More constification of things. More comments added. No functionality

[oota-llvm.git] / lib / CodeGen / SelectionDAG / DAGCombiner.cpp

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index a2f36f33b452481b81132293a47d80dc9b6adce9..026666c45fc7af4ef8789a323edd432a6028db6d 100644 (file)
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -137,6 +137,7 @@ namespace {
     //   otherwise            - N should be replaced by the returned Operand.
     //
     SDOperand visitTokenFactor(SDNode *N);
+    SDOperand visitMERGE_VALUES(SDNode *N);
     SDOperand visitADD(SDNode *N);
     SDOperand visitSUB(SDNode *N);
     SDOperand visitADDC(SDNode *N);
@@ -662,6 +663,7 @@ SDOperand DAGCombiner::visit(SDNode *N) {
   switch(N->getOpcode()) {
   default: break;
   case ISD::TokenFactor:        return visitTokenFactor(N);
+  case ISD::MERGE_VALUES:       return visitMERGE_VALUES(N);
   case ISD::ADD:                return visitADD(N);
   case ISD::SUB:                return visitSUB(N);
   case ISD::ADDC:               return visitADDC(N);
@@ -837,6 +839,18 @@ SDOperand DAGCombiner::visitTokenFactor(SDNode *N) {
   return Result;
 }
 
+/// MERGE_VALUES can always be eliminated.
+SDOperand DAGCombiner::visitMERGE_VALUES(SDNode *N) {
+  WorkListRemover DeadNodes(*this);
+  for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
+    DAG.ReplaceAllUsesOfValueWith(SDOperand(N, i), N->getOperand(i),
+                                  &DeadNodes);
+  removeFromWorkList(N);
+  DAG.DeleteNode(N);
+  return SDOperand(N, 0);   // Return N so it doesn't get rechecked!
+}
+
+
 static
 SDOperand combineShlAddConstant(SDOperand N0, SDOperand N1, SelectionDAG &DAG) {
   MVT::ValueType VT = N0.getValueType();
@@ -3436,14 +3450,16 @@ ConstantFoldBIT_CONVERTofBUILD_VECTOR(SDNode *BV, MVT::ValueType DstEltVT) {
         Ops.push_back(DAG.getConstant(NewBits, DstEltVT));
     }
 
-    MVT::ValueType VT = MVT::getVectorType(DstEltVT,
-                                           Ops.size());
+    MVT::ValueType VT = MVT::getVectorType(DstEltVT, Ops.size()); 
     return DAG.getNode(ISD::BUILD_VECTOR, VT, &Ops[0], Ops.size());
   }
   
   // Finally, this must be the case where we are shrinking elements: each input
   // turns into multiple outputs.
+  bool isS2V = ISD::isScalarToVector(BV);
   unsigned NumOutputsPerInput = SrcBitSize/DstBitSize;
+  MVT::ValueType VT = MVT::getVectorType(DstEltVT,
+                                     NumOutputsPerInput * BV->getNumOperands());
   SmallVector<SDOperand, 8> Ops;
   for (unsigned i = 0, e = BV->getNumOperands(); i != e; ++i) {
     if (BV->getOperand(i).getOpcode() == ISD::UNDEF) {
@@ -3452,18 +3468,19 @@ ConstantFoldBIT_CONVERTofBUILD_VECTOR(SDNode *BV, MVT::ValueType DstEltVT) {
       continue;
     }
     uint64_t OpVal = cast<ConstantSDNode>(BV->getOperand(i))->getValue();
-
     for (unsigned j = 0; j != NumOutputsPerInput; ++j) {
       unsigned ThisVal = OpVal & ((1ULL << DstBitSize)-1);
-      OpVal >>= DstBitSize;
       Ops.push_back(DAG.getConstant(ThisVal, DstEltVT));
+      if (isS2V && i == 0 && j == 0 && ThisVal == OpVal)
+        // Simply turn this into a SCALAR_TO_VECTOR of the new type.
+        return DAG.getNode(ISD::SCALAR_TO_VECTOR, VT, Ops[0]);
+      OpVal >>= DstBitSize;
     }
 
     // For big endian targets, swap the order of the pieces of each element.
     if (TLI.isBigEndian())
       std::reverse(Ops.end()-NumOutputsPerInput, Ops.end());
   }
-  MVT::ValueType VT = MVT::getVectorType(DstEltVT, Ops.size());
   return DAG.getNode(ISD::BUILD_VECTOR, VT, &Ops[0], Ops.size());
 }