2 files changed, 60 insertions, 12 deletions

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 458e865a6b..ac4e709105 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -701,6 +701,7 @@ void SelectionDAGBuilder::clear() {
   UnusedArgNodeMap.clear();
   PendingLoads.clear();
   PendingExports.clear();
+  DanglingDebugInfoMap.clear();
   CurDebugLoc = DebugLoc();
   HasTailCall = false;
 }
@@ -805,6 +806,33 @@ void SelectionDAGBuilder::visit(unsigned Opcode, const User &I) {
   }
 }
 
+// resolveDanglingDebugInfo - if we saw an earlier dbg_value referring to V,
+// generate the debug data structures now that we've seen its definition.
+void SelectionDAGBuilder::resolveDanglingDebugInfo(const Value *V,
+                                                   SDValue Val) {
+  DanglingDebugInfo &DDI = DanglingDebugInfoMap[V];
+  if (DDI.getDI()) {
+    const DbgValueInst *DI = DDI.getDI();
+    DebugLoc dl = DDI.getdl();
+    unsigned DbgSDNodeOrder = DDI.getSDNodeOrder();
+    MDNode *Variable = DI->getVariable();
+    uint64_t Offset = DI->getOffset();
+    SDDbgValue *SDV;
+    if (Val.getNode()) {
+      if (!EmitFuncArgumentDbgValue(*DI, V, Variable, Offset, Val)) {
+        SDV = DAG.getDbgValue(Variable, Val.getNode(),
+                              Val.getResNo(), Offset, dl, DbgSDNodeOrder);
+        DAG.AddDbgValue(SDV, Val.getNode(), false);
+      }
+    } else {
+      SDV = DAG.getDbgValue(Variable, UndefValue::get(V->getType()),
+                            Offset, dl, SDNodeOrder);
+      DAG.AddDbgValue(SDV, 0, false);
+    }
+    DanglingDebugInfoMap[V] = DanglingDebugInfo();
+  }
+}
+
 // getValue - Return an SDValue for the given Value.
 SDValue SelectionDAGBuilder::getValue(const Value *V) {
   // If we already have an SDValue for this value, use it. It's important
@@ -826,6 +854,7 @@ SDValue SelectionDAGBuilder::getValue(const Value *V) {
   // Otherwise create a new SDValue and remember it.
   SDValue Val = getValueImpl(V);
   NodeMap[V] = Val;
+  resolveDanglingDebugInfo(V, Val);
   return Val;
 }
 
@@ -839,10 +868,11 @@ SDValue SelectionDAGBuilder::getNonRegisterValue(const Value *V) {
   // Otherwise create a new SDValue and remember it.
   SDValue Val = getValueImpl(V);
   NodeMap[V] = Val;
+  resolveDanglingDebugInfo(V, Val);
   return Val;
 }
 
-/// getValueImpl - Helper function for getValue and getMaterializedValue.
+/// getValueImpl - Helper function for getValue and getNonRegisterValue.
 /// Create an SDValue for the given value.
 SDValue SelectionDAGBuilder::getValueImpl(const Value *V) {
   if (const Constant *C = dyn_cast<Constant>(V)) {
@@ -4049,7 +4079,8 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
       DAG.AddDbgValue(SDV, 0, false);
     } else {
       bool createUndef = false;
-      // FIXME : Why not use getValue() directly ?
+      // Do not use getValue() in here; we don't want to generate code at
+      // this point if it hasn't been done yet.
       SDValue N = NodeMap[V];
       if (!N.getNode() && isa<Argument>(V))
         // Check unused arguments map.
@@ -4060,16 +4091,11 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
                                 N.getResNo(), Offset, dl, SDNodeOrder);
           DAG.AddDbgValue(SDV, N.getNode(), false);
         }
-      } else if (isa<PHINode>(V) && !V->use_empty()) {
-        SDValue N = getValue(V);
-        if (N.getNode()) {
-          if (!EmitFuncArgumentDbgValue(DI, V, Variable, Offset, N)) {
-            SDV = DAG.getDbgValue(Variable, N.getNode(),
-                                  N.getResNo(), Offset, dl, SDNodeOrder);
-            DAG.AddDbgValue(SDV, N.getNode(), false);
-          }
-        } else
-          createUndef = true;
+      } else if (isa<PHINode>(V) && !V->use_empty() ) {
+        // Do not call getValue(V) yet, as we don't want to generate code.
+        // Remember it for later.
+        DanglingDebugInfo DDI(&DI, dl, SDNodeOrder);
+        DanglingDebugInfoMap[V] = DDI;
       } else
         createUndef = true;
       if (createUndef) {
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 46733d6db1..bc3fd62c3f 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -64,6 +64,7 @@ class PHINode;
 class PtrToIntInst;
 class ReturnInst;
 class SDISelAsmOperandInfo;
+class SDDbgValue;
 class SExtInst;
 class SelectInst;
 class ShuffleVectorInst;
@@ -93,6 +94,24 @@ class SelectionDAGBuilder {
   /// to preserve debug information for incoming arguments.
   DenseMap<const Value*, SDValue> UnusedArgNodeMap;
 
+  /// DanglingDebugInfo - Helper type for DanglingDebugInfoMap.
+  class DanglingDebugInfo {
+    const DbgValueInst* DI;
+    DebugLoc dl;
+    unsigned SDNodeOrder;
+  public:
+    DanglingDebugInfo() : DI(0), dl(DebugLoc()), SDNodeOrder(0) { }
+    DanglingDebugInfo(const DbgValueInst *di, DebugLoc DL, unsigned SDNO) :
+      DI(di), dl(DL), SDNodeOrder(SDNO) { }
+    const DbgValueInst* getDI() { return DI; }
+    DebugLoc getdl() { return dl; }
+    unsigned getSDNodeOrder() { return SDNodeOrder; }
+  };
+
+  /// DanglingDebugInfoMap - Keeps track of dbg_values for which we have not
+  /// yet seen the referent.  We defer handling these until we do see it.
+  DenseMap<const Value*, DanglingDebugInfo> DanglingDebugInfoMap;
+
 public:
   /// PendingLoads - Loads are not emitted to the program immediately.  We bunch
   /// them up and then emit token factor nodes when possible.  This allows us to
@@ -345,6 +364,9 @@ public:
 
   void visit(unsigned Opcode, const User &I);
 
+  // resolveDanglingDebugInfo - if we saw an earlier dbg_value referring to V,
+  // generate the debug data structures now that we've seen its definition.
+  void resolveDanglingDebugInfo(const Value *V, SDValue Val);
   SDValue getValue(const Value *V);
   SDValue getNonRegisterValue(const Value *V);
   SDValue getValueImpl(const Value *V);