Differential Revision: https://reviews.llvm.org/D70268
This is a recommit of f978ea4983 with a fix for the PowerPC failure.
The issue was that:
* `CompilerInstance::ExecuteAction` calls
`getTarget().adjust(getLangOpts());`.
* `PPCTargetInfo::adjust` changes `LangOptions::HasAltivec`.
* This happens after the first few calls to `getModuleHash`.
There’s even a FIXME saying:
```
// FIXME: We shouldn't need to do this, the target should be immutable once
// created. This complexity should be lifted elsewhere.
```
This only showed up on PowerPC because it's one of the few targets that
almost always changes a hashed langopt.
I looked into addressing the fixme, but that would be a much larger
change, and it's not the only thing that happens in `ExecuteAction` that
can change the module context hash. Instead I changed the code to not
call `getModuleHash` until after it has been modified in `ExecuteAction`.
This fixes two issues that prevent simple uses of modules from working.
* We would previously minimize _every_ file opened by clang, even module maps
and module pcm files. Now we only minimize files with known extensions. It
would be better if we knew which files clang intended to open as a source
file, but this works for now.
* We previously cached every lookup, even failed lookups. This is a problem
because clang stats the module cache directory before building a module and
creating that directory. If we cache that failure then the subsequent pcm
load doesn't see the module cache and fails.
Overall this still leaves us building minmized modules on disk during scanning.
This will need to be improved eventually for performance, but this is correct,
and works for now.
Differential Revision: https://reviews.llvm.org/D68835
Michael Spencer