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
23namespace 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 ConstantExpr;
33  class GlobalValue;
34  class TargetMachine;
35
36class TargetLoweringObjectFile : public MCObjectFileInfo {
37  MCContext *Ctx;
38  const DataLayout *DL;
39
40  TargetLoweringObjectFile(
41    const TargetLoweringObjectFile&) LLVM_DELETED_FUNCTION;
42  void operator=(const TargetLoweringObjectFile&) LLVM_DELETED_FUNCTION;
43
44public:
45  MCContext &getContext() const { return *Ctx; }
46
47  TargetLoweringObjectFile() : MCObjectFileInfo(), Ctx(nullptr), DL(nullptr) {}
48
49  virtual ~TargetLoweringObjectFile();
50
51  /// This method must be called before any actual lowering is done.  This
52  /// specifies the current context for codegen, and gives the lowering
53  /// implementations a chance to set up their default sections.
54  virtual void Initialize(MCContext &ctx, const TargetMachine &TM);
55
56  virtual void emitPersonalityValue(MCStreamer &Streamer,
57                                    const TargetMachine &TM,
58                                    const MCSymbol *Sym) const;
59
60  /// Extract the dependent library name from a linker option string. Returns
61  /// StringRef() if the option does not specify a library.
62  virtual StringRef getDepLibFromLinkerOpt(StringRef LinkerOption) const {
63    return StringRef();
64  }
65
66  /// Emit the module flags that the platform cares about.
67  virtual void emitModuleFlags(MCStreamer &Streamer,
68                               ArrayRef<Module::ModuleFlagEntry> Flags,
69                               Mangler &Mang, const TargetMachine &TM) const {}
70
71  /// Given a constant with the SectionKind, return a section that it should be
72  /// placed in.
73  virtual const MCSection *getSectionForConstant(SectionKind Kind) const;
74
75  /// Classify the specified global variable into a set of target independent
76  /// categories embodied in SectionKind.
77  static SectionKind getKindForGlobal(const GlobalValue *GV,
78                                      const TargetMachine &TM);
79
80  /// This method computes the appropriate section to emit the specified global
81  /// variable or function definition. This should not be passed external (or
82  /// available externally) globals.
83  const MCSection *SectionForGlobal(const GlobalValue *GV,
84                                    SectionKind Kind, Mangler &Mang,
85                                    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  const MCSection *SectionForGlobal(const GlobalValue *GV,
91                                    Mangler &Mang,
92                                    const TargetMachine &TM) const {
93    return SectionForGlobal(GV, getKindForGlobal(GV, TM), Mang, TM);
94  }
95
96  /// Targets should implement this method to assign a section to globals with
97  /// an explicit section specfied. The implementation of this method can
98  /// assume that GV->hasSection() is true.
99  virtual const MCSection *
100  getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
101                           Mangler &Mang, const TargetMachine &TM) const = 0;
102
103  /// Allow the target to completely override section assignment of a global.
104  virtual const MCSection *getSpecialCasedSectionGlobals(const GlobalValue *GV,
105                                                         SectionKind Kind,
106                                                         Mangler &Mang) const {
107    return nullptr;
108  }
109
110  /// Return an MCExpr to use for a reference to the specified global variable
111  /// from exception handling information.
112  virtual const MCExpr *
113  getTTypeGlobalReference(const GlobalValue *GV, unsigned Encoding,
114                          Mangler &Mang, const TargetMachine &TM,
115                          MachineModuleInfo *MMI, MCStreamer &Streamer) const;
116
117  /// Return the MCSymbol for a private symbol with global value name as its
118  /// base, with the specified suffix.
119  MCSymbol *getSymbolWithGlobalValueBase(const GlobalValue *GV,
120                                         StringRef Suffix, Mangler &Mang,
121                                         const TargetMachine &TM) const;
122
123  // The symbol that gets passed to .cfi_personality.
124  virtual MCSymbol *getCFIPersonalitySymbol(const GlobalValue *GV,
125                                            Mangler &Mang,
126                                            const TargetMachine &TM,
127                                            MachineModuleInfo *MMI) const;
128
129  const MCExpr *
130  getTTypeReference(const MCSymbolRefExpr *Sym, unsigned Encoding,
131                    MCStreamer &Streamer) const;
132
133  virtual const MCSection *getStaticCtorSection(unsigned Priority,
134                                                const MCSymbol *KeySym) const {
135    return StaticCtorSection;
136  }
137
138  virtual const MCSection *getStaticDtorSection(unsigned Priority,
139                                                const MCSymbol *KeySym) const {
140    return StaticDtorSection;
141  }
142
143  /// \brief Create a symbol reference to describe the given TLS variable when
144  /// emitting the address in debug info.
145  virtual const MCExpr *getDebugThreadLocalSymbol(const MCSymbol *Sym) const;
146
147  virtual const MCExpr *
148  getExecutableRelativeSymbol(const ConstantExpr *CE, Mangler &Mang,
149                              const TargetMachine &TM) const {
150    return nullptr;
151  }
152
153  /// \brief True if the section is atomized using the symbols in it.
154  /// This is false if the section is not atomized at all (most ELF sections) or
155  /// if it is atomized based on its contents (MachO' __TEXT,__cstring for
156  /// example).
157  virtual bool isSectionAtomizableBySymbols(const MCSection &Section) const;
158
159protected:
160  virtual const MCSection *
161  SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
162                         Mangler &Mang, const TargetMachine &TM) const;
163};
164
165} // end namespace llvm
166
167#endif
168