[AArch64 NEON] Fix invalid constant used in vselect condition.

There is a wrong assumption that the vector element type and the
type of each ConstantSDNode in the build_vector were the same.
However, when promoting the integer operand of a legally typed
build_vector, the operand type and the vector element type do not
need to be the same
(See method 'DAGTypeLegalizer::PromoteIntOp_BUILD_VECTOR' in
LegalizeIntegerTypes.cpp).

  in AArch64 backend, the following dag sequence:

  C0: i1 = Constant<0>
  C1: i1 = Constant<-1>
  V: v8i1 = BUILD_VECTOR C1, C1, C0, C0, C0, C0, C0, C0

  is type-legalized into:

  NewC0: i32 = Constant<0>
  NewC1: i32 = Constant<1>
  V: v8i8 = BUILD_VECTOR NewC1, NewC1, NewC0, NewC0, NewC0, NewC0, NewC0, NewC0

Forcing a getZeroExtend to VTBits to ensure that the new constant
is correctly.

llvm-svn: 198582

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 3b87922b789..422e83ab7d5 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -5527,8 +5527,8 @@ SDValue DAGCombiner::visitSIGN_EXTEND_INREG(SDNode *N) {
       }
 
       ConstantSDNode *CurrentND = cast<ConstantSDNode>(Op);
-      const APInt &C = CurrentND->getAPIntValue();
-      Elts.push_back(DAG.getConstant(C.shl(ShAmt).ashr(ShAmt),
+      const APInt &C = APInt(VTBits, CurrentND->getAPIntValue().getZExtValue());
+      Elts.push_back(DAG.getConstant(C.shl(ShAmt).ashr(ShAmt).getZExtValue(),
                                      Op.getValueType()));
     }