Add b_thinlto_cache for automatically configuring incremental ThinLTO

1 files changed, 12 insertions, 4 deletions

diff --git a/mesonbuild/compilers/compilers.py b/mesonbuild/compilers/compilers.py
index ea03869..53b4307 100644
--- a/mesonbuild/compilers/compilers.py
+++ b/mesonbuild/compilers/compilers.py
@@ -281,11 +281,12 @@ clike_debug_args = {False: [],
 base_options: 'KeyedOptionDictType' = {
     OptionKey('b_pch'): coredata.UserBooleanOption('Use precompiled headers', True),
     OptionKey('b_lto'): coredata.UserBooleanOption('Use link time optimization', False),
-    OptionKey('b_lto'): coredata.UserBooleanOption('Use link time optimization', False),
     OptionKey('b_lto_threads'): coredata.UserIntegerOption('Use multiple threads for Link Time Optimization', (None, None, 0)),
     OptionKey('b_lto_mode'): coredata.UserComboOption('Select between different LTO modes.',
                                                       ['default', 'thin'],
                                                       'default'),
+    OptionKey('b_thinlto_cache'): coredata.UserBooleanOption('Use LLVM ThinLTO caching for faster incremental builds', False),
+    OptionKey('b_thinlto_cache_dir'): coredata.UserStringOption('Directory to store ThinLTO cache objects', ''),
     OptionKey('b_sanitize'): coredata.UserComboOption('Code sanitizer to use',
                                                       ['none', 'address', 'thread', 'undefined', 'memory', 'leak', 'address,undefined'],
                                                       'none'),
@@ -383,13 +384,19 @@ def get_base_compile_args(options: 'KeyedOptionDictType', compiler: 'Compiler')
     return args
 
 def get_base_link_args(options: 'KeyedOptionDictType', linker: 'Compiler',
-                       is_shared_module: bool) -> T.List[str]:
+                       is_shared_module: bool, build_dir: str) -> T.List[str]:
     args = []  # type: T.List[str]
     try:
         if options[OptionKey('b_lto')].value:
+            thinlto_cache_dir = None
+            if get_option_value(options, OptionKey('b_thinlto_cache'), False):
+                thinlto_cache_dir = get_option_value(options, OptionKey('b_thinlto_cache_dir'), '')
+                if thinlto_cache_dir == '':
+                    thinlto_cache_dir = os.path.join(build_dir, 'meson-private', 'thinlto-cache')
             args.extend(linker.get_lto_link_args(
                 threads=get_option_value(options, OptionKey('b_lto_threads'), 0),
-                mode=get_option_value(options, OptionKey('b_lto_mode'), 'default')))
+                mode=get_option_value(options, OptionKey('b_lto_mode'), 'default'),
+                thinlto_cache_dir=thinlto_cache_dir))
     except KeyError:
         pass
     try:
@@ -975,7 +982,8 @@ class Compiler(HoldableObject, metaclass=abc.ABCMeta):
     def get_lto_compile_args(self, *, threads: int = 0, mode: str = 'default') -> T.List[str]:
         return []
 
-    def get_lto_link_args(self, *, threads: int = 0, mode: str = 'default') -> T.List[str]:
+    def get_lto_link_args(self, *, threads: int = 0, mode: str = 'default',
+                          thinlto_cache_dir: T.Optional[str] = None) -> T.List[str]:
         return self.linker.get_lto_args()
 
     def sanitizer_compile_args(self, value: str) -> T.List[str]: