Remove VPInstruction::MergeUntilPivot

Author: Mel-Chen

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -1277,11 +1277,6 @@ class VPInstruction : public VPRecipeWithIRFlags,
     // operand). Only generates scalar values (either for the first lane only or
     // for all lanes, depending on its uses).
     PtrAdd,
-    // Selects elements from two vectors (second and third operand) based on a
-    // condition vector (first operand) and a pivot index (fourth operand). The
-    // lanes whose positions are greater than or equal to the pivot are taken
-    // from the third operand.
-    MergeUntilPivot,
   };
 
 private:

llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp

@@ -65,7 +65,6 @@ bool VPRecipeBase::mayWriteToMemory() const {
     case VPInstruction::FirstOrderRecurrenceSplice:
     case VPInstruction::LogicalAnd:
     case VPInstruction::PtrAdd:
-    case VPInstruction::MergeUntilPivot:
       return false;
     default:
       return true;
@@ -678,16 +677,7 @@ Value *VPInstruction::generate(VPTransformState &State) {
     }
     return NewPhi;
   }
-  case VPInstruction::MergeUntilPivot: {
-    Value *Cond = State.get(getOperand(0));
-    Value *OnTrue = State.get(getOperand(1));
-    Value *OnFalse = State.get(getOperand(2));
-    Value *Pivot = State.get(getOperand(3), /* IsScalar */ true);
-    assert(Pivot->getType()->isIntegerTy() && "Pivot should be an integer.");
-    return Builder.CreateIntrinsic(Intrinsic::vp_merge, {OnTrue->getType()},
-                                   {Cond, OnTrue, OnFalse, Pivot}, nullptr,
-                                   Name);
-  }
+
   default:
     llvm_unreachable("Unsupported opcode for instruction");
   }
@@ -769,9 +759,6 @@ bool VPInstruction::onlyFirstLaneUsed(const VPValue *Op) const {
   case VPInstruction::BranchOnCond:
   case VPInstruction::ResumePhi:
     return true;
-  case VPInstruction::MergeUntilPivot:
-    // Pivot must be an integer.
-    return Op == getOperand(3);
   };
   llvm_unreachable("switch should return");
 }
@@ -790,7 +777,6 @@ bool VPInstruction::onlyFirstPartUsed(const VPValue *Op) const {
   case VPInstruction::BranchOnCount:
   case VPInstruction::BranchOnCond:
   case VPInstruction::CanonicalIVIncrementForPart:
-  case VPInstruction::MergeUntilPivot:
     return true;
   };
   llvm_unreachable("switch should return");
@@ -857,9 +843,6 @@ void VPInstruction::print(raw_ostream &O, const Twine &Indent,
   case VPInstruction::PtrAdd:
     O << "ptradd";
     break;
-  case VPInstruction::MergeUntilPivot:
-    O << "merge-until-pivot";
-    break;
   default:
     O << Instruction::getOpcodeName(getOpcode());
   }