2 files changed, 125 insertions, 11 deletions

diff --git a/lib/Frontend/PCHReader.cpp b/lib/Frontend/PCHReader.cpp
index 759865c7eb..ab7ad04e9d 100644
--- a/lib/Frontend/PCHReader.cpp
+++ b/lib/Frontend/PCHReader.cpp
@@ -1218,6 +1218,10 @@ PCHReader::ReadPCHBlock() {
       }
       ObjCCategoryImpls.swap(Record);
       break;
+
+    case pch::ORIGINAL_FILE_NAME:
+      OriginalFileName.assign(BlobStart, BlobLen);
+      break;
     }
   }
   Error("premature end of bitstream in PCH file");
@@ -1364,6 +1368,87 @@ PCHReader::PCHReadResult PCHReader::ReadPCH(const std::string &FileName) {
   return Success;
 }
 
+/// \brief Retrieve the name of the original source file name
+/// directly from the PCH file, without actually loading the PCH
+/// file.
+std::string PCHReader::getOriginalSourceFile(const std::string &PCHFileName) {
+  // Open the PCH file.
+  std::string ErrStr;
+  llvm::OwningPtr<llvm::MemoryBuffer> Buffer;
+  Buffer.reset(llvm::MemoryBuffer::getFile(PCHFileName.c_str(), &ErrStr));
+  if (!Buffer) {
+    fprintf(stderr, "error: %s\n", ErrStr.c_str());
+    return std::string();
+  }
+
+  // Initialize the stream
+  llvm::BitstreamReader StreamFile;
+  llvm::BitstreamCursor Stream;
+  StreamFile.init((const unsigned char *)Buffer->getBufferStart(), 
+                  (const unsigned char *)Buffer->getBufferEnd());
+  Stream.init(StreamFile);
+
+  // Sniff for the signature.
+  if (Stream.Read(8) != 'C' ||
+      Stream.Read(8) != 'P' ||
+      Stream.Read(8) != 'C' ||
+      Stream.Read(8) != 'H') {
+    fprintf(stderr, 
+            "error: '%s' does not appear to be a precompiled header file\n",
+            PCHFileName.c_str());
+    return std::string();
+  }
+
+  RecordData Record;
+  while (!Stream.AtEndOfStream()) {
+    unsigned Code = Stream.ReadCode();
+    
+    if (Code == llvm::bitc::ENTER_SUBBLOCK) {
+      unsigned BlockID = Stream.ReadSubBlockID();
+      
+      // We only know the PCH subblock ID.
+      switch (BlockID) {
+      case pch::PCH_BLOCK_ID:
+        if (Stream.EnterSubBlock(pch::PCH_BLOCK_ID)) {
+          fprintf(stderr, "error: malformed block record in PCH file\n");
+          return std::string();
+        }
+        break;
+        
+      default:
+        if (Stream.SkipBlock()) {
+          fprintf(stderr, "error: malformed block record in PCH file\n");
+          return std::string();
+        }
+        break;
+      }
+      continue;
+    }
+
+    if (Code == llvm::bitc::END_BLOCK) {
+      if (Stream.ReadBlockEnd()) {
+        fprintf(stderr, "error: error at end of module block in PCH file\n");
+        return std::string();
+      }
+      continue;
+    }
+
+    if (Code == llvm::bitc::DEFINE_ABBREV) {
+      Stream.ReadAbbrevRecord();
+      continue;
+    }
+
+    Record.clear();
+    const char *BlobStart = 0;
+    unsigned BlobLen = 0;
+    if (Stream.ReadRecord(Code, Record, &BlobStart, &BlobLen) 
+          == pch::ORIGINAL_FILE_NAME)
+      return std::string(BlobStart, BlobLen);
+  }  
+
+  return std::string();
+}
+
 /// \brief Parse the record that corresponds to a LangOptions data
 /// structure.
 ///
diff --git a/lib/Frontend/PCHWriter.cpp b/lib/Frontend/PCHWriter.cpp
index fc6aa4709e..dbe0e536e5 100644
--- a/lib/Frontend/PCHWriter.cpp
+++ b/lib/Frontend/PCHWriter.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Bitcode/BitstreamWriter.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/MemoryBuffer.h"
+#include "llvm/System/Path.h"
 #include <cstdio>
 using namespace clang;
 
@@ -442,16 +443,44 @@ void PCHWriter::WriteBlockInfoBlock() {
 
 
 /// \brief Write the PCH metadata (e.g., i686-apple-darwin9).
-void PCHWriter::WriteMetadata(const TargetInfo &Target) {
+void PCHWriter::WriteMetadata(ASTContext &Context) {
   using namespace llvm;
-  BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
-  Abbrev->Add(BitCodeAbbrevOp(pch::METADATA));
-  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // PCH major
-  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // PCH minor
-  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // Clang major
-  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // Clang minor
-  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Target triple
-  unsigned AbbrevCode = Stream.EmitAbbrev(Abbrev);
+
+  // Original file name
+  SourceManager &SM = Context.getSourceManager();
+  if (const FileEntry *MainFile = SM.getFileEntryForID(SM.getMainFileID())) {
+    BitCodeAbbrev *FileAbbrev = new BitCodeAbbrev();
+    FileAbbrev->Add(BitCodeAbbrevOp(pch::ORIGINAL_FILE_NAME));
+    FileAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // File name
+    unsigned FileAbbrevCode = Stream.EmitAbbrev(FileAbbrev);
+
+    llvm::sys::Path MainFilePath(MainFile->getName());
+    std::string MainFileName;
+  
+    if (!MainFilePath.isAbsolute()) {
+      llvm::sys::Path P = llvm::sys::Path::GetCurrentDirectory();
+      P.appendComponent(MainFilePath.toString());
+      MainFileName = P.toString();
+    } else {
+      MainFileName = MainFilePath.toString();
+    }
+
+    RecordData Record;
+    Record.push_back(pch::ORIGINAL_FILE_NAME);
+    Stream.EmitRecordWithBlob(FileAbbrevCode, Record, MainFileName.c_str(),
+                              MainFileName.size());
+  }
+
+  // Metadata
+  const TargetInfo &Target = Context.Target;
+  BitCodeAbbrev *MetaAbbrev = new BitCodeAbbrev();
+  MetaAbbrev->Add(BitCodeAbbrevOp(pch::METADATA));
+  MetaAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // PCH major
+  MetaAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // PCH minor
+  MetaAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // Clang major
+  MetaAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // Clang minor
+  MetaAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Target triple
+  unsigned MetaAbbrevCode = Stream.EmitAbbrev(MetaAbbrev);
 
   RecordData Record;
   Record.push_back(pch::METADATA);
@@ -460,7 +489,7 @@ void PCHWriter::WriteMetadata(const TargetInfo &Target) {
   Record.push_back(CLANG_VERSION_MAJOR);
   Record.push_back(CLANG_VERSION_MINOR);
   const char *Triple = Target.getTargetTriple();
-  Stream.EmitRecordWithBlob(AbbrevCode, Record, Triple, strlen(Triple));
+  Stream.EmitRecordWithBlob(MetaAbbrevCode, Record, Triple, strlen(Triple));
 }
 
 /// \brief Write the LangOptions structure.
@@ -1672,7 +1701,7 @@ void PCHWriter::WritePCH(Sema &SemaRef, MemorizeStatCalls *StatCalls) {
   // Write the remaining PCH contents.
   RecordData Record;
   Stream.EnterSubblock(pch::PCH_BLOCK_ID, 4);
-  WriteMetadata(Context.Target);
+  WriteMetadata(Context);
   WriteLanguageOptions(Context.getLangOptions());
   if (StatCalls)
     WriteStatCache(*StatCalls);