[llvm] [PowerPC] cost modeling for length type VP intrinsic load/store (PR #168938)

[zhijian lin via llvm-commits]

================
@@ -1078,3 +1082,61 @@ PPCTTIImpl::getVPLegalizationStrategy(const VPIntrinsic &PI) const {
 
   return VPLegalization(VPLegalization::Legal, VPLegalization::Legal);
 }
+
+bool PPCTTIImpl::hasActiveVectorLength() const {
+  unsigned CPU = ST->getCPUDirective();
+  if (!PPCEVL)
+    return false;
+  if (CPU == PPC::DIR_PWR10 || CPU == PPC::DIR_PWR_FUTURE ||
+      (Pwr9EVL && CPU == PPC::DIR_PWR9))
+    return true;
+  return false;
+}
+
+static inline bool isLegalLoadWithLengthType(EVT VT) {
+  if (VT != MVT::i64 && VT != MVT::i32 && VT != MVT::i16 && VT != MVT::i8)
+    return false;
+  return true;
+}
+
+bool PPCTTIImpl::isLegalMaskedLoad(Type *DataType, Align Alignment,
+                                   unsigned AddressSpace) const {
+  if (!hasActiveVectorLength())
+    return false;
+  if (!isLegalLoadWithLengthType(TLI->getValueType(DL, DataType, true)))
+    return false;
+  return true;
+}
+
+bool PPCTTIImpl::isLegalMaskedStore(Type *DataType, Align Alignment,
+                                    unsigned AddressSpace) const {
+  return isLegalMaskedLoad(DataType, Alignment, AddressSpace);
+}
+
+InstructionCost
+PPCTTIImpl::getMaskedMemoryOpCost(const MemIntrinsicCostAttributes &MICA,
+                                  TTI::TargetCostKind CostKind) const {
+  Type *DataTy = MICA.getDataType();
+  Align Alignment = MICA.getAlignment();
+  unsigned Opcode = MICA.getID() == Intrinsic::masked_load ? Instruction::Load
+                                                           : Instruction::Store;
+  unsigned AddressSpace = MICA.getAddressSpace();
+
+  InstructionCost BaseCost = BaseT::getMaskedMemoryOpCost(MICA, CostKind);
+
+  auto VecTy = dyn_cast<FixedVectorType>(DataTy);
+  if (!VecTy)
+    return BaseCost;
+  if (!isLegalMaskedLoad(VecTy->getScalarType(), Alignment, AddressSpace))
+    return BaseCost;
+  if (VecTy->getPrimitiveSizeInBits() > 128)
+    return BaseCost;
+
+  // Is scalar compare + select + maybe shift + vector load
+  InstructionCost Adj = vectorCostAdjustmentFactor(Opcode, DataTy, nullptr);
+  InstructionCost Cost = 2 + Adj;
----------------
diggerlin wrote:

nit: change to 
InstructionCost Cost = 2 + vectorCostAdjustmentFactor(Opcode, DataTy, nullptr);

and I am curiously what the `2` means for? is it possible to have comment for it ?  

https://github.com/llvm/llvm-project/pull/168938