TargetLoweringObjectFile.h revision 35039ac24163e99cfab161620a9fb41f944a63d5 
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/SmallVector.h"
19#include "llvm/ADT/StringMap.h"
20#include "llvm/MC/SectionKind.h"
21
22namespace llvm {
23  class MCSection;
24  class MCContext;
25  class GlobalValue;
26  class Mangler;
27  class TargetMachine;
28
29
30class TargetLoweringObjectFile {
31  MCContext *Ctx;
32protected:
33
34  TargetLoweringObjectFile();
35
36  /// TextSection - Section directive for standard text.
37  ///
38  const MCSection *TextSection;
39
40  /// DataSection - Section directive for standard data.
41  ///
42  const MCSection *DataSection;
43
44  /// BSSSection - Section that is default initialized to zero.
45  const MCSection *BSSSection;
46
47  /// ReadOnlySection - Section that is readonly and can contain arbitrary
48  /// initialized data.  Targets are not required to have a readonly section.
49  /// If they don't, various bits of code will fall back to using the data
50  /// section for constants.
51  const MCSection *ReadOnlySection;
52
53  /// StaticCtorSection - This section contains the static constructor pointer
54  /// list.
55  const MCSection *StaticCtorSection;
56
57  /// StaticDtorSection - This section contains the static destructor pointer
58  /// list.
59  const MCSection *StaticDtorSection;
60
61  /// LSDASection - If exception handling is supported by the target, this is
62  /// the section the Language Specific Data Area information is emitted to.
63  const MCSection *LSDASection;
64
65  /// EHFrameSection - If exception handling is supported by the target, this is
66  /// the section the EH Frame is emitted to.
67  const MCSection *EHFrameSection;
68
69
70public:
71  // FIXME: NONPUB.
72  const MCSection *getOrCreateSection(const char *Name,
73                                      bool isDirective,
74                                      SectionKind K) const;
75public:
76
77  virtual ~TargetLoweringObjectFile();
78
79  /// Initialize - this method must be called before any actual lowering is
80  /// done.  This specifies the current context for codegen, and gives the
81  /// lowering implementations a chance to set up their default sections.
82  virtual void Initialize(MCContext &ctx, const TargetMachine &TM) {
83    Ctx = &ctx;
84  }
85
86
87  const MCSection *getTextSection() const { return TextSection; }
88  const MCSection *getDataSection() const { return DataSection; }
89  const MCSection *getStaticCtorSection() const { return StaticCtorSection; }
90  const MCSection *getStaticDtorSection() const { return StaticDtorSection; }
91  const MCSection *getLSDASection() const { return LSDASection; }
92  const MCSection *getEHFrameSection() const { return EHFrameSection; }
93
94  /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively
95  /// decide not to emit the UsedDirective for some symbols in llvm.used.
96  /// FIXME: REMOVE this (rdar://7071300)
97  virtual bool shouldEmitUsedDirectiveFor(const GlobalValue *GV,
98                                          Mangler *) const {
99    return GV != 0;
100  }
101
102  /// getSectionForConstant - Given a constant with the SectionKind, return a
103  /// section that it should be placed in.
104  virtual const MCSection *getSectionForConstant(SectionKind Kind) const;
105
106  /// getKindForNamedSection - If this target wants to be able to override
107  /// section flags based on the name of the section specified for a global
108  /// variable, it can implement this.  This is used on ELF systems so that
109  /// ".tbss" gets the TLS bit set etc.
110  virtual SectionKind getKindForNamedSection(const char *Section,
111                                             SectionKind K) const {
112    return K;
113  }
114
115  /// SectionForGlobal - This method computes the appropriate section to emit
116  /// the specified global variable or function definition.  This should not
117  /// be passed external (or available externally) globals.
118  const MCSection *SectionForGlobal(const GlobalValue *GV,
119                                    Mangler *Mang,
120                                    const TargetMachine &TM) const;
121
122  /// getSpecialCasedSectionGlobals - Allow the target to completely override
123  /// section assignment of a global.
124  /// FIXME: ELIMINATE this by making PIC16 implement ADDRESS with
125  /// getFlagsForNamedSection.
126  virtual const MCSection *
127  getSpecialCasedSectionGlobals(const GlobalValue *GV, Mangler *Mang,
128                                SectionKind Kind) const {
129    return 0;
130  }
131
132  /// getSectionFlagsAsString - Turn the flags in the specified SectionKind
133  /// into a string that can be printed to the assembly file after the
134  /// ".section foo" part of a section directive.
135  virtual void getSectionFlagsAsString(SectionKind Kind,
136                                       SmallVectorImpl<char> &Str) const {
137  }
138
139protected:
140  virtual const MCSection *
141  SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
142                         Mangler *Mang, const TargetMachine &TM) const;
143};
144
145
146
147
148class TargetLoweringObjectFileELF : public TargetLoweringObjectFile {
149  bool AtIsCommentChar;  // True if @ is the comment character on this target.
150  bool HasCrazyBSS;
151protected:
152  /// TLSDataSection - Section directive for Thread Local data.
153  ///
154  const MCSection *TLSDataSection;        // Defaults to ".tdata".
155
156  /// TLSBSSSection - Section directive for Thread Local uninitialized data.
157  /// Null if this target doesn't support a BSS section.
158  ///
159  const MCSection *TLSBSSSection;         // Defaults to ".tbss".
160
161  const MCSection *CStringSection;
162
163  const MCSection *DataRelSection;
164  const MCSection *DataRelLocalSection;
165  const MCSection *DataRelROSection;
166  const MCSection *DataRelROLocalSection;
167
168  const MCSection *MergeableConst4Section;
169  const MCSection *MergeableConst8Section;
170  const MCSection *MergeableConst16Section;
171public:
172  /// ELF Constructor - AtIsCommentChar is true if the CommentCharacter from TAI
173  /// is "@".
174  TargetLoweringObjectFileELF(bool atIsCommentChar = false,
175                              // FIXME: REMOVE AFTER UNIQUING IS FIXED.
176                              bool hasCrazyBSS = false)
177    : AtIsCommentChar(atIsCommentChar), HasCrazyBSS(hasCrazyBSS) {}
178
179  virtual void Initialize(MCContext &Ctx, const TargetMachine &TM);
180
181
182  /// getSectionForConstant - Given a constant with the SectionKind, return a
183  /// section that it should be placed in.
184  virtual const MCSection *getSectionForConstant(SectionKind Kind) const;
185
186  virtual SectionKind getKindForNamedSection(const char *Section,
187                                             SectionKind K) const;
188  void getSectionFlagsAsString(SectionKind Kind,
189                               SmallVectorImpl<char> &Str) const;
190
191  virtual const MCSection *
192  SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
193                         Mangler *Mang, const TargetMachine &TM) const;
194};
195
196
197
198class TargetLoweringObjectFileMachO : public TargetLoweringObjectFile {
199  const MCSection *CStringSection;
200  const MCSection *TextCoalSection;
201  const MCSection *ConstTextCoalSection;
202  const MCSection *ConstDataCoalSection;
203  const MCSection *ConstDataSection;
204  const MCSection *DataCoalSection;
205  const MCSection *FourByteConstantSection;
206  const MCSection *EightByteConstantSection;
207  const MCSection *SixteenByteConstantSection;
208public:
209
210  virtual void Initialize(MCContext &Ctx, const TargetMachine &TM);
211
212  virtual const MCSection *
213  SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
214                         Mangler *Mang, const TargetMachine &TM) const;
215
216  virtual const MCSection *getSectionForConstant(SectionKind Kind) const;
217
218  /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively
219  /// decide not to emit the UsedDirective for some symbols in llvm.used.
220  /// FIXME: REMOVE this (rdar://7071300)
221  virtual bool shouldEmitUsedDirectiveFor(const GlobalValue *GV,
222                                          Mangler *) const;
223};
224
225
226
227class TargetLoweringObjectFileCOFF : public TargetLoweringObjectFile {
228public:
229  virtual void Initialize(MCContext &Ctx, const TargetMachine &TM);
230
231  virtual void getSectionFlagsAsString(SectionKind Kind,
232                                       SmallVectorImpl<char> &Str) const;
233
234  virtual const MCSection *
235  SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
236                         Mangler *Mang, const TargetMachine &TM) const;
237};
238
239} // end namespace llvm
240
241#endif
242