[RISCV] Fix cost of legal fixed length masked load and stores

[reames]

Summary

We can cost them the same way as a scalable masked load/store. By hitting the default path, we were costing them as if they were being scalarized. This is a significant over estimate.

[frasercrmck]

LGTM

llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp

InstructionCost RISCVTTIImpl::getShuffleCost(TTI::ShuffleKind Kind,
 
   return BaseT::getShuffleCost(Kind, Tp, Mask, CostKind, Index, SubTp);
 }
 
 InstructionCost
 RISCVTTIImpl::getMaskedMemoryOpCost(unsigned Opcode, Type *Src, Align Alignment,
                                     unsigned AddressSpace,
                                     TTI::TargetCostKind CostKind) {
-  if (!isa<ScalableVectorType>(Src))
+  if (!isLegalMaskedLoadStore(Src, Alignment) ||
+      CostKind != TTI::TCK_RecipThroughput)
     return BaseT::getMaskedMemoryOpCost(Opcode, Src, Alignment, AddressSpace,
                                         CostKind);
 
   return getMemoryOpCost(Opcode, Src, Alignment, AddressSpace, CostKind);
 }
 
 InstructionCost RISCVTTIImpl::getGatherScatterOpCost(
     unsigned Opcode, Type *DataTy, const Value *Ptr, bool VariableMask,

llvm/test/Analysis/CostModel/RISCV/masked_ldst.ll

 ; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py
 ; RUN: opt < %s -passes="print<cost-model>" -disable-output -mtriple=riscv64 -mattr=+v 2>&1 | FileCheck %s
 
 define void @fixed() {
 ; CHECK-LABEL: 'fixed'
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 11 for instruction: %v2i8 = call <2 x i8> @llvm.masked.load.v2i8.p0v2i8(<2 x i8>* undef, i32 8, <2 x i1> undef, <2 x i8> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 23 for instruction: %v4i8 = call <4 x i8> @llvm.masked.load.v4i8.p0v4i8(<4 x i8>* undef, i32 8, <4 x i1> undef, <4 x i8> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 47 for instruction: %v8i8 = call <8 x i8> @llvm.masked.load.v8i8.p0v8i8(<8 x i8>* undef, i32 8, <8 x i1> undef, <8 x i8> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 95 for instruction: %v16i8 = call <16 x i8> @llvm.masked.load.v16i8.p0v16i8(<16 x i8>* undef, i32 8, <16 x i1> undef, <16 x i8> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 11 for instruction: %v2i16 = call <2 x i16> @llvm.masked.load.v2i16.p0v2i16(<2 x i16>* undef, i32 8, <2 x i1> undef, <2 x i16> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 23 for instruction: %v4i16 = call <4 x i16> @llvm.masked.load.v4i16.p0v4i16(<4 x i16>* undef, i32 8, <4 x i1> undef, <4 x i16> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 47 for instruction: %v8i16 = call <8 x i16> @llvm.masked.load.v8i16.p0v8i16(<8 x i16>* undef, i32 8, <8 x i1> undef, <8 x i16> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 11 for instruction: %v2i32 = call <2 x i32> @llvm.masked.load.v2i32.p0v2i32(<2 x i32>* undef, i32 8, <2 x i1> undef, <2 x i32> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 23 for instruction: %v4i32 = call <4 x i32> @llvm.masked.load.v4i32.p0v4i32(<4 x i32>* undef, i32 8, <4 x i1> undef, <4 x i32> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 11 for instruction: %v2i64 = call <2 x i64> @llvm.masked.load.v2i64.p0v2i64(<2 x i64>* undef, i32 8, <2 x i1> undef, <2 x i64> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2i8 = call <2 x i8> @llvm.masked.load.v2i8.p0v2i8(<2 x i8>* undef, i32 8, <2 x i1> undef, <2 x i8> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v4i8 = call <4 x i8> @llvm.masked.load.v4i8.p0v4i8(<4 x i8>* undef, i32 8, <4 x i1> undef, <4 x i8> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v8i8 = call <8 x i8> @llvm.masked.load.v8i8.p0v8i8(<8 x i8>* undef, i32 8, <8 x i1> undef, <8 x i8> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v16i8 = call <16 x i8> @llvm.masked.load.v16i8.p0v16i8(<16 x i8>* undef, i32 8, <16 x i1> undef, <16 x i8> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2i16 = call <2 x i16> @llvm.masked.load.v2i16.p0v2i16(<2 x i16>* undef, i32 8, <2 x i1> undef, <2 x i16> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v4i16 = call <4 x i16> @llvm.masked.load.v4i16.p0v4i16(<4 x i16>* undef, i32 8, <4 x i1> undef, <4 x i16> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v8i16 = call <8 x i16> @llvm.masked.load.v8i16.p0v8i16(<8 x i16>* undef, i32 8, <8 x i1> undef, <8 x i16> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2i32 = call <2 x i32> @llvm.masked.load.v2i32.p0v2i32(<2 x i32>* undef, i32 8, <2 x i1> undef, <2 x i32> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v4i32 = call <4 x i32> @llvm.masked.load.v4i32.p0v4i32(<4 x i32>* undef, i32 8, <4 x i1> undef, <4 x i32> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2i64 = call <2 x i64> @llvm.masked.load.v2i64.p0v2i64(<2 x i64>* undef, i32 8, <2 x i1> undef, <2 x i64> undef)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %v2f16 = call <2 x half> @llvm.masked.load.v2f16.p0v2f16(<2 x half>* undef, i32 8, <2 x i1> undef, <2 x half> undef)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %v4f16 = call <4 x half> @llvm.masked.load.v4f16.p0v4f16(<4 x half>* undef, i32 8, <4 x i1> undef, <4 x half> undef)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 32 for instruction: %v8f16 = call <8 x half> @llvm.masked.load.v8f16.p0v8f16(<8 x half>* undef, i32 8, <8 x i1> undef, <8 x half> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 11 for instruction: %v2f32 = call <2 x float> @llvm.masked.load.v2f32.p0v2f32(<2 x float>* undef, i32 8, <2 x i1> undef, <2 x float> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 23 for instruction: %v4f32 = call <4 x float> @llvm.masked.load.v4f32.p0v4f32(<4 x float>* undef, i32 8, <4 x i1> undef, <4 x float> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 11 for instruction: %v2f64 = call <2 x double> @llvm.masked.load.v2f64.p0v2f64(<2 x double>* undef, i32 8, <2 x i1> undef, <2 x double> undef)
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 23 for instruction: %v4i64 = call <4 x i64> @llvm.masked.load.v4i64.p0v4i64(<4 x i64>* undef, i32 8, <4 x i1> undef, <4 x i64> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2f32 = call <2 x float> @llvm.masked.load.v2f32.p0v2f32(<2 x float>* undef, i32 8, <2 x i1> undef, <2 x float> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v4f32 = call <4 x float> @llvm.masked.load.v4f32.p0v4f32(<4 x float>* undef, i32 8, <4 x i1> undef, <4 x float> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v2f64 = call <2 x double> @llvm.masked.load.v2f64.p0v2f64(<2 x double>* undef, i32 8, <2 x i1> undef, <2 x double> undef)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %v4i64 = call <4 x i64> @llvm.masked.load.v4i64.p0v4i64(<4 x i64>* undef, i32 8, <4 x i1> undef, <4 x i64> undef)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 128 for instruction: %v32f16 = call <32 x half> @llvm.masked.load.v32f16.p0v32f16(<32 x half>* undef, i32 8, <32 x i1> undef, <32 x half> undef)
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret void
 ;
 entry:
   ; fixed-width integer types
   %v2i8 = call <2 x i8> @llvm.masked.load.v2i8.p0v2i8(<2 x i8> *undef, i32 8, <2 x i1> undef, <2 x i8> undef)
   %v4i8 = call <4 x i8> @llvm.masked.load.v4i8.p0v4i8(<4 x i8> *undef, i32 8, <4 x i1> undef, <4 x i8> undef)
   %v8i8 = call <8 x i8> @llvm.masked.load.v8i8.p0v8i8(<8 x i8> *undef, i32 8, <8 x i1> undef, <8 x i8> undef)