Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===- MCExpr.h - Assembly Level Expressions --------------------*- 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

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_MC_MCEXPR_H

#define LLVM_MC_MCEXPR_H

#include "llvm/ADT/DenseMap.h"

#include "llvm/Support/SMLoc.h"

#include <cstdint>

namespace llvm {

class MCAsmInfo;

class MCAsmLayout;

class MCAssembler;

class MCContext;

class MCFixup;

class MCFragment;

class MCSection;

class MCStreamer;

class MCSymbol;

class MCValue;

class raw_ostream;

class StringRef;

using SectionAddrMap = DenseMap<const MCSection *, uint64_t>;

/// Base class for the full range of assembler expressions which are

/// needed for parsing.

class MCExpr {

public:

  enum ExprKind : uint8_t {

    Binary,    ///< Binary expressions.

    Constant,  ///< Constant expressions.

    SymbolRef, ///< References to labels and assigned expressions.

    Unary,     ///< Unary expressions.

    Target     ///< Target specific expression.

  };

private:

  static const unsigned NumSubclassDataBits = 24;

  static_assert(

      NumSubclassDataBits == CHAR_BIT * (sizeof(unsigned) - sizeof(ExprKind)),

      "ExprKind and SubclassData together should take up one word");

  ExprKind Kind;

  /// Field reserved for use by MCExpr subclasses.

  unsigned SubclassData : NumSubclassDataBits;

  SMLoc Loc;

  bool evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,

                          const MCAsmLayout *Layout,

                          const SectionAddrMap *Addrs, bool InSet) const;

protected:

  explicit MCExpr(ExprKind Kind, SMLoc Loc, unsigned SubclassData = 0)

      : Kind(Kind), SubclassData(SubclassData), Loc(Loc) {

    assert(SubclassData < (1 << NumSubclassDataBits) &&

           "Subclass data too large");

  }

  bool evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,

                                 const MCAsmLayout *Layout,

                                 const MCFixup *Fixup,

                                 const SectionAddrMap *Addrs, bool InSet) const;

  unsigned getSubclassData() const { return SubclassData; }

public:

  MCExpr(const MCExpr &) = delete;

  MCExpr &operator=(const MCExpr &) = delete;

  /// \name Accessors

  /// @{

  ExprKind getKind() const { return Kind; }

  SMLoc getLoc() const { return Loc; }

  /// @}

  /// \name Utility Methods

  /// @{

  void print(raw_ostream &OS, const MCAsmInfo *MAI,

             bool InParens = false) const;

  void dump() const;

  /// @}

  /// \name Expression Evaluation

  /// @{

  /// Try to evaluate the expression to an absolute value.

  ///

  /// \param Res - The absolute value, if evaluation succeeds.

  /// \param Layout - The assembler layout object to use for evaluating symbol

  /// values. If not given, then only non-symbolic expressions will be

  /// evaluated.

  /// \return - True on success.

  bool evaluateAsAbsolute(int64_t &Res, const MCAsmLayout &Layout,

                          const SectionAddrMap &Addrs) const;

  bool evaluateAsAbsolute(int64_t &Res) const;

  bool evaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const;

  bool evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm) const;

  bool evaluateAsAbsolute(int64_t &Res, const MCAsmLayout &Layout) const;

  bool evaluateKnownAbsolute(int64_t &Res, const MCAsmLayout &Layout) const;

  /// Try to evaluate the expression to a relocatable value, i.e. an

  /// expression of the fixed form (a - b + constant).

  ///

  /// \param Res - The relocatable value, if evaluation succeeds.

  /// \param Layout - The assembler layout object to use for evaluating values.

  /// \param Fixup - The Fixup object if available.

  /// \return - True on success.

  bool evaluateAsRelocatable(MCValue &Res, const MCAsmLayout *Layout,

                             const MCFixup *Fixup) const;

  /// Try to evaluate the expression to the form (a - b + constant) where

  /// neither a nor b are variables.

  ///

  /// This is a more aggressive variant of evaluateAsRelocatable. The intended

  /// use is for when relocations are not available, like the .size directive.

  bool evaluateAsValue(MCValue &Res, const MCAsmLayout &Layout) const;

  /// Find the "associated section" for this expression, which is

  /// currently defined as the absolute section for constants, or

  /// otherwise the section associated with the first defined symbol in the

  /// expression.

  MCFragment *findAssociatedFragment() const;

  /// @}

};

inline raw_ostream &operator<<(raw_ostream &OS, const MCExpr &E) {

  E.print(OS, nullptr);

  return OS;

}

////  Represent a constant integer expression.

class MCConstantExpr : public MCExpr {

  int64_t Value;

  // Subclass data stores SizeInBytes in bits 0..7 and PrintInHex in bit 8.

  static const unsigned SizeInBytesBits = 8;

  static const unsigned SizeInBytesMask = (1 << SizeInBytesBits) - 1;

  static const unsigned PrintInHexBit = 1 << SizeInBytesBits;

  static unsigned encodeSubclassData(bool PrintInHex, unsigned SizeInBytes) {

    assert(SizeInBytes <= sizeof(int64_t) && "Excessive size");

    return SizeInBytes | (PrintInHex ? PrintInHexBit : 0);

  }

  MCConstantExpr(int64_t Value, bool PrintInHex, unsigned SizeInBytes)

      : MCExpr(MCExpr::Constant, SMLoc(),

               encodeSubclassData(PrintInHex, SizeInBytes)), Value(Value) {}

public:

  /// \name Construction

  /// @{

  static const MCConstantExpr *create(int64_t Value, MCContext &Ctx,

                                      bool PrintInHex = false,

                                      unsigned SizeInBytes = 0);

  /// @}

  /// \name Accessors

  /// @{

  int64_t getValue() const { return Value; }

  unsigned getSizeInBytes() const {

    return getSubclassData() & SizeInBytesMask;

  }

  bool useHexFormat() const { return (getSubclassData() & PrintInHexBit) != 0; }

  /// @}

  static bool classof(const MCExpr *E) {

    return E->getKind() == MCExpr::Constant;

  }

};

///  Represent a reference to a symbol from inside an expression.

///

/// A symbol reference in an expression may be a use of a label, a use of an

/// assembler variable (defined constant), or constitute an implicit definition

/// of the symbol as external.

class MCSymbolRefExpr : public MCExpr {

public:

  enum VariantKind : uint16_t {

    VK_None,

    VK_Invalid,

    VK_GOT,

    VK_GOTOFF,

    VK_GOTREL,

    VK_PCREL,

    VK_GOTPCREL,

    VK_GOTPCREL_NORELAX,

    VK_GOTTPOFF,

    VK_INDNTPOFF,

    VK_NTPOFF,

    VK_GOTNTPOFF,

    VK_PLT,

    VK_TLSGD,

    VK_TLSLD,

    VK_TLSLDM,

    VK_TPOFF,

    VK_DTPOFF,

    VK_TLSCALL, // symbol(tlscall)

    VK_TLSDESC, // symbol(tlsdesc)

    VK_TLVP,    // Mach-O thread local variable relocations

    VK_TLVPPAGE,

    VK_TLVPPAGEOFF,

    VK_PAGE,

    VK_PAGEOFF,

    VK_GOTPAGE,

    VK_GOTPAGEOFF,

    VK_SECREL,

    VK_SIZE,    // symbol@SIZE

    VK_WEAKREF, // The link between the symbols in .weakref foo, bar

    VK_X86_ABS8,

    VK_X86_PLTOFF,

    VK_ARM_NONE,

    VK_ARM_GOT_PREL,

    VK_ARM_TARGET1,

    VK_ARM_TARGET2,

    VK_ARM_PREL31,

    VK_ARM_SBREL,  // symbol(sbrel)

    VK_ARM_TLSLDO, // symbol(tlsldo)

    VK_ARM_TLSDESCSEQ,

    VK_AVR_NONE,

    VK_AVR_LO8,

    VK_AVR_HI8,

    VK_AVR_HLO8,

    VK_AVR_DIFF8,

    VK_AVR_DIFF16,

    VK_AVR_DIFF32,

    VK_AVR_PM,

    VK_PPC_LO,              // symbol@l

    VK_PPC_HI,              // symbol@h

    VK_PPC_HA,              // symbol@ha

    VK_PPC_HIGH,            // symbol@high

    VK_PPC_HIGHA,           // symbol@higha

    VK_PPC_HIGHER,          // symbol@higher

    VK_PPC_HIGHERA,         // symbol@highera

    VK_PPC_HIGHEST,         // symbol@highest

    VK_PPC_HIGHESTA,        // symbol@highesta

    VK_PPC_GOT_LO,          // symbol@got@l

    VK_PPC_GOT_HI,          // symbol@got@h

    VK_PPC_GOT_HA,          // symbol@got@ha

    VK_PPC_TOCBASE,         // symbol@tocbase

    VK_PPC_TOC,             // symbol@toc

    VK_PPC_TOC_LO,          // symbol@toc@l

    VK_PPC_TOC_HI,          // symbol@toc@h

    VK_PPC_TOC_HA,          // symbol@toc@ha

    VK_PPC_U,               // symbol@u

    VK_PPC_L,               // symbol@l

    VK_PPC_DTPMOD,          // symbol@dtpmod

    VK_PPC_TPREL_LO,        // symbol@tprel@l

    VK_PPC_TPREL_HI,        // symbol@tprel@h

    VK_PPC_TPREL_HA,        // symbol@tprel@ha

    VK_PPC_TPREL_HIGH,      // symbol@tprel@high

    VK_PPC_TPREL_HIGHA,     // symbol@tprel@higha

    VK_PPC_TPREL_HIGHER,    // symbol@tprel@higher

    VK_PPC_TPREL_HIGHERA,   // symbol@tprel@highera

    VK_PPC_TPREL_HIGHEST,   // symbol@tprel@highest

    VK_PPC_TPREL_HIGHESTA,  // symbol@tprel@highesta

    VK_PPC_DTPREL_LO,       // symbol@dtprel@l

    VK_PPC_DTPREL_HI,       // symbol@dtprel@h

    VK_PPC_DTPREL_HA,       // symbol@dtprel@ha

    VK_PPC_DTPREL_HIGH,     // symbol@dtprel@high

    VK_PPC_DTPREL_HIGHA,    // symbol@dtprel@higha

    VK_PPC_DTPREL_HIGHER,   // symbol@dtprel@higher

    VK_PPC_DTPREL_HIGHERA,  // symbol@dtprel@highera

    VK_PPC_DTPREL_HIGHEST,  // symbol@dtprel@highest

    VK_PPC_DTPREL_HIGHESTA, // symbol@dtprel@highesta

    VK_PPC_GOT_TPREL,       // symbol@got@tprel

    VK_PPC_GOT_TPREL_LO,    // symbol@got@tprel@l

    VK_PPC_GOT_TPREL_HI,    // symbol@got@tprel@h

    VK_PPC_GOT_TPREL_HA,    // symbol@got@tprel@ha

    VK_PPC_GOT_DTPREL,      // symbol@got@dtprel

    VK_PPC_GOT_DTPREL_LO,   // symbol@got@dtprel@l

    VK_PPC_GOT_DTPREL_HI,   // symbol@got@dtprel@h

    VK_PPC_GOT_DTPREL_HA,   // symbol@got@dtprel@ha

    VK_PPC_TLS,             // symbol@tls

    VK_PPC_GOT_TLSGD,       // symbol@got@tlsgd

    VK_PPC_GOT_TLSGD_LO,    // symbol@got@tlsgd@l

    VK_PPC_GOT_TLSGD_HI,    // symbol@got@tlsgd@h

    VK_PPC_GOT_TLSGD_HA,    // symbol@got@tlsgd@ha

    VK_PPC_TLSGD,           // symbol@tlsgd

    VK_PPC_AIX_TLSGD,       // symbol@gd

    VK_PPC_AIX_TLSGDM,      // symbol@m

    VK_PPC_GOT_TLSLD,       // symbol@got@tlsld

    VK_PPC_GOT_TLSLD_LO,    // symbol@got@tlsld@l

    VK_PPC_GOT_TLSLD_HI,    // symbol@got@tlsld@h

    VK_PPC_GOT_TLSLD_HA,    // symbol@got@tlsld@ha

    VK_PPC_GOT_PCREL,       // symbol@got@pcrel

    VK_PPC_GOT_TLSGD_PCREL, // symbol@got@tlsgd@pcrel

    VK_PPC_GOT_TLSLD_PCREL, // symbol@got@tlsld@pcrel

    VK_PPC_GOT_TPREL_PCREL, // symbol@got@tprel@pcrel

    VK_PPC_TLS_PCREL,       // symbol@tls@pcrel

    VK_PPC_TLSLD,           // symbol@tlsld

    VK_PPC_LOCAL,           // symbol@local

    VK_PPC_NOTOC,           // symbol@notoc

    VK_PPC_PCREL_OPT,       // .reloc expr, R_PPC64_PCREL_OPT, expr

    VK_COFF_IMGREL32, // symbol@imgrel (image-relative)

    VK_Hexagon_LO16,

    VK_Hexagon_HI16,

    VK_Hexagon_GPREL,

    VK_Hexagon_GD_GOT,

    VK_Hexagon_LD_GOT,

    VK_Hexagon_GD_PLT,

    VK_Hexagon_LD_PLT,

    VK_Hexagon_IE,

    VK_Hexagon_IE_GOT,

    VK_WASM_TYPEINDEX, // Reference to a symbol's type (signature)

    VK_WASM_TLSREL,    // Memory address relative to __tls_base

    VK_WASM_MBREL,     // Memory address relative to __memory_base

    VK_WASM_TBREL,     // Table index relative to __table_base

    VK_WASM_GOT_TLS,   // Wasm global index of TLS symbol.

    VK_AMDGPU_GOTPCREL32_LO, // symbol@gotpcrel32@lo

    VK_AMDGPU_GOTPCREL32_HI, // symbol@gotpcrel32@hi

    VK_AMDGPU_REL32_LO,      // symbol@rel32@lo

    VK_AMDGPU_REL32_HI,      // symbol@rel32@hi

    VK_AMDGPU_REL64,         // symbol@rel64

    VK_AMDGPU_ABS32_LO,      // symbol@abs32@lo

    VK_AMDGPU_ABS32_HI,      // symbol@abs32@hi

    VK_VE_HI32,        // symbol@hi

    VK_VE_LO32,        // symbol@lo

    VK_VE_PC_HI32,     // symbol@pc_hi

    VK_VE_PC_LO32,     // symbol@pc_lo

    VK_VE_GOT_HI32,    // symbol@got_hi

    VK_VE_GOT_LO32,    // symbol@got_lo

    VK_VE_GOTOFF_HI32, // symbol@gotoff_hi

    VK_VE_GOTOFF_LO32, // symbol@gotoff_lo

    VK_VE_PLT_HI32,    // symbol@plt_hi

    VK_VE_PLT_LO32,    // symbol@plt_lo

    VK_VE_TLS_GD_HI32, // symbol@tls_gd_hi

    VK_VE_TLS_GD_LO32, // symbol@tls_gd_lo

    VK_VE_TPOFF_HI32,  // symbol@tpoff_hi

    VK_VE_TPOFF_LO32,  // symbol@tpoff_lo

    VK_TPREL,

    VK_DTPREL

  };

private:

  /// The symbol being referenced.

  const MCSymbol *Symbol;

  // Subclass data stores VariantKind in bits 0..15 and HasSubsectionsViaSymbols

  // in bit 16.

  static const unsigned VariantKindBits = 16;

  static const unsigned VariantKindMask = (1 << VariantKindBits) - 1;

  // FIXME: Remove this bit.

  static const unsigned HasSubsectionsViaSymbolsBit = 1 << VariantKindBits;

  static unsigned encodeSubclassData(VariantKind Kind,

                                     bool HasSubsectionsViaSymbols) {

    return (unsigned)Kind |

           (HasSubsectionsViaSymbols ? HasSubsectionsViaSymbolsBit : 0);

  }

  explicit MCSymbolRefExpr(const MCSymbol *Symbol, VariantKind Kind,

                           const MCAsmInfo *MAI, SMLoc Loc = SMLoc());

public:

  /// \name Construction

  /// @{

  static const MCSymbolRefExpr *create(const MCSymbol *Symbol, MCContext &Ctx) {

    return MCSymbolRefExpr::create(Symbol, VK_None, Ctx);

  }

  static const MCSymbolRefExpr *create(const MCSymbol *Symbol, VariantKind Kind,

                                       MCContext &Ctx, SMLoc Loc = SMLoc());

  static const MCSymbolRefExpr *create(StringRef Name, VariantKind Kind,

                                       MCContext &Ctx);

  /// @}

  /// \name Accessors

  /// @{

  const MCSymbol &getSymbol() const { return *Symbol; }

  VariantKind getKind() const {

    return (VariantKind)(getSubclassData() & VariantKindMask);

  }

  bool hasSubsectionsViaSymbols() const {

    return (getSubclassData() & HasSubsectionsViaSymbolsBit) != 0;

  }

  /// @}

  /// \name Static Utility Functions

  /// @{

  static StringRef getVariantKindName(VariantKind Kind);

  static VariantKind getVariantKindForName(StringRef Name);

  /// @}

  static bool classof(const MCExpr *E) {

    return E->getKind() == MCExpr::SymbolRef;

  }

};

/// Unary assembler expressions.

class MCUnaryExpr : public MCExpr {

public:

  enum Opcode {

    LNot,  ///< Logical negation.

    Minus, ///< Unary minus.

    Not,   ///< Bitwise negation.

    Plus   ///< Unary plus.

  };

private:

  const MCExpr *Expr;

  MCUnaryExpr(Opcode Op, const MCExpr *Expr, SMLoc Loc)

      : MCExpr(MCExpr::Unary, Loc, Op), Expr(Expr) {}

public:

  /// \name Construction

  /// @{

  static const MCUnaryExpr *create(Opcode Op, const MCExpr *Expr,

                                   MCContext &Ctx, SMLoc Loc = SMLoc());

  static const MCUnaryExpr *createLNot(const MCExpr *Expr, MCContext &Ctx, SMLoc Loc = SMLoc()) {

    return create(LNot, Expr, Ctx, Loc);

  }

  static const MCUnaryExpr *createMinus(const MCExpr *Expr, MCContext &Ctx, SMLoc Loc = SMLoc()) {

    return create(Minus, Expr, Ctx, Loc);

  }

  static const MCUnaryExpr *createNot(const MCExpr *Expr, MCContext &Ctx, SMLoc Loc = SMLoc()) {

    return create(Not, Expr, Ctx, Loc);

  }

  static const MCUnaryExpr *createPlus(const MCExpr *Expr, MCContext &Ctx, SMLoc Loc = SMLoc()) {

    return create(Plus, Expr, Ctx, Loc);

  }

  /// @}

  /// \name Accessors

  /// @{

  /// Get the kind of this unary expression.

  Opcode getOpcode() const { return (Opcode)getSubclassData(); }

  /// Get the child of this unary expression.

  const MCExpr *getSubExpr() const { return Expr; }

  /// @}

  static bool classof(const MCExpr *E) {

    return E->getKind() == MCExpr::Unary;

  }

};

/// Binary assembler expressions.

class MCBinaryExpr : public MCExpr {

public:

  enum Opcode {

    Add,  ///< Addition.

    And,  ///< Bitwise and.

    Div,  ///< Signed division.

    EQ,   ///< Equality comparison.

    GT,   ///< Signed greater than comparison (result is either 0 or some

          ///< target-specific non-zero value)

    GTE,  ///< Signed greater than or equal comparison (result is either 0 or

          ///< some target-specific non-zero value).

    LAnd, ///< Logical and.

    LOr,  ///< Logical or.

    LT,   ///< Signed less than comparison (result is either 0 or

          ///< some target-specific non-zero value).

    LTE,  ///< Signed less than or equal comparison (result is either 0 or

          ///< some target-specific non-zero value).

    Mod,  ///< Signed remainder.

    Mul,  ///< Multiplication.

    NE,   ///< Inequality comparison.

    Or,   ///< Bitwise or.

    OrNot, ///< Bitwise or not.

    Shl,  ///< Shift left.

    AShr, ///< Arithmetic shift right.

    LShr, ///< Logical shift right.

    Sub,  ///< Subtraction.

    Xor   ///< Bitwise exclusive or.

  };

private:

  const MCExpr *LHS, *RHS;

  MCBinaryExpr(Opcode Op, const MCExpr *LHS, const MCExpr *RHS,

               SMLoc Loc = SMLoc())

      : MCExpr(MCExpr::Binary, Loc, Op), LHS(LHS), RHS(RHS) {}

public:

  /// \name Construction

  /// @{

  static const MCBinaryExpr *create(Opcode Op, const MCExpr *LHS,

                                    const MCExpr *RHS, MCContext &Ctx,

                                    SMLoc Loc = SMLoc());

  static const MCBinaryExpr *createAdd(const MCExpr *LHS, const MCExpr *RHS,

                                       MCContext &Ctx) {

    return create(Add, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createAnd(const MCExpr *LHS, const MCExpr *RHS,

                                       MCContext &Ctx) {

    return create(And, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createDiv(const MCExpr *LHS, const MCExpr *RHS,

                                       MCContext &Ctx) {

    return create(Div, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createEQ(const MCExpr *LHS, const MCExpr *RHS,

                                      MCContext &Ctx) {

    return create(EQ, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createGT(const MCExpr *LHS, const MCExpr *RHS,

                                      MCContext &Ctx) {

    return create(GT, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createGTE(const MCExpr *LHS, const MCExpr *RHS,

                                       MCContext &Ctx) {

    return create(GTE, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createLAnd(const MCExpr *LHS, const MCExpr *RHS,

                                        MCContext &Ctx) {

    return create(LAnd, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createLOr(const MCExpr *LHS, const MCExpr *RHS,

                                       MCContext &Ctx) {

    return create(LOr, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createLT(const MCExpr *LHS, const MCExpr *RHS,

                                      MCContext &Ctx) {

    return create(LT, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createLTE(const MCExpr *LHS, const MCExpr *RHS,

                                       MCContext &Ctx) {

    return create(LTE, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createMod(const MCExpr *LHS, const MCExpr *RHS,

                                       MCContext &Ctx) {

    return create(Mod, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createMul(const MCExpr *LHS, const MCExpr *RHS,

                                       MCContext &Ctx) {

    return create(Mul, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createNE(const MCExpr *LHS, const MCExpr *RHS,

                                      MCContext &Ctx) {

    return create(NE, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createOr(const MCExpr *LHS, const MCExpr *RHS,

                                      MCContext &Ctx) {

    return create(Or, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createShl(const MCExpr *LHS, const MCExpr *RHS,

                                       MCContext &Ctx) {

    return create(Shl, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createAShr(const MCExpr *LHS, const MCExpr *RHS,

                                       MCContext &Ctx) {

    return create(AShr, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createLShr(const MCExpr *LHS, const MCExpr *RHS,

                                       MCContext &Ctx) {

    return create(LShr, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createSub(const MCExpr *LHS, const MCExpr *RHS,

                                       MCContext &Ctx) {

    return create(Sub, LHS, RHS, Ctx);

  }

  static const MCBinaryExpr *createXor(const MCExpr *LHS, const MCExpr *RHS,

                                       MCContext &Ctx) {

    return create(Xor, LHS, RHS, Ctx);

  }

  /// @}

  /// \name Accessors

  /// @{

  /// Get the kind of this binary expression.

  Opcode getOpcode() const { return (Opcode)getSubclassData(); }

  /// Get the left-hand side expression of the binary operator.

  const MCExpr *getLHS() const { return LHS; }

  /// Get the right-hand side expression of the binary operator.

  const MCExpr *getRHS() const { return RHS; }

  /// @}

  static bool classof(const MCExpr *E) {

    return E->getKind() == MCExpr::Binary;

  }

};

/// This is an extension point for target-specific MCExpr subclasses to

/// implement.

///

/// NOTE: All subclasses are required to have trivial destructors because

/// MCExprs are bump pointer allocated and not destructed.

class MCTargetExpr : public MCExpr {

  virtual void anchor();

protected:

  MCTargetExpr() : MCExpr(Target, SMLoc()) {}

  virtual ~MCTargetExpr() = default;

public:

  virtual void printImpl(raw_ostream &OS, const MCAsmInfo *MAI) const = 0;

  virtual bool evaluateAsRelocatableImpl(MCValue &Res,

                                         const MCAsmLayout *Layout,

                                         const MCFixup *Fixup) const = 0;

  // allow Target Expressions to be checked for equality

  virtual bool isEqualTo(const MCExpr *x) const { return false; }

  // This should be set when assigned expressions are not valid ".set"

  // expressions, e.g. registers, and must be inlined.

  virtual bool inlineAssignedExpr() const { return false; }

  virtual void visitUsedExpr(MCStreamer& Streamer) const = 0;

  virtual MCFragment *findAssociatedFragment() const = 0;

  virtual void fixELFSymbolsInTLSFixups(MCAssembler &) const = 0;

  static bool classof(const MCExpr *E) {

    return E->getKind() == MCExpr::Target;

  }

};

} // end namespace llvm

#endif // LLVM_MC_MCEXPR_H