llvm/MC/MCELFStreamer.h

0001 //===- MCELFStreamer.h - MCStreamer ELF Object File Interface ---*- C++ -*-===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef LLVM_MC_MCELFSTREAMER_H
0010 #define LLVM_MC_MCELFSTREAMER_H
0011
0012 #include "llvm/ADT/SmallVector.h"
0013 #include "llvm/MC/MCDirectives.h"
0014 #include "llvm/MC/MCObjectStreamer.h"
0015
0016 namespace llvm {
0017
0018 class ELFObjectWriter;
0019 class MCContext;
0020 class MCDataFragment;
0021 class MCFragment;
0022 class MCObjectWriter;
0023 class MCSection;
0024 class MCSubtargetInfo;
0025 class MCSymbol;
0026 class MCSymbolRefExpr;
0027 class MCAsmBackend;
0028 class MCCodeEmitter;
0029 class MCExpr;
0030 class MCInst;
0031
0032 class MCELFStreamer : public MCObjectStreamer {
0033 public:
0034   MCELFStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> TAB,
0035                 std::unique_ptr<MCObjectWriter> OW,
0036                 std::unique_ptr<MCCodeEmitter> Emitter);
0037
0038   ~MCELFStreamer() override = default;
0039
0040   /// state management
0041   void reset() override {
0042     SeenIdent = false;
0043     MCObjectStreamer::reset();
0044   }
0045
0046   ELFObjectWriter &getWriter();
0047
0048   /// \name MCStreamer Interface
0049   /// @{
0050
0051   void initSections(bool NoExecStack, const MCSubtargetInfo &STI) override;
0052   void changeSection(MCSection *Section, uint32_t Subsection = 0) override;
0053   void emitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()) override;
0054   void emitLabelAtPos(MCSymbol *Symbol, SMLoc Loc, MCDataFragment &F,
0055                       uint64_t Offset) override;
0056   void emitAssemblerFlag(MCAssemblerFlag Flag) override;
0057   void emitThumbFunc(MCSymbol *Func) override;
0058   void emitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) override;
0059   bool emitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override;
0060   void emitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) override;
0061   void emitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
0062                         Align ByteAlignment) override;
0063
0064   void emitELFSize(MCSymbol *Symbol, const MCExpr *Value) override;
0065   void emitELFSymverDirective(const MCSymbol *OriginalSym, StringRef Name,
0066                               bool KeepOriginalSym) override;
0067
0068   void emitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
0069                              Align ByteAlignment) override;
0070
0071   void emitZerofill(MCSection *Section, MCSymbol *Symbol = nullptr,
0072                     uint64_t Size = 0, Align ByteAlignment = Align(1),
0073                     SMLoc L = SMLoc()) override;
0074   void emitTBSSSymbol(MCSection *Section, MCSymbol *Symbol, uint64_t Size,
0075                       Align ByteAlignment = Align(1)) override;
0076   void emitValueImpl(const MCExpr *Value, unsigned Size,
0077                      SMLoc Loc = SMLoc()) override;
0078
0079   void emitIdent(StringRef IdentString) override;
0080
0081   void emitValueToAlignment(Align, int64_t, unsigned, unsigned) override;
0082
0083   void emitCGProfileEntry(const MCSymbolRefExpr *From,
0084                           const MCSymbolRefExpr *To, uint64_t Count) override;
0085
0086   // This is final. Override MCTargetStreamer::finish instead for
0087   // target-specific code.
0088   void finishImpl() final;
0089
0090   void emitBundleAlignMode(Align Alignment) override;
0091   void emitBundleLock(bool AlignToEnd) override;
0092   void emitBundleUnlock() override;
0093
0094   /// ELF object attributes section emission support
0095   struct AttributeItem {
0096     // This structure holds all attributes, accounting for their string /
0097     // numeric value, so we can later emit them in declaration order, keeping
0098     // all in the same vector.
0099     enum Types {
0100       HiddenAttribute = 0,
0101       NumericAttribute,
0102       TextAttribute,
0103       NumericAndTextAttributes
0104     } Type;
0105     unsigned Tag;
0106     unsigned IntValue;
0107     std::string StringValue;
0108     AttributeItem(Types Ty, unsigned Tg, unsigned IV, std::string SV)
0109         : Type(Ty), Tag(Tg), IntValue(IV), StringValue(SV) {}
0110   };
0111
0112   /// ELF object attributes subsection support
0113   struct AttributeSubSection {
0114     bool IsActive;
0115     StringRef VendorName;
0116     unsigned IsOptional;
0117     unsigned ParameterType;
0118     SmallVector<AttributeItem, 64> Content;
0119   };
0120
0121   // Attributes that are added and managed entirely by target.
0122   SmallVector<AttributeItem, 64> Contents;
0123   void setAttributeItem(unsigned Attribute, unsigned Value,
0124                         bool OverwriteExisting);
0125   void setAttributeItem(unsigned Attribute, StringRef Value,
0126                         bool OverwriteExisting);
0127   void setAttributeItems(unsigned Attribute, unsigned IntValue,
0128                          StringRef StringValue, bool OverwriteExisting);
0129   void emitAttributesSection(StringRef Vendor, const Twine &Section,
0130                              unsigned Type, MCSection *&AttributeSection) {
0131     createAttributesSection(Vendor, Section, Type, AttributeSection, Contents);
0132   }
0133   void
0134   emitAttributesSection(MCSection *&AttributeSection, const Twine &Section,
0135                         unsigned Type,
0136                         SmallVector<AttributeSubSection, 64> &SubSectionVec) {
0137     createAttributesWithSubsection(AttributeSection, Section, Type,
0138                                    SubSectionVec);
0139   }
0140
0141 private:
0142   AttributeItem *getAttributeItem(unsigned Attribute);
0143   size_t calculateContentSize(SmallVector<AttributeItem, 64> &AttrsVec) const;
0144   void createAttributesSection(StringRef Vendor, const Twine &Section,
0145                                unsigned Type, MCSection *&AttributeSection,
0146                                SmallVector<AttributeItem, 64> &AttrsVec);
0147   void createAttributesWithSubsection(
0148       MCSection *&AttributeSection, const Twine &Section, unsigned Type,
0149       SmallVector<AttributeSubSection, 64> &SubSectionVec);
0150
0151   // GNU attributes that will get emitted at the end of the asm file.
0152   SmallVector<AttributeItem, 64> GNUAttributes;
0153
0154 public:
0155   void emitGNUAttribute(unsigned Tag, unsigned Value) override {
0156     AttributeItem Item = {AttributeItem::NumericAttribute, Tag, Value,
0157                           std::string(StringRef(""))};
0158     GNUAttributes.push_back(Item);
0159   }
0160
0161 private:
0162   bool isBundleLocked() const;
0163   void emitInstToFragment(const MCInst &Inst, const MCSubtargetInfo &) override;
0164   void emitInstToData(const MCInst &Inst, const MCSubtargetInfo &) override;
0165
0166   void fixSymbolsInTLSFixups(const MCExpr *expr);
0167   void finalizeCGProfileEntry(const MCSymbolRefExpr *&S, uint64_t Offset);
0168   void finalizeCGProfile();
0169
0170   bool SeenIdent = false;
0171 };
0172
0173 MCELFStreamer *createARMELFStreamer(MCContext &Context,
0174                                     std::unique_ptr<MCAsmBackend> TAB,
0175                                     std::unique_ptr<MCObjectWriter> OW,
0176                                     std::unique_ptr<MCCodeEmitter> Emitter,
0177                                     bool IsThumb, bool IsAndroid);
0178
0179 } // end namespace llvm
0180
0181 #endif // LLVM_MC_MCELFSTREAMER_H