1 //===-- llvm/Target/TargetLoweringObjectFile.h - Object Info ----*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements classes used to handle lowerings specific to common 11 // object file formats. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_TARGET_TARGETLOWERINGOBJECTFILE_H 16 #define LLVM_TARGET_TARGETLOWERINGOBJECTFILE_H 17 18 #include "llvm/ADT/ArrayRef.h" 19 #include "llvm/IR/Module.h" 20 #include "llvm/MC/MCObjectFileInfo.h" 21 #include "llvm/MC/SectionKind.h" 22 23 namespace llvm { 24 class MachineModuleInfo; 25 class Mangler; 26 class MCContext; 27 class MCExpr; 28 class MCSection; 29 class MCSymbol; 30 class MCSymbolRefExpr; 31 class MCStreamer; 32 class MCValue; 33 class ConstantExpr; 34 class GlobalValue; 35 class TargetMachine; 36 37 class TargetLoweringObjectFile : public MCObjectFileInfo { 38 MCContext *Ctx; 39 40 TargetLoweringObjectFile( 41 const TargetLoweringObjectFile&) = delete; 42 void operator=(const TargetLoweringObjectFile&) = delete; 43 44 protected: 45 bool SupportIndirectSymViaGOTPCRel; 46 bool SupportGOTPCRelWithOffset; 47 48 public: 49 MCContext &getContext() const { return *Ctx; } 50 51 TargetLoweringObjectFile() 52 : MCObjectFileInfo(), Ctx(nullptr), SupportIndirectSymViaGOTPCRel(false), 53 SupportGOTPCRelWithOffset(true) {} 54 55 virtual ~TargetLoweringObjectFile(); 56 57 /// This method must be called before any actual lowering is done. This 58 /// specifies the current context for codegen, and gives the lowering 59 /// implementations a chance to set up their default sections. 60 virtual void Initialize(MCContext &ctx, const TargetMachine &TM); 61 62 virtual void emitPersonalityValue(MCStreamer &Streamer, const DataLayout &TM, 63 const MCSymbol *Sym) const; 64 65 /// Emit the module flags that the platform cares about. 66 virtual void emitModuleFlags(MCStreamer &Streamer, 67 ArrayRef<Module::ModuleFlagEntry> Flags, 68 Mangler &Mang, const TargetMachine &TM) const {} 69 70 /// Given a constant with the SectionKind, return a section that it should be 71 /// placed in. 72 virtual MCSection *getSectionForConstant(const DataLayout &DL, 73 SectionKind Kind, 74 const Constant *C) const; 75 76 /// Classify the specified global variable into a set of target independent 77 /// categories embodied in SectionKind. 78 static SectionKind getKindForGlobal(const GlobalValue *GV, 79 const TargetMachine &TM); 80 81 /// This method computes the appropriate section to emit the specified global 82 /// variable or function definition. This should not be passed external (or 83 /// available externally) globals. 84 MCSection *SectionForGlobal(const GlobalValue *GV, SectionKind Kind, 85 Mangler &Mang, const TargetMachine &TM) const; 86 87 /// This method computes the appropriate section to emit the specified global 88 /// variable or function definition. This should not be passed external (or 89 /// available externally) globals. 90 MCSection *SectionForGlobal(const GlobalValue *GV, Mangler &Mang, 91 const TargetMachine &TM) const { 92 return SectionForGlobal(GV, getKindForGlobal(GV, TM), Mang, TM); 93 } 94 95 virtual void getNameWithPrefix(SmallVectorImpl<char> &OutName, 96 const GlobalValue *GV, Mangler &Mang, 97 const TargetMachine &TM) const; 98 99 virtual MCSection *getSectionForJumpTable(const Function &F, Mangler &Mang, 100 const TargetMachine &TM) const; 101 102 virtual bool shouldPutJumpTableInFunctionSection(bool UsesLabelDifference, 103 const Function &F) const; 104 105 /// Targets should implement this method to assign a section to globals with 106 /// an explicit section specfied. The implementation of this method can 107 /// assume that GV->hasSection() is true. 108 virtual MCSection * 109 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 110 Mangler &Mang, const TargetMachine &TM) const = 0; 111 112 /// Allow the target to completely override section assignment of a global. 113 virtual const MCSection *getSpecialCasedSectionGlobals(const GlobalValue *GV, 114 SectionKind Kind, 115 Mangler &Mang) const { 116 return nullptr; 117 } 118 119 /// Return an MCExpr to use for a reference to the specified global variable 120 /// from exception handling information. 121 virtual const MCExpr * 122 getTTypeGlobalReference(const GlobalValue *GV, unsigned Encoding, 123 Mangler &Mang, const TargetMachine &TM, 124 MachineModuleInfo *MMI, MCStreamer &Streamer) const; 125 126 /// Return the MCSymbol for a private symbol with global value name as its 127 /// base, with the specified suffix. 128 MCSymbol *getSymbolWithGlobalValueBase(const GlobalValue *GV, 129 StringRef Suffix, Mangler &Mang, 130 const TargetMachine &TM) const; 131 132 // The symbol that gets passed to .cfi_personality. 133 virtual MCSymbol *getCFIPersonalitySymbol(const GlobalValue *GV, 134 Mangler &Mang, 135 const TargetMachine &TM, 136 MachineModuleInfo *MMI) const; 137 138 const MCExpr * 139 getTTypeReference(const MCSymbolRefExpr *Sym, unsigned Encoding, 140 MCStreamer &Streamer) const; 141 142 virtual MCSection *getStaticCtorSection(unsigned Priority, 143 const MCSymbol *KeySym) const { 144 return StaticCtorSection; 145 } 146 147 virtual MCSection *getStaticDtorSection(unsigned Priority, 148 const MCSymbol *KeySym) const { 149 return StaticDtorSection; 150 } 151 152 /// \brief Create a symbol reference to describe the given TLS variable when 153 /// emitting the address in debug info. 154 virtual const MCExpr *getDebugThreadLocalSymbol(const MCSymbol *Sym) const; 155 156 virtual const MCExpr * 157 getExecutableRelativeSymbol(const ConstantExpr *CE, Mangler &Mang, 158 const TargetMachine &TM) const { 159 return nullptr; 160 } 161 162 /// \brief Target supports replacing a data "PC"-relative access to a symbol 163 /// through another symbol, by accessing the later via a GOT entry instead? 164 bool supportIndirectSymViaGOTPCRel() const { 165 return SupportIndirectSymViaGOTPCRel; 166 } 167 168 /// \brief Target GOT "PC"-relative relocation supports encoding an additional 169 /// binary expression with an offset? 170 bool supportGOTPCRelWithOffset() const { 171 return SupportGOTPCRelWithOffset; 172 } 173 174 /// \brief Get the target specific PC relative GOT entry relocation 175 virtual const MCExpr *getIndirectSymViaGOTPCRel(const MCSymbol *Sym, 176 const MCValue &MV, 177 int64_t Offset, 178 MachineModuleInfo *MMI, 179 MCStreamer &Streamer) const { 180 return nullptr; 181 } 182 183 virtual void emitLinkerFlagsForGlobal(raw_ostream &OS, const GlobalValue *GV, 184 const Mangler &Mang) const {} 185 186 protected: 187 virtual MCSection *SelectSectionForGlobal(const GlobalValue *GV, 188 SectionKind Kind, Mangler &Mang, 189 const TargetMachine &TM) const = 0; 190 }; 191 192 } // end namespace llvm 193 194 #endif 195
