src/llvm-project/llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h

//===- RISCVTargetTransformInfo.h - RISC-V specific TTI ---------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
/// This file defines a TargetTransformInfo::Concept conforming object specific
/// to the RISC-V target machine. It uses the target's detailed information to
/// provide more precise answers to certain TTI queries, while letting the
/// target independent and default TTI implementations handle the rest.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_LIB_TARGET_RISCV_RISCVTARGETTRANSFORMINFO_H
#define LLVM_LIB_TARGET_RISCV_RISCVTARGETTRANSFORMINFO_H

#include "RISCVSubtarget.h"
#include "RISCVTargetMachine.h"
#include "llvm/Analysis/IVDescriptors.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/CodeGen/BasicTTIImpl.h"
#include "llvm/IR/Function.h"

namespace llvm {

class RISCVTTIImpl : public BasicTTIImplBase<RISCVTTIImpl> {
  using BaseT = BasicTTIImplBase<RISCVTTIImpl>;
  using TTI = TargetTransformInfo;

  friend BaseT;

  const RISCVSubtarget *ST;
  const RISCVTargetLowering *TLI;

  const RISCVSubtarget *getST() const { return ST; }
  const RISCVTargetLowering *getTLI() const { return TLI; }

public:
  explicit RISCVTTIImpl(const RISCVTargetMachine *TM, const Function &F)
      : BaseT(TM, F.getParent()->getDataLayout()), ST(TM->getSubtargetImpl(F)),
        TLI(ST->getTargetLowering()) {}

  InstructionCost getIntImmCost(const APInt &Imm, Type *Ty,
                                TTI::TargetCostKind CostKind);
  InstructionCost getIntImmCostInst(unsigned Opcode, unsigned Idx,
                                    const APInt &Imm, Type *Ty,
                                    TTI::TargetCostKind CostKind,
                                    Instruction *Inst = nullptr);
  InstructionCost getIntImmCostIntrin(Intrinsic::ID IID, unsigned Idx,
                                      const APInt &Imm, Type *Ty,
                                      TTI::TargetCostKind CostKind);

  TargetTransformInfo::PopcntSupportKind getPopcntSupport(unsigned TyWidth);

  bool shouldExpandReduction(const IntrinsicInst *II) const;
  bool supportsScalableVectors() const { return ST->hasVInstructions(); }
  Optional<unsigned> getMaxVScale() const;

  TypeSize getRegisterBitWidth(TargetTransformInfo::RegisterKind K) const;

  InstructionCost getRegUsageForType(Type *Ty);

  void getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
                               TTI::UnrollingPreferences &UP,
                               OptimizationRemarkEmitter *ORE);

  void getPeelingPreferences(Loop *L, ScalarEvolution &SE,
                             TTI::PeelingPreferences &PP);

  unsigned getMinVectorRegisterBitWidth() const {
    return ST->useRVVForFixedLengthVectors() ? 16 : 0;
  }

  InstructionCost getGatherScatterOpCost(unsigned Opcode, Type *DataTy,
                                         const Value *Ptr, bool VariableMask,
                                         Align Alignment,
                                         TTI::TargetCostKind CostKind,
                                         const Instruction *I);

  bool isLegalMaskedLoadStore(Type *DataType, Align Alignment) {
    if (!ST->hasVInstructions())
      return false;

    // Only support fixed vectors if we know the minimum vector size.
    if (isa<FixedVectorType>(DataType) && ST->getMinRVVVectorSizeInBits() == 0)
      return false;

    // Don't allow elements larger than the ELEN.
    // FIXME: How to limit for scalable vectors?
    if (isa<FixedVectorType>(DataType) &&
        DataType->getScalarSizeInBits() > ST->getMaxELENForFixedLengthVectors())
      return false;

    if (Alignment <
        DL.getTypeStoreSize(DataType->getScalarType()).getFixedSize())
      return false;

    return TLI->isLegalElementTypeForRVV(DataType->getScalarType());
  }

  bool isLegalMaskedLoad(Type *DataType, Align Alignment) {
    return isLegalMaskedLoadStore(DataType, Alignment);
  }
  bool isLegalMaskedStore(Type *DataType, Align Alignment) {
    return isLegalMaskedLoadStore(DataType, Alignment);
  }

  bool isLegalMaskedGatherScatter(Type *DataType, Align Alignment) {
    if (!ST->hasVInstructions())
      return false;

    // Only support fixed vectors if we know the minimum vector size.
    if (isa<FixedVectorType>(DataType) && ST->getMinRVVVectorSizeInBits() == 0)
      return false;

    // Don't allow elements larger than the ELEN.
    // FIXME: How to limit for scalable vectors?
    if (isa<FixedVectorType>(DataType) &&
        DataType->getScalarSizeInBits() > ST->getMaxELENForFixedLengthVectors())
      return false;

    if (Alignment <
        DL.getTypeStoreSize(DataType->getScalarType()).getFixedSize())
      return false;

    return TLI->isLegalElementTypeForRVV(DataType->getScalarType());
  }

  bool isLegalMaskedGather(Type *DataType, Align Alignment) {
    return isLegalMaskedGatherScatter(DataType, Alignment);
  }
  bool isLegalMaskedScatter(Type *DataType, Align Alignment) {
    return isLegalMaskedGatherScatter(DataType, Alignment);
  }

  /// \returns How the target needs this vector-predicated operation to be
  /// transformed.
  TargetTransformInfo::VPLegalization
  getVPLegalizationStrategy(const VPIntrinsic &PI) const {
    using VPLegalization = TargetTransformInfo::VPLegalization;
    return VPLegalization(VPLegalization::Legal, VPLegalization::Legal);
  }

  bool isLegalToVectorizeReduction(const RecurrenceDescriptor &RdxDesc,
                                   ElementCount VF) const {
    if (!ST->hasVInstructions())
      return false;

    if (!VF.isScalable())
      return true;

    Type *Ty = RdxDesc.getRecurrenceType();
    if (!TLI->isLegalElementTypeForRVV(Ty))
      return false;

    switch (RdxDesc.getRecurrenceKind()) {
    case RecurKind::Add:
    case RecurKind::FAdd:
    case RecurKind::And:
    case RecurKind::Or:
    case RecurKind::Xor:
    case RecurKind::SMin:
    case RecurKind::SMax:
    case RecurKind::UMin:
    case RecurKind::UMax:
    case RecurKind::FMin:
    case RecurKind::FMax:
      return true;
    default:
      return false;
    }
  }

  unsigned getMaxInterleaveFactor(unsigned VF) {
    // If the loop will not be vectorized, don't interleave the loop.
    // Let regular unroll to unroll the loop.
    return VF == 1 ? 1 : ST->getMaxInterleaveFactor();
  }

  // TODO: We should define RISC-V's own register classes.
  //       e.g. register class for FPR.
  unsigned getNumberOfRegisters(unsigned ClassID) const {
    bool Vector = (ClassID == 1);
    if (Vector) {
      if (ST->hasVInstructions())
        return 32;
      return 0;
    }
    // 31 = 32 GPR - x0 (zero register)
    // FIXME: Should we exclude fixed registers like SP, TP or GP?
    return 31;
  }
};

} // end namespace llvm

#endif // LLVM_LIB_TARGET_RISCV_RISCVTARGETTRANSFORMINFO_H