Put the assignment back at the top of this method.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66611 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AsmPrinter/DwarfWriter.cpp b/lib/CodeGen/AsmPrinter/DwarfWriter.cpp
index 8dc7c4c..4120d9f 100644
--- a/lib/CodeGen/AsmPrinter/DwarfWriter.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfWriter.cpp
@@ -3135,13 +3135,13 @@
   /// BeginFunction - Gather pre-function debug information.  Assumes being
   /// emitted immediately after the function entry point.
   void BeginFunction(MachineFunction *MF) {
+    this->MF = MF;
+
     if (!ShouldEmitDwarfDebug()) return;
 
     if (TimePassesIsEnabled)
       DebugTimer->startTimer();
 
-    this->MF = MF;
-
     // Begin accumulating function debug information.
     MMI->BeginFunction(MF);