Preserve DebugInfo when replacing values in DAGCombiner

Recommiting after correcting over-eager Debug Value transfer fixing PR28270.

[DAG] Previously debug values would transfer debuginfo for the selected
start node for a replacement which allows for debug to be dropped.

Push debug value transfer to occur with node/value replacement in
SelectionDAG, remove now extraneous transfers of debug values.

This refixes PR9817 which was being incompletely checked in the
testsuite.

Reviewers: jyknight

Subscribers: dblaikie, llvm-commits

Differential Revision: http://reviews.llvm.org/D21037

llvm-svn: 273585

6 files changed, 28 insertions, 18 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index e9e68b72fa6..1da1f0acb39 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1333,8 +1333,6 @@ void DAGCombiner::Run(CombineLevel AtLevel) {
     DEBUG(dbgs() << " ... into: ";
           RV.getNode()->dump(&DAG));
 
-    // Transfer debug value.
-    DAG.TransferDbgValues(SDValue(N, 0), RV);
     if (N->getNumValues() == RV.getNode()->getNumValues())
       DAG.ReplaceAllUsesWith(N, RV.getNode());
     else {
diff --git a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index 4448b0582ba..a44b936ba92 100644
--- a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -320,7 +320,6 @@ InstrEmitter::AddRegisterOperand(MachineInstrBuilder &MIB,
          "Chain and glue operands should occur at end of operand list!");
   // Get/emit the operand.
   unsigned VReg = getVR(Op, VRBaseMap);
-  assert(TargetRegisterInfo::isVirtualRegister(VReg) && "Not a vreg?");
 
   const MCInstrDesc &MCID = MIB->getDesc();
   bool isOptDef = IIOpNum < MCID.getNumOperands() &&
@@ -334,6 +333,8 @@ InstrEmitter::AddRegisterOperand(MachineInstrBuilder &MIB,
     const TargetRegisterClass *DstRC = nullptr;
     if (IIOpNum < II->getNumOperands())
       DstRC = TRI->getAllocatableClass(TII->getRegClass(*II,IIOpNum,TRI,*MF));
+    assert((!DstRC || TargetRegisterInfo::isVirtualRegister(VReg)) &&
+           "Expected VReg");
     if (DstRC && !MRI->constrainRegClass(VReg, DstRC, MinRCSize)) {
       unsigned NewVReg = MRI->createVirtualRegister(DstRC);
       BuildMI(*MBB, InsertPos, Op.getNode()->getDebugLoc(),
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 129765e8cd2..ac68bcdb426 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -179,8 +179,6 @@ public:
            "Replacing one node with another that produces a different number "
            "of values!");
     DAG.ReplaceAllUsesWith(Old, New);
-    for (unsigned i = 0, e = Old->getNumValues(); i != e; ++i)
-      DAG.TransferDbgValues(SDValue(Old, i), SDValue(New, i));
     if (UpdatedNodes)
       UpdatedNodes->insert(New);
     ReplacedNode(Old);
@@ -190,7 +188,6 @@ public:
           dbgs() << "     with:      "; New->dump(&DAG));
 
     DAG.ReplaceAllUsesWith(Old, New);
-    DAG.TransferDbgValues(Old, New);
     if (UpdatedNodes)
       UpdatedNodes->insert(New.getNode());
     ReplacedNode(Old.getNode());
@@ -203,7 +200,6 @@ public:
       DEBUG(dbgs() << (i == 0 ? "     with:      "
                               : "      and:      ");
             New[i]->dump(&DAG));
-      DAG.TransferDbgValues(SDValue(Old, i), New[i]);
       if (UpdatedNodes)
         UpdatedNodes->insert(New[i].getNode());
     }
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 0f43fd483d3..3073e22b9d6 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -6333,6 +6333,9 @@ void SelectionDAG::ReplaceAllUsesWith(SDValue FromN, SDValue To) {
     AddModifiedNodeToCSEMaps(User);
   }
 
+  // Preserve Debug Values
+  TransferDbgValues(FromN, To);
+
   // If we just RAUW'd the root, take note.
   if (FromN == getRoot())
     setRoot(To);
@@ -6356,6 +6359,13 @@ void SelectionDAG::ReplaceAllUsesWith(SDNode *From, SDNode *To) {
   if (From == To)
     return;
 
+  // Preserve Debug Info. Only do this if there's a use.
+  for (unsigned i = 0, e = From->getNumValues(); i != e; ++i)
+    if (From->hasAnyUseOfValue(i)) {
+      assert((i < To->getNumValues()) && "Invalid To location");
+      TransferDbgValues(SDValue(From, i), SDValue(To, i));
+    }
+
   // Iterate over just the existing users of From. See the comments in
   // the ReplaceAllUsesWith above.
   SDNode::use_iterator UI = From->use_begin(), UE = From->use_end();
@@ -6395,6 +6405,10 @@ void SelectionDAG::ReplaceAllUsesWith(SDNode *From, const SDValue *To) {
   if (From->getNumValues() == 1)  // Handle the simple case efficiently.
     return ReplaceAllUsesWith(SDValue(From, 0), To[0]);
 
+  // Preserve Debug Info.
+  for (unsigned i = 0, e = From->getNumValues(); i != e; ++i)
+    TransferDbgValues(SDValue(From, i), *To);
+
   // Iterate over just the existing users of From. See the comments in
   // the ReplaceAllUsesWith above.
   SDNode::use_iterator UI = From->use_begin(), UE = From->use_end();
@@ -6439,6 +6453,9 @@ void SelectionDAG::ReplaceAllUsesOfValueWith(SDValue From, SDValue To){
     return;
   }
 
+  // Preserve Debug Info.
+  TransferDbgValues(From, To);
+
   // Iterate over just the existing users of From. See the comments in
   // the ReplaceAllUsesWith above.
   SDNode::use_iterator UI = From.getNode()->use_begin(),
@@ -6513,6 +6530,8 @@ void SelectionDAG::ReplaceAllUsesOfValuesWith(const SDValue *From,
   if (Num == 1)
     return ReplaceAllUsesOfValueWith(*From, *To);
 
+  TransferDbgValues(*From, *To);
+
   // Read up all the uses and make records of them. This helps
   // processing new uses that are introduced during the
   // replacement process.
@@ -6661,28 +6680,26 @@ void SelectionDAG::AddDbgValue(SDDbgValue *DB, SDNode *SD, bool isParameter) {
   DbgInfo->add(DB, SD, isParameter);
 }
 
-/// TransferDbgValues - Transfer SDDbgValues.
+/// TransferDbgValues - Transfer SDDbgValues. Called in replace nodes.
 void SelectionDAG::TransferDbgValues(SDValue From, SDValue To) {
   if (From == To || !From.getNode()->getHasDebugValue())
     return;
   SDNode *FromNode = From.getNode();
   SDNode *ToNode = To.getNode();
   ArrayRef<SDDbgValue *> DVs = GetDbgValues(FromNode);
-  SmallVector<SDDbgValue *, 2> ClonedDVs;
   for (ArrayRef<SDDbgValue *>::iterator I = DVs.begin(), E = DVs.end();
        I != E; ++I) {
     SDDbgValue *Dbg = *I;
-    if (Dbg->getKind() == SDDbgValue::SDNODE) {
+    // Only add Dbgvalues attached to same ResNo.
+    if (Dbg->getKind() == SDDbgValue::SDNODE &&
+        Dbg->getResNo() == From.getResNo()) {
       SDDbgValue *Clone =
           getDbgValue(Dbg->getVariable(), Dbg->getExpression(), ToNode,
                       To.getResNo(), Dbg->isIndirect(), Dbg->getOffset(),
                       Dbg->getDebugLoc(), Dbg->getOrder());
-      ClonedDVs.push_back(Clone);
+      AddDbgValue(Clone, ToNode, false);
     }
   }
-  for (SmallVectorImpl<SDDbgValue *>::iterator I = ClonedDVs.begin(),
-         E = ClonedDVs.end(); I != E; ++I)
-    AddDbgValue(*I, ToNode, false);
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/llvm/lib/Target/Hexagon/HexagonISelDAGToDAG.cpp b/llvm/lib/Target/Hexagon/HexagonISelDAGToDAG.cpp
index 724076020e7..1ddb9327776 100644
--- a/llvm/lib/Target/Hexagon/HexagonISelDAGToDAG.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonISelDAGToDAG.cpp
@@ -1308,8 +1308,6 @@ void HexagonDAGToDAGISel::SelectFrameIndex(SDNode *N) {
     R = CurDAG->getMachineNode(Hexagon::TFR_FIA, DL, MVT::i32, Ops);
   }
 
-  if (N->getHasDebugValue())
-    CurDAG->TransferDbgValues(SDValue(N, 0), SDValue(R, 0));
   ReplaceNode(N, R);
 }
 
diff --git a/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp b/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
index 60e8c3a6e21..bd36978c436 100644
--- a/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
@@ -1058,8 +1058,8 @@ HexagonTargetLowering::LowerDYNAMIC_STACKALLOC(SDValue Op,
   SDValue AC = DAG.getConstant(A, dl, MVT::i32);
   SDVTList VTs = DAG.getVTList(MVT::i32, MVT::Other);
   SDValue AA = DAG.getNode(HexagonISD::ALLOCA, dl, VTs, Chain, Size, AC);
-  if (Op.getNode()->getHasDebugValue())
-    DAG.TransferDbgValues(Op, AA);
+
+  DAG.ReplaceAllUsesOfValueWith(Op, AA);
   return AA;
 }