1 files changed, 11 insertions, 4 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index c9aeef7..90edaf3 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5063,8 +5063,7 @@ unsigned SelectionDAG::ComputeNumSignBits(SDValue Op, const APInt &DemandedElts,
     break;
   case ISD::ADD:
   case ISD::ADDC:
-    // Add can have at most one carry bit.  Thus we know that the output
-    // is, at worst, one more bit than the inputs.
+    // TODO: Move Operand 1 check before Operand 0 check
     Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
     if (Tmp == 1) return 1; // Early out.
 
@@ -5088,6 +5087,9 @@ unsigned SelectionDAG::ComputeNumSignBits(SDValue Op, const APInt &DemandedElts,
 
     Tmp2 = ComputeNumSignBits(Op.getOperand(1), DemandedElts, Depth + 1);
     if (Tmp2 == 1) return 1; // Early out.
+
+    // Add can have at most one carry bit.  Thus we know that the output
+    // is, at worst, one more bit than the inputs.
     return std::min(Tmp, Tmp2) - 1;
   case ISD::SUB:
     Tmp2 = ComputeNumSignBits(Op.getOperand(1), DemandedElts, Depth + 1);
@@ -6403,8 +6405,9 @@ static SDValue foldCONCAT_VECTORS(const SDLoc &DL, EVT VT,
   if (VT.isScalableVector())
     return SDValue();
 
-  // A CONCAT_VECTOR with all UNDEF/BUILD_VECTOR operands can be
-  // simplified to one big BUILD_VECTOR.
+  // A CONCAT_VECTOR of scalar sources, such as UNDEF, BUILD_VECTOR and
+  // single-element INSERT_VECTOR_ELT operands can be simplified to one big
+  // BUILD_VECTOR.
   // FIXME: Add support for SCALAR_TO_VECTOR as well.
   EVT SVT = VT.getScalarType();
   SmallVector<SDValue, 16> Elts;
@@ -6414,6 +6417,10 @@ static SDValue foldCONCAT_VECTORS(const SDLoc &DL, EVT VT,
       Elts.append(OpVT.getVectorNumElements(), DAG.getUNDEF(SVT));
     else if (Op.getOpcode() == ISD::BUILD_VECTOR)
       Elts.append(Op->op_begin(), Op->op_end());
+    else if (Op.getOpcode() == ISD::INSERT_VECTOR_ELT &&
+             OpVT.getVectorNumElements() == 1 &&
+             isNullConstant(Op.getOperand(2)))
+      Elts.push_back(Op.getOperand(1));
     else
       return SDValue();
   }