3cda32d590
Similar to previous no transitive changes to decls, types, identifiers and source locations ( https://github.com/llvm/llvm-project/pull/92083 https://github.com/llvm/llvm-project/pull/92085 https://github.com/llvm/llvm-project/pull/92511 https://github.com/llvm/llvm-project/pull/86912 ) This patch does the same thing for MacroID and PreprocessedEntityID. --- ### Some background Previously we record different IDs linearly. That is, when writing a module, if we have 17 decls in imported modules, the ID of decls in the module will start from 18. This makes the contents of the BMI changes if the we add/remove any decls, types, identifiers and source locations in the imported modules. This makes it hard for us to reduce recompilations with modules. We want to skip recompilations as we think the modules can help us to remove fake dependencies. This can be done by split the ID into <ModuleIndex, LocalIndex> pairs. This is ALREADY done for several different ID above. We call it non-casacading changes (https://clang.llvm.org/docs/StandardCPlusPlusModules.html#experimental-non-cascading-changes). Our internal users have already used this feature and it works well for years. Now we want to extend this to MacroID and PreprocessedEntityID. This is helpful for us in the downstream as we allowed named modules to export macros. But I believe this is also helpful for header-like modules if you'd like to explore the area. And also I think this is a nice cleanup too. --- Given the use of MacroID and PreprocessedEntityID are not as complicated as other IDs in the above series, I feel the patch itself should be good. I hope the vendors can test the patch to make sure it won't affect existing users.
3.2 KiB
3.2 KiB