TargetLoweringObjectFile.h revision 263508 
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 GlobalValue;
33  class TargetMachine;
34
35class TargetLoweringObjectFile : public MCObjectFileInfo {
36  MCContext *Ctx;
37
38  TargetLoweringObjectFile(
39    const TargetLoweringObjectFile&) LLVM_DELETED_FUNCTION;
40  void operator=(const TargetLoweringObjectFile&) LLVM_DELETED_FUNCTION;
41
42public:
43  MCContext &getContext() const { return *Ctx; }
44
45  TargetLoweringObjectFile() : MCObjectFileInfo(), Ctx(0) {}
46
47  virtual ~TargetLoweringObjectFile();
48
49  /// Initialize - this method must be called before any actual lowering is
50  /// done.  This specifies the current context for codegen, and gives the
51  /// lowering implementations a chance to set up their default sections.
52  virtual void Initialize(MCContext &ctx, const TargetMachine &TM);
53
54  virtual void emitPersonalityValue(MCStreamer &Streamer,
55                                    const TargetMachine &TM,
56                                    const MCSymbol *Sym) const;
57
58  /// emitModuleFlags - Emit the module flags that the platform cares about.
59  virtual void emitModuleFlags(MCStreamer &,
60                               ArrayRef<Module::ModuleFlagEntry>,
61                               Mangler *, const TargetMachine &) const {
62  }
63
64  /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively
65  /// decide not to emit the UsedDirective for some symbols in llvm.used.
66  /// FIXME: REMOVE this (rdar://7071300)
67  virtual bool shouldEmitUsedDirectiveFor(const GlobalValue *GV,
68                                          Mangler *) const {
69    return GV != 0;
70  }
71
72  /// getSectionForConstant - Given a constant with the SectionKind, return a
73  /// section that it should be placed in.
74  virtual const MCSection *getSectionForConstant(SectionKind Kind) const;
75
76  /// getKindForGlobal - Classify the specified global variable into a set of
77  /// target independent categories embodied in SectionKind.
78  static SectionKind getKindForGlobal(const GlobalValue *GV,
79                                      const TargetMachine &TM);
80
81  /// SectionForGlobal - This method computes the appropriate section to emit
82  /// the specified global variable or function definition.  This should not
83  /// be passed external (or available externally) globals.
84  const MCSection *SectionForGlobal(const GlobalValue *GV,
85                                    SectionKind Kind, Mangler *Mang,
86                                    const TargetMachine &TM) const;
87
88  /// SectionForGlobal - This method computes the appropriate section to emit
89  /// the specified global variable or function definition.  This should not
90  /// be passed external (or available externally) globals.
91  const MCSection *SectionForGlobal(const GlobalValue *GV,
92                                    Mangler *Mang,
93                                    const TargetMachine &TM) const {
94    return SectionForGlobal(GV, getKindForGlobal(GV, TM), Mang, TM);
95  }
96
97  /// getExplicitSectionGlobal - Targets should implement this method to assign
98  /// a section to globals with an explicit section specfied.  The
99  /// implementation of this method can assume that GV->hasSection() is true.
100  virtual const MCSection *
101  getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
102                           Mangler *Mang, const TargetMachine &TM) const = 0;
103
104  /// getSpecialCasedSectionGlobals - Allow the target to completely override
105  /// section assignment of a global.
106  virtual const MCSection *
107  getSpecialCasedSectionGlobals(const GlobalValue *GV, Mangler *Mang,
108                                SectionKind Kind) const {
109    return 0;
110  }
111
112  /// getTTypeGlobalReference - Return an MCExpr to use for a reference
113  /// to the specified global variable from exception handling information.
114  ///
115  virtual const MCExpr *
116  getTTypeGlobalReference(const GlobalValue *GV, Mangler *Mang,
117                          MachineModuleInfo *MMI, unsigned Encoding,
118                          MCStreamer &Streamer) const;
119
120  /// Return the MCSymbol for the specified global value.  This symbol is the
121  /// main label that is the address of the global
122  MCSymbol *getSymbol(Mangler &M, const GlobalValue *GV) const;
123
124  // getCFIPersonalitySymbol - The symbol that gets passed to .cfi_personality.
125  virtual MCSymbol *
126  getCFIPersonalitySymbol(const GlobalValue *GV, Mangler *Mang,
127                          MachineModuleInfo *MMI) const;
128
129  ///
130  const MCExpr *
131  getTTypeReference(const MCSymbolRefExpr *Sym, unsigned Encoding,
132                    MCStreamer &Streamer) const;
133
134  virtual const MCSection *
135  getStaticCtorSection(unsigned Priority = 65535) const {
136    (void)Priority;
137    return StaticCtorSection;
138  }
139  virtual const MCSection *
140  getStaticDtorSection(unsigned Priority = 65535) const {
141    (void)Priority;
142    return StaticDtorSection;
143  }
144
145  /// \brief Create a symbol reference to describe the given TLS variable when
146  /// emitting the address in debug info.
147  virtual const MCExpr *getDebugThreadLocalSymbol(const MCSymbol *Sym) const;
148
149protected:
150  virtual const MCSection *
151  SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
152                         Mangler *Mang, const TargetMachine &TM) const;
153};
154
155} // end namespace llvm
156
157#endif
158