diff --git a/docs/markdown/snippets/thinlto.md b/docs/markdown/snippets/thinlto.md new file mode 100644 index 000000000..ac242a8b1 --- /dev/null +++ b/docs/markdown/snippets/thinlto.md @@ -0,0 +1,27 @@ +## Add support for thin LTO + +The `b_lto` option has been updated and now can be set to the value +`thin`. This enables [thin +LTO](https://clang.llvm.org/docs/ThinLTO.html) on all compilers where +it is supported. At the time of writing this means only Clang. + +This change is potentially backwards incompatible. If you have +examined the value of `b_lto` in your build file, note that its type +has changed from a boolean to a string. Thus comparisons like this: + +```meson +if get_option('b_lto') +... +endif +``` + +need to be changed to something like this instead: + +```meson +if get_option('b_lto') == 'true' +... +endif +``` + +This should not affect any comman line invocations as configuring LTO +with `-Db_lto=true` still works and behaves the same way as before. diff --git a/mesonbuild/compilers/compilers.py b/mesonbuild/compilers/compilers.py index 0f074bb17..6a54622c3 100644 --- a/mesonbuild/compilers/compilers.py +++ b/mesonbuild/compilers/compilers.py @@ -266,7 +266,9 @@ clike_debug_args = {False: [], True: ['-g']} # type: T.Dict[bool, T.List[str]] base_options = {'b_pch': coredata.UserBooleanOption('Use precompiled headers', True), - 'b_lto': coredata.UserBooleanOption('Use link time optimization', False), + 'b_lto': coredata.UserComboOption('Use link time optimization', + ['false', 'true', 'thin'], + 'false'), 'b_sanitize': coredata.UserComboOption('Code sanitizer to use', ['none', 'address', 'thread', 'undefined', 'memory', 'address,undefined'], 'none'), @@ -307,8 +309,7 @@ def option_enabled(boptions: T.List[str], options: 'OptionDictType', def get_base_compile_args(options: 'OptionDictType', compiler: 'Compiler') -> T.List[str]: args = [] # type T.List[str] try: - if options['b_lto'].value: - args.extend(compiler.get_lto_compile_args()) + args.extend(compiler.get_lto_compile_args(options['b_lto'].value)) except KeyError: pass try: @@ -357,8 +358,7 @@ def get_base_link_args(options: 'OptionDictType', linker: 'Compiler', is_shared_module: bool) -> T.List[str]: args = [] # type: T.List[str] try: - if options['b_lto'].value: - args.extend(linker.get_lto_link_args()) + args.extend(linker.get_lto_link_args(options['b_lto'].value)) except KeyError: pass try: @@ -940,11 +940,11 @@ class Compiler(metaclass=abc.ABCMeta): ret.append(arg) return ret - def get_lto_compile_args(self) -> T.List[str]: + def get_lto_compile_args(self, lto_type: str) -> T.List[str]: return [] - def get_lto_link_args(self) -> T.List[str]: - return self.linker.get_lto_args() + def get_lto_link_args(self, lto_type: str) -> T.List[str]: + return self.linker.get_lto_args(lto_type) def sanitizer_compile_args(self, value: str) -> T.List[str]: return [] diff --git a/mesonbuild/compilers/mixins/clang.py b/mesonbuild/compilers/mixins/clang.py index acdb3526e..773d9dc67 100644 --- a/mesonbuild/compilers/mixins/clang.py +++ b/mesonbuild/compilers/mixins/clang.py @@ -77,6 +77,13 @@ class ClangCompiler(GnuLikeCompiler): # so it might change semantics at any time. return ['-include-pch', os.path.join(pch_dir, self.get_pch_name(header))] + def get_lto_compile_args(self, lto_type: str) -> T.List[str]: + if lto_type == 'thin': + return ['-flto=thin'] + if lto_type == 'true': + return ['-flto'] + return [] + def get_compiler_check_args(self, mode: CompileCheckMode) -> T.List[str]: myargs = [] # type: T.List[str] if mode is CompileCheckMode.COMPILE: diff --git a/mesonbuild/compilers/mixins/gnu.py b/mesonbuild/compilers/mixins/gnu.py index bb1fc6631..5771ad811 100644 --- a/mesonbuild/compilers/mixins/gnu.py +++ b/mesonbuild/compilers/mixins/gnu.py @@ -295,8 +295,10 @@ class GnuLikeCompiler(Compiler, metaclass=abc.ABCMeta): return self._split_fetch_real_dirs(line.split('=', 1)[1]) return [] - def get_lto_compile_args(self) -> T.List[str]: - return ['-flto'] + def get_lto_compile_args(self, lto_type: str) -> T.List[str]: + if lto_type != 'false': + return ['-flto'] + return [] def sanitizer_compile_args(self, value: str) -> T.List[str]: if value == 'none': diff --git a/mesonbuild/compilers/mixins/islinker.py b/mesonbuild/compilers/mixins/islinker.py index 2445eecb7..67ac497c3 100644 --- a/mesonbuild/compilers/mixins/islinker.py +++ b/mesonbuild/compilers/mixins/islinker.py @@ -48,7 +48,7 @@ class BasicLinkerIsCompilerMixin(Compiler): def sanitizer_link_args(self, value: str) -> T.List[str]: return [] - def get_lto_link_args(self) -> T.List[str]: + def get_lto_link_args(self, lto_type: str) -> T.List[str]: return [] def can_linker_accept_rsp(self) -> bool: diff --git a/mesonbuild/linkers.py b/mesonbuild/linkers.py index 589945c51..cc3db5fd4 100644 --- a/mesonbuild/linkers.py +++ b/mesonbuild/linkers.py @@ -411,7 +411,7 @@ class DynamicLinker(LinkerEnvVarsMixin, metaclass=abc.ABCMeta): m = 'Linker {} does not support position-independent executable' raise mesonlib.EnvironmentException(m.format(self.id)) - def get_lto_args(self) -> T.List[str]: + def get_lto_args(self, lto_type: str) -> T.List[str]: return [] def sanitizer_args(self, value: str) -> T.List[str]: @@ -550,8 +550,10 @@ class GnuLikeDynamicLinkerMixin: def get_allow_undefined_args(self) -> T.List[str]: return self._apply_prefix('--allow-shlib-undefined') - def get_lto_args(self) -> T.List[str]: - return ['-flto'] + def get_lto_args(self, lto_type: str) -> T.List[str]: + if lto_type != 'false': + return ['-flto'] + return [] def sanitizer_args(self, value: str) -> T.List[str]: if value == 'none': diff --git a/test cases/common/41 options/meson.build b/test cases/common/41 options/meson.build index 2eccef7b0..4b38c6f87 100644 --- a/test cases/common/41 options/meson.build +++ b/test cases/common/41 options/meson.build @@ -18,7 +18,7 @@ if get_option('array_opt') != ['one', 'two'] endif # If the default changes, update test cases/unit/13 reconfigure -if get_option('b_lto') != false +if get_option('b_lto') != 'false' error('Incorrect value in base option.') endif