Introduce FileEntryRef and use it when handling includes to report correct dependencies

when the FileManager is reused across invocations

This commit introduces a parallel API to FileManager's getFile: getFileEntryRef, which returns
a reference to the FileEntry, and the name that was used to access the file. In the case of
a VFS with 'use-external-names', the FileEntyRef contains the external name of the file,
not the filename that was used to access it.

The new API is adopted only in the HeaderSearch and Preprocessor for include file lookup, so that the
accessed path can be propagated to SourceManager's FileInfo. SourceManager's FileInfo now can report this accessed path, using
the new getName method. This API is then adopted in the dependency collector, which now correctly reports dependencies when a file
is included both using a symlink and a real path in the case when the FileManager is reused across multiple Preprocessor invocations.

Note that this patch does not fix all dependency collector issues, as the same problem is still present in other cases when dependencies
are obtained using FileSkipped, InclusionDirective, and HasInclude. This will be fixed in follow-up commits.

Differential Revision: https://reviews.llvm.org/D65907

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@369680 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 43 insertions, 8 deletions

diff --git a/include/clang/Basic/SourceManager.h b/include/clang/Basic/SourceManager.h
index e32f749ae6..48b25de7c5 100644
--- a/include/clang/Basic/SourceManager.h
+++ b/include/clang/Basic/SourceManager.h
@@ -265,16 +265,21 @@ namespace SrcMgr {
     llvm::PointerIntPair<const ContentCache*, 3, CharacteristicKind>
         ContentAndKind;
 
+    /// The filename that is used to access the file entry represented by the
+    /// content cache.
+    StringRef Filename;
+
   public:
     /// Return a FileInfo object.
     static FileInfo get(SourceLocation IL, const ContentCache *Con,
-                        CharacteristicKind FileCharacter) {
+                        CharacteristicKind FileCharacter, StringRef Filename) {
       FileInfo X;
       X.IncludeLoc = IL.getRawEncoding();
       X.NumCreatedFIDs = 0;
       X.HasLineDirectives = false;
       X.ContentAndKind.setPointer(Con);
       X.ContentAndKind.setInt(FileCharacter);
+      X.Filename = Filename;
       return X;
     }
 
@@ -299,6 +304,10 @@ namespace SrcMgr {
     void setHasLineDirectives() {
       HasLineDirectives = true;
     }
+
+    /// Returns the name of the file that was used when the file was loaded from
+    /// the underlying file system.
+    StringRef getName() const { return Filename; }
   };
 
   /// Each ExpansionInfo encodes the expansion location - where
@@ -821,7 +830,18 @@ public:
     const SrcMgr::ContentCache *IR =
         getOrCreateContentCache(SourceFile, isSystem(FileCharacter));
     assert(IR && "getOrCreateContentCache() cannot return NULL");
-    return createFileID(IR, IncludePos, FileCharacter, LoadedID, LoadedOffset);
+    return createFileID(IR, SourceFile->getName(), IncludePos, FileCharacter,
+                        LoadedID, LoadedOffset);
+  }
+
+  FileID createFileID(FileEntryRef SourceFile, SourceLocation IncludePos,
+                      SrcMgr::CharacteristicKind FileCharacter,
+                      int LoadedID = 0, unsigned LoadedOffset = 0) {
+    const SrcMgr::ContentCache *IR = getOrCreateContentCache(
+        &SourceFile.getFileEntry(), isSystem(FileCharacter));
+    assert(IR && "getOrCreateContentCache() cannot return NULL");
+    return createFileID(IR, SourceFile.getName(), IncludePos, FileCharacter,
+                        LoadedID, LoadedOffset);
   }
 
   /// Create a new FileID that represents the specified memory buffer.
@@ -832,9 +852,10 @@ public:
                       SrcMgr::CharacteristicKind FileCharacter = SrcMgr::C_User,
                       int LoadedID = 0, unsigned LoadedOffset = 0,
                       SourceLocation IncludeLoc = SourceLocation()) {
+    StringRef Name = Buffer->getBufferIdentifier();
     return createFileID(
         createMemBufferContentCache(Buffer.release(), /*DoNotFree*/ false),
-        IncludeLoc, FileCharacter, LoadedID, LoadedOffset);
+        Name, IncludeLoc, FileCharacter, LoadedID, LoadedOffset);
   }
 
   enum UnownedTag { Unowned };
@@ -847,8 +868,9 @@ public:
                       SrcMgr::CharacteristicKind FileCharacter = SrcMgr::C_User,
                       int LoadedID = 0, unsigned LoadedOffset = 0,
                       SourceLocation IncludeLoc = SourceLocation()) {
-    return createFileID(createMemBufferContentCache(Buffer, /*DoNotFree*/true),
-                        IncludeLoc, FileCharacter, LoadedID, LoadedOffset);
+    return createFileID(createMemBufferContentCache(Buffer, /*DoNotFree*/ true),
+                        Buffer->getBufferIdentifier(), IncludeLoc,
+                        FileCharacter, LoadedID, LoadedOffset);
   }
 
   /// Get the FileID for \p SourceFile if it exists. Otherwise, create a
@@ -997,6 +1019,19 @@ public:
     return Content->OrigEntry;
   }
 
+  /// Returns the FileEntryRef for the provided FileID.
+  Optional<FileEntryRef> getFileEntryRefForID(FileID FID) const {
+    bool Invalid = false;
+    const SrcMgr::SLocEntry &Entry = getSLocEntry(FID, &Invalid);
+    if (Invalid || !Entry.isFile())
+      return None;
+
+    const SrcMgr::ContentCache *Content = Entry.getFile().getContentCache();
+    if (!Content || !Content->OrigEntry)
+      return None;
+    return FileEntryRef(Entry.getFile().getName(), *Content->OrigEntry);
+  }
+
   /// Returns the FileEntry record for the provided SLocEntry.
   const FileEntry *getFileEntryForSLocEntry(const SrcMgr::SLocEntry &sloc) const
   {
@@ -1785,10 +1820,10 @@ private:
   ///
   /// This works regardless of whether the ContentCache corresponds to a
   /// file or some other input source.
-  FileID createFileID(const SrcMgr::ContentCache* File,
+  FileID createFileID(const SrcMgr::ContentCache *File, StringRef Filename,
                       SourceLocation IncludePos,
-                      SrcMgr::CharacteristicKind DirCharacter,
-                      int LoadedID, unsigned LoadedOffset);
+                      SrcMgr::CharacteristicKind DirCharacter, int LoadedID,
+                      unsigned LoadedOffset);
 
   const SrcMgr::ContentCache *
     getOrCreateContentCache(const FileEntry *SourceFile,