Right now, Debugging information to encode scopes (DW_TAG_lexical_block) relies on DBG_LABEL. Unfortunately this intefers with the quality of optimized code. 
This patch updates dwarf writer to encode scoping information in DWARF only in FastISel mode.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68973 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AsmPrinter/DwarfWriter.cpp b/lib/CodeGen/AsmPrinter/DwarfWriter.cpp
index c619bc5..c4191e5 100644
--- a/lib/CodeGen/AsmPrinter/DwarfWriter.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfWriter.cpp
@@ -3296,7 +3296,7 @@
   }
 
   /// ValidDebugInfo - Return true if V represents valid debug info value.
-  bool ValidDebugInfo(Value *V) {
+  bool ValidDebugInfo(Value *V, bool FastISel) {
     if (!V)
       return false;
 
@@ -3335,6 +3335,11 @@
     case DW_TAG_subprogram:
       assert(DISubprogram(GV).Verify() && "Invalid DebugInfo value");
       break;
+    case DW_TAG_lexical_block:
+      /// FIXME. This interfers with the qualitfy of generated code when 
+      /// during optimization.
+      if (FastISel == false)
+        return false;
     default:
       break;
     }
@@ -4621,8 +4626,8 @@
 }
 
 /// ValidDebugInfo - Return true if V represents valid debug info value.
-bool DwarfWriter::ValidDebugInfo(Value *V) {
-  return DD && DD->ValidDebugInfo(V);
+bool DwarfWriter::ValidDebugInfo(Value *V, bool FastISel) {
+  return DD && DD->ValidDebugInfo(V, FastISel);
 }
 
 /// RecordSourceLine - Records location information and associates it with a