[llvm] [VPlan] Remove VPInstruction::Not. NFC (PR #222228)

[Ramkumar Ramachandra via llvm-commits]

================
@@ -1331,12 +1325,19 @@ InstructionCost VPRecipeWithIRFlags::getCostForRecipeWithOpcode(
 InstructionCost VPInstruction::computeCost(ElementCount VF,
                                            VPCostContext &Ctx) const {
   if (Instruction::isBinaryOp(getOpcode())) {
-    if (!getUnderlyingValue() && getOpcode() != Instruction::FMul) {
+    if (!getUnderlyingValue() && getOpcode() != Instruction::FMul &&
----------------
artagnon wrote:

As a side note, would be good to remove the `&& getOpcode() != Instruction::FMul`, as I don't think it's relevant any longer? Would probably be good to remove the getUnderlyingValue() check as well?

https://github.com/llvm/llvm-project/pull/222228