Add a FIXME for an unfortunate issue in ConvertBackendLocation()

This function is copying the entire file contents into memory repeatedly and
allocating new file IDs *each time* a source location is processed.

llvm-svn: 211874

1 files changed, 3 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
index 2b7fab3beb9..1a092fcedb1 100644
--- a/clang/lib/CodeGen/CodeGenAction.cpp
+++ b/clang/lib/CodeGen/CodeGenAction.cpp
@@ -267,13 +267,15 @@ static FullSourceLoc ConvertBackendLocation(const llvm::SMDiagnostic &D,
   LSM.getMemoryBuffer(LSM.FindBufferContainingLoc(D.getLoc()));
 
   // Create the copy and transfer ownership to clang::SourceManager.
+  // TODO: Avoid copying files into memory.
   llvm::MemoryBuffer *CBuf =
   llvm::MemoryBuffer::getMemBufferCopy(LBuf->getBuffer(),
                                        LBuf->getBufferIdentifier());
+  // FIXME: Keep a file ID map instead of creating new IDs for each location.
   FileID FID = CSM.createFileID(CBuf);
 
   // Translate the offset into the file.
-  unsigned Offset = D.getLoc().getPointer()  - LBuf->getBufferStart();
+  unsigned Offset = D.getLoc().getPointer() - LBuf->getBufferStart();
   SourceLocation NewLoc =
   CSM.getLocForStartOfFile(FID).getLocWithOffset(Offset);
   return FullSourceLoc(NewLoc, CSM);