[PATCH] D114968: [clang][deps] Avoid reading file for stat calls

[Jan Svoboda via Phabricator via cfe-commits]

jansvoboda11 created this revision.
jansvoboda11 requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

Depends on D114966 <https://reviews.llvm.org/D114966>.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D114968

Files:
  clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
  clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp


Index: clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
===================================================================
--- clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
+++ clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
@@ -290,7 +290,7 @@
 
 llvm::ErrorOr<FileSystemEntryResult>
 DependencyScanningWorkerFilesystem::getOrCreateFileSystemEntry(
-    StringRef Filename) {
+    StringRef Filename, RequestedInformation RI) {
   SharedStat *SharedStat = nullptr;
   llvm::Optional<std::unique_lock<std::mutex>> GuardLock;
 
@@ -304,6 +304,12 @@
   llvm::sys::fs::UniqueID UID = (*LocalStat)->getUniqueID();
 
   if (!shouldMinimize(Filename)) {
+    if (RI == RI_Status) {
+      // If the caller wants a status of a file that doesn't need minimization,
+      // reading it is not necessary.
+      return FileSystemEntryResult(*LocalStat, nullptr, nullptr);
+    }
+
     const OriginalContents *LocalOriginalContents =
         getOrCreateLocalOriginalContents(Filename, UID, SharedStat, GuardLock);
     return FileSystemEntryResult(*LocalStat, LocalOriginalContents, nullptr);
@@ -321,7 +327,7 @@
 DependencyScanningWorkerFilesystem::status(const Twine &Path) {
   SmallString<256> OwnedFilename;
   StringRef Filename = Path.toStringRef(OwnedFilename);
-  auto Result = getOrCreateFileSystemEntry(Filename);
+  auto Result = getOrCreateFileSystemEntry(Filename, RI_Status);
   if (!Result)
     return Result.getError();
   return Result->Status;
@@ -381,7 +387,7 @@
   SmallString<256> OwnedFilename;
   StringRef Filename = Path.toStringRef(OwnedFilename);
 
-  auto Result = getOrCreateFileSystemEntry(Filename);
+  auto Result = getOrCreateFileSystemEntry(Filename, RI_Contents);
   if (!Result)
     return Result.getError();
   if (!Result->Status)
Index: clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
===================================================================
--- clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
+++ clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
@@ -223,10 +223,16 @@
       StringRef Filename, llvm::sys::fs::UniqueID UID, SharedStat *&SharedStat,
       llvm::Optional<std::unique_lock<std::mutex>> &Lock);
 
+  /// The information requested from \c getOrCreateFileSystemEntry.
+  enum RequestedInformation {
+    RI_Status,
+    RI_Contents,
+  };
+
   /// Get the full filesystem entry for \p Path from local cache, populating it
   /// if necessary.
   llvm::ErrorOr<FileSystemEntryResult>
-  getOrCreateFileSystemEntry(StringRef Path);
+  getOrCreateFileSystemEntry(StringRef Path, RequestedInformation RI);
 
   /// The global cache shared between worker threads.
   DependencyScanningFilesystemSharedCache &SharedCache;


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