MCELFStreamer.h

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//===- MCELFStreamer.h - MCStreamer ELF Object File 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
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_MC_MCELFSTREAMER_H
#define LLVM_MC_MCELFSTREAMER_H
 
#include "llvm/ADT/SmallVector.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/MC/MCDirectives.h"
#include "llvm/MC/MCObjectStreamer.h"
 
namespace llvm {
 
class MCAsmBackend;
class MCCodeEmitter;
class MCExpr;
class MCInst;
 
class MCELFStreamer : public MCObjectStreamer {
public:
  MCELFStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> TAB,
                std::unique_ptr<MCObjectWriter> OW,
                std::unique_ptr<MCCodeEmitter> Emitter);
 
  ~MCELFStreamer() override = default;
 
  /// state management
  void reset() override {
    SeenIdent = false;
    BundleGroups.clear();
    MCObjectStreamer::reset();
  }
 
  /// \name MCStreamer Interface
  /// @{
 
  void initSections(bool NoExecStack, const MCSubtargetInfo &STI) override;
  void changeSection(MCSection *Section, const MCExpr *Subsection) override;
  void emitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()) override;
  void emitLabelAtPos(MCSymbol *Symbol, SMLoc Loc, MCFragment *F,
                      uint64_t Offset) override;
  void emitAssemblerFlag(MCAssemblerFlag Flag) override;
  void emitThumbFunc(MCSymbol *Func) override;
  void emitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) override;
  bool emitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override;
  void emitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) override;
  void emitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                        unsigned ByteAlignment) override;
 
  void emitELFSize(MCSymbol *Symbol, const MCExpr *Value) override;
  void emitELFSymverDirective(const MCSymbol *OriginalSym, StringRef Name,
                              bool KeepOriginalSym) override;
 
  void emitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                             unsigned ByteAlignment) override;
 
  void emitZerofill(MCSection *Section, MCSymbol *Symbol = nullptr,
                    uint64_t Size = 0, unsigned ByteAlignment = 0,
                    SMLoc L = SMLoc()) override;
  void emitTBSSSymbol(MCSection *Section, MCSymbol *Symbol, uint64_t Size,
                      unsigned ByteAlignment = 0) override;
  void emitValueImpl(const MCExpr *Value, unsigned Size,
                     SMLoc Loc = SMLoc()) override;
 
  void emitIdent(StringRef IdentString) override;
 
  void emitValueToAlignment(unsigned, int64_t, unsigned, unsigned) override;
 
  void emitCGProfileEntry(const MCSymbolRefExpr *From,
                          const MCSymbolRefExpr *To, uint64_t Count) override;
 
  void finishImpl() override;
 
  void emitBundleAlignMode(unsigned AlignPow2) override;
  void emitBundleLock(bool AlignToEnd) override;
  void emitBundleUnlock() override;
 
  /// ELF object attributes section emission support
  struct AttributeItem {
    // This structure holds all attributes, accounting for their string /
    // numeric value, so we can later emit them in declaration order, keeping
    // all in the same vector.
    enum {
      HiddenAttribute = 0,
      NumericAttribute,
      TextAttribute,
      NumericAndTextAttributes
    } Type;
    unsigned Tag;
    unsigned IntValue;
    std::string StringValue;
  };
 
  // Attributes that are added and managed entirely by target.
  SmallVector<AttributeItem, 64> Contents;
  void setAttributeItem(unsigned Attribute, unsigned Value,
                        bool OverwriteExisting);
  void setAttributeItem(unsigned Attribute, StringRef Value,
                        bool OverwriteExisting);
  void setAttributeItems(unsigned Attribute, unsigned IntValue,
                         StringRef StringValue, bool OverwriteExisting);
  void emitAttributesSection(StringRef Vendor, const Twine &Section,
                             unsigned Type, MCSection *&AttributeSection) {
    createAttributesSection(Vendor, Section, Type, AttributeSection, Contents);
  }
 
private:
  AttributeItem *getAttributeItem(unsigned Attribute);
  size_t calculateContentSize(SmallVector<AttributeItem, 64> &AttrsVec);
  void createAttributesSection(StringRef Vendor, const Twine &Section,
                               unsigned Type, MCSection *&AttributeSection,
                               SmallVector<AttributeItem, 64> &AttrsVec);
 
  // GNU attributes that will get emitted at the end of the asm file.
  SmallVector<AttributeItem, 64> GNUAttributes;
 
public:
  void emitGNUAttribute(unsigned Tag, unsigned Value) override {
    AttributeItem Item = {AttributeItem::NumericAttribute, Tag, Value,
                          std::string(StringRef(""))};
    GNUAttributes.push_back(Item);
  }
 
private:
  bool isBundleLocked() const;
  void emitInstToFragment(const MCInst &Inst, const MCSubtargetInfo &) override;
  void emitInstToData(const MCInst &Inst, const MCSubtargetInfo &) override;
 
  void fixSymbolsInTLSFixups(const MCExpr *expr);
  void finalizeCGProfileEntry(const MCSymbolRefExpr *&S, uint64_t Offset);
  void finalizeCGProfile();
 
  /// Merge the content of the fragment \p EF into the fragment \p DF.
  void mergeFragment(MCDataFragment *, MCDataFragment *);
 
  bool SeenIdent = false;
 
  /// BundleGroups - The stack of fragments holding the bundle-locked
  /// instructions.
  SmallVector<MCDataFragment *, 4> BundleGroups;
};
 
MCELFStreamer *createARMELFStreamer(MCContext &Context,
                                    std::unique_ptr<MCAsmBackend> TAB,
                                    std::unique_ptr<MCObjectWriter> OW,
                                    std::unique_ptr<MCCodeEmitter> Emitter,
                                    bool RelaxAll, bool IsThumb, bool IsAndroid);
 
} // end namespace llvm
 
#endif // LLVM_MC_MCELFSTREAMER_H