//===-- HexagonISelLowering.h - Hexagon DAG Lowering Interface --*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the interfaces that Hexagon uses to lower LLVM code into a
// selection DAG.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_LIB_TARGET_HEXAGON_HEXAGONISELLOWERING_H
#define LLVM_LIB_TARGET_HEXAGON_HEXAGONISELLOWERING_H

#include "Hexagon.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/CodeGen/ISDOpcodes.h"
#include "llvm/CodeGen/MachineValueType.h"
#include "llvm/CodeGen/SelectionDAGNodes.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/Target/TargetLowering.h"
#include <cstdint>
#include <utility>

namespace llvm {

namespace HexagonISD {

    enum NodeType : unsigned {
      OP_BEGIN = ISD::BUILTIN_OP_END,

      CONST32 = OP_BEGIN,
      CONST32_GP,  // For marking data present in GP.
      ALLOCA,

      AT_GOT,      // Index in GOT.
      AT_PCREL,    // Offset relative to PC.

      CALL,        // Function call.
      CALLnr,      // Function call that does not return.
      CALLR,

      RET_FLAG,    // Return with a flag operand.
      BARRIER,     // Memory barrier.
      JT,          // Jump table.
      CP,          // Constant pool.

      COMBINE,
      PACKHL,
      VSPLAT,
      VASL,
      VASR,
      VLSR,

      INSERT,
      INSERTRP,
      EXTRACTU,
      EXTRACTURP,
      VCOMBINE,
      VPACKE,
      VPACKO,
      TC_RETURN,
      EH_RETURN,
      DCFETCH,
      READCYCLE,

      OP_END
    };

} // end namespace HexagonISD

  class HexagonSubtarget;

  class HexagonTargetLowering : public TargetLowering {
    int VarArgsFrameOffset;   // Frame offset to start of varargs area.
    const HexagonTargetMachine &HTM;
    const HexagonSubtarget &Subtarget;

    bool CanReturnSmallStruct(const Function* CalleeFn, unsigned& RetSize)
        const;
    void promoteLdStType(MVT VT, MVT PromotedLdStVT);

  public:
    explicit HexagonTargetLowering(const TargetMachine &TM,
                                   const HexagonSubtarget &ST);

    /// IsEligibleForTailCallOptimization - Check whether the call is eligible
    /// for tail call optimization. Targets which want to do tail call
    /// optimization should implement this function.
    bool IsEligibleForTailCallOptimization(SDValue Callee,
        CallingConv::ID CalleeCC, bool isVarArg, bool isCalleeStructRet,
        bool isCallerStructRet, const SmallVectorImpl<ISD::OutputArg> &Outs,
        const SmallVectorImpl<SDValue> &OutVals,
        const SmallVectorImpl<ISD::InputArg> &Ins, SelectionDAG& DAG) const;

    bool isTruncateFree(Type *Ty1, Type *Ty2) const override;
    bool isTruncateFree(EVT VT1, EVT VT2) const override;

    bool allowTruncateForTailCall(Type *Ty1, Type *Ty2) const override;

    /// Return true if an FMA operation is faster than a pair of mul and add
    /// instructions. fmuladd intrinsics will be expanded to FMAs when this
    /// method returns true (and FMAs are legal), otherwise fmuladd is
    /// expanded to mul + add.
    bool isFMAFasterThanFMulAndFAdd(EVT) const override;

    // Should we expand the build vector with shuffles?
    bool shouldExpandBuildVectorWithShuffles(EVT VT,
        unsigned DefinedValues) const override;

    bool isShuffleMaskLegal(ArrayRef<int> Mask, EVT VT) const override;

    SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const override;
    const char *getTargetNodeName(unsigned Opcode) const override;
    SDValue LowerCONCAT_VECTORS(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerEXTRACT_VECTOR(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerEXTRACT_SUBVECTOR_HVX(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerINSERT_VECTOR(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerVECTOR_SHUFFLE(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerVECTOR_SHIFT(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerDYNAMIC_STACKALLOC(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerINLINEASM(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerPREFETCH(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerREADCYCLECOUNTER(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerEH_LABEL(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerEH_RETURN(SDValue Op, SelectionDAG &DAG) const;
    SDValue
    LowerFormalArguments(SDValue Chain, CallingConv::ID CallConv, bool isVarArg,
                         const SmallVectorImpl<ISD::InputArg> &Ins,
                         const SDLoc &dl, SelectionDAG &DAG,
                         SmallVectorImpl<SDValue> &InVals) const override;
    SDValue LowerGLOBALADDRESS(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerBlockAddress(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerGlobalTLSAddress(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerToTLSGeneralDynamicModel(GlobalAddressSDNode *GA,
        SelectionDAG &DAG) const;
    SDValue LowerToTLSInitialExecModel(GlobalAddressSDNode *GA,
        SelectionDAG &DAG) const;
    SDValue LowerToTLSLocalExecModel(GlobalAddressSDNode *GA,
        SelectionDAG &DAG) const;
    SDValue GetDynamicTLSAddr(SelectionDAG &DAG, SDValue Chain,
        GlobalAddressSDNode *GA, SDValue InFlag, EVT PtrVT,
        unsigned ReturnReg, unsigned char OperandFlags) const;
    SDValue LowerGLOBAL_OFFSET_TABLE(SDValue Op, SelectionDAG &DAG) const;

    SDValue LowerCall(TargetLowering::CallLoweringInfo &CLI,
        SmallVectorImpl<SDValue> &InVals) const override;
    SDValue LowerCallResult(SDValue Chain, SDValue InFlag,
                            CallingConv::ID CallConv, bool isVarArg,
                            const SmallVectorImpl<ISD::InputArg> &Ins,
                            const SDLoc &dl, SelectionDAG &DAG,
                            SmallVectorImpl<SDValue> &InVals,
                            const SmallVectorImpl<SDValue> &OutVals,
                            SDValue Callee) const;

    SDValue LowerSETCC(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerVSELECT(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerFRAMEADDR(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerATOMIC_FENCE(SDValue Op, SelectionDAG& DAG) const;
    SDValue LowerRETURNADDR(SDValue Op, SelectionDAG &DAG) const;

    bool CanLowerReturn(CallingConv::ID CallConv,
                        MachineFunction &MF, bool isVarArg,
                        const SmallVectorImpl<ISD::OutputArg> &Outs,
                        LLVMContext &Context) const override;

    SDValue LowerReturn(SDValue Chain, CallingConv::ID CallConv, bool isVarArg,
                        const SmallVectorImpl<ISD::OutputArg> &Outs,
                        const SmallVectorImpl<SDValue> &OutVals,
                        const SDLoc &dl, SelectionDAG &DAG) const override;

    bool mayBeEmittedAsTailCall(const CallInst *CI) const override;

    /// If a physical register, this returns the register that receives the
    /// exception address on entry to an EH pad.
    unsigned
    getExceptionPointerRegister(const Constant *PersonalityFn) const override {
      return Hexagon::R0;
    }

    /// If a physical register, this returns the register that receives the
    /// exception typeid on entry to a landing pad.
    unsigned
    getExceptionSelectorRegister(const Constant *PersonalityFn) const override {
      return Hexagon::R1;
    }

    SDValue LowerVASTART(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerConstantPool(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerJumpTable(SDValue Op, SelectionDAG &DAG) const;

    EVT getSetCCResultType(const DataLayout &, LLVMContext &C,
                           EVT VT) const override {
      if (!VT.isVector())
        return MVT::i1;
      else
        return EVT::getVectorVT(C, MVT::i1, VT.getVectorNumElements());
    }

    bool getPostIndexedAddressParts(SDNode *N, SDNode *Op,
                                    SDValue &Base, SDValue &Offset,
                                    ISD::MemIndexedMode &AM,
                                    SelectionDAG &DAG) const override;

    ConstraintType getConstraintType(StringRef Constraint) const override;

    std::pair<unsigned, const TargetRegisterClass *>
    getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI,
                                 StringRef Constraint, MVT VT) const override;

    unsigned
    getInlineAsmMemConstraint(StringRef ConstraintCode) const override {
      if (ConstraintCode == "o")
        return InlineAsm::Constraint_o;
      return TargetLowering::getInlineAsmMemConstraint(ConstraintCode);
    }

    // Intrinsics
    SDValue LowerINTRINSIC_WO_CHAIN(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerINTRINSIC_VOID(SDValue Op, SelectionDAG &DAG) const;
    /// isLegalAddressingMode - Return true if the addressing mode represented
    /// by AM is legal for this target, for a load/store of the specified type.
    /// The type may be VoidTy, in which case only return true if the addressing
    /// mode is legal for a load/store of any legal type.
    /// TODO: Handle pre/postinc as well.
    bool isLegalAddressingMode(const DataLayout &DL, const AddrMode &AM,
                               Type *Ty, unsigned AS,
                               Instruction *I = nullptr) const override;
    /// Return true if folding a constant offset with the given GlobalAddress
    /// is legal.  It is frequently not legal in PIC relocation models.
    bool isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const override;

    bool isFPImmLegal(const APFloat &Imm, EVT VT) const override;

    /// isLegalICmpImmediate - Return true if the specified immediate is legal
    /// icmp immediate, that is the target has icmp instructions which can
    /// compare a register against the immediate without having to materialize
    /// the immediate into a register.
    bool isLegalICmpImmediate(int64_t Imm) const override;

    EVT getOptimalMemOpType(uint64_t Size, unsigned DstAlign,
        unsigned SrcAlign, bool IsMemset, bool ZeroMemset, bool MemcpyStrSrc,
        MachineFunction &MF) const override;

    bool allowsMisalignedMemoryAccesses(EVT VT, unsigned AddrSpace,
        unsigned Align, bool *Fast) const override;

    /// Returns relocation base for the given PIC jumptable.
    SDValue getPICJumpTableRelocBase(SDValue Table, SelectionDAG &DAG)
                                     const override;

    // Handling of atomic RMW instructions.
    Value *emitLoadLinked(IRBuilder<> &Builder, Value *Addr,
        AtomicOrdering Ord) const override;
    Value *emitStoreConditional(IRBuilder<> &Builder, Value *Val,
        Value *Addr, AtomicOrdering Ord) const override;
    AtomicExpansionKind shouldExpandAtomicLoadInIR(LoadInst *LI) const override;
    bool shouldExpandAtomicStoreInIR(StoreInst *SI) const override;
    bool shouldExpandAtomicCmpXchgInIR(AtomicCmpXchgInst *AI) const override;

    AtomicExpansionKind
    shouldExpandAtomicRMWInIR(AtomicRMWInst *AI) const override {
      return AtomicExpansionKind::LLSC;
    }

  protected:
    std::pair<const TargetRegisterClass*, uint8_t>
    findRepresentativeClass(const TargetRegisterInfo *TRI, MVT VT)
        const override;
  };

} // end namespace llvm

#endif // LLVM_LIB_TARGET_HEXAGON_HEXAGONISELLOWERING_H