Constant fold bitconvert(undef)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27391 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 6eb6570467fa9721af1636c6c305d9cdae359832..a2b575ff31d83eec5e13c024c4c65eebd332c0ca 100644 (file)
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1167,6 +1167,8 @@ SDOperand SelectionDAG::getNode(unsigned Opcode, MVT::ValueType VT,
     if (VT == Operand.getValueType()) return Operand;  // noop conversion.
     if (OpOpcode == ISD::BIT_CONVERT)  // bitconv(bitconv(x)) -> bitconv(x)
       return getNode(ISD::BIT_CONVERT, VT, Operand.getOperand(0));
+    if (OpOpcode == ISD::UNDEF)
+      return getNode(ISD::UNDEF, VT);
     break;
   case ISD::SCALAR_TO_VECTOR:
     assert(MVT::isVector(VT) && !MVT::isVector(Operand.getValueType()) &&