serialized diagnostics: simplify code.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@144277 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/SerializedDiagnosticPrinter.cpp b/lib/Frontend/SerializedDiagnosticPrinter.cpp
index 974ec53..be9ab55 100644
--- a/lib/Frontend/SerializedDiagnosticPrinter.cpp
+++ b/lib/Frontend/SerializedDiagnosticPrinter.cpp
@@ -207,11 +207,7 @@
   Record.push_back(getEmitFile(Loc));
   Record.push_back(SM.getSpellingLineNumber(Loc));
   Record.push_back(SM.getSpellingColumnNumber(Loc)+TokSize);
-  
-  std::pair<FileID, unsigned> LocInfo = SM.getDecomposedLoc(Loc);
-  FileID FID = LocInfo.first;
-  unsigned FileOffset = LocInfo.second;
-  Record.push_back(FileOffset);
+  Record.push_back(SM.getFileOffset(Loc));
 }
 
 void SDiagsWriter::AddCharSourceRangeToRecord(CharSourceRange Range,