TargetLoweringObjectFileImpl.cpp revision 4c6741f7078f3a9f655e67bf56bd4d5d427fc6bc 
1//===-- llvm/CodeGen/TargetLoweringObjectFileImpl.cpp - Object File Info --===//
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#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
16#include "llvm/Constants.h"
17#include "llvm/DerivedTypes.h"
18#include "llvm/Function.h"
19#include "llvm/GlobalVariable.h"
20#include "llvm/CodeGen/MachineModuleInfoImpls.h"
21#include "llvm/MC/MCContext.h"
22#include "llvm/MC/MCExpr.h"
23#include "llvm/MC/MCSectionMachO.h"
24#include "llvm/MC/MCSectionELF.h"
25#include "llvm/MC/MCSymbol.h"
26#include "llvm/Target/Mangler.h"
27#include "llvm/Target/TargetData.h"
28#include "llvm/Target/TargetMachine.h"
29#include "llvm/Target/TargetOptions.h"
30#include "llvm/Support/Dwarf.h"
31#include "llvm/Support/ErrorHandling.h"
32#include "llvm/Support/raw_ostream.h"
33#include "llvm/ADT/SmallString.h"
34#include "llvm/ADT/StringExtras.h"
35using namespace llvm;
36using namespace dwarf;
37
38//===----------------------------------------------------------------------===//
39//                                  ELF
40//===----------------------------------------------------------------------===//
41typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
42
43TargetLoweringObjectFileELF::~TargetLoweringObjectFileELF() {
44  // If we have the section uniquing map, free it.
45  delete (ELFUniqueMapTy*)UniquingMap;
46}
47
48const MCSection *TargetLoweringObjectFileELF::
49getELFSection(StringRef Section, unsigned Type, unsigned Flags,
50              SectionKind Kind, bool IsExplicit) const {
51  if (UniquingMap == 0)
52    UniquingMap = new ELFUniqueMapTy();
53  ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)UniquingMap;
54
55  // Do the lookup, if we have a hit, return it.
56  StringMapEntry<const MCSectionELF*> &Entry = Map.GetOrCreateValue(Section);
57  if (Entry.getValue()) return Entry.getValue();
58
59  MCSectionELF *Result = MCSectionELF::Create(Entry.getKey(), Type, Flags, Kind,
60                                              IsExplicit, getContext());
61  Entry.setValue(Result);
62  return Result;
63}
64
65void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
66                                             const TargetMachine &TM) {
67  if (UniquingMap != 0)
68    ((ELFUniqueMapTy*)UniquingMap)->clear();
69  TargetLoweringObjectFile::Initialize(Ctx, TM);
70
71  BSSSection =
72    getELFSection(".bss", MCSectionELF::SHT_NOBITS,
73                  MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
74                  SectionKind::getBSS());
75
76  TextSection =
77    getELFSection(".text", MCSectionELF::SHT_PROGBITS,
78                  MCSectionELF::SHF_EXECINSTR | MCSectionELF::SHF_ALLOC,
79                  SectionKind::getText());
80
81  DataSection =
82    getELFSection(".data", MCSectionELF::SHT_PROGBITS,
83                  MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
84                  SectionKind::getDataRel());
85
86  ReadOnlySection =
87    getELFSection(".rodata", MCSectionELF::SHT_PROGBITS,
88                  MCSectionELF::SHF_ALLOC,
89                  SectionKind::getReadOnly());
90
91  TLSDataSection =
92    getELFSection(".tdata", MCSectionELF::SHT_PROGBITS,
93                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
94                  MCSectionELF::SHF_WRITE, SectionKind::getThreadData());
95
96  TLSBSSSection =
97    getELFSection(".tbss", MCSectionELF::SHT_NOBITS,
98                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
99                  MCSectionELF::SHF_WRITE, SectionKind::getThreadBSS());
100
101  DataRelSection =
102    getELFSection(".data.rel", MCSectionELF::SHT_PROGBITS,
103                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
104                  SectionKind::getDataRel());
105
106  DataRelLocalSection =
107    getELFSection(".data.rel.local", MCSectionELF::SHT_PROGBITS,
108                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
109                  SectionKind::getDataRelLocal());
110
111  DataRelROSection =
112    getELFSection(".data.rel.ro", MCSectionELF::SHT_PROGBITS,
113                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
114                  SectionKind::getReadOnlyWithRel());
115
116  DataRelROLocalSection =
117    getELFSection(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS,
118                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
119                  SectionKind::getReadOnlyWithRelLocal());
120
121  MergeableConst4Section =
122    getELFSection(".rodata.cst4", MCSectionELF::SHT_PROGBITS,
123                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
124                  SectionKind::getMergeableConst4());
125
126  MergeableConst8Section =
127    getELFSection(".rodata.cst8", MCSectionELF::SHT_PROGBITS,
128                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
129                  SectionKind::getMergeableConst8());
130
131  MergeableConst16Section =
132    getELFSection(".rodata.cst16", MCSectionELF::SHT_PROGBITS,
133                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
134                  SectionKind::getMergeableConst16());
135
136  StaticCtorSection =
137    getELFSection(".ctors", MCSectionELF::SHT_PROGBITS,
138                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
139                  SectionKind::getDataRel());
140
141  StaticDtorSection =
142    getELFSection(".dtors", MCSectionELF::SHT_PROGBITS,
143                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
144                  SectionKind::getDataRel());
145
146  // Exception Handling Sections.
147
148  // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
149  // it contains relocatable pointers.  In PIC mode, this is probably a big
150  // runtime hit for C++ apps.  Either the contents of the LSDA need to be
151  // adjusted or this should be a data section.
152  LSDASection =
153    getELFSection(".gcc_except_table", MCSectionELF::SHT_PROGBITS,
154                  MCSectionELF::SHF_ALLOC, SectionKind::getReadOnly());
155  EHFrameSection =
156    getELFSection(".eh_frame", MCSectionELF::SHT_PROGBITS,
157                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
158                  SectionKind::getDataRel());
159
160  // Debug Info Sections.
161  DwarfAbbrevSection =
162    getELFSection(".debug_abbrev", MCSectionELF::SHT_PROGBITS, 0,
163                  SectionKind::getMetadata());
164  DwarfInfoSection =
165    getELFSection(".debug_info", MCSectionELF::SHT_PROGBITS, 0,
166                  SectionKind::getMetadata());
167  DwarfLineSection =
168    getELFSection(".debug_line", MCSectionELF::SHT_PROGBITS, 0,
169                  SectionKind::getMetadata());
170  DwarfFrameSection =
171    getELFSection(".debug_frame", MCSectionELF::SHT_PROGBITS, 0,
172                  SectionKind::getMetadata());
173  DwarfPubNamesSection =
174    getELFSection(".debug_pubnames", MCSectionELF::SHT_PROGBITS, 0,
175                  SectionKind::getMetadata());
176  DwarfPubTypesSection =
177    getELFSection(".debug_pubtypes", MCSectionELF::SHT_PROGBITS, 0,
178                  SectionKind::getMetadata());
179  DwarfStrSection =
180    getELFSection(".debug_str", MCSectionELF::SHT_PROGBITS, 0,
181                  SectionKind::getMetadata());
182  DwarfLocSection =
183    getELFSection(".debug_loc", MCSectionELF::SHT_PROGBITS, 0,
184                  SectionKind::getMetadata());
185  DwarfARangesSection =
186    getELFSection(".debug_aranges", MCSectionELF::SHT_PROGBITS, 0,
187                  SectionKind::getMetadata());
188  DwarfRangesSection =
189    getELFSection(".debug_ranges", MCSectionELF::SHT_PROGBITS, 0,
190                  SectionKind::getMetadata());
191  DwarfMacroInfoSection =
192    getELFSection(".debug_macinfo", MCSectionELF::SHT_PROGBITS, 0,
193                  SectionKind::getMetadata());
194}
195
196
197static SectionKind
198getELFKindForNamedSection(StringRef Name, SectionKind K) {
199  if (Name.empty() || Name[0] != '.') return K;
200
201  // Some lame default implementation based on some magic section names.
202  if (Name == ".bss" ||
203      Name.startswith(".bss.") ||
204      Name.startswith(".gnu.linkonce.b.") ||
205      Name.startswith(".llvm.linkonce.b.") ||
206      Name == ".sbss" ||
207      Name.startswith(".sbss.") ||
208      Name.startswith(".gnu.linkonce.sb.") ||
209      Name.startswith(".llvm.linkonce.sb."))
210    return SectionKind::getBSS();
211
212  if (Name == ".tdata" ||
213      Name.startswith(".tdata.") ||
214      Name.startswith(".gnu.linkonce.td.") ||
215      Name.startswith(".llvm.linkonce.td."))
216    return SectionKind::getThreadData();
217
218  if (Name == ".tbss" ||
219      Name.startswith(".tbss.") ||
220      Name.startswith(".gnu.linkonce.tb.") ||
221      Name.startswith(".llvm.linkonce.tb."))
222    return SectionKind::getThreadBSS();
223
224  return K;
225}
226
227
228static unsigned getELFSectionType(StringRef Name, SectionKind K) {
229
230  if (Name == ".init_array")
231    return MCSectionELF::SHT_INIT_ARRAY;
232
233  if (Name == ".fini_array")
234    return MCSectionELF::SHT_FINI_ARRAY;
235
236  if (Name == ".preinit_array")
237    return MCSectionELF::SHT_PREINIT_ARRAY;
238
239  if (K.isBSS() || K.isThreadBSS())
240    return MCSectionELF::SHT_NOBITS;
241
242  return MCSectionELF::SHT_PROGBITS;
243}
244
245
246static unsigned
247getELFSectionFlags(SectionKind K) {
248  unsigned Flags = 0;
249
250  if (!K.isMetadata())
251    Flags |= MCSectionELF::SHF_ALLOC;
252
253  if (K.isText())
254    Flags |= MCSectionELF::SHF_EXECINSTR;
255
256  if (K.isWriteable())
257    Flags |= MCSectionELF::SHF_WRITE;
258
259  if (K.isThreadLocal())
260    Flags |= MCSectionELF::SHF_TLS;
261
262  // K.isMergeableConst() is left out to honour PR4650
263  if (K.isMergeableCString() || K.isMergeableConst4() ||
264      K.isMergeableConst8() || K.isMergeableConst16())
265    Flags |= MCSectionELF::SHF_MERGE;
266
267  if (K.isMergeableCString())
268    Flags |= MCSectionELF::SHF_STRINGS;
269
270  return Flags;
271}
272
273
274const MCSection *TargetLoweringObjectFileELF::
275getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
276                         Mangler *Mang, const TargetMachine &TM) const {
277  StringRef SectionName = GV->getSection();
278
279  // Infer section flags from the section name if we can.
280  Kind = getELFKindForNamedSection(SectionName, Kind);
281
282  return getELFSection(SectionName,
283                       getELFSectionType(SectionName, Kind),
284                       getELFSectionFlags(Kind), Kind, true);
285}
286
287static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) {
288  if (Kind.isText())                 return ".gnu.linkonce.t.";
289  if (Kind.isReadOnly())             return ".gnu.linkonce.r.";
290
291  if (Kind.isThreadData())           return ".gnu.linkonce.td.";
292  if (Kind.isThreadBSS())            return ".gnu.linkonce.tb.";
293
294  if (Kind.isDataNoRel())            return ".gnu.linkonce.d.";
295  if (Kind.isDataRelLocal())         return ".gnu.linkonce.d.rel.local.";
296  if (Kind.isDataRel())              return ".gnu.linkonce.d.rel.";
297  if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local.";
298
299  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
300  return ".gnu.linkonce.d.rel.ro.";
301}
302
303const MCSection *TargetLoweringObjectFileELF::
304SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
305                       Mangler *Mang, const TargetMachine &TM) const {
306
307  // If this global is linkonce/weak and the target handles this by emitting it
308  // into a 'uniqued' section name, create and return the section now.
309  if (GV->isWeakForLinker() && !Kind.isCommon() && !Kind.isBSS()) {
310    const char *Prefix = getSectionPrefixForUniqueGlobal(Kind);
311    SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
312    MCSymbol *Sym = Mang->getSymbol(GV);
313    Name.append(Sym->getName().begin(), Sym->getName().end());
314    return getELFSection(Name.str(), getELFSectionType(Name.str(), Kind),
315                         getELFSectionFlags(Kind), Kind);
316  }
317
318  if (Kind.isText()) return TextSection;
319
320  if (Kind.isMergeable1ByteCString() ||
321      Kind.isMergeable2ByteCString() ||
322      Kind.isMergeable4ByteCString()) {
323
324    // We also need alignment here.
325    // FIXME: this is getting the alignment of the character, not the
326    // alignment of the global!
327    unsigned Align =
328      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
329
330    const char *SizeSpec = ".rodata.str1.";
331    if (Kind.isMergeable2ByteCString())
332      SizeSpec = ".rodata.str2.";
333    else if (Kind.isMergeable4ByteCString())
334      SizeSpec = ".rodata.str4.";
335    else
336      assert(Kind.isMergeable1ByteCString() && "unknown string width");
337
338
339    std::string Name = SizeSpec + utostr(Align);
340    return getELFSection(Name, MCSectionELF::SHT_PROGBITS,
341                         MCSectionELF::SHF_ALLOC |
342                         MCSectionELF::SHF_MERGE |
343                         MCSectionELF::SHF_STRINGS,
344                         Kind);
345  }
346
347  if (Kind.isMergeableConst()) {
348    if (Kind.isMergeableConst4() && MergeableConst4Section)
349      return MergeableConst4Section;
350    if (Kind.isMergeableConst8() && MergeableConst8Section)
351      return MergeableConst8Section;
352    if (Kind.isMergeableConst16() && MergeableConst16Section)
353      return MergeableConst16Section;
354    return ReadOnlySection;  // .const
355  }
356
357  if (Kind.isReadOnly())             return ReadOnlySection;
358
359  if (Kind.isThreadData())           return TLSDataSection;
360  if (Kind.isThreadBSS())            return TLSBSSSection;
361
362  // Note: we claim that common symbols are put in BSSSection, but they are
363  // really emitted with the magic .comm directive, which creates a symbol table
364  // entry but not a section.
365  if (Kind.isBSS() || Kind.isCommon()) return BSSSection;
366
367  if (Kind.isDataNoRel())            return DataSection;
368  if (Kind.isDataRelLocal())         return DataRelLocalSection;
369  if (Kind.isDataRel())              return DataRelSection;
370  if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
371
372  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
373  return DataRelROSection;
374}
375
376/// getSectionForConstant - Given a mergeable constant with the
377/// specified size and relocation information, return a section that it
378/// should be placed in.
379const MCSection *TargetLoweringObjectFileELF::
380getSectionForConstant(SectionKind Kind) const {
381  if (Kind.isMergeableConst4() && MergeableConst4Section)
382    return MergeableConst4Section;
383  if (Kind.isMergeableConst8() && MergeableConst8Section)
384    return MergeableConst8Section;
385  if (Kind.isMergeableConst16() && MergeableConst16Section)
386    return MergeableConst16Section;
387  if (Kind.isReadOnly())
388    return ReadOnlySection;
389
390  if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
391  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
392  return DataRelROSection;
393}
394
395const MCExpr *TargetLoweringObjectFileELF::
396getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
397                               MachineModuleInfo *MMI,
398                               unsigned Encoding, MCStreamer &Streamer) const {
399
400  if (Encoding & dwarf::DW_EH_PE_indirect) {
401    MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
402
403    SmallString<128> Name;
404    Mang->getNameWithPrefix(Name, GV, true);
405    Name += ".DW.stub";
406
407    // Add information about the stub reference to ELFMMI so that the stub
408    // gets emitted by the asmprinter.
409    MCSymbol *SSym = getContext().GetOrCreateTemporarySymbol(Name.str());
410    MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
411    if (StubSym.getPointer() == 0) {
412      MCSymbol *Sym = Mang->getSymbol(GV);
413      StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
414    }
415
416    return TargetLoweringObjectFile::
417      getExprForDwarfReference(SSym, Mang, MMI,
418                               Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
419  }
420
421  return TargetLoweringObjectFile::
422    getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
423}
424
425//===----------------------------------------------------------------------===//
426//                                 MachO
427//===----------------------------------------------------------------------===//
428
429typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
430
431TargetLoweringObjectFileMachO::~TargetLoweringObjectFileMachO() {
432  // If we have the MachO uniquing map, free it.
433  delete (MachOUniqueMapTy*)UniquingMap;
434}
435
436
437const MCSectionMachO *TargetLoweringObjectFileMachO::
438getMachOSection(StringRef Segment, StringRef Section,
439                unsigned TypeAndAttributes,
440                unsigned Reserved2, SectionKind Kind) const {
441  // We unique sections by their segment/section pair.  The returned section
442  // may not have the same flags as the requested section, if so this should be
443  // diagnosed by the client as an error.
444
445  // Create the map if it doesn't already exist.
446  if (UniquingMap == 0)
447    UniquingMap = new MachOUniqueMapTy();
448  MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)UniquingMap;
449
450  // Form the name to look up.
451  SmallString<64> Name;
452  Name += Segment;
453  Name.push_back(',');
454  Name += Section;
455
456  // Do the lookup, if we have a hit, return it.
457  const MCSectionMachO *&Entry = Map[Name.str()];
458  if (Entry) return Entry;
459
460  // Otherwise, return a new section.
461  return Entry = MCSectionMachO::Create(Segment, Section, TypeAndAttributes,
462                                        Reserved2, Kind, getContext());
463}
464
465
466void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
467                                               const TargetMachine &TM) {
468  // _foo.eh symbols are currently always exported so that the linker knows
469  // about them.  This is not necessary on 10.6 and later, but it
470  // doesn't hurt anything.
471  // FIXME: I need to get this from Triple.
472  IsFunctionEHSymbolGlobal = true;
473  IsFunctionEHFrameSymbolPrivate = false;
474  SupportsWeakOmittedEHFrame = false;
475
476  if (UniquingMap != 0)
477    ((MachOUniqueMapTy*)UniquingMap)->clear();
478  TargetLoweringObjectFile::Initialize(Ctx, TM);
479
480  TextSection // .text
481    = getMachOSection("__TEXT", "__text",
482                      MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
483                      SectionKind::getText());
484  DataSection // .data
485    = getMachOSection("__DATA", "__data", 0, SectionKind::getDataRel());
486
487  CStringSection // .cstring
488    = getMachOSection("__TEXT", "__cstring", MCSectionMachO::S_CSTRING_LITERALS,
489                      SectionKind::getMergeable1ByteCString());
490  UStringSection
491    = getMachOSection("__TEXT","__ustring", 0,
492                      SectionKind::getMergeable2ByteCString());
493  FourByteConstantSection // .literal4
494    = getMachOSection("__TEXT", "__literal4", MCSectionMachO::S_4BYTE_LITERALS,
495                      SectionKind::getMergeableConst4());
496  EightByteConstantSection // .literal8
497    = getMachOSection("__TEXT", "__literal8", MCSectionMachO::S_8BYTE_LITERALS,
498                      SectionKind::getMergeableConst8());
499
500  // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
501  // to using it in -static mode.
502  SixteenByteConstantSection = 0;
503  if (TM.getRelocationModel() != Reloc::Static &&
504      TM.getTargetData()->getPointerSize() == 32)
505    SixteenByteConstantSection =   // .literal16
506      getMachOSection("__TEXT", "__literal16",MCSectionMachO::S_16BYTE_LITERALS,
507                      SectionKind::getMergeableConst16());
508
509  ReadOnlySection  // .const
510    = getMachOSection("__TEXT", "__const", 0, SectionKind::getReadOnly());
511
512  TextCoalSection
513    = getMachOSection("__TEXT", "__textcoal_nt",
514                      MCSectionMachO::S_COALESCED |
515                      MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
516                      SectionKind::getText());
517  ConstTextCoalSection
518    = getMachOSection("__TEXT", "__const_coal", MCSectionMachO::S_COALESCED,
519                      SectionKind::getText());
520  ConstDataCoalSection
521    = getMachOSection("__DATA","__const_coal", MCSectionMachO::S_COALESCED,
522                      SectionKind::getText());
523  ConstDataSection  // .const_data
524    = getMachOSection("__DATA", "__const", 0,
525                      SectionKind::getReadOnlyWithRel());
526  DataCoalSection
527    = getMachOSection("__DATA","__datacoal_nt", MCSectionMachO::S_COALESCED,
528                      SectionKind::getDataRel());
529  DataCommonSection
530    = getMachOSection("__DATA","__common", MCSectionMachO::S_ZEROFILL,
531                      SectionKind::getBSS());
532  DataBSSSection
533    = getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL,
534                    SectionKind::getBSS());
535
536
537  LazySymbolPointerSection
538    = getMachOSection("__DATA", "__la_symbol_ptr",
539                      MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
540                      SectionKind::getMetadata());
541  NonLazySymbolPointerSection
542    = getMachOSection("__DATA", "__nl_symbol_ptr",
543                      MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
544                      SectionKind::getMetadata());
545
546  if (TM.getRelocationModel() == Reloc::Static) {
547    StaticCtorSection
548      = getMachOSection("__TEXT", "__constructor", 0,SectionKind::getDataRel());
549    StaticDtorSection
550      = getMachOSection("__TEXT", "__destructor", 0, SectionKind::getDataRel());
551  } else {
552    StaticCtorSection
553      = getMachOSection("__DATA", "__mod_init_func",
554                        MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
555                        SectionKind::getDataRel());
556    StaticDtorSection
557      = getMachOSection("__DATA", "__mod_term_func",
558                        MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
559                        SectionKind::getDataRel());
560  }
561
562  // Exception Handling.
563  LSDASection = getMachOSection("__DATA", "__gcc_except_tab", 0,
564                                SectionKind::getDataRel());
565  EHFrameSection =
566    getMachOSection("__TEXT", "__eh_frame",
567                    MCSectionMachO::S_COALESCED |
568                    MCSectionMachO::S_ATTR_NO_TOC |
569                    MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
570                    MCSectionMachO::S_ATTR_LIVE_SUPPORT,
571                    SectionKind::getReadOnly());
572
573  // Debug Information.
574  DwarfAbbrevSection =
575    getMachOSection("__DWARF", "__debug_abbrev", MCSectionMachO::S_ATTR_DEBUG,
576                    SectionKind::getMetadata());
577  DwarfInfoSection =
578    getMachOSection("__DWARF", "__debug_info", MCSectionMachO::S_ATTR_DEBUG,
579                    SectionKind::getMetadata());
580  DwarfLineSection =
581    getMachOSection("__DWARF", "__debug_line", MCSectionMachO::S_ATTR_DEBUG,
582                    SectionKind::getMetadata());
583  DwarfFrameSection =
584    getMachOSection("__DWARF", "__debug_frame", MCSectionMachO::S_ATTR_DEBUG,
585                    SectionKind::getMetadata());
586  DwarfPubNamesSection =
587    getMachOSection("__DWARF", "__debug_pubnames", MCSectionMachO::S_ATTR_DEBUG,
588                    SectionKind::getMetadata());
589  DwarfPubTypesSection =
590    getMachOSection("__DWARF", "__debug_pubtypes", MCSectionMachO::S_ATTR_DEBUG,
591                    SectionKind::getMetadata());
592  DwarfStrSection =
593    getMachOSection("__DWARF", "__debug_str", MCSectionMachO::S_ATTR_DEBUG,
594                    SectionKind::getMetadata());
595  DwarfLocSection =
596    getMachOSection("__DWARF", "__debug_loc", MCSectionMachO::S_ATTR_DEBUG,
597                    SectionKind::getMetadata());
598  DwarfARangesSection =
599    getMachOSection("__DWARF", "__debug_aranges", MCSectionMachO::S_ATTR_DEBUG,
600                    SectionKind::getMetadata());
601  DwarfRangesSection =
602    getMachOSection("__DWARF", "__debug_ranges", MCSectionMachO::S_ATTR_DEBUG,
603                    SectionKind::getMetadata());
604  DwarfMacroInfoSection =
605    getMachOSection("__DWARF", "__debug_macinfo", MCSectionMachO::S_ATTR_DEBUG,
606                    SectionKind::getMetadata());
607  DwarfDebugInlineSection =
608    getMachOSection("__DWARF", "__debug_inlined", MCSectionMachO::S_ATTR_DEBUG,
609                    SectionKind::getMetadata());
610}
611
612const MCSection *TargetLoweringObjectFileMachO::
613getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
614                         Mangler *Mang, const TargetMachine &TM) const {
615  // Parse the section specifier and create it if valid.
616  StringRef Segment, Section;
617  unsigned TAA, StubSize;
618  std::string ErrorCode =
619    MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
620                                          TAA, StubSize);
621  if (!ErrorCode.empty()) {
622    // If invalid, report the error with llvm_report_error.
623    llvm_report_error("Global variable '" + GV->getNameStr() +
624                      "' has an invalid section specifier '" + GV->getSection()+
625                      "': " + ErrorCode + ".");
626    // Fall back to dropping it into the data section.
627    return DataSection;
628  }
629
630  // Get the section.
631  const MCSectionMachO *S =
632    getMachOSection(Segment, Section, TAA, StubSize, Kind);
633
634  // Okay, now that we got the section, verify that the TAA & StubSize agree.
635  // If the user declared multiple globals with different section flags, we need
636  // to reject it here.
637  if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
638    // If invalid, report the error with llvm_report_error.
639    llvm_report_error("Global variable '" + GV->getNameStr() +
640                      "' section type or attributes does not match previous"
641                      " section specifier");
642  }
643
644  return S;
645}
646
647const MCSection *TargetLoweringObjectFileMachO::
648SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
649                       Mangler *Mang, const TargetMachine &TM) const {
650  assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS");
651
652  if (Kind.isText())
653    return GV->isWeakForLinker() ? TextCoalSection : TextSection;
654
655  // If this is weak/linkonce, put this in a coalescable section, either in text
656  // or data depending on if it is writable.
657  if (GV->isWeakForLinker()) {
658    if (Kind.isReadOnly())
659      return ConstTextCoalSection;
660    return DataCoalSection;
661  }
662
663  // FIXME: Alignment check should be handled by section classifier.
664  if (Kind.isMergeable1ByteCString() &&
665      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
666    return CStringSection;
667
668  // Do not put 16-bit arrays in the UString section if they have an
669  // externally visible label, this runs into issues with certain linker
670  // versions.
671  if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
672      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
673    return UStringSection;
674
675  if (Kind.isMergeableConst()) {
676    if (Kind.isMergeableConst4())
677      return FourByteConstantSection;
678    if (Kind.isMergeableConst8())
679      return EightByteConstantSection;
680    if (Kind.isMergeableConst16() && SixteenByteConstantSection)
681      return SixteenByteConstantSection;
682  }
683
684  // Otherwise, if it is readonly, but not something we can specially optimize,
685  // just drop it in .const.
686  if (Kind.isReadOnly())
687    return ReadOnlySection;
688
689  // If this is marked const, put it into a const section.  But if the dynamic
690  // linker needs to write to it, put it in the data segment.
691  if (Kind.isReadOnlyWithRel())
692    return ConstDataSection;
693
694  // Put zero initialized globals with strong external linkage in the
695  // DATA, __common section with the .zerofill directive.
696  if (Kind.isBSSExtern())
697    return DataCommonSection;
698
699  // Put zero initialized globals with local linkage in __DATA,__bss directive
700  // with the .zerofill directive (aka .lcomm).
701  if (Kind.isBSSLocal())
702    return DataBSSSection;
703
704  // Otherwise, just drop the variable in the normal data section.
705  return DataSection;
706}
707
708const MCSection *
709TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
710  // If this constant requires a relocation, we have to put it in the data
711  // segment, not in the text segment.
712  if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
713    return ConstDataSection;
714
715  if (Kind.isMergeableConst4())
716    return FourByteConstantSection;
717  if (Kind.isMergeableConst8())
718    return EightByteConstantSection;
719  if (Kind.isMergeableConst16() && SixteenByteConstantSection)
720    return SixteenByteConstantSection;
721  return ReadOnlySection;  // .const
722}
723
724/// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
725/// not to emit the UsedDirective for some symbols in llvm.used.
726// FIXME: REMOVE this (rdar://7071300)
727bool TargetLoweringObjectFileMachO::
728shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
729  /// On Darwin, internally linked data beginning with "L" or "l" does not have
730  /// the directive emitted (this occurs in ObjC metadata).
731  if (!GV) return false;
732
733  // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
734  if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
735    // FIXME: ObjC metadata is currently emitted as internal symbols that have
736    // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
737    // this horrible hack can go away.
738    MCSymbol *Sym = Mang->getSymbol(GV);
739    if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
740      return false;
741  }
742
743  return true;
744}
745
746const MCExpr *TargetLoweringObjectFileMachO::
747getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
748                               MachineModuleInfo *MMI, unsigned Encoding,
749                               MCStreamer &Streamer) const {
750  // The mach-o version of this method defaults to returning a stub reference.
751
752  if (Encoding & DW_EH_PE_indirect) {
753    MachineModuleInfoMachO &MachOMMI =
754      MMI->getObjFileInfo<MachineModuleInfoMachO>();
755
756    SmallString<128> Name;
757    Mang->getNameWithPrefix(Name, GV, true);
758    Name += "$non_lazy_ptr";
759
760    // Add information about the stub reference to MachOMMI so that the stub
761    // gets emitted by the asmprinter.
762    MCSymbol *SSym = getContext().GetOrCreateTemporarySymbol(Name.str());
763    MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
764    if (StubSym.getPointer() == 0) {
765      MCSymbol *Sym = Mang->getSymbol(GV);
766      StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
767    }
768
769    return TargetLoweringObjectFile::
770      getExprForDwarfReference(SSym, Mang, MMI,
771                               Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
772  }
773
774  return TargetLoweringObjectFile::
775    getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
776}
777
778unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const {
779  return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
780}
781
782unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const {
783  return DW_EH_PE_pcrel;
784}
785
786unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const {
787  return DW_EH_PE_pcrel;
788}
789
790unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const {
791  return DW_EH_PE_absptr;
792}
793
794//===----------------------------------------------------------------------===//
795//                                  COFF
796//===----------------------------------------------------------------------===//
797
798typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
799
800TargetLoweringObjectFileCOFF::~TargetLoweringObjectFileCOFF() {
801  delete (COFFUniqueMapTy*)UniquingMap;
802}
803
804
805const MCSection *TargetLoweringObjectFileCOFF::
806getCOFFSection(StringRef Name, bool isDirective, SectionKind Kind) const {
807  // Create the map if it doesn't already exist.
808  if (UniquingMap == 0)
809    UniquingMap = new MachOUniqueMapTy();
810  COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)UniquingMap;
811
812  // Do the lookup, if we have a hit, return it.
813  const MCSectionCOFF *&Entry = Map[Name];
814  if (Entry) return Entry;
815
816  return Entry = MCSectionCOFF::Create(Name, isDirective, Kind, getContext());
817}
818
819void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
820                                              const TargetMachine &TM) {
821  if (UniquingMap != 0)
822    ((COFFUniqueMapTy*)UniquingMap)->clear();
823  TargetLoweringObjectFile::Initialize(Ctx, TM);
824  TextSection = getCOFFSection("\t.text", true, SectionKind::getText());
825  DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel());
826  StaticCtorSection =
827    getCOFFSection(".ctors", false, SectionKind::getDataRel());
828  StaticDtorSection =
829    getCOFFSection(".dtors", false, SectionKind::getDataRel());
830
831  // FIXME: We're emitting LSDA info into a readonly section on COFF, even
832  // though it contains relocatable pointers.  In PIC mode, this is probably a
833  // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
834  // adjusted or this should be a data section.
835  LSDASection =
836    getCOFFSection(".gcc_except_table", false, SectionKind::getReadOnly());
837  EHFrameSection =
838    getCOFFSection(".eh_frame", false, SectionKind::getDataRel());
839
840  // Debug info.
841  // FIXME: Don't use 'directive' mode here.
842  DwarfAbbrevSection =
843    getCOFFSection("\t.section\t.debug_abbrev,\"dr\"",
844                   true, SectionKind::getMetadata());
845  DwarfInfoSection =
846    getCOFFSection("\t.section\t.debug_info,\"dr\"",
847                   true, SectionKind::getMetadata());
848  DwarfLineSection =
849    getCOFFSection("\t.section\t.debug_line,\"dr\"",
850                   true, SectionKind::getMetadata());
851  DwarfFrameSection =
852    getCOFFSection("\t.section\t.debug_frame,\"dr\"",
853                   true, SectionKind::getMetadata());
854  DwarfPubNamesSection =
855    getCOFFSection("\t.section\t.debug_pubnames,\"dr\"",
856                   true, SectionKind::getMetadata());
857  DwarfPubTypesSection =
858    getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"",
859                   true, SectionKind::getMetadata());
860  DwarfStrSection =
861    getCOFFSection("\t.section\t.debug_str,\"dr\"",
862                   true, SectionKind::getMetadata());
863  DwarfLocSection =
864    getCOFFSection("\t.section\t.debug_loc,\"dr\"",
865                   true, SectionKind::getMetadata());
866  DwarfARangesSection =
867    getCOFFSection("\t.section\t.debug_aranges,\"dr\"",
868                   true, SectionKind::getMetadata());
869  DwarfRangesSection =
870    getCOFFSection("\t.section\t.debug_ranges,\"dr\"",
871                   true, SectionKind::getMetadata());
872  DwarfMacroInfoSection =
873    getCOFFSection("\t.section\t.debug_macinfo,\"dr\"",
874                   true, SectionKind::getMetadata());
875}
876
877const MCSection *TargetLoweringObjectFileCOFF::
878getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
879                         Mangler *Mang, const TargetMachine &TM) const {
880  return getCOFFSection(GV->getSection(), false, Kind);
881}
882
883static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
884  if (Kind.isText())
885    return ".text$linkonce";
886  if (Kind.isWriteable())
887    return ".data$linkonce";
888  return ".rdata$linkonce";
889}
890
891
892const MCSection *TargetLoweringObjectFileCOFF::
893SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
894                       Mangler *Mang, const TargetMachine &TM) const {
895  assert(!Kind.isThreadLocal() && "Doesn't support TLS");
896
897  // If this global is linkonce/weak and the target handles this by emitting it
898  // into a 'uniqued' section name, create and return the section now.
899  if (GV->isWeakForLinker()) {
900    const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
901    SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
902    MCSymbol *Sym = Mang->getSymbol(GV);
903    Name.append(Sym->getName().begin(), Sym->getName().end());
904    return getCOFFSection(Name.str(), false, Kind);
905  }
906
907  if (Kind.isText())
908    return getTextSection();
909
910  return getDataSection();
911}
912
913