[clang] Stop adjusting the module cache path

[jansvoboda11]

This patch stops adjustments of the module cache path beyond what is done in ParseHeaderSearchArgs (making it absolute and removing dots). This enables more efficient implementation of the caching VFS in #88800.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Jan Svoboda (jansvoboda11)

Changes

This patch stops adjustments of the module cache path beyond what is done in ParseHeaderSearchArgs (making it absolute and removing dots). This enables more efficient implementation of the caching VFS in #88800.

---

Full diff: https://github.com/llvm/llvm-project/pull/102540.diff

2 Files Affected:

• (modified) clang/lib/Frontend/CompilerInstance.cpp (+2-3)
• (modified) clang/lib/Lex/HeaderSearch.cpp (-1)

diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 6242b5a7d9fe39..1364641a9b71e1 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -1659,9 +1659,8 @@ static void pruneModuleCache(const HeaderSearchOptions &HSOpts) {
   // Walk the entire module cache, looking for unused module files and module
   // indices.
   std::error_code EC;
-  SmallString<128> ModuleCachePathNative;
-  llvm::sys::path::native(HSOpts.ModuleCachePath, ModuleCachePathNative);
-  for (llvm::sys::fs::directory_iterator Dir(ModuleCachePathNative, EC), DirEnd;
+  for (llvm::sys::fs::directory_iterator Dir(HSOpts.ModuleCachePath, EC),
+       DirEnd;
        Dir != DirEnd && !EC; Dir.increment(EC)) {
     // If we don't have a directory, there's nothing to look into.
     if (!llvm::sys::fs::is_directory(Dir->path()))
diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index d2210e7e18628a..4914c10e62d0c5 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -267,7 +267,6 @@ std::string HeaderSearch::getCachedModuleFileNameImpl(StringRef ModuleName,
     return {};
 
   SmallString<256> Result(CachePath);
-  llvm::sys::fs::make_absolute(Result);
 
   if (HSOpts->DisableModuleHash) {
     llvm::sys::path::append(Result, ModuleName + ".pcm");

[aganea]

This enables more efficient implementation of the caching VFS in #88800.

Thanks @jansvoboda11 for working on this, I appreciate. One question, what do you mean by "more efficient"?

[jansvoboda11]

This enables more efficient implementation of the caching VFS in #88800.

Thanks @jansvoboda11 for working on this, I appreciate. One question, what do you mean by "more efficient"?

Sorry, I should've clarified. I think that without this patch, #88800 would need to apply llvm::sys::path::native() and llvm::sys::fs::make_absolute() on DependencyScanningWorkerFilesystem::BypassedPathPrefix within each invocation to DependencyScanningWorkerFilesystem::shouldBypass() where simple string prefix did not match. Only then would it recognize the modules cache path in all its forms.

[aganea]

Thanks for the explanation!