[DAGTypeLegalizer] Handle widening truncate to vector of i1.

Previously, PromoteIntRes_TRUNCATE() did not handle the case where
the operand needs widening, which resulted in llvm_unreachable().

This patch adds the needed handling, along with a test case.

Review: Eli Friedman, Simon Pilgrim.
https://reviews.llvm.org/D31077

llvm-svn: 298357

1 files changed, 21 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
index 39aef98362c..85068e89075 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
@@ -690,7 +690,7 @@ SDValue DAGTypeLegalizer::PromoteIntRes_TRUNCATE(SDNode *N) {
   case TargetLowering::TypePromoteInteger:
     Res = GetPromotedInteger(InOp);
     break;
-  case TargetLowering::TypeSplitVector:
+  case TargetLowering::TypeSplitVector: {
     EVT InVT = InOp.getValueType();
     assert(InVT.isVector() && "Cannot split scalar types");
     unsigned NumElts = InVT.getVectorNumElements();
@@ -709,6 +709,26 @@ SDValue DAGTypeLegalizer::PromoteIntRes_TRUNCATE(SDNode *N) {
 
     return DAG.getNode(ISD::CONCAT_VECTORS, dl, NVT, EOp1, EOp2);
   }
+  case TargetLowering::TypeWidenVector: {
+    SDValue WideInOp = GetWidenedVector(InOp);
+
+    // Truncate widened InOp.
+    unsigned NumElem = WideInOp.getValueType().getVectorNumElements();
+    EVT TruncVT = EVT::getVectorVT(*DAG.getContext(),
+                                   N->getValueType(0).getScalarType(), NumElem);
+    SDValue WideTrunc = DAG.getNode(ISD::TRUNCATE, dl, TruncVT, WideInOp);
+
+    // Zero extend so that the elements are of same type as those of NVT
+    EVT ExtVT = EVT::getVectorVT(*DAG.getContext(), NVT.getVectorElementType(),
+                                 NumElem);
+    SDValue WideExt = DAG.getNode(ISD::ZERO_EXTEND, dl, ExtVT, WideTrunc);
+
+    // Extract the low NVT subvector.
+    MVT IdxTy = TLI.getVectorIdxTy(DAG.getDataLayout());
+    SDValue ZeroIdx = DAG.getConstant(0, dl, IdxTy);
+    return DAG.getNode(ISD::EXTRACT_SUBVECTOR, dl, NVT, WideExt, ZeroIdx);
+  }
+  }
 
   // Truncate to NVT instead of VT
   return DAG.getNode(ISD::TRUNCATE, dl, NVT, Res);