Keep track of incoming debug value of unused argument.

Radar 7927666.

llvm-svn: 105285

1 files changed, 10 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 3fcd4b9dc43..86903caa8a5 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -88,6 +88,10 @@ class SelectionDAGBuilder {
   DebugLoc CurDebugLoc;
 
   DenseMap<const Value*, SDValue> NodeMap;
+  
+  /// UnusedArgNodeMap - Maps argument value for unused arguments. This is used
+  /// to preserve debug information for incoming arguments.
+  DenseMap<const Value*, SDValue> UnusedArgNodeMap;
 
 public:
   /// PendingLoads - Loads are not emitted to the program immediately.  We bunch
@@ -349,6 +353,12 @@ public:
     N = NewN;
   }
   
+  void setUnusedArgValue(const Value *V, SDValue NewN) {
+    SDValue &N = UnusedArgNodeMap[V];
+    assert(N.getNode() == 0 && "Already set a value for this node!");
+    N = NewN;
+  }
+  
   void GetRegistersForValue(SDISelAsmOperandInfo &OpInfo,
                             std::set<unsigned> &OutputRegs, 
                             std::set<unsigned> &InputRegs);