MSP430ISelLowering.h

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//===-- MSP430ISelLowering.h - MSP430 DAG Lowering Interface ----*- 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
//
//===----------------------------------------------------------------------===//
//
// This file defines the interfaces that MSP430 uses to lower LLVM code into a
// selection DAG.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_LIB_TARGET_MSP430_MSP430ISELLOWERING_H
#define LLVM_LIB_TARGET_MSP430_MSP430ISELLOWERING_H

#include "MSP430.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/TargetLowering.h"

namespace llvm {
  namespace MSP430ISD {
    enum NodeType : unsigned {
      FIRST_NUMBER = ISD::BUILTIN_OP_END,

      /// Return with a flag operand. Operand 0 is the chain operand.
      RET_FLAG,

      /// Same as RET_FLAG, but used for returning from ISRs.
      RETI_FLAG,

      /// Y = R{R,L}A X, rotate right (left) arithmetically
      RRA, RLA,

      /// Y = RRC X, rotate right via carry
      RRC,

      /// Rotate right via carry, carry gets cleared beforehand by clrc
      RRCL,

      /// CALL - These operations represent an abstract call
      /// instruction, which includes a bunch of information.
      CALL,

      /// Wrapper - A wrapper node for TargetConstantPool, TargetExternalSymbol,
      /// and TargetGlobalAddress.
      Wrapper,

      /// CMP - Compare instruction.
      CMP,

      /// SetCC - Operand 0 is condition code, and operand 1 is the flag
      /// operand produced by a CMP instruction.
      SETCC,

      /// MSP430 conditional branches. Operand 0 is the chain operand, operand 1
      /// is the block to branch if condition is true, operand 2 is the
      /// condition code, and operand 3 is the flag operand produced by a CMP
      /// instruction.
      BR_CC,

      /// SELECT_CC - Operand 0 and operand 1 are selection variable, operand 3
      /// is condition code and operand 4 is flag operand.
      SELECT_CC,

      /// DADD - Decimal addition with carry
      /// TODO Nothing generates a node of this type yet.
      DADD,
    };
  }

  class MSP430Subtarget;
  class MSP430TargetLowering : public TargetLowering {
  public:
    explicit MSP430TargetLowering(const TargetMachine &TM,
                                  const MSP430Subtarget &STI);

    MVT getScalarShiftAmountTy(const DataLayout &, EVT) const override {
      return MVT::i8;
    }

    /// LowerOperation - Provide custom lowering hooks for some operations.
    SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const override;

    /// getTargetNodeName - This method returns the name of a target specific
    /// DAG node.
    const char *getTargetNodeName(unsigned Opcode) const override;

    SDValue LowerShifts(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerGlobalAddress(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerBlockAddress(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerExternalSymbol(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerBR_CC(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerSETCC(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerSIGN_EXTEND(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerRETURNADDR(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerFRAMEADDR(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerVASTART(SDValue Op, SelectionDAG &DAG) const;
    SDValue LowerJumpTable(SDValue Op, SelectionDAG &DAG) const;
    SDValue getReturnAddressFrameIndex(SelectionDAG &DAG) const;

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

    /// isTruncateFree - Return true if it's free to truncate a value of type
    /// Ty1 to type Ty2. e.g. On msp430 it's free to truncate a i16 value in
    /// register R15W to i8 by referencing its sub-register R15B.
    bool isTruncateFree(Type *Ty1, Type *Ty2) const override;
    bool isTruncateFree(EVT VT1, EVT VT2) const override;

    /// isZExtFree - Return true if any actual instruction that defines a value
    /// of type Ty1 implicit zero-extends the value to Ty2 in the result
    /// register. This does not necessarily include registers defined in unknown
    /// ways, such as incoming arguments, or copies from unknown virtual
    /// registers. Also, if isTruncateFree(Ty2, Ty1) is true, this does not
    /// necessarily apply to truncate instructions. e.g. on msp430, all
    /// instructions that define 8-bit values implicit zero-extend the result
    /// out to 16 bits.
    bool isZExtFree(Type *Ty1, Type *Ty2) const override;
    bool isZExtFree(EVT VT1, EVT VT2) const override;
    bool isZExtFree(SDValue Val, EVT VT2) const override;

    unsigned getShiftAmountThreshold(EVT VT) const override;

    MachineBasicBlock *
    EmitInstrWithCustomInserter(MachineInstr &MI,
                                MachineBasicBlock *BB) const override;
    MachineBasicBlock *EmitShiftInstr(MachineInstr &MI,
                                      MachineBasicBlock *BB) const;

  private:
    SDValue LowerCCCCallTo(SDValue Chain, SDValue Callee,
                           CallingConv::ID CallConv, bool isVarArg,
                           bool isTailCall,
                           const SmallVectorImpl<ISD::OutputArg> &Outs,
                           const SmallVectorImpl<SDValue> &OutVals,
                           const SmallVectorImpl<ISD::InputArg> &Ins,
                           const SDLoc &dl, SelectionDAG &DAG,
                           SmallVectorImpl<SDValue> &InVals) const;

    SDValue LowerCCCArguments(SDValue Chain, CallingConv::ID CallConv,
                              bool isVarArg,
                              const SmallVectorImpl<ISD::InputArg> &Ins,
                              const SDLoc &dl, SelectionDAG &DAG,
                              SmallVectorImpl<SDValue> &InVals) const;

    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;

    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
      LowerCall(TargetLowering::CallLoweringInfo &CLI,
                SmallVectorImpl<SDValue> &InVals) const override;

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

#endif