[VPlan] Use createScalarZExtOrTrunc when expanding expandVPWidenIntOrFpInduction

Split off from llvm#144666

Author: lukel97

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

@@ -2608,8 +2608,8 @@ expandVPWidenIntOrFpInduction(VPWidenIntOrFpInductionRecipe *WidenIVR,
       VF = Builder.createScalarCast(Instruction::CastOps::UIToFP, VF, StepTy,
                                     DL);
     else
-      VF =
-          Builder.createScalarCast(Instruction::CastOps::Trunc, VF, StepTy, DL);
+      VF = Builder.createScalarZExtOrTrunc(VF, StepTy,
+                                           TypeInfo.inferScalarType(VF), DL);
 
     Inc = Builder.createNaryOp(MulOp, {Step, VF}, Flags);
     Inc = Builder.createNaryOp(VPInstruction::Broadcast, Inc);

llvm/test/Transforms/LoopVectorize/vplan-iv-transforms.ll

@@ -96,8 +96,7 @@ define void @iv_expand(ptr %p, i64 %n) {
 ; CHECK-NEXT:     EMIT vp<[[BROADCAST_1:%.+]]> = broadcast ir<1>
 ; CHECK-NEXT:     EMIT vp<[[MUL:%.+]]> = mul vp<[[STEP_VECTOR]]>, vp<[[BROADCAST_1]]>
 ; CHECK-NEXT:     EMIT vp<[[INDUCTION:%.+]]> = add vp<[[BROADCAST_0]]>, vp<[[MUL]]>
-; CHECK-NEXT:     EMIT vp<[[TRUNC:%.+]]> = trunc ir<8> to i64
-; CHECK-NEXT:     EMIT vp<[[INC:%.+]]> = mul ir<1>, vp<[[TRUNC]]>
+; CHECK-NEXT:     EMIT vp<[[INC:%.+]]> = mul ir<1>, ir<8>
 ; CHECK-NEXT:     EMIT vp<[[BROADCAST_INC:%.+]]> = broadcast vp<[[INC]]>
 ; CHECK-NEXT: Successor(s): vector.body
 ; CHECK-EMPTY: