Add a build.py flag to build with extra optimizations (#679)
This enables ThinLTO for LLVM and Binaryen and disables assertions on LLVM. It's off by default.
diff --git a/src/build.py b/src/build.py
index 7c194a1..7d57c61 100755
--- a/src/build.py
+++ b/src/build.py
@@ -764,10 +764,15 @@
return []
cc = 'clang-cl' if IsWindows() else 'clang'
cxx = 'clang-cl' if IsWindows() else 'clang++'
- return [
+ tools = [
'-DCMAKE_C_COMPILER=' + Executable(GetPrebuiltClang(cc)),
- '-DCMAKE_CXX_COMPILER=' + Executable(GetPrebuiltClang(cxx))
+ '-DCMAKE_CXX_COMPILER=' + Executable(GetPrebuiltClang(cxx)),
]
+ if IsWindows():
+ tools.append('-DCMAKE_LINKER=' +
+ Executable(GetPrebuiltClang('lld-link')))
+
+ return tools
def CMakeCommandBase():
@@ -875,7 +880,7 @@
build_dir = os.path.join(work_dirs.GetBuild(), 'llvm-out')
Mkdir(build_dir)
cc_env = BuildEnv(build_dir, bin_subdir=True)
- build_dylib = 'ON' if not IsWindows() else 'OFF'
+ build_dylib = 'ON' if not IsWindows() and not options.use_lto else 'OFF'
command = CMakeCommandNative([
GetLLVMSrcDir('llvm'),
'-DCMAKE_CXX_FLAGS=-Wno-nonportable-include-path',
@@ -890,7 +895,6 @@
# Our mac bot's toolchain's ld64 is too old for trunk libLTO.
'-DLLVM_TOOL_LTO_BUILD=OFF',
'-DLLVM_INSTALL_TOOLCHAIN_ONLY=ON',
- '-DLLVM_ENABLE_ASSERTIONS=ON',
'-DLLVM_TARGETS_TO_BUILD=X86;WebAssembly',
'-DLLVM_ENABLE_PROJECTS=lld;clang',
# linking libtinfo dynamically causes problems on some linuxes,
@@ -898,6 +902,15 @@
'-DLLVM_ENABLE_TERMINFO=%d' % (not IsLinux()),
], build_dir)
+ if options.use_lto:
+ command.extend(['-DLLVM_ENABLE_ASSERTIONS=OFF',
+ '-DLLVM_BUILD_TESTS=OFF',
+ '-DLLVM_INCLUDE_TESTS=OFF',
+ '-DLLVM_ENABLE_LTO=Thin',
+ '-DLLVM_ENABLE_LLD=ON'])
+ else:
+ command.extend(['-DLLVM_ENABLE_ASSERTIONS=ON'])
+
jobs = host_toolchains.NinjaJobs()
proc.check_call(command, cwd=build_dir, env=cc_env)
@@ -1047,7 +1060,10 @@
# Currently it's a bad idea to do a non-asserts build of Binaryen
cc_env = BuildEnv(out_dir, bin_subdir=True, runtime='Debug')
- proc.check_call(CMakeCommandNative([GetSrcDir('binaryen')], out_dir),
+ cmake_command = CMakeCommandNative([GetSrcDir('binaryen')], out_dir)
+ if options.use_lto:
+ cmake_command.append('-DBYN_ENABLE_LTO=ON')
+ proc.check_call(cmake_command,
cwd=out_dir,
env=cc_env)
proc.check_call(['ninja', '-v'] + host_toolchains.NinjaJobs(),
@@ -1785,6 +1801,9 @@
parser.add_argument(
'--clobber', dest='clobber', default=False, action='store_true',
help="Delete working directories, forcing a clean build")
+ parser.add_argument(
+ '--use-lto', dest='use_lto', default=False, action='store_true',
+ help='Use extra optimization for host binaries')
return parser.parse_args()
