import("//llvm/utils/gn/build/buildflags.gni")
import("//llvm/utils/gn/build/mac_sdk.gni")
import("//llvm/utils/gn/build/sysroot.gni")
import("//llvm/utils/gn/build/toolchain/compiler.gni")
import("//llvm/utils/gn/build/toolchain/target_flags.gni")
declare_args() {
# Whether to build everything with coverage information.
# After building with this, run tests and then run
# llvm/utils/prepare-code-coverage-artifact.py \
# --compilation-dir=out/gn \
# .../llvm-profdata .../llvm-cov out/gn/profiles/ report/ \
# out/gn/bin/llvm-undname ...
# to generate a HTML report for the binaries passed in the last line.
llvm_build_instrumented_coverage = false
# If set, puts relative paths in debug info.
# Makes the build output independent of the build directory, but makes
# most debuggers harder to use. See "Getting to local determinism" and
# "Getting debuggers to work well with locally deterministic builds" in
# http://blog.llvm.org/2019/11/deterministic-builds-with-clang-and-lld.html
# for more information.
use_relative_paths_in_debug_info = false
# The version of host gcc. Ignored if is_clang is true.
gcc_version = 9
}
assert(!llvm_build_instrumented_coverage || is_clang,
"llvm_build_instrumented_coverage requires clang as host compiler")
config("compiler_defaults") {
defines = []
if (!llvm_enable_assertions) {
defines += [ "NDEBUG" ]
}
if (llvm_enable_expensive_checks) {
defines += [ "EXPENSIVE_CHECKS" ]
}
asmflags = target_flags
cflags = target_flags
cflags_cc = []
ldflags = target_flags + target_ldflags
# Mostly for compiler-rt, see compiler-rt/cmake/config-ix.cmake
if (current_os == "ios") {
asmflags += [ "-miphoneos-version-min=8.0" ]
cflags += [ "-miphoneos-version-min=8.0" ]
ldflags += [ "-miphoneos-version-min=8.0" ]
}
if (current_os == "mac") {
asmflags += [ "-mmacos-version-min=10.10" ]
cflags += [ "-mmacos-version-min=10.10" ]
ldflags += [ "-mmacos-version-min=10.10" ]
}
assert(symbol_level == 0 || symbol_level == 1 || symbol_level == 2,
"Unexpected symbol_level")
if (current_os != "win") {
if (symbol_level == 2) {
cflags += [ "-g" ]
# For full debug-info -g builds, --gdb-index makes links ~15% slower, and
# gdb symbol reading time 1500% faster (lld links in 4.4 instead of 3.9s,
# and gdb loads and runs it in 2s instead of in 30s). It's likely that
# people doing symbol_level=2 want to run a debugger (since
# symbol_level=2 isn't the default). So this seems like the right
# tradeoff.
if (current_os != "mac" && use_lld) {
cflags += [ "-ggnu-pubnames" ] # PR34820
ldflags += [ "-Wl,--gdb-index" ]
# Use debug fission. In this mode, detailed debug information is
# written to a .dwo file next to each .o file instead of into the .o
# file directly. The linker then only links the .o files, which contain
# a pointer to each .dwo file. The debugger then reads debug info out
# of all the .dwo files instead of from the binary.
#
# (The dwp tool can link all the debug info together into a single
# "debug info binary", but that's not done as part of the build.)
#
# This requires `-Wl,--gdb-index` (above) to work well.
#
# With lld, this reduces link time:
# - in release + symbol_level=2 builds: From 2.3s to 1.3s
# - in debug builds: From 5.2s to 4.6s
#
# Time needed for gdb startup and setting a breakpoint is comparable,
# the time from from `r` to hititng a breakpoint on main goes from 4s
# to 2s.
#
# (macOS's linker always keeps debug info out of its output executables
# and debuggers there also know to load debug info from the .o files.
# macOS also has a debug info linker like dwp, it's called dsymutil.
# This happens by default, so there's no need to pass a flag there.)
cflags += [ "-gsplit-dwarf" ]
ldflags += [ "-gsplit-dwarf" ] # Needed for ThinLTO builds.
}
} else if (symbol_level == 1) {
cflags += [ "-g1" ]
# For linetable-only -g1 builds, --gdb-index makes links ~8% slower, but
# links are 4x faster than -g builds so it's a fairly small absolute cost.
# On the other hand, gdb startup is well below 1s with and without the
# index, and people using -g1 likely don't use a debugger. So don't use
# the flag here.
# Linetables always go in the .o file, even with -gsplit-dwarf, so there's
# no point in passing -gsplit-dwarf here.
}
if (is_optimized) {
cflags += [ "-O3" ]
}
cflags += [ "-fdiagnostics-color" ]
if (use_lld) {
ldflags += [ "-Wl,--color-diagnostics" ]
}
cflags_cc += [
"-std=c++14",
"-fvisibility-inlines-hidden",
]
} else {
if (symbol_level != 0) {
cflags += [
"/Zi",
"/FS",
]
if (symbol_level == 1 && is_clang) {
cflags += [ "-gline-tables-only" ]
}
ldflags += [ "/DEBUG" ]
# Speed up links with ghash on windows.
if (use_lld && is_clang) {
cflags += [ "-gcodeview-ghash" ]
ldflags += [ "/DEBUG:GHASH" ]
}
}
if (is_optimized) {
cflags += [
"/O2",
"/Gw",
"/Zc:inline",
]
ldflags += [
"/OPT:REF",
"/OPT:ICF",
]
}
defines += [
"_CRT_SECURE_NO_DEPRECATE",
"_CRT_SECURE_NO_WARNINGS",
"_CRT_NONSTDC_NO_DEPRECATE",
"_CRT_NONSTDC_NO_WARNINGS",
"_SCL_SECURE_NO_DEPRECATE",
"_SCL_SECURE_NO_WARNINGS",
"_HAS_EXCEPTIONS=0",
"_UNICODE",
"UNICODE",
]
cflags += [ "/EHs-c-" ]
# The MSVC default value (1 MB) is not enough for parsing recursive C++
# templates in Clang.
ldflags += [ "/STACK:10000000" ]
}
# Warning setup.
if (current_os == "win" && !is_clang) {
cflags += [
# Suppress ''modifier' : used more than once' (__forceinline and inline).
"-wd4141",
# Suppress 'conversion from 'type1' to 'type2', possible loss of data'.
"-wd4244",
# Suppress 'conversion from 'size_t' to 'type', possible loss of data'.
"-wd4267",
# Suppress 'no matching operator delete found'.
"-wd4291",
# Suppress 'noexcept used with no exception handling mode specified'.
"-wd4577",
# Suppress 'destructor was implicitly defined as deleted'.
"-wd4624",
# Suppress 'unsafe mix of type <type> and type <type> in operation'.
"-wd4805",
]
} else {
if (current_os == "win") {
cflags += [ "/W4" ]
} else {
cflags += [
"-Wall",
"-Wextra",
]
}
cflags += [ "-Wno-unused-parameter" ]
if (is_clang) {
cflags += [
"-Wdelete-non-virtual-dtor",
"-Wstring-conversion",
]
} else {
cflags += [
# GCC's -Wcomment complains about // comments ending with '\' if the
# next line is also a // comment.
"-Wno-comment",
# Disable gcc's potentially uninitialized use analysis as it presents
# lots of false positives.
"-Wno-maybe-uninitialized",
]
cflags_cc += [
# The LLVM libraries have no stable C++ API, so -Wnoexcept-type is not
# useful.
"-Wno-noexcept-type",
]
if (gcc_version >= 8) {
cflags_cc += [
# Disable -Wclass-memaccess, a C++-only warning from GCC 8 that fires
# on LLVM's ADT classes.
"-Wno-class-memaccess",
]
}
if (gcc_version >= 9) {
cflags_cc += [
# Disable -Wredundant-move on GCC>=9. GCC wants to remove std::move
# in code like "A foo(ConvertibleToA a) { return std::move(a); }",
# but this code does not compile (or uses the copy constructor
# instead) on clang<=3.8. Clang also has a -Wredundant-move, but it
# only fires when the types match exactly, so we can keep it here.
"-Wno-redundant-move",
]
}
}
if (is_clang && use_goma) {
# goma converts all paths to lowercase on the server, breaking this
# warning.
cflags += [ "-Wno-nonportable-include-path" ]
}
}
# On Windows, the linker is not invoked through the compiler driver.
if (use_lld && current_os != "win") {
ldflags += [ "-fuse-ld=lld" ]
}
if (llvm_build_instrumented_coverage) {
cflags += [
"-fcoverage-mapping",
# For build determinism. Using this requires passing --compilation-dir to
# llvm/utils/prepare-code-coverage-artifact.py.
"-fcoverage-compilation-dir=.",
# Using an absolute path here is lame, but it's used at test execution
# time to generate the profiles, and lit doesn't specify a fixed folder
# for test execution -- so this is the only way to get all profiles into
# a single folder like llvm/utils/prepare-code-coverage-artifact.py
# expects.
"-fprofile-instr-generate=" +
rebase_path("$root_build_dir/profiles/%4m.profraw"),
]
if (current_os != "win") {
ldflags += [ "-fprofile-instr-generate" ]
}
}
# Deterministic build setup, see
# http://blog.llvm.org/2019/11/deterministic-builds-with-clang-and-lld.html
if (current_os == "win") {
ldflags += [ "/pdbaltpath:%_PDB%" ]
}
if (is_clang) {
cflags += [
"-no-canonical-prefixes",
"-Werror=date-time",
]
if (current_os == "win") {
cflags += [ "-fmsc-version=1926" ]
if (use_lld) {
cflags += [ "/Brepro" ]
ldflags += [ "/Brepro" ]
}
}
if (use_relative_paths_in_debug_info) {
cflags += [ "-fdebug-compilation-dir=." ]
}
}
if (sysroot != "") {
if (current_os == "win") {
assert(is_clang, "sysroot only works with clang-cl as host compiler")
cflags += [ "/winsysroot" + rebase_path(sysroot, root_build_dir) ]
if (use_lld) {
ldflags += [ "/winsysroot:" + rebase_path(sysroot, root_build_dir) ]
# FIXME: Remove once PR54409 is fixed.
ldflags += [ "/machine:x64" ]
}
} else if (current_os != "ios" && current_os != "mac" &&
current_os != "android") {
cflags += [ "--sysroot=" + rebase_path(sysroot, root_build_dir) ]
}
}
if ((current_os == "ios" || current_os == "mac") &&
(clang_base_path != "" || sysroot != "")) {
if (current_os == "ios" && current_cpu == "arm64") {
sdk_path = ios_sdk_path
} else if (current_os == "ios" && current_cpu == "x64") {
sdk_path = iossim_sdk_path
} else if (current_os == "mac") {
sdk_path = mac_sdk_path
}
cflags += [
"-isysroot",
rebase_path(sdk_path, root_build_dir),
]
ldflags += [
"-isysroot",
rebase_path(sdk_path, root_build_dir),
]
}
if (sysroot != "" && current_os != "win" && is_clang) {
cflags += [ "-Wpoison-system-directories" ]
}
assert(
!use_goma || sysroot != "",
"goma needs a sysroot: run `llvm/utils/sysroot.py make-fake --out-dir=sysroot` and add `sysroot = \"//sysroot\"` to your args.gn")
if (use_ubsan) {
assert(is_clang && (current_os == "ios" || current_os == "linux" ||
current_os == "mac"),
"ubsan only supported on iOS/Clang, Linux/Clang, or macOS/Clang")
cflags += [
"-fsanitize=undefined",
"-fno-sanitize-recover=all",
]
ldflags += [ "-fsanitize=undefined" ]
}
if (use_asan) {
assert(is_clang && (current_os == "ios" || current_os == "linux" ||
current_os == "mac"),
"asan only supported on iOS/Clang, Linux/Clang, or macOS/Clang")
cflags += [ "-fsanitize=address" ]
ldflags += [ "-fsanitize=address" ]
}
if (use_tsan) {
assert(is_clang && current_os == "linux",
"tsan only supported on Linux/Clang")
cflags += [ "-fsanitize=thread" ]
ldflags += [ "-fsanitize=thread" ]
}
if (use_thinlto) {
assert(is_clang, "ThinLTO only supported on Clang")
lto_opt_level = 2
cflags += [ "-flto=thin" ]
if (current_os == "win") {
ldflags += [
"/opt:lldlto=" + lto_opt_level,
"/opt:lldltojobs=" + max_jobs_per_lto_link,
]
} else {
ldflags += [
"-flto=thin",
"-Wl,--thinlto-jobs=" + max_jobs_per_lto_link,
"-Wl,--lto-O" + lto_opt_level,
]
}
}
cflags_objcc = cflags_cc
}
config("no_exceptions") {
cflags_cc = []
if (current_os != "win") {
cflags_cc += [ "-fno-exceptions" ]
}
cflags_objcc = cflags_cc
}
config("no_rtti") {
if (current_os == "win") {
cflags_cc = [ "/GR-" ]
} else {
cflags_cc = [ "-fno-rtti" ]
}
cflags_objcc = cflags_cc
}
config("zdefs") {
# -Wl,-z,defs doesn't work with sanitizers.
# https://clang.llvm.org/docs/AddressSanitizer.html
if (current_os != "ios" && current_os != "mac" && current_os != "win" &&
!(use_asan || use_tsan || use_ubsan)) {
ldflags = [ "-Wl,-z,defs" ]
}
}
# To make an archive that can be distributed, you need to remove this config and
# set complete_static_lib.
config("thin_archive") {
if (current_os != "ios" && current_os != "mac" && current_os != "win") {
arflags = [ "-T" ]
}
}
config("llvm_code") {
include_dirs = [
"//llvm/include",
"$root_gen_dir/llvm/include",
]
if (current_os != "win") {
cflags = [ "-fPIC" ]
}
}
config("lld_code") {
include_dirs = [
"//lld/include",
"$root_gen_dir/lld/include",
]
}
config("clang_code") {
if (current_os != "win") {
cflags = [ "-fno-strict-aliasing" ]
}
include_dirs = [
"//clang/include",
"$root_gen_dir/clang/include",
]
}
config("crt_code") {
include_dirs = [ "//compiler-rt/lib" ]
cflags = [
"-fno-builtin",
"-gline-tables-only",
]
if (current_os != "win") {
cflags += [
"-fPIC",
"-funwind-tables",
"-fvisibility=hidden",
]
} else {
cflags += [
# Disable thread safe initialization for static locals. ASan shouldn't need it.
# Thread safe initialization assumes that the CRT has already been initialized, but ASan initializes before the CRT.
"/Zc:threadSafeInit-",
]
}
if (is_clang) {
cflags += [
"-Werror=thread-safety",
"-Werror=thread-safety-reference",
"-Werror=thread-safety-beta",
]
}
}
config("lldb_code") {
if (current_os != "win") {
cflags = [ "-fno-strict-aliasing" ]
}
include_dirs = [
"//lldb/include",
"$root_gen_dir/lldb/include",
]
}
config("warn_covered_switch_default") {
if (is_clang) {
cflags = [ "-Wcovered-switch-default" ]
}
}