518 lines
17 KiB
C++
518 lines
17 KiB
C++
//===- MCExpr.h - Assembly Level Expressions --------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_MC_MCEXPR_H
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#define LLVM_MC_MCEXPR_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/SMLoc.h"
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#include <cstdint>
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namespace llvm {
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class MCAsmInfo;
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class MCAssembler;
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class MCContext;
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class MCFixup;
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class MCFragment;
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class MCSection;
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class MCStreamer;
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class MCSymbol;
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class MCValue;
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class raw_ostream;
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class StringRef;
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class MCSymbolRefExpr;
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/// Base class for the full range of assembler expressions which are
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/// needed for parsing.
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class MCExpr {
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public:
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// Allow MC classes to access the private `print` function.
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friend class MCAsmInfo;
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friend class MCFragment;
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friend class MCOperand;
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enum ExprKind : uint8_t {
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Binary, ///< Binary expressions.
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Constant, ///< Constant expressions.
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SymbolRef, ///< References to labels and assigned expressions.
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Unary, ///< Unary expressions.
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Specifier, ///< Expression with a relocation specifier.
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Target ///< Target specific expression.
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};
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private:
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static const unsigned NumSubclassDataBits = 24;
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static_assert(
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NumSubclassDataBits == CHAR_BIT * (sizeof(unsigned) - sizeof(ExprKind)),
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"ExprKind and SubclassData together should take up one word");
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ExprKind Kind;
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/// Field reserved for use by MCExpr subclasses.
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unsigned SubclassData : NumSubclassDataBits;
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SMLoc Loc;
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void print(raw_ostream &OS, const MCAsmInfo *MAI,
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int SurroundingPrec = 0) const;
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bool evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
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bool InSet) const;
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protected:
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using Spec = uint16_t;
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explicit MCExpr(ExprKind Kind, SMLoc Loc, unsigned SubclassData = 0)
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: Kind(Kind), SubclassData(SubclassData), Loc(Loc) {
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assert(SubclassData < (1 << NumSubclassDataBits) &&
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"Subclass data too large");
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}
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LLVM_ABI bool evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
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bool InSet) const;
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unsigned getSubclassData() const { return SubclassData; }
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public:
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MCExpr(const MCExpr &) = delete;
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MCExpr &operator=(const MCExpr &) = delete;
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/// \name Accessors
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/// @{
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ExprKind getKind() const { return Kind; }
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SMLoc getLoc() const { return Loc; }
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/// @}
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/// \name Utility Methods
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/// @{
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LLVM_ABI void dump() const;
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/// @}
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/// \name Expression Evaluation
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/// @{
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/// Try to evaluate the expression to an absolute value.
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///
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/// \param Res - The absolute value, if evaluation succeeds.
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/// \return - True on success.
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LLVM_ABI bool evaluateAsAbsolute(int64_t &Res) const;
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LLVM_ABI bool evaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const;
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LLVM_ABI bool evaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm) const;
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/// Aggressive variant of evaluateAsRelocatable when relocations are
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/// unavailable (e.g. .fill). Expects callers to handle errors when true is
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/// returned.
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LLVM_ABI bool evaluateKnownAbsolute(int64_t &Res,
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const MCAssembler &Asm) const;
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/// Try to evaluate the expression to a relocatable value, i.e. an
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/// expression of the fixed form (a - b + constant).
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///
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/// \param Res - The relocatable value, if evaluation succeeds.
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/// \param Asm - The assembler object to use for evaluating values.
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/// \return - True on success.
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LLVM_ABI bool evaluateAsRelocatable(MCValue &Res,
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const MCAssembler *Asm) const;
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/// Try to evaluate the expression to the form (a - b + constant) where
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/// neither a nor b are variables.
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///
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/// This is a more aggressive variant of evaluateAsRelocatable. The intended
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/// use is for when relocations are not available, like the .size directive.
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LLVM_ABI bool evaluateAsValue(MCValue &Res, const MCAssembler &Asm) const;
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/// Find the "associated section" for this expression, which is
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/// currently defined as the absolute section for constants, or
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/// otherwise the section associated with the first defined symbol in the
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/// expression.
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LLVM_ABI MCFragment *findAssociatedFragment() const;
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/// @}
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LLVM_ABI static bool evaluateSymbolicAdd(const MCAssembler *, bool,
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const MCValue &, const MCValue &,
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MCValue &);
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};
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//// Represent a constant integer expression.
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class MCConstantExpr : public MCExpr {
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int64_t Value;
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// Subclass data stores SizeInBytes in bits 0..7 and PrintInHex in bit 8.
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static const unsigned SizeInBytesBits = 8;
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static const unsigned SizeInBytesMask = (1 << SizeInBytesBits) - 1;
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static const unsigned PrintInHexBit = 1 << SizeInBytesBits;
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static unsigned encodeSubclassData(bool PrintInHex, unsigned SizeInBytes) {
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assert(SizeInBytes <= sizeof(int64_t) && "Excessive size");
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return SizeInBytes | (PrintInHex ? PrintInHexBit : 0);
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}
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MCConstantExpr(int64_t Value, bool PrintInHex, unsigned SizeInBytes)
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: MCExpr(MCExpr::Constant, SMLoc(),
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encodeSubclassData(PrintInHex, SizeInBytes)), Value(Value) {}
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public:
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/// \name Construction
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/// @{
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LLVM_ABI static const MCConstantExpr *create(int64_t Value, MCContext &Ctx,
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bool PrintInHex = false,
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unsigned SizeInBytes = 0);
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/// @}
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/// \name Accessors
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/// @{
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int64_t getValue() const { return Value; }
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unsigned getSizeInBytes() const {
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return getSubclassData() & SizeInBytesMask;
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}
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bool useHexFormat() const { return (getSubclassData() & PrintInHexBit) != 0; }
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/// @}
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static bool classof(const MCExpr *E) {
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return E->getKind() == MCExpr::Constant;
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}
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};
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/// Represent a reference to a symbol from inside an expression.
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///
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/// A symbol reference in an expression may be a use of a label, a use of an
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/// assembler variable (defined constant), or constitute an implicit definition
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/// of the symbol as external.
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class MCSymbolRefExpr : public MCExpr {
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public:
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// VariantKind isn't ideal for encoding relocation operators because:
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// (a) other expressions, like MCConstantExpr (e.g., 4@l) and MCBinaryExpr
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// (e.g., (a+1)@l), also need it; (b) semantics become unclear (e.g., folding
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// expressions with @). MCSpecifierExpr, as used by AArch64 and RISC-V, offers
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// a cleaner approach.
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enum VariantKind : uint16_t {
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VK_COFF_IMGREL32 = 3, // symbol@imgrel (image-relative)
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FirstTargetSpecifier,
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};
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private:
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/// The symbol being referenced.
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const MCSymbol *Symbol;
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explicit MCSymbolRefExpr(const MCSymbol *Symbol, Spec specifier, SMLoc Loc);
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public:
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/// \name Construction
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/// @{
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static const MCSymbolRefExpr *create(const MCSymbol *Symbol, MCContext &Ctx,
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SMLoc Loc = SMLoc()) {
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return MCSymbolRefExpr::create(Symbol, 0, Ctx, Loc);
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}
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LLVM_ABI static const MCSymbolRefExpr *create(const MCSymbol *Symbol,
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Spec specifier, MCContext &Ctx,
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SMLoc Loc = SMLoc());
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/// @}
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/// \name Accessors
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/// @{
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const MCSymbol &getSymbol() const { return *Symbol; }
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// Some targets encode the relocation specifier within SymA using
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// MCSymbolRefExpr::SubclassData, which is copied to MCValue::Specifier,
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// though this method is now deprecated.
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VariantKind getKind() const { return VariantKind(getSubclassData()); }
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uint16_t getSpecifier() const { return getSubclassData(); }
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/// @}
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static bool classof(const MCExpr *E) {
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return E->getKind() == MCExpr::SymbolRef;
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}
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};
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/// Unary assembler expressions.
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class MCUnaryExpr : public MCExpr {
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public:
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enum Opcode {
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LNot, ///< Logical negation.
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Minus, ///< Unary minus.
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Not, ///< Bitwise negation.
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Plus ///< Unary plus.
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};
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private:
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const MCExpr *Expr;
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MCUnaryExpr(Opcode Op, const MCExpr *Expr, SMLoc Loc)
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: MCExpr(MCExpr::Unary, Loc, Op), Expr(Expr) {}
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public:
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/// \name Construction
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/// @{
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LLVM_ABI static const MCUnaryExpr *
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create(Opcode Op, const MCExpr *Expr, MCContext &Ctx, SMLoc Loc = SMLoc());
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static const MCUnaryExpr *createLNot(const MCExpr *Expr, MCContext &Ctx, SMLoc Loc = SMLoc()) {
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return create(LNot, Expr, Ctx, Loc);
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}
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static const MCUnaryExpr *createMinus(const MCExpr *Expr, MCContext &Ctx, SMLoc Loc = SMLoc()) {
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return create(Minus, Expr, Ctx, Loc);
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}
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static const MCUnaryExpr *createNot(const MCExpr *Expr, MCContext &Ctx, SMLoc Loc = SMLoc()) {
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return create(Not, Expr, Ctx, Loc);
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}
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static const MCUnaryExpr *createPlus(const MCExpr *Expr, MCContext &Ctx, SMLoc Loc = SMLoc()) {
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return create(Plus, Expr, Ctx, Loc);
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}
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/// @}
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/// \name Accessors
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/// @{
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/// Get the kind of this unary expression.
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Opcode getOpcode() const { return (Opcode)getSubclassData(); }
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/// Get the child of this unary expression.
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const MCExpr *getSubExpr() const { return Expr; }
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/// @}
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static bool classof(const MCExpr *E) {
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return E->getKind() == MCExpr::Unary;
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}
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};
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/// Binary assembler expressions.
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class MCBinaryExpr : public MCExpr {
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public:
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enum Opcode {
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Add, ///< Addition.
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And, ///< Bitwise and.
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Div, ///< Signed division.
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EQ, ///< Equality comparison.
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GT, ///< Signed greater than comparison (result is either 0 or some
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///< target-specific non-zero value)
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GTE, ///< Signed greater than or equal comparison (result is either 0 or
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///< some target-specific non-zero value).
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LAnd, ///< Logical and.
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LOr, ///< Logical or.
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LT, ///< Signed less than comparison (result is either 0 or
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///< some target-specific non-zero value).
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LTE, ///< Signed less than or equal comparison (result is either 0 or
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///< some target-specific non-zero value).
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Mod, ///< Signed remainder.
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Mul, ///< Multiplication.
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NE, ///< Inequality comparison.
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Or, ///< Bitwise or.
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OrNot, ///< Bitwise or not.
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Shl, ///< Shift left.
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AShr, ///< Arithmetic shift right.
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LShr, ///< Logical shift right.
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Sub, ///< Subtraction.
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Xor ///< Bitwise exclusive or.
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};
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private:
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const MCExpr *LHS, *RHS;
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MCBinaryExpr(Opcode Op, const MCExpr *LHS, const MCExpr *RHS,
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SMLoc Loc = SMLoc())
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: MCExpr(MCExpr::Binary, Loc, Op), LHS(LHS), RHS(RHS) {}
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public:
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/// \name Construction
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/// @{
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LLVM_ABI static const MCBinaryExpr *create(Opcode Op, const MCExpr *LHS,
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const MCExpr *RHS, MCContext &Ctx,
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SMLoc Loc = SMLoc());
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static const MCBinaryExpr *createAdd(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx, SMLoc Loc = SMLoc()) {
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return create(Add, LHS, RHS, Ctx, Loc);
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}
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static const MCBinaryExpr *createAnd(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(And, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createDiv(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(Div, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createEQ(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(EQ, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createGT(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(GT, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createGTE(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(GTE, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createLAnd(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(LAnd, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createLOr(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(LOr, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createLT(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(LT, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createLTE(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(LTE, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createMod(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(Mod, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createMul(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(Mul, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createNE(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(NE, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createOr(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(Or, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createShl(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(Shl, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createAShr(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(AShr, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createLShr(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(LShr, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createSub(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(Sub, LHS, RHS, Ctx);
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}
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static const MCBinaryExpr *createXor(const MCExpr *LHS, const MCExpr *RHS,
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MCContext &Ctx) {
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return create(Xor, LHS, RHS, Ctx);
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}
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/// @}
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/// \name Accessors
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/// @{
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/// Get the kind of this binary expression.
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Opcode getOpcode() const { return (Opcode)getSubclassData(); }
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/// Get the left-hand side expression of the binary operator.
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const MCExpr *getLHS() const { return LHS; }
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/// Get the right-hand side expression of the binary operator.
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const MCExpr *getRHS() const { return RHS; }
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/// @}
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static bool classof(const MCExpr *E) {
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return E->getKind() == MCExpr::Binary;
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}
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};
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/// Extension point for target-specific MCExpr subclasses to implement.
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/// This can encode a relocation operator, serving as a replacement for
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/// MCSymbolRefExpr::VariantKind. Ideally, limit this to
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/// top-level use, avoiding its inclusion as a subexpression.
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///
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/// NOTE: All subclasses are required to have trivial destructors because
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/// MCExprs are bump pointer allocated and not destructed.
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class LLVM_ABI MCTargetExpr : public MCExpr {
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virtual void anchor();
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protected:
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MCTargetExpr() : MCExpr(Target, SMLoc()) {}
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virtual ~MCTargetExpr() = default;
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public:
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virtual void printImpl(raw_ostream &OS, const MCAsmInfo *MAI) const = 0;
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virtual bool evaluateAsRelocatableImpl(MCValue &Res,
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const MCAssembler *Asm) const = 0;
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// allow Target Expressions to be checked for equality
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virtual bool isEqualTo(const MCExpr *x) const { return false; }
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// This should be set when assigned expressions are not valid ".set"
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// expressions, e.g. registers, and must be inlined.
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virtual bool inlineAssignedExpr() const { return false; }
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virtual void visitUsedExpr(MCStreamer& Streamer) const = 0;
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virtual MCFragment *findAssociatedFragment() const = 0;
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static bool classof(const MCExpr *E) {
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return E->getKind() == MCExpr::Target;
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}
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};
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/// Extension point for target-specific MCExpr subclasses with a relocation
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/// specifier, serving as a replacement for MCSymbolRefExpr::VariantKind.
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/// Limit this to top-level use, avoiding its inclusion as a subexpression.
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///
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/// NOTE: All subclasses are required to have trivial destructors because
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/// MCExprs are bump pointer allocated and not destructed.
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class LLVM_ABI MCSpecifierExpr : public MCExpr {
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protected:
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const MCExpr *Expr;
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explicit MCSpecifierExpr(const MCExpr *Expr, Spec S, SMLoc Loc = SMLoc())
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: MCExpr(Specifier, Loc, S), Expr(Expr) {}
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public:
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static const MCSpecifierExpr *create(const MCExpr *Expr, Spec S,
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MCContext &Ctx, SMLoc Loc = SMLoc());
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static const MCSpecifierExpr *create(const MCSymbol *Sym, Spec S,
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MCContext &Ctx, SMLoc Loc = SMLoc());
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Spec getSpecifier() const { return getSubclassData(); }
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const MCExpr *getSubExpr() const { return Expr; }
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static bool classof(const MCExpr *E) {
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return E->getKind() == MCExpr::Specifier;
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}
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};
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} // end namespace llvm
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#endif // LLVM_MC_MCEXPR_H
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