[SourceKit] Remove some dupliate computation of realpaths

Author: ahoppen

tools/SourceKit/lib/SwiftLang/SwiftASTManager.cpp

@@ -605,7 +605,8 @@ struct SwiftASTManager::Implementation {
 
   BufferStamp
   getBufferStamp(StringRef FilePath,
-                 IntrusiveRefCntPtr<llvm::vfs::FileSystem> FileSystem) const;
+                 IntrusiveRefCntPtr<llvm::vfs::FileSystem> FileSystem,
+                 bool CheckEditorDocs = true) const;
 
   std::unique_ptr<llvm::MemoryBuffer>
   getMemoryBuffer(StringRef Filename,
@@ -793,24 +794,29 @@ FileContentRef SwiftASTManager::Implementation::getFileContent(
     llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> FileSystem,
     std::string &Error) const {
   std::string FilePath = SwiftLangSupport::resolvePathSymlinks(UnresolvedPath);
-  if (auto EditorDoc = EditorDocs->findByPath(FilePath))
+  if (auto EditorDoc = EditorDocs->findByPath(FilePath, /*IsRealpath=*/true))
     return getFileContentFromSnap(EditorDoc->getLatestSnapshot(), IsPrimary,
                                   FilePath);
 
   // FIXME: Is there a way to get timestamp and buffer for a file atomically ?
-  auto Stamp = getBufferStamp(FilePath, FileSystem);
+  // No need to check EditorDocs again. We did so above.
+  auto Stamp = getBufferStamp(FilePath, FileSystem, /*CheckEditorDocs=*/false);
   auto Buffer = getMemoryBuffer(FilePath, FileSystem, Error);
   return new FileContent(nullptr, UnresolvedPath.str(), std::move(Buffer),
                          IsPrimary, Stamp);
 }
 
 BufferStamp SwiftASTManager::Implementation::getBufferStamp(
     StringRef FilePath,
-    llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> FileSystem) const {
+    llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> FileSystem,
+    bool CheckEditorDocs) const {
   assert(FileSystem);
 
-  if (auto EditorDoc = EditorDocs->findByPath(FilePath))
-    return EditorDoc->getLatestSnapshot()->getStamp();
+  if (CheckEditorDocs) {
+    if (auto EditorDoc = EditorDocs->findByPath(FilePath)) {
+      return EditorDoc->getLatestSnapshot()->getStamp();
+    }
+  }
 
   auto StatusOrErr = FileSystem->status(FilePath);
   if (std::error_code Err = StatusOrErr.getError()) {

tools/SourceKit/lib/SwiftLang/SwiftEditor.cpp

@@ -245,14 +245,18 @@ SwiftEditorDocumentFileMap::getByUnresolvedName(StringRef FilePath) {
 }
 
 SwiftEditorDocumentRef
-SwiftEditorDocumentFileMap::findByPath(StringRef FilePath) {
+SwiftEditorDocumentFileMap::findByPath(StringRef FilePath, bool IsRealpath) {
   SwiftEditorDocumentRef EditorDoc;
 
-  std::string ResolvedPath = SwiftLangSupport::resolvePathSymlinks(FilePath);
+  std::string Scratch;
+  if (!IsRealpath) {
+    Scratch = SwiftLangSupport::resolvePathSymlinks(FilePath);
+    FilePath = Scratch;
+  }
   Queue.dispatchSync([&]{
     for (auto &Entry : Docs) {
       if (Entry.getKey() == FilePath ||
-          Entry.getValue().ResolvedPath == ResolvedPath) {
+          Entry.getValue().ResolvedPath == FilePath) {
         EditorDoc = Entry.getValue().DocRef;
         break;
       }

tools/SourceKit/lib/SwiftLang/SwiftLangSupport.h

@@ -156,7 +156,10 @@ class SwiftEditorDocumentFileMap {
   /// Looks up the document only by the path name that was given initially.
   SwiftEditorDocumentRef getByUnresolvedName(StringRef FilePath);
   /// Looks up the document by resolving symlinks in the paths.
-  SwiftEditorDocumentRef findByPath(StringRef FilePath);
+  /// If \p IsRealpath is \c true, then \p FilePath must already be
+  /// canonicalized to a realpath.
+  SwiftEditorDocumentRef findByPath(StringRef FilePath,
+                                    bool IsRealpath = false);
   SwiftEditorDocumentRef remove(StringRef FilePath);
 };