-deprecated-declarations" ]
# -Wcomment gives too many false positives in the case a
# backslash ended comment line is followed by a new line of
# comments
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61638
cflags += [ "-Wno-comments" ]
# -Wpacked-not-aligned complains all generated mojom-shared-internal.h
# files.
cflags += [ "-Wno-packed-not-aligned" ]
}
}
# Common Clang and GCC warning setup.
if (!is_win || is_clang) {
cflags += [
# Disables.
"-Wno-missing-field-initializers", # "struct foo f = {0};"
"-Wno-unused-parameter", # Unused function parameters.
]
if (!is_nacl || is_nacl_saigo) {
cflags += [
# An ABI compat warning we don't care about, https://crbug.com/1102157
# TODO(thakis): Push this to the (few) targets that need it,
# instead of having a global flag.
"-Wno-psabi",
]
}
}
if (is_clang) {
cflags += [
"-Wloop-analysis",
# TODO(thakis): This used to be implied by -Wno-unused-function,
# which we no longer use. Check if it makes sense to remove
# this as well. http://crbug.com/316352
"-Wno-unneeded-internal-declaration",
]
if (!is_nacl || is_nacl_saigo) {
if (is_win) {
# TODO(thakis): https://crbug.com/617318
# Currently goma can not handle case sensitiveness for windows well.
cflags += [ "-Wno-nonportable-include-path" ]
}
if (is_fuchsia) {
cflags_cc += [
# TODO(https://crbug.com/1474434): fix and reenable
"-Wno-missing-field-initializers",
]
}
cflags += [
"-Wenum-compare-conditional",
# Ignore warnings about MSVC optimization pragmas.
# TODO(thakis): Only for no_chromium_code? http://crbug.com/912662
"-Wno-ignored-pragma-optimize",
]
if (!is_nacl) {
cflags += [
# TODO(crbug.com/1343975) Evaluate and possibly enable.
"-Wno-deprecated-builtins",
# TODO(crbug.com/1352183) Evaluate and possibly enable.
"-Wno-bitfield-constant-conversion",
# TODO(crbug.com/1412713) Evaluate and possibly enable.
"-Wno-deprecated-this-capture",
]
}
}
# Some builders, such as Cronet, use a different version of Clang than
# Chromium. This can cause minor errors when compiling Chromium changes. We
# want to avoid these errors.
if (llvm_android_mainline) {
cflags += [
"-Wno-error=unknown-warning-option",
"-Wno-error=unused-command-line-argument",
]
}
}
# Rust warnings
# Require `unsafe` blocks even in `unsafe` fns. This is intended to become
# an error by default eventually; see
# https://github.com/rust-lang/rust/issues/71668
rustflags = [ "-Dunsafe_op_in_unsafe_fn" ]
}
# prevent_unsafe_narrowing ----------------------------------------------------
#
# Warnings that prevent narrowing or comparisons of integer types that are
# likely to cause out-of-bound read/writes or Undefined Behaviour. In
# particular, size_t is used for memory sizes, allocation, indexing, and
# offsets. Using other integer types along with size_t produces risk of
# memory-safety bugs and thus security exploits.
#
# In order to prevent these bugs, allocation sizes were historically limited to
# sizes that can be represented within 31 bits of information, allowing `int` to
# be safely misused instead of `size_t` (https://crbug.com/169327). In order to
# support increasing the allocation limit we require strictly adherence to
# using the correct types, avoiding lossy conversions, and preventing overflow.
# To do so, enable this config and fix errors by converting types to be
# `size_t`, which is both large enough and unsigned, when dealing with memory
# sizes, allocations, indices, or offsets.In cases where type conversion is not
# possible or is superfluous, use base::strict_cast<> or base::checked_cast<>
# to convert to size_t as needed.
# See also: https://docs.google.com/document/d/1CTbQ-5cQjnjU8aCOtLiA7G6P0i5C6HpSDNlSNq6nl5E
#
# To enable in a GN target, use:
# configs += [ "//build/config/compiler:prevent_unsafe_narrowing" ]
config("prevent_unsafe_narrowing") {
if (is_clang) {
cflags = [
"-Wshorten-64-to-32",
"-Wimplicit-int-conversion",
"-Wsign-compare",
"-Wsign-conversion",
]
if (!is_nacl) {
cflags += [
# Avoid bugs of the form `if (size_t i = size; i >= 0; --i)` while
# fixing types to be sign-correct.
"-Wtautological-unsigned-zero-compare",
]
}
}
}
# chromium_code ---------------------------------------------------------------
#
# Toggles between higher and lower warnings for code that is (or isn't)
# part of Chromium.
config("chromium_code") {
if (is_win) {
if (is_clang) {
cflags = [ "/W4" ] # Warning level 4.
# Opt in to additional [[nodiscard]] on standard library methods.
defines = [ "_HAS_NODISCARD" ]
}
} else {
cflags = [ "-Wall" ]
if (is_clang) {
# Enable extra warnings for chromium_code when we control the compiler.
cflags += [ "-Wextra" ]
}
# In Chromium code, we define __STDC_foo_MACROS in order to get the
# C99 macros on Mac and Linux.
defines = [
"__STDC_CONSTANT_MACROS",
"__STDC_FORMAT_MACROS",
]
if (!is_debug && !using_sanitizer && current_cpu != "s390x" &&
current_cpu != "s390" && current_cpu != "ppc64" &&
current_cpu != "mips" && current_cpu != "mips64" &&
current_cpu != "riscv64" && current_cpu != "loong64") {
# Non-chromium code is not guaranteed to compile cleanly with
# _FORTIFY_SOURCE. Also, fortified build may fail when optimizations are
# disabled, so only do that for Release build.
fortify_level = "2"
# ChromeOS supports a high-quality _FORTIFY_SOURCE=3 implementation
# with a few custom glibc patches. Use that if it's available.
if (is_chromeos_ash) {
fortify_level = "3"
}
defines += [ "_FORTIFY_SOURCE=" + fortify_level ]
}
if (is_apple) {
cflags_objc = [ "-Wimplicit-retain-self" ]
cflags_objcc = [ "-Wimplicit-retain-self" ]
}
if (is_mac) {
cflags_objc += [ "-Wobjc-missing-property-synthesis" ]
cflags_objcc += [ "-Wobjc-missing-property-synthesis" ]
}
}
if (is_clang) {
cflags += [
# Warn on missing break statements at the end of switch cases.
# For intentional fallthrough, use [[fallthrough]].
"-Wimplicit-fallthrough",
# Warn on unnecessary extra semicolons outside of function definitions.
"-Wextra-semi",
# Warn on unreachable code, including unreachable breaks and returns.
# See https://crbug.com/346399#c148 for suppression strategies.
"-Wunreachable-code-aggressive",
]
# Thread safety analysis is broken under nacl: https://crbug.com/982423.
if (!is_nacl || is_nacl_saigo) {
cflags += [
# Thread safety analysis. See base/thread_annotations.h and
# https://clang.llvm.org/docs/ThreadSafetyAnalysis.html
"-Wthread-safety",
]
}
}
configs = [
":default_warnings",
":noshadowing",
]
if (treat_warnings_as_errors) {
configs += [ ":treat_warnings_as_errors" ]
}
}
config("no_chromium_code") {
cflags = []
cflags_cc = []
defines = []
if (is_win) {
if (is_clang) {
cflags += [ "/W3" ] # Warning level 3.
}
cflags += [
"/wd4800", # Disable warning when forcing value to bool.
"/wd4267", # TODO(jschuh): size_t to int.
]
} else {
if (is_clang && !is_nacl) {
# TODO(thakis): Remove !is_nacl once
# https://codereview.webrtc.org/1552863002/ made its way into chromium.
cflags += [ "-Wall" ]
}
}
if (is_clang) {
cflags += [
# Lots of third-party libraries have unused variables. Instead of
# suppressing them individually, we just blanket suppress them here.
"-Wno-unused-variable",
# Similarly, we're not going to fix all the C++11 narrowing issues in
# third-party libraries.
"-Wno-c++11-narrowing",
]
if (!is_nacl) {
cflags += [
# Disabled for similar reasons as -Wunused-variable.
"-Wno-unused-but-set-variable",
# TODO(https://crbug.com/1202159): Clean up and enable.
"-Wno-misleading-indentation",
]
}
}
# Suppress all warnings in third party, as Cargo does:
# https://doc.rust-lang.org/rustc/lints/levels.html#capping-lints
rustflags = [ "--cap-lints=allow" ]
configs = [ ":default_warnings" ]
# GCC may emit unsuppressible warnings so only apply this config when
# building with clang. crbug.com/589724
if (treat_warnings_as_errors && is_clang) {
configs += [ ":treat_warnings_as_errors" ]
}
}
# noshadowing -----------------------------------------------------------------
#
# Allows turning -Wshadow on.
config("noshadowing") {
# This flag has to be disabled for nacl because the nacl compiler is too
# strict about shadowing.
if (is_clang && (!is_nacl || is_nacl_saigo)) {
cflags = [ "-Wshadow" ]
}
}
# rtti ------------------------------------------------------------------------
#
# Allows turning Run-Time Type Identification on or off.
config("rtti") {
if (is_win) {
cflags_cc = [ "/GR" ]
} else {
cflags_cc = [ "-frtti" ]
}
}
config("no_rtti") {
# Some sanitizer configs may require RTTI to be left enabled globally
if (!use_rtti) {
if (is_win) {
cflags_cc = [ "/GR-" ]
} else {
cflags_cc = [ "-fno-rtti" ]
cflags_objcc = cflags_cc
}
}
}
# export_dynamic ---------------------------------------------------------------
#
# Ensures all exported symbols are added to the dynamic symbol table. This is
# necessary to expose Chrome's custom operator new() and operator delete() (and
# other memory-related symbols) to libraries. Otherwise, they might
# (de)allocate memory on a different heap, which would spell trouble if pointers
# to heap-allocated memory are passed over shared library boundaries.
config("export_dynamic") {
# TODO(crbug.com/1052397): Revisit after target_os flip is completed.
if (is_linux || is_chromeos_lacros || export_libcxxabi_from_executables) {
ldflags = [ "-rdynamic" ]
}
}
# thin_archive -----------------------------------------------------------------
#
# Enables thin archives on posix, and on windows when the lld linker is used.
# Regular archives directly include the object files used to generate it.
# Thin archives merely reference the object files.
# This makes building them faster since it requires less disk IO, but is
# inappropriate if you wish to redistribute your static library.
# This config is added to the global config, so thin archives should already be
# enabled. If you want to make a distributable static library, you need to do 2
# things:
# 1. Set complete_static_lib so that all dependencies of the library make it
# into the library. See `gn help complete_static_lib` for details.
# 2. Remove the thin_archive config, so that the .a file actually contains all
# .o files, instead of just references to .o files in the build directoy
config("thin_archive") {
# The macOS and iOS default linker ld64 does not support reading thin
# archives.
# TODO(crbug.com/1221615): Enable on is_apple if use_lld once that no longer
# confuses lldb.
if ((is_posix && !is_nacl && !is_apple) || is_fuchsia) {
arflags = [ "-T" ]
} else if (is_win && use_lld) {
arflags = [ "/llvmlibthin" ]
}
}
# exceptions -------------------------------------------------------------------
#
# Allows turning Exceptions on or off.
# Note: exceptions are disallowed in Google code.
config("exceptions") {
if (is_win) {
# Enables exceptions in the STL.
if (!use_custom_libcxx) {
defines = [ "_HAS_EXCEPTIONS=1" ]
}
cflags_cc = [ "/EHsc" ]
} else {
cflags_cc = [ "-fexceptions" ]
cflags_objcc = cflags_cc
}
}
config("no_exceptions") {
if (is_win) {
# Disables exceptions in the STL.
# libc++ uses the __has_feature macro to control whether to use exceptions,
# so defining this macro is unnecessary. Defining _HAS_EXCEPTIONS to 0 also
# breaks libc++ because it depends on MSVC headers that only provide certain
# declarations if _HAS_EXCEPTIONS is 1. Those MSVC headers do not use
# exceptions, despite being conditional on _HAS_EXCEPTIONS.
if (!use_custom_libcxx) {
defines = [ "_HAS_EXCEPTIONS=0" ]
}
} else {
cflags_cc = [ "-fno-exceptions" ]
cflags_objcc = cflags_cc
}
}
# Warnings ---------------------------------------------------------------------
# Generate a warning for code that might emit a static initializer.
# See: //docs/static_initializers.md
# See: https://groups.google.com/a/chromium.org/d/topic/chromium-dev/B9Q5KTD7iCo/discussion
config("wglobal_constructors") {
if (is_clang) {
cflags = [ "-Wglobal-constructors" ]
}
}
# This will generate warnings when using Clang if code generates exit-time
# destructors, which will slow down closing the program.
# TODO(thakis): Make this a blocklist instead, http://crbug.com/101600
config("wexit_time_destructors") {
if (is_clang) {
cflags = [ "-Wexit-time-destructors" ]
}
}
# Some code presumes that pointers to structures/objects are compatible
# regardless of whether what they point to is already known to be valid.
# gcc 4.9 and earlier had no way of suppressing this warning without
# suppressing the rest of them. Here we centralize the identification of
# the gcc 4.9 toolchains.
config("no_incompatible_pointer_warnings") {
cflags = []
if (is_clang) {
cflags += [ "-Wno-incompatible-pointer-types" ]
} else if (current_cpu == "mipsel" || current_cpu == "mips64el") {
cflags += [ "-w" ]
} else if (is_chromeos_ash && current_cpu == "arm") {
cflags += [ "-w" ]
}
}
# Optimization -----------------------------------------------------------------
#
# The BUILDCONFIG file sets the "default_optimization" config on targets by
# default. It will be equivalent to either "optimize" (release) or
# "no_optimize" (debug) optimization configs.
#
# You can override the optimization level on a per-target basis by removing the
# default config and then adding the named one you want:
#
# configs -= [ "//build/config/compiler:default_optimization" ]
# configs += [ "//build/config/compiler:optimize_max" ]
# Shared settings for both "optimize" and "optimize_max" configs.
# IMPORTANT: On Windows "/O1" and "/O2" must go before the common flags.
if (is_win) {
common_optimize_on_cflags = [
"/Ob2", # Both explicit and auto inlining.
"/Oy-", # Disable omitting frame pointers, must be after /O2.
"/Zc:inline", # Remove unreferenced COMDAT (faster links).
]
if (!is_asan) {
common_optimize_on_cflags += [
# Put data in separate COMDATs. This allows the linker
# to put bit-identical constants at the same address even if
# they're unrelated constants, which saves binary size.
# This optimization can't be used when ASan is enabled because
# it is not compatible with the ASan ODR checker.
"/Gw",
]
}
common_optimize_on_ldflags = []
# /OPT:ICF is not desirable in Debug builds, since code-folding can result in
# misleading symbols in stack traces.
if (!is_debug && !is_component_build) {
common_optimize_on_ldflags += [ "/OPT:ICF" ] # Redundant COMDAT folding.
}
if (is_official_build) {
common_optimize_on_ldflags += [ "/OPT:REF" ] # Remove unreferenced data.
# TODO(thakis): Add LTO/PGO clang flags eventually, https://crbug.com/598772
}
} else {
common_optimize_on_cflags = []
common_optimize_on_ldflags = []
if (is_android) {
# TODO(jdduke) Re-enable on mips after resolving linking
# issues with libc++ (crbug.com/456380).
if (current_cpu != "mipsel" && current_cpu != "mips64el") {
common_optimize_on_ldflags += [
# Warn in case of text relocations.
"-Wl,--warn-shared-textrel",
]
}
}
if (is_apple) {
common_optimize_on_ldflags += [ "-Wl,-dead_strip" ]
if (is_official_build) {
common_optimize_on_ldflags += [
"-Wl,-no_data_in_code_info",
"-Wl,-no_function_starts",
]
}
} else if (current_os != "aix" && current_os != "zos") {
# Non-Mac Posix flags.
# Aix does not support these.
common_optimize_on_cflags += [
# Put data and code in their own sections, so that unused symbols
# can be removed at link time with --gc-sections.
"-fdata-sections",
"-ffunction-sections",
]
if ((!is_nacl || is_nacl_saigo) && is_clang) {
# We don't care about unique section names, this makes object files a bit
# smaller.
common_optimize_on_cflags += [ "-fno-unique-section-names" ]
}
common_optimize_on_ldflags += [
# Specifically tell the linker to perform optimizations.
# See http://lwn.net/Articles/192624/ .
# -O2 enables string tail merge optimization in gold and lld.
"-Wl,-O2",
"-Wl,--gc-sections",
]
}
}
config("default_stack_frames") {
if (!is_win) {
if (enable_frame_pointers) {
cflags = [ "-fno-omit-frame-pointer" ]
# Omit frame pointers for leaf functions on x86, otherwise building libyuv
# gives clang's register allocator issues, see llvm.org/PR15798 /
# crbug.com/233709
if (is_clang && current_cpu == "x86" && !is_apple) {
cflags += [ "-momit-leaf-frame-pointer" ]
}
} else {
cflags = [ "-fomit-frame-pointer" ]
}
}
# On Windows, the flag to enable framepointers "/Oy-" must always come after
# the optimization flag [e.g. "/O2"]. The optimization flag is set by one of
# the "optimize" configs, see rest of this file. The ordering that cflags are
# applied is well-defined by the GN spec, and there is no way to ensure that
# cflags set by "default_stack_frames" is applied after those set by an
# "optimize" config. Similarly, there is no way to propagate state from this
# config into the "optimize" config. We always apply the "/Oy-" config in the
# definition for common_optimize_on_cflags definition, even though this may
# not be correct.
}
# Default "optimization on" config.
config("optimize") {
if (is_win) {
if (chrome_pgo_phase != 2) {
# Favor size over speed, /O1 must be before the common flags.
# /O1 implies /Os and /GF.
cflags = [ "/O1" ] + common_optimize_on_cflags + [ "/Oi" ]
rustflags = [ "-Copt-level=s" ]
} else {
# PGO requires all translation units to be compiled with /O2. The actual
# optimization level will be decided based on the profiling data.
cflags = [ "/O2" ] + common_optimize_on_cflags + [ "/Oi" ]
# https://doc.rust-lang.org/rustc/profile-guided-optimization.html#usage
# suggests not using an explicit `-Copt-level` at all, and the default is
# to optimize for performance like `/O2` for clang.
rustflags = []
}
} else if (optimize_for_size) {
# Favor size over speed.
if (is_clang) {
cflags = [ "-Oz" ] + common_optimize_on_cflags
if (use_ml_inliner && is_a_target_toolchain) {
cflags += [
"-mllvm",
"-enable-ml-inliner=release",
]
}
} else {
cflags = [ "-Os" ] + common_optimize_on_cflags
}
# Like with `-Oz` on Clang, `-Copt-level=z` will also turn off loop
# vectorization.
rustflags = [ "-Copt-level=z" ]
} else if (is_chromeos) {
# TODO(gbiv): This is partially favoring size over speed. CrOS exclusively
# uses clang, and -Os in clang is more of a size-conscious -O2 than "size at
# any cost" (AKA -Oz). It'd be nice to:
# - Make `optimize_for_size` apply to all platforms where we're optimizing
# for size by default (so, also Windows)
# - Investigate -Oz here, maybe just for ARM?
cflags = [ "-Os" ] + common_optimize_on_cflags
# Similar to clang, we optimize with `-Copt-level=s` to keep loop
# vectorization while otherwise optimizing for size.
rustflags = [ "-Copt-level=s" ]
} else {
cflags = [ "-O2" ] + common_optimize_on_cflags
# The `-O3` for clang turns on extra optimizations compared to the standard
# `-O2`. But for rust, `-Copt-level=3` is the default and is thus reliable
# to use.
rustflags = [ "-Copt-level=3" ]
}
ldflags = common_optimize_on_ldflags
}
# Turn off optimizations.
config("no_optimize") {
if (is_win) {
cflags = [
"/Od", # Disable optimization.
"/Ob0", # Disable all inlining (on by default).
"/GF", # Enable string pooling (off by default).
]
if (target_cpu == "arm64") {
# Disable omitting frame pointers for no_optimize build because stack
# traces on Windows ARM64 rely on it.
cflags += [ "/Oy-" ]
}
} else if (is_android && !android_full_debug) {
# On Android we kind of optimize some things that don't affect debugging
# much even when optimization is disabled to get the binary size down.
if (is_clang) {
cflags = [ "-Oz" ] + common_optimize_on_cflags
} else {
cflags = [ "-Os" ] + common_optimize_on_cflags
}
if (!is_component_build) {
# Required for library partitions. Without this all symbols just end up
# in the base partition.
ldflags = [ "-Wl,--gc-sections" ]
}
} else if (is_fuchsia) {
# On Fuchsia, we optimize for size here to reduce the size of debug build
# packages so they can be run in a KVM. See crbug.com/910243 for details.
cflags = [ "-Og" ]
} else {
cflags = [ "-O0" ]
ldflags = []
}
}
# Turns up the optimization level. On Windows, this implies whole program
# optimization and link-time code generation which is very expensive and should
# be used sparingly.
config("optimize_max") {
if (is_nacl && is_nacl_irt) {
# The NaCl IRT is a special case and always wants its own config.
# Various components do:
# if (!is_debug) {
# configs -= [ "//build/config/compiler:default_optimization" ]
# configs += [ "//build/config/compiler:optimize_max" ]
# }
# So this config has to have the selection logic just like
# "default_optimization", below.
configs = [ "//build/config/nacl:irt_optimize" ]
} else {
ldflags = common_optimize_on_ldflags
if (is_win) {
# Favor speed over size, /O2 must be before the common flags.
# /O2 implies /Ot, /Oi, and /GF.
cflags = [ "/O2" ] + common_optimize_on_cflags
} else if (optimize_for_fuzzing) {
cflags = [ "-O1" ] + common_optimize_on_cflags
} else {
cflags = [ "-O2" ] + common_optimize_on_cflags
}
rustflags = [ "-Copt-level=3" ]
}
}
# This config can be used to override the default settings for per-component
# and whole-program optimization, optimizing the particular target for speed
# instead of code size. This config is exactly the same as "optimize_max"
# except that we use -O3 instead of -O2 on non-win, non-IRT platforms.
#
# TODO(crbug.com/621335) - rework how all of these configs are related
# so that we don't need this disclaimer.
config("optimize_speed") {
if (is_nacl && is_nacl_irt) {
# The NaCl IRT is a special case and always wants its own config.
# Various components do:
# if (!is_debug) {
# configs -= [ "//build/config/compiler:default_optimization" ]
# configs += [ "//build/config/compiler:optimize_max" ]
# }
# So this config has to have the selection logic just like
# "default_optimization", below.
configs = [ "//build/config/nacl:irt_optimize" ]
} else {
ldflags = common_optimize_on_ldflags
if (is_win) {
# Favor speed over size, /O2 must be before the common flags.
# /O2 implies /Ot, /Oi, and /GF.
cflags = [ "/O2" ] + common_optimize_on_cflags
} else if (optimize_for_fuzzing) {
cflags = [ "-O1" ] + common_optimize_on_cflags
} else {
cflags = [ "-O3" ] + common_optimize_on_cflags
}
rustflags = [ "-Copt-level=3" ]
}
}
config("optimize_fuzzing") {
cflags = [ "-O1" ] + common_optimize_on_cflags
rustflags = [ "-Copt-level=1" ]
ldflags = common_optimize_on_ldflags
visibility = [ ":default_optimization" ]
}
# The default optimization applied to all targets. This will be equivalent to
# either "optimize" or "no_optimize", depending on the build flags.
config("default_optimization") {
if (is_nacl && is_nacl_irt) {
# The NaCl IRT is a special case and always wants its own config.
# It gets optimized the same way regardless of the type of build.
configs = [ "//build/config/nacl:irt_optimize" ]
} else if (is_debug) {
configs = [ ":no_optimize" ]
} else if (optimize_for_fuzzing) {
assert(!is_win, "Fuzzing optimize level not supported on Windows")
# Coverage build is quite slow. Using "optimize_for_fuzzing" makes it even
# slower as it uses "-O1" instead of "-O3". Prevent that from happening.
assert(!use_clang_coverage,
"optimize_for_fuzzing=true should not be used with " +
"use_clang_coverage=true.")
configs = [ ":optimize_fuzzing" ]
} else {
configs = [ ":optimize" ]
}
}
_clang_sample_profile = ""
if (is_clang && is_a_target_toolchain) {
if (clang_sample_profile_path != "") {
_clang_sample_profile = clang_sample_profile_path
} else if (clang_use_default_sample_profile) {
assert(build_with_chromium,
"Our default profiles currently only apply to Chromium")
assert(is_android || is_chromeos || is_castos,
"The current platform has no default profile")
if (is_android || is_castos) {
_clang_sample_profile = "//chrome/android/profiles/afdo.prof"
} else {
assert(
chromeos_afdo_platform == "atom" ||
chromeos_afdo_platform == "bigcore" ||
chromeos_afdo_platform == "arm" ||
chromeos_afdo_platform == "arm-exp",
"Only 'atom', 'bigcore', 'arm' and 'arm-exp' are valid ChromeOS profiles.")
_clang_sample_profile =
"//chromeos/profiles/${chromeos_afdo_platform}.afdo.prof"
}
}
}
# Clang offers a way to assert that AFDO profiles are accurate, which causes it
# to optimize functions not represented in a profile more aggressively for size.
# This config can be toggled in cases where shaving off binary size hurts
# performance too much.
config("afdo_optimize_size") {
if (_clang_sample_profile != "" && sample_profile_is_accurate) {
cflags = [ "-fprofile-sample-accurate" ]
}
}
# GCC and clang support a form of profile-guided optimization called AFDO.
# There are some targeted places that AFDO regresses, so we provide a separate
# config to allow AFDO to be disabled per-target.
config("afdo") {
if (is_clang) {
cflags = []
if (clang_emit_debug_info_for_profiling) {
# Add the following flags to generate debug info for profiling.
cflags += [ "-gline-tables-only" ]
if (!is_nacl) {
cflags += [ "-fdebug-info-for-profiling" ]
}
}
if (_clang_sample_profile != "") {
assert(chrome_pgo_phase == 0, "AFDO can't be used in PGO builds")
rebased_clang_sample_profile =
rebase_path(_clang_sample_profile, root_build_dir)
cflags += [ "-fprofile-sample-use=${rebased_clang_sample_profile}" ]
if (use_profi) {
cflags += [ "-fsample-profile-use-profi" ]
}
# crbug.com/1459429: ARM builds see failures due to -Wbackend-plugin.
# These seem to be false positives - the complaints are about functions
# marked with `__nodebug__` not having associated debuginfo. In the case
# where this was observed, the `__nodebug__` function was also marked
# `__always_inline__` and had no branches, so AFDO info is likely useless
# there.
cflags += [ "-Wno-backend-plugin" ]
inputs = [ _clang_sample_profile ]
}
} else if (auto_profile_path != "" && is_a_target_toolchain) {
cflags = [ "-fauto-profile=${auto_profile_path}" ]
inputs = [ auto_profile_path ]
}
}
# Symbols ----------------------------------------------------------------------
# The BUILDCONFIG file sets the "default_symbols" config on targets by
# default. It will be equivalent to one the three specific symbol levels.
#
# You can override the symbol level on a per-target basis by removing the
# default config and then adding the named one you want:
#
# configs -= [ "//build/config/compiler:default_symbols" ]
# configs += [ "//build/config/compiler:symbols" ]
# A helper config that all configs passing /DEBUG to the linker should
# include as sub-config.
config("win_pdbaltpath") {
visibility = [
":minimal_symbols",
":symbols",
]
# /DEBUG causes the linker to generate a pdb file, and to write the absolute
# path to it in the executable file it generates. This flag turns that
# absolute path into just the basename of the pdb file, which helps with
# build reproducibility. Debuggers look for pdb files next to executables,
# so there's minimal downside to always using this. However, post-mortem
# debugging of Chromium crash dumps and ETW tracing can be complicated by this
# switch so an option to omit it is important.
if (!use_full_pdb_paths) {
ldflags = [ "/pdbaltpath:%_PDB%" ]
}
}
# Full symbols.
config("symbols") {
rustflags = []
if (is_win) {
if (is_clang) {
cflags = [
# Debug information in the .obj files.
"/Z7",
# Disable putting the compiler command line into the debug info to
# prevent some types of non-determinism.
"-gno-codeview-command-line",
]
} else {
cflags = [ "/Zi" ] # Produce PDB file, no edit and continue.
}
if (is_clang && use_lld && use_ghash) {
cflags += [ "-gcodeview-ghash" ]
ldflags = [ "/DEBUG:GHASH" ]
} else {
ldflags = [ "/DEBUG" ]
}
# All configs using /DEBUG should include this:
configs = [ ":win_pdbaltpath" ]
} else {
cflags = []
if (is_mac && enable_dsyms) {
# If generating dSYMs, specify -fno-standalone-debug. This was
# originally specified for https://crbug.com/479841 because dsymutil
# could not handle a 4GB dSYM file. But dsymutil from Xcodes prior to
# version 7 also produces debug data that is incompatible with Breakpad
# dump_syms, so this is still required (https://crbug.com/622406).
cflags += [ "-fno-standalone-debug" ]
}
# On aix -gdwarf causes linker failures due to thread_local variables.
if (!is_nacl && current_os != "aix") {
if (use_dwarf5) {
cflags += [ "-gdwarf-5" ]
rustflags += [ "-Zdwarf-version=5" ]
} else {
# Recent clang versions default to DWARF5 on Linux, and Android is about
# to switch. TODO: Adopt that in controlled way. For now, keep DWARF4.
# Apple platforms still default to 4 in clang, so they don't need the
# cflags.
if (!is_apple) {
cflags += [ "-gdwarf-4" ]
}
# On Apple, rustc defaults to DWARF2 so it needs to be told how to
# match clang.
rustflags += [ "-Zdwarf-version=4" ]
}
}
# The gcc-based nacl compilers don't support -fdebug-compilation-dir (see
# elsewhere in this file), so they can't have build-dir-independent output.
# Moreover pnacl does not support newer flags such as -fdebug-prefix-map
# Disable symbols for nacl object files to get deterministic,
# build-directory-independent output.
# Keeping -g2 for saigo as it's the only toolchain whose artifacts that are
# part of chromium release (other nacl toolchains are used only for tests).
if ((!is_nacl || is_nacl_saigo) && current_os != "zos") {
cflags += [ "-g2" ]
}
if (!is_nacl && is_clang && !is_tsan && !is_asan) {
# gcc generates dwarf-aranges by default on -g1 and -g2. On clang it has
# to be manually enabled.
#
# It is skipped in tsan and asan because enabling it causes some
# formatting changes in the output which would require fixing bunches
# of expectation regexps.
cflags += [ "-gdwarf-aranges" ]
}
if (is_apple) {
swiftflags = [ "-g" ]
}
if (use_debug_fission) {
cflags += [ "-gsplit-dwarf" ]
}
asmflags = cflags
ldflags = []
# Split debug info with all thinlto builds except nacl and apple.
# thinlto requires -gsplit-dwarf in ldflags.
if (use_debug_fission && use_thin_lto && !is_nacl && !is_apple) {
ldflags += [ "-gsplit-dwarf" ]
}
# TODO(thakis): Figure out if there's a way to make this go for 32-bit,
# currently we get "warning:
# obj/native_client/src/trusted/service_runtime/sel_asm/nacl_switch_32.o:
# DWARF info may be corrupt; offsets in a range list entry are in different
# sections" there. Maybe just a bug in nacl_switch_32.S.
_enable_gdb_index =
symbol_level == 2 && !is_apple && !is_nacl && current_cpu != "x86" &&
current_os != "zos" && (use_gold || use_lld) &&
# Disable on non-fission 32-bit Android because it pushes
# libcomponents_unittests over the 4gb size limit.
!(is_android && !use_debug_fission && current_cpu != "x64" &&
current_cpu != "arm64")
if (_enable_gdb_index) {
if (is_clang) {
# This flag enables the GNU-format pubnames and pubtypes sections,
# which lld needs in order to generate a correct GDB index.
# TODO(pcc): Try to make lld understand non-GNU-format pubnames
# sections (llvm.org/PR34820).
cflags += [ "-ggnu-pubnames" ]
}
ldflags += [ "-Wl,--gdb-index" ]
}
}
configs = []
# Compress debug on 32-bit ARM to stay under 4GB for ChromeOS
# https://b/243982712.
if (symbol_level == 2 && is_chromeos_device && !use_debug_fission &&
!is_nacl && current_cpu == "arm") {
configs += [ "//build/config:compress_debug_sections" ]
}
if (is_clang && (!is_nacl || is_nacl_saigo) && current_os != "zos") {
if (is_apple) {
# TODO(https://crbug.com/1050118): Investigate missing debug info on mac.
# Make sure we don't use constructor homing on mac.
cflags += [
"-Xclang",
"-debug-info-kind=limited",
]
} else {
# Use constructor homing for debug info. This option reduces debug info
# by emitting class type info only when constructors are emitted.
cflags += [
"-Xclang",
"-fuse-ctor-homing",
]
}
}
rustflags += [ "-g" ]
}
# Minimal symbols.
# This config guarantees to hold symbol for stack trace which are shown to user
# when crash happens in unittests running on buildbot.
config("minimal_symbols") {
rustflags = []
if (is_win) {
# Functions, files, and line tables only.
cflags = []
if (is_clang) {
cflags += [
# Disable putting the compiler command line into the debug info to
# prevent some types of non-determinism.
"-gno-codeview-command-line",
]
}
if (is_clang && use_lld && use_ghash) {
cflags += [ "-gcodeview-ghash" ]
ldflags = [ "/DEBUG:GHASH" ]
} else {
ldflags = [ "/DEBUG" ]
}
# All configs using /DEBUG should include this:
configs = [ ":win_pdbaltpath" ]
# Enable line tables for clang. MSVC doesn't have an equivalent option.
if (is_clang) {
# -gline-tables-only is the same as -g1, but clang-cl only exposes the
# former.
cflags += [ "-gline-tables-only" ]
}
} else {
cflags = []
if (is_mac && !use_dwarf5) {
# clang defaults to DWARF2 on macOS unless mac_deployment_target is
# at least 10.11.
# TODO(thakis): Remove this once mac_deployment_target is 10.11.
cflags += [ "-gdwarf-4" ]
rustflags += [ "-Zdwarf-version=4" ]
} else if (!use_dwarf5 && !is_nacl && current_os != "aix") {
# On aix -gdwarf causes linker failures due to thread_local variables.
# Recent clang versions default to DWARF5 on Linux, and Android is about
# to switch. TODO: Adopt that in controlled way.
cflags += [ "-gdwarf-4" ]
rustflags += [ "-Zdwarf-version=4" ]
}
if (use_dwarf5 && !is_nacl) {
cflags += [ "-gdwarf-5" ]
rustflags += [ "-Zdwarf-version=5" ]
}
# The gcc-based nacl compilers don't support -fdebug-compilation-dir (see
# elsewhere in this file), so they can't have build-dir-independent output.
# Moreover pnacl does not support newer flags such as -fdebug-prefix-map
# Disable symbols for nacl object files to get deterministic,
# build-directory-independent output.
# Keeping -g1 for saigo as it's the only toolchain whose artifacts that are
# part of chromium release (other nacl toolchains are used only for tests).
if (!is_nacl || is_nacl_saigo) {
cflags += [ "-g1" ]
}
if (!is_nacl && is_clang && !is_tsan && !is_asan) {
# See comment for -gdwarf-aranges in config("symbols").
cflags += [ "-gdwarf-aranges" ]
}
ldflags = []
if (is_android && is_clang) {
# Android defaults to symbol_level=1 builds, but clang, unlike gcc,
# doesn't emit DW_AT_linkage_name in -g1 builds.
# -fdebug-info-for-profiling enables that (and a bunch of other things we
# don't need), so that we get qualified names in stacks.
# TODO(thakis): Consider making clang emit DW_AT_linkage_name in -g1 mode;
# failing that consider doing this on non-Android too.
cflags += [ "-fdebug-info-for-profiling" ]
}
asmflags = cflags
}
rustflags += [ "-Cdebuginfo=1" ]
}
# This configuration contains function names only. That is, the compiler is
# told to not generate debug information and the linker then just puts function
# names in the final debug information.
config("no_symbols") {
if (is_win) {
ldflags = [ "/DEBUG" ]
# All configs using /DEBUG should include this:
configs = [ ":win_pdbaltpath" ]
} else {
cflags = [ "-g0" ]
asmflags = cflags
}
}
# Default symbols.
config("default_symbols") {
if (symbol_level == 0) {
configs = [ ":no_symbols" ]
} else if (symbol_level == 1) {
configs = [ ":minimal_symbols" ]
} else if (symbol_level == 2) {
configs = [ ":symbols" ]
} else {
assert(false)
}
# This config is removed by base unittests apk.
if (is_android && is_clang && strip_debug_info) {
configs += [ ":strip_debug" ]
}
}
config("strip_debug") {
if (!defined(ldflags)) {
ldflags = []
}
ldflags += [ "-Wl,--strip-debug" ]
}
if (is_apple) {
# On macOS and iOS, this enables support for ARC (automatic reference
# counting). See http://clang.llvm.org/docs/AutomaticReferenceCounting.html.
#
# -fobjc-arc enables ARC overall.
#
# ARC does not add exception handlers to pure Objective-C code, but does add
# them to Objective-C++ code with the rationale that C++ pervasively adds them
# in for exception safety. However, exceptions are banned in Chromium code for
# C++ and exceptions in Objective-C code are intended to be fatal, so
# -fno-objc-arc-exceptions is specified to disable these unwanted exception
# handlers.
config("enable_arc") {
common_flags = [
"-fobjc-arc",
"-fno-objc-arc-exceptions",
]
cflags_objc = common_flags
cflags_objcc = common_flags
}
}
if (is_android) {
# Use orderfile for linking Chrome on Android.
# This config enables using an orderfile for linking in LLD.
config("chrome_orderfile_config") {
# Don't try to use an orderfile with call graph sorting, except on Android,
# where we care about memory used by code, so we still want to mandate
# ordering.
if (chrome_orderfile_path != "") {
assert(use_lld)
_rebased_orderfile = rebase_path(chrome_orderfile_path, root_build_dir)
ldflags = [
"-Wl,--symbol-ordering-file",
"-Wl,$_rebased_orderfile",
"-Wl,--no-warn-symbol-ordering",
]
inputs = [ chrome_orderfile_path ]
}
}
}
# Initialize all variables on the stack if needed.
config("default_init_stack_vars") {
cflags = []
if (init_stack_vars && is_clang && !is_nacl && !using_sanitizer) {
if (init_stack_vars_zero) {
cflags += [ "-ftrivial-auto-var-init=zero" ]
} else {
cflags += [ "-ftrivial-auto-var-init=pattern" ]
}
}
}
buildflag_header("compiler_buildflags") {
header = "compiler_buildflags.h"
flags = [
"CLANG_PGO=$chrome_pgo_phase",
"SYMBOL_LEVEL=$symbol_level",
]
}
config("cet_shadow_stack") {
if (enable_cet_shadow_stack && is_win) {
assert(target_cpu == "x64")
ldflags = [ "/CETCOMPAT" ]
}
}
Radix cross Linux
The main Radix cross Linux repository contains the build scripts of packages, which have the most complete and common functionality for desktop machines
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