Fixed scalarizing an extract subvector and prevent an infinite loop

when simplify a vector. 

llvm-svn: 58820

2 files changed, 9 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index f9d1ddc6157..c17ef9cedcb 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -7516,8 +7516,8 @@ SDValue SelectionDAGLegalize::ScalarizeVectorOp(SDValue Op) {
     break;
   }
   case ISD::EXTRACT_SUBVECTOR:
-    Result = Node->getOperand(0);
-    assert(Result.getValueType() == NewVT);
+    Result = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, NewVT, Node->getOperand(0),
+                          Node->getOperand(1));
     break;
   case ISD::BIT_CONVERT: {
     SDValue Op0 = Op.getOperand(0);
@@ -8174,7 +8174,7 @@ void SelectionDAGLegalize::genWidenVectorStores(SDValueVector& StChain,
 
   SDValue VecOp = DAG.getNode(ISD::BIT_CONVERT, VecEVT, ValOp);
   SDValue EOp = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, EVT, VecOp,
-                                  DAG.getIntPtrConstant(0));
+                            DAG.getIntPtrConstant(0));
   SDValue StOp = DAG.getStore(Chain, EOp, BasePtr, SV, SVOffset,
                                isVolatile, Alignment);
   StChain.push_back(StOp);
diff --git a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
index 3210b12cbb9..743d8bb15f7 100644
--- a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -1410,6 +1410,12 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, uint64_t DemandedElts,
   } else if (isa<ConstantAggregateZero>(V)) {
     // Simplify the CAZ to a ConstantVector where the non-demanded elements are
     // set to undef.
+    
+    // Check if this is identity. If so, return 0 since we are not simplifying
+    // anything.
+    if (DemandedElts == ((1ULL << VWidth) -1))
+      return 0;
+    
     const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
     Constant *Zero = Constant::getNullValue(EltTy);
     Constant *Undef = UndefValue::get(EltTy);