Google Git
Sign in
cobalt / cobalt / 5dc6e1dd9b36936aa4526d24488ccc9b689c75d2 / . / build / config / compiler / BUILD.gn
blob: 838ebcdfbba2bfa020ca0c922a332989ce448379 [file] [log] [blame]
# Copyright (c) 2013 The Chromium Authors. All rights reserved.
# 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/chromecast_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")
if (!use_cobalt_customizations) {
import("//build/config/gclient_args.gni")
}
import("//build/config/host_byteorder.gni")
import("//build/config/sanitizers/sanitizers.gni")
import("//build/config/ui.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 (current_cpu == "x64") {
import("//build/config/x64.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")
}
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.
# TODO(thakis): Set this to true unconditionally once lld/MachO bring-up
# is along far enough that it no longer emits linker warnings.
fatal_linker_warnings = !(is_apple && use_lld)
# 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 = ""
# Allow projects that wish to stay on C++11 to override Chromium's default.
use_cxx11 = false
# 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 || is_chromecast)
# 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.
clang_emit_debug_info_for_profiling = false
# 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_ash || is_android || is_win || is_linux) && 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): Enabling this when 'is_android' is true breaks
# content_shell_test_apk on both ARM and x86.
#
# TODO(crbug.com/977230): Enabling this when 'use_xcode_clang' is true may
# call an old clang that doesn't support auto-init.
init_stack_vars = !is_android && !use_xcode_clang
# 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 may be mlocked or mapped to huge page to
# reduce TLB misses which gives performance improvement on cpu usage.
# The gold linker by default has text section splitting enabled.
use_text_section_splitting = false
# Token limits may not be accurate for build configs not covered by the CQ,
# so only enable them by default for mainstream build configs.
enable_wmax_tokens =
!is_official_build &&
((is_mac && target_cpu == "x64" && !use_system_xcode) ||
(is_linux && !is_chromeos && target_cpu == "x64") ||
(is_win && target_cpu == "x86") || (is_win && target_cpu == "x64") ||
(is_android && target_cpu == "arm") ||
(is_android && target_cpu == "arm64"))
# 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
# 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
}
declare_args() {
# C++11 may not be an option if Android test infrastructure is used.
use_cxx11_on_android = use_cxx11
}
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 && !(is_android && use_order_profiling) &&
(use_lld || (use_gold && (is_chromeos_ash || !(current_cpu == "x86" ||
current_cpu == "x64"))))
}
if (is_android || (is_chromeos_ash && is_chromeos_device)) {
# 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
} else if (is_chromeos_ash && is_chromeos_device) {
chrome_orderfile_path = "//chromeos/profiles/chromeos.orderfile.txt"
}
}
}
assert(!(llvm_force_head_revision && use_goma),
"can't use goma with trunk clang")
assert(!(llvm_force_head_revision && use_rbe), "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 ---------------------------------------------------------------------
#
# 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 = []
ldflags = []
defines = []
configs = []
# 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" ]
if (is_chromeos_ash) {
configs += [ "//build/config/chromeos: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" ]
}
configs += [
# See the definitions below.
":clang_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.
if (is_mac) {
# 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_ash && !is_nacl) || is_fuchsia) {
# TODO(phajdan.jr): Use -fstack-protector-strong when our gcc supports it.
# See also https://crbug.com/533294
cflags += [ "--param=ssp-buffer-size=4" ]
# 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" ]
}
# Linker warnings.
if (fatal_linker_warnings && !is_apple && current_os != "aix") {
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-Mac 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") {
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",
]
defines += [ "NO_UNWIND_TABLES" ]
} else {
cflags += [ "-funwind-tables" ]
}
}
}
# Linux/Android/Fuchsia common flags setup.
# ---------------------------------
if (is_linux || is_chromeos || is_android || is_fuchsia) {
asmflags += [ "-fPIC" ]
cflags += [ "-fPIC" ]
ldflags += [ "-fPIC" ]
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" ]
}
# Compiler instrumentation can introduce dependencies in DSOs to symbols in
# the executable they are loaded into, so they are unresolved at link-time.
if (!using_sanitizer) {
ldflags += [
"-Wl,-z,defs",
"-Wl,--as-needed",
]
}
}
# Linux-specific compiler flags setup.
# ------------------------------------
if ((is_posix || is_fuchsia) && use_lld) {
if (current_cpu == "arm64") {
# Reduce the page size from 65536 in order to reduce binary size slightly
# by shrinking the alignment gap between segments. This also causes all
# segments to be mapped adjacently, which breakpad relies on.
ldflags += [ "-Wl,-z,max-page-size=4096" ]
}
} else 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) {
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 && !use_xcode_clang) {
cflags += [ "-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" ]
}
}
}
# C11/C++11 compiler flags setup.
# ---------------------------
if (is_linux || is_chromeos || is_android || (is_nacl && is_clang) ||
current_os == "aix") {
if (target_os == "android") {
cxx11_override = use_cxx11_on_android
} else {
cxx11_override = use_cxx11
}
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 (cxx11_override) {
# Override Chromium's default for projects that wish to stay on C++11.
cflags_cc += [ "-std=${standard_prefix}++11" ]
} else {
cflags_cc += [ "-std=${standard_prefix}++14" ]
}
} else if (!is_win && !is_nacl) {
if (target_os == "android") {
cxx11_override = use_cxx11_on_android
} else {
cxx11_override = use_cxx11
}
# 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 (cxx11_override) {
cflags_cc += [ "-std=c++11" ]
} else {
cflags_cc += [ "-std=c++14" ]
}
}
# C++17 removes trigraph support, so preemptively disable trigraphs. This is
# especially useful given the collision with ecmascript's logical assignment
# operators: https://github.com/tc39/proposal-logical-assignment
if (is_clang) {
# clang-cl disables trigraphs by default
if (!is_win) {
# The gnu variants of C++11 and C++14 already disable trigraph support,
# but when building with clang, we use -std=c++11 / -std=c++14, which
# enables trigraph support: override that here.
cflags_cc += [ "-fno-trigraphs" ]
}
# Don't warn that trigraphs are ignored, since trigraphs are disabled
# anyway.
cflags_cc += [ "-Wno-trigraphs" ]
}
if (is_mac) {
# The system libc++ on Mac doesn't have aligned allocation in C++17.
defines += [ "_LIBCPP_HAS_NO_ALIGNED_ALLOCATION" ]
cflags_cc += [ "-stdlib=libc++" ]
ldflags += [ "-stdlib=libc++" ]
}
# 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"
# 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 = 5
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:$cache_policy",
]
} else {
ldflags += [ "-flto=thin" ]
# Enabling ThinLTO on Chrome OS too, in an effort to reduce the memory
# usage in crbug.com/1038040. Note this will increase build time in
# Chrome OS.
# In ThinLTO builds, we run at most one link process at a time,
# and let it use all cores.
# TODO(thakis): Check if '=0' (that is, number of cores, instead
# of "all" which means number of hardware threads) is faster.
ldflags += [ "-Wl,--thinlto-jobs=all" ]
ldflags += [
"-Wl,--thinlto-cache-dir=" +
rebase_path("$root_out_dir/thinlto-cache", root_build_dir),
"-Wl,--thinlto-cache-policy,$cache_policy",
]
if (is_chromeos_ash) {
# Not much performance difference was noted between the default (100)
# and these. ARM was originally set lower than x86 to keep the size
# bloat of ThinLTO to <10%, but that's potentially no longer true.
# FIXME(inglorion): maybe tune these?
if (target_cpu == "arm" || target_cpu == "arm64") {
import_instr_limit = 20
} else {
import_instr_limit = 30
}
}
ldflags += [ "-Wl,-mllvm,-import-instr-limit=$import_instr_limit" ]
}
# Whole-program devirtualization increases android libchrome.so size
# by ~100kb on arm32 and reduces it by ~108kb on arm64 instead.
# Tracked by llvm bug: https://bugs.llvm.org/show_bug.cgi?id=48245
if (!is_android || current_cpu == "arm64") {
cflags += [ "-fwhole-program-vtables" ]
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" ]
}
# 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 if (!is_apple) {
# TODO(thakis): Once LLD's Mach-O port basically works, implement call
# graph profile sorting for it, add an opt-out flag, and pass it here.
ldflags += [ "-Wl,--no-call-graph-profile-sort" ]
}
}
if (is_clang && !is_nacl && show_includes) {
assert(!is_win, "show_includes is not supported on Windows")
cflags += [
"-H",
"-Xclang",
"-show-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).
# TODO(crbug/1052397): Remove is_chromeos_lacros once lacros-chrome switches
# to target_os="chromeos".
if (is_clang && !is_nacl && target_os != "chromeos" && !use_xcode_clang &&
!is_chromeos_lacros && (is_win || use_custom_libcxx)) {
cflags += [ "-fcomplete-member-pointers" ]
}
# 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
}
}
# 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 ]
}
}
}
# 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 ]
}
}
}
# 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 = []
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",
"-march=$x64_arch",
"-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) {
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=$arm_tune" ]
}
} else if (current_cpu == "arm64") {
if (is_clang && !is_android && !is_nacl && !is_fuchsia) {
cflags += [ "--target=aarch64-linux-gnu" ]
ldflags += [ "--target=aarch64-linux-gnu" ]
}
} else if (current_cpu == "mipsel" && !is_nacl) {
ldflags += [ "-Wl,--hash-style=sysv" ]
if (custom_toolchain == "") {
if (is_clang) {
if (is_android) {
cflags += [ "--target=mipsel-linux-android" ]
ldflags += [ "--target=mipsel-linux-android" ]
} else {
cflags += [ "--target=mipsel-linux-gnu" ]
ldflags += [ "--target=mipsel-linux-gnu" ]
}
} else {
cflags += [ "-EL" ]
ldflags += [ "-EL" ]
}
}
if (mips_arch_variant == "r6") {
cflags += [ "-mno-odd-spreg" ]
ldflags += [ "-mips32r6" ]
if (is_clang) {
cflags += [
"-march=mipsel",
"-mcpu=mips32r6",
]
} else {
cflags += [
"-mips32r6",
"-Wa,-mips32r6",
]
if (is_android) {
ldflags += [ "-Wl,-melf32ltsmip" ]
}
}
if (mips_use_msa == true) {
cflags += [
"-mmsa",
"-mfp64",
]
}
} else if (mips_arch_variant == "r2") {
ldflags += [ "-mips32r2" ]
if (is_clang) {
cflags += [
"-march=mipsel",
"-mcpu=mips32r2",
]
} else {
cflags += [
"-mips32r2",
"-Wa,-mips32r2",
]
if (mips_float_abi == "hard" && mips_fpu_mode != "") {
cflags += [ "-m$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 == "pnacl" && is_nacl_nonsfi) {
if (target_cpu == "x86" || target_cpu == "x64") {
cflags += [
"-arch",
"x86-32-nonsfi",
"--pnacl-bias=x86-32-nonsfi",
"--target=i686-unknown-nacl",
]
ldflags += [
"-arch",
"x86-32-nonsfi",
"--target=i686-unknown-nacl",
]
} else if (target_cpu == "arm") {
cflags += [
"-arch",
"arm-nonsfi",
"-mfloat-abi=hard",
"--pnacl-bias=arm-nonsfi",
"--target=armv7-unknown-nacl-gnueabihf",
]
ldflags += [
"-arch",
"arm-nonsfi",
"--target=armv7-unknown-nacl-gnueabihf",
]
}
} else if (current_cpu == "ppc64") {
if (current_os == "aix") {
cflags += [ "-maix64" ]
ldflags += [ "-maix64" ]
} else {
cflags += [ "-m64" ]
ldflags += [ "-m64" ]
}
} 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_android) {
# On arm64 disable outlining for Android. See crbug.com/931297 for more
# information.
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 = []
# 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 $cwd in debug info by default.
# For such build, this flag generates reproducible obj files even we use
# different build directory like "out/feature_a" and "out/feature_b" if
# we build same files with same compile flag.
# Other paths are already given in relative, no need to normalize them.
cflags += [
"-Xclang",
"-fdebug-compilation-dir",
"-Xclang",
".",
]
if (!is_win) {
# We don't use clang -cc1as on Windows (yet? https://crbug.com/762167)
asmflags = [ "-Wa,-fdebug-compilation-dir,." ]
}
if (is_win && use_lld) {
if (symbol_level == 2 || (is_clang && using_sanitizer)) {
# Absolutize source file paths for PDB. Pass the real build directory
# if the pdb contains source-level debug information and if linker
# reproducibility is not critical.
ldflags += [ "/PDBSourcePath:" + rebase_path(root_build_dir) ]
} else {
# Use a fake fixed base directory for paths in the pdb to make the pdb
# output fully deterministic and independent of the build directory.
ldflags += [ "/PDBSourcePath:o:\fake\prefix" ]
}
}
}
# Tells the compiler not to use absolute paths when passing the default
# paths to the tools it invokes. We don't want this because we don't
# really need it and it can mess up the goma cache entries.
if (is_clang && !is_nacl) {
cflags += [ "-no-canonical-prefixes" ]
}
}
config("clang_revision") {
if (!use_cobalt_customizations && is_clang &&
clang_base_path == default_clang_base_path) {
update_args = [
"--print-revision",
"--verify-version=$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=\"$clang_revision\"" ]
}
}
config("compiler_arm_fpu") {
if (current_cpu == "arm" && !is_ios && !is_nacl) {
cflags = [ "-mfpu=$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_ash || is_chromeos_lacros)) {
# 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_cobalt_customizations && use_custom_libcxx) {
configs += [ "//build/config/c++:runtime_library" ]
}
# 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" ]
}
# 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" ]
} 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" ]
}
}
# 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 = []
if (is_win) {
if (treat_warnings_as_errors) {
cflags += [ "/WX" ]
}
if (fatal_linker_warnings) {
ldflags = [ "/WX" ]
}
cflags += [
# Warnings permanently disabled:
# C4091: 'typedef ': ignored on left of 'X' when no variable is
# declared.
# This happens in a number of Windows headers. Dumb.
"/wd4091",
# C4127: conditional expression is constant
# This warning can in theory catch dead code and other problems, but
# triggers in far too many desirable cases where the conditional
# expression is either set by macros or corresponds some legitimate
# compile-time constant expression (due to constant template args,
# conditionals comparing the sizes of different types, etc.). Some of
# these can be worked around, but it's not worth it.
"/wd4127",
# C4251: 'identifier' : class 'type' needs to have dll-interface to be
# used by clients of class 'type2'
# This is necessary for the shared library build.
"/wd4251",
# C4275: non dll-interface class used as base for dll-interface class
# This points out a potential (but rare) problem with referencing static
# fields of a non-exported base, through the base's non-exported inline
# functions, or directly. The warning is subtle enough that people just
# suppressed it when they saw it, so it's not worth it.
"/wd4275",
# C4312 is a VS 2015 64-bit warning for integer to larger pointer.
# TODO(brucedawson): fix warnings, crbug.com/554200
"/wd4312",
# C4324 warns when padding is added to fulfill alignas requirements,
# but can trigger in benign cases that are difficult to individually
# suppress.
"/wd4324",
# C4351: new behavior: elements of array 'array' will be default
# initialized
# This is a silly "warning" that basically just alerts you that the
# compiler is going to actually follow the language spec like it's
# supposed to, instead of not following it like old buggy versions did.
# There's absolutely no reason to turn this on.
"/wd4351",
# C4355: 'this': used in base member initializer list
# It's commonly useful to pass |this| to objects in a class' initializer
# list. While this warning can catch real bugs, most of the time the
# constructors in question don't attempt to call methods on the passed-in
# pointer (until later), and annotating every legit usage of this is
# simply more hassle than the warning is worth.
"/wd4355",
# C4503: 'identifier': decorated name length exceeded, name was
# truncated
# This only means that some long error messages might have truncated
# identifiers in the presence of lots of templates. It has no effect on
# program correctness and there's no real reason to waste time trying to
# prevent it.
"/wd4503",
# Warning C4589 says: "Constructor of abstract class ignores
# initializer for virtual base class." Disable this warning because it
# is flaky in VS 2015 RTM. It triggers on compiler generated
# copy-constructors in some cases.
"/wd4589",
# C4611: interaction between 'function' and C++ object destruction is
# non-portable
# This warning is unavoidable when using e.g. setjmp/longjmp. MSDN
# suggests using exceptions instead of setjmp/longjmp for C++, but
# Chromium code compiles without exception support. We therefore have to
# use setjmp/longjmp for e.g. JPEG decode error handling, which means we
# have to turn off this warning (and be careful about how object
# destruction happens in such cases).
"/wd4611",
# Warnings to evaluate and possibly fix/reenable later:
"/wd4100", # Unreferenced formal function parameter.
"/wd4121", # Alignment of a member was sensitive to packing.
"/wd4244", # Conversion: possible loss of data.
"/wd4505", # Unreferenced local function has been removed.
"/wd4510", # Default constructor could not be generated.
"/wd4512", # Assignment operator could not be generated.
"/wd4610", # Class can never be instantiated, constructor required.
"/wd4838", # Narrowing conversion. Doesn't seem to be very useful.
"/wd4995", # 'X': name was marked as #pragma deprecated
"/wd4996", # Deprecated function warning.
# These are variable shadowing warnings that are new in VS2015. We
# should work through these at some point -- they may be removed from
# the RTM release in the /W4 set.
"/wd4456",
"/wd4457",
"/wd4458",
"/wd4459",
# All of our compilers support the extensions below.
"/wd4200", # nonstandard extension used: zero-sized array in struct/union
"/wd4201", # nonstandard extension used: nameless struct/union
"/wd4204", # nonstandard extension used : non-constant aggregate
# initializer
"/wd4221", # nonstandard extension used : 'identifier' : cannot be
# initialized using address of automatic variable
# http://crbug.com/588506 - Conversion suppressions waiting on Clang
# -Wconversion.
"/wd4245", # 'conversion' : conversion from 'type1' to 'type2',
# signed/unsigned mismatch
"/wd4267", # 'var' : conversion from 'size_t' to 'type', possible loss of
# data
"/wd4305", # 'identifier' : truncation from 'type1' to 'type2'
"/wd4389", # 'operator' : signed/unsigned mismatch
"/wd4702", # unreachable code
# http://crbug.com/848979 - MSVC is more conservative than Clang with
# regards to variables initialized and consumed in different branches.
"/wd4701", # Potentially uninitialized local variable 'name' used
"/wd4703", # Potentially uninitialized local pointer variable 'name' used
# http://crbug.com/848979 - Remaining Clang permitted warnings.
"/wd4661", # 'identifier' : no suitable definition provided for explicit
# template instantiation request
"/wd4706", # assignment within conditional expression
# MSVC is stricter and requires a boolean expression.
"/wd4715", # 'function' : not all control paths return a value'
# MSVC does not analyze switch (enum) for completeness.
]
cflags_cc += [
# Allow "noexcept" annotations even though we compile with exceptions
# disabled.
"/wd4577",
]
if (current_cpu == "x86") {
cflags += [
# VC++ 2015 changes 32-bit size_t truncation warnings from 4244 to
# 4267. Example: short TruncTest(size_t x) { return x; }
# Since we disable 4244 we need to disable 4267 during migration.
# TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
"/wd4267",
]
}
} 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_clang) {
cflags += [
# TODO(thakis): Consider -Wloop-analysis (turns on
# -Wrange-loop-analysis too).
# This warns on using ints as initializers for floats in
# initializer lists (e.g. |int a = f(); CGSize s = { a, a };|),
# which happens in several places in chrome code. Not sure if
# this is worth fixing.
"-Wno-c++11-narrowing",
# 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",
]
# use_xcode_clang only refers to the iOS toolchain, host binaries use
# chromium's clang always.
if (!is_nacl) {
cflags += [
# TODO(thakis): https://crbug.com/604888
"-Wno-undefined-var-template",
]
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 ((current_toolchain == host_toolchain || !use_xcode_clang) &&
!using_old_compiler) {
# Flags NaCl (Clang 3.7) and Xcode 9.2 (Clang clang-900.0.39.2) do not
# recognize.
cflags += [
# Ignore warnings about MSVC optimization pragmas.
# TODO(thakis): Only for no_chromium_code? http://crbug.com/912662
"-Wno-ignored-pragma-optimize",
]
if (!use_cobalt_customizations) {
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",
# TODO(https://crbug.com/989932): Evaluate and possibly enable.
"-Wno-implicit-int-float-conversion",
# TODO(https://crbug.com/999886): Clean up, enable.
"-Wno-final-dtor-non-final-class",
# TODO(https://crbug.com/1016945) Clean up, enable.
"-Wno-builtin-assume-aligned-alignment",
# TODO(https://crbug.com/1028110): Evaluate and possible enable.
"-Wno-deprecated-copy",
# TODO(https://crbug.com/1050281): Clean up, enable.
"-Wno-non-c-typedef-for-linkage",
]
}
cflags_c += [
# TODO(https://crbug.com/995993): Clean up and enable.
"-Wno-implicit-fallthrough",
]
if (!use_cobalt_customizations) {
if (enable_wmax_tokens) {
cflags += [ "-Wmax-tokens" ]
} else {
# TODO(https://crbug.com/1049569): Remove after Clang 87b235db.
cflags += [ "-Wno-max-tokens" ]
}
}
}
}
}
}
# 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_starboard) {
# The platform should set warning flags.
cflags = []
} else {
cflags = [ "/W4" ] # Warning level 4.
}
if (is_clang) {
# Opt in to additional [[nodiscard]] on standard library methods.
defines = [ "_HAS_NODISCARD" ]
}
} else if (is_starboard) {
# TODO(b/205790602): Revisit this code to be more compatible with platforms.
defines = [
"__STDC_CONSTANT_MACROS",
"__STDC_FORMAT_MACROS",
]
cflags = [ "-Werror" ]
} else {
cflags = [ "-Wall" ]
if (treat_warnings_as_errors) {
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" ]
}
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") {
# 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.
defines += [ "_FORTIFY_SOURCE=2" ]
}
if (is_mac) {
cflags_objc = [ "-Wobjc-missing-property-synthesis" ]
cflags_objcc = [ "-Wobjc-missing-property-synthesis" ]
}
if (is_ios) {
cflags_objc = [ "-Wimplicit-retain-self" ]
cflags_objcc = cflags_objc
}
}
if (is_clang) {
cflags += [
# Warn on missing break statements at the end of switch cases.
# For intentional fallthrough, use FALLTHROUGH; from
# base/compiler_specific.h
"-Wimplicit-fallthrough",
]
# TODO(thakis): Enable this more often, https://crbug.com/346399
# use_libfuzzer: https://crbug.com/1063180
if (!is_starboard && !is_nacl && !use_libfuzzer) {
cflags += [ "-Wunreachable-code" ]
}
# Thread safety analysis is broken under nacl: https://crbug.com/982423.
if (!is_nacl) {
cflags += [
# Thread safety analysis. See base/thread_annotations.h and
# https://clang.llvm.org/docs/ThreadSafetyAnalysis.html
"-Wthread-safety",
]
}
# TODO(thakis): Enable this for more platforms, https://crbug.com/926235
# ChromeOS: http://crbug.com/940863
# Chromecast: http://crbug.com/942554
has_dchecks = is_debug || dcheck_always_on
if (!has_dchecks && is_chromeos_ash && is_chrome_branded) {
# Temporarily disable -Wextra-semi for Chrome on Chrome OS.
} else if (is_chromecast && chromecast_branding != "public") {
# Temporarily disable -Wextra-semi for Chromecast.
} else if (!is_starboard) {
cflags += [ "-Wextra-semi" ]
}
}
configs = [ ":default_warnings" ]
}
config("no_chromium_code") {
cflags = []
cflags_cc = []
defines = []
if (is_win) {
cflags += [
"/W3", # Warning level 3.
"/wd4800", # Disable warning when forcing value to bool.
"/wd4267", # TODO(jschuh): size_t to int.
"/wd4996", # Deprecated function warning.
]
if (is_starboard) {
# The platform should set warning flags.
cflags -= [ "/W3" ]
}
defines += [
"_CRT_NONSTDC_NO_WARNINGS",
"_CRT_NONSTDC_NO_DEPRECATE",
]
} else {
# GCC may emit unsuppressible warnings so don't add -Werror for no chromium
# code. crbug.com/589724
if (treat_warnings_as_errors && is_clang) {
cflags += [ "-Werror" ]
ldflags = [ "-Werror" ]
}
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",
]
if (!use_cobalt_customizations && !is_nacl &&
(current_toolchain == host_toolchain || !use_xcode_clang)) {
cflags += [
# TODO(https://crbug.com/1202159): Clean up and enable.
"-Wno-misleading-indentation",
]
}
}
configs = [ ":default_warnings" ]
}
# 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) {
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.
if ((is_posix && !is_nacl && (!is_apple || use_lld)) || 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 {
# This hack ensures raspi does not compile anything with -fno-exceptions.
if (!defined(enable_exceptions_override) || !enable_exceptions_override) {
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" ]
}
}
# On Windows compiling on x64, VC will issue a warning when converting
# size_t to int because it will truncate the value. Our code should not have
# these warnings and one should use a static_cast or a checked_cast for the
# conversion depending on the case. However, a lot of code still needs to be
# fixed. Apply this config to such targets to disable the warning.
#
# Note that this can be applied regardless of platform and architecture to
# clean up the call sites. This will only apply the flag when necessary.
#
# This config is just an alias to no_shorten_64_warnings and will
# suppress a superset of warning 4267 and any 64-bit -> 32-bit implicit
# conversions. Having both for a time means not having to go through and
# update all references to no_size_t_to_int_warning throughout the codebase
# atomically.
#
# Any new warning suppressions should use the no_shorten_64_warnings
# config below and not this.
#
# TODO(jschuh): crbug.com/167187 fix this and delete this config.
config("no_size_t_to_int_warning") {
configs = [ ":no_shorten_64_warnings" ]
}
# As part of re-enabling -Wconversion (see issue 588506) some code
# will continue to generate warnings.
# The first warning to be enabled will be -Wshorten-64-to-32.
#
# Code that currently generates warnings for this can include this
# config to disable them.
config("no_shorten_64_warnings") {
if (current_cpu == "x64" || current_cpu == "arm64") {
if (is_clang) {
cflags = [ "-Wno-shorten-64-to-32" ]
} else {
if (is_win) {
# MSVC does not have an explicit warning equivalent to
# -Wshorten-64-to-32 but 4267 warns for size_t -> int
# on 64-bit builds, so is the closest.
cflags = [ "/wd4267" ]
}
}
}
}
# 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) {
if (is_starboard) {
common_optimize_on_cflags = []
} else {
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") {
# 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",
]
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_posix || is_fuchsia) {
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" ]
} 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" ]
}
} else if (optimize_for_size && !is_nacl) {
# Favor size over speed.
# TODO(crbug.com/718650): Fix -Os in PNaCl compiler and remove the is_nacl
# guard above.
if (is_clang) {
cflags = [ "-Oz" ] + common_optimize_on_cflags
} else {
cflags = [ "-Os" ] + common_optimize_on_cflags
}
} else if (is_chromeos_ash) {
# 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
} else {
cflags = [ "-O2" ] + common_optimize_on_cflags
}
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
}
}
}
# 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
}
}
}
config("optimize_fuzzing") {
cflags = [ "-O1" ] + common_optimize_on_cflags
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_lacros || is_chromeos_ash || is_chromecast,
"The current platform has no default profile")
if (is_android || is_chromecast) {
_clang_sample_profile = "//chrome/android/profiles/afdo.prof"
} else {
assert(chromeos_afdo_platform == "atom" ||
chromeos_afdo_platform == "bigcore",
"Only atom and bigcore are valid Chrome OS profiles.")
_clang_sample_profile =
"//chromeos/profiles/${chromeos_afdo_platform}.afdo.prof"
}
}
}
# Clang offers a way to assert that AFDO profiles are accurate, which causes it
# to optimize functions not represented in a profile more aggressively for size.
# This config can be toggled in cases where shaving off binary size hurts
# performance too much.
config("afdo_optimize_size") {
if (_clang_sample_profile != "" && sample_profile_is_accurate) {
cflags = [ "-fprofile-sample-accurate" ]
}
}
# GCC and clang support a form of profile-guided optimization called AFDO.
# There are some targeted places that AFDO regresses (and an icky interaction
# between //base/allocator:tcmalloc and AFDO on GCC), so we provide a separate
# config to allow AFDO to be disabled per-target.
config("afdo") {
if (is_clang) {
cflags = []
if (clang_emit_debug_info_for_profiling) {
# Add the following flags to generate debug info for profiling.
cflags += [ "-gline-tables-only" ]
if (!is_nacl) {
cflags += [ "-fdebug-info-for-profiling" ]
}
}
if (_clang_sample_profile != "") {
assert(chrome_pgo_phase == 0, "AFDO can't be used in PGO builds")
rebased_clang_sample_profile =
rebase_path(_clang_sample_profile, root_build_dir)
cflags += [ "-fprofile-sample-use=${rebased_clang_sample_profile}" ]
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") {
if (is_win) {
if (is_clang) {
cflags = [ "/Z7" ] # Debug information in the .obj files.
} 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" ]
# TODO(crbug.com/1138553): Re-enable constructor homing on windows after
# libc++ fix is in.
} 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" ]
} else 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" ]
}
if (use_dwarf5 && !is_nacl) {
cflags += [ "-gdwarf-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.
# Disable symbols for nacl object files to get deterministic,
# build-directory-independent output. pnacl and nacl-clang do support that
# flag, so we can use use -g1 for pnacl and nacl-clang compiles.
# gcc nacl is is_nacl && !is_clang, pnacl and nacl-clang are && is_clang.
if (!is_nacl || is_clang) {
cflags += [ "-g2" ]
}
# TODO(https://crbug.com/1050118): Investigate missing debug info on mac.
if (is_clang && !is_nacl && !use_xcode_clang && !is_apple) {
cflags += [
"-Xclang",
"-debug-info-kind=constructor",
]
}
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.
if (!is_apple && !is_nacl && current_cpu != "x86" &&
(use_gold || use_lld)) {
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" ]
}
}
}
# 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") {
if (is_win) {
# Functions, files, and line tables only.
cflags = []
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" ]
}
if (use_dwarf5 && !is_nacl) {
cflags += [ "-gdwarf-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.
# Disable symbols for nacl object files to get deterministic,
# build-directory-independent output. pnacl and nacl-clang do support that
# flag, so we can use use -g1 for pnacl and nacl-clang compiles.
# gcc nacl is is_nacl && !is_clang, pnacl and nacl-clang are && is_clang.
if (!is_nacl || is_clang) {
cflags += [ "-g1" ]
}
ldflags = []
if (is_android && is_clang) {
# Android defaults to symbol_level=1 builds in production builds
# (https://crbug.com/648948), 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" ]
}
# Note: debug_fission is no-op with symbol_level=1 since all -g1 debug_info
# will stay in the executable.
asmflags = cflags
}
}
# 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 Mac and iOS, this enables support for ARC (automatic ref-counting).
# See http://clang.llvm.org/docs/AutomaticReferenceCounting.html.
config("enable_arc") {
common_flags = [ "-fobjc-arc" ]
cflags_objc = common_flags
cflags_objcc = common_flags
}
}
if (is_chromeos_ash && is_chromeos_device) {
# This config is intended to be a temporary to facilitate
# the transition to use orderfile in Chrome OS. Once orderfile
# use becomes a default in Chrome OS, this config should not
# be needed.
config("use_orderfile_for_hugepage") {
if (chrome_orderfile_path != "") {
defines = [ "CHROMEOS_ORDERFILE_USE" ]
}
}
}
if (is_android || (is_chromeos_ash && is_chromeos_device)) {
# Use orderfile for linking Chrome on Android and Chrome OS.
# This config enables using an orderfile for linking in LLD.
# TODO: Consider using call graph sort instead, at least on Android.
config("chrome_orderfile_config") {
if (chrome_orderfile_path != "" && !enable_call_graph_profile_sort) {
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) {
cflags += [ "-ftrivial-auto-var-init=pattern" ]
}
}
buildflag_header("compiler_buildflags") {
header = "compiler_buildflags.h"
flags = [ "CLANG_PGO=$chrome_pgo_phase" ]
}
config("cet_shadow_stack") {
if (enable_cet_shadow_stack && is_win) {
assert(target_cpu == "x64")
ldflags = [ "/CETCOMPAT" ]
}
}