TargetLoweringObjectFileImpl.cpp revision ca5b752d1873707c5c7d846515998ccf5002edca 
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/Module.h"
21#include "llvm/CodeGen/MachineModuleInfoImpls.h"
22#include "llvm/MC/MCContext.h"
23#include "llvm/MC/MCExpr.h"
24#include "llvm/MC/MCSectionMachO.h"
25#include "llvm/MC/MCSectionELF.h"
26#include "llvm/MC/MCSectionCOFF.h"
27#include "llvm/MC/MCStreamer.h"
28#include "llvm/MC/MCSymbol.h"
29#include "llvm/Target/Mangler.h"
30#include "llvm/Target/TargetData.h"
31#include "llvm/Target/TargetMachine.h"
32#include "llvm/Target/TargetOptions.h"
33#include "llvm/Support/Dwarf.h"
34#include "llvm/Support/ELF.h"
35#include "llvm/Support/ErrorHandling.h"
36#include "llvm/Support/raw_ostream.h"
37#include "llvm/ADT/SmallString.h"
38#include "llvm/ADT/StringExtras.h"
39#include "llvm/ADT/Triple.h"
40using namespace llvm;
41using namespace dwarf;
42
43//===----------------------------------------------------------------------===//
44//                                  ELF
45//===----------------------------------------------------------------------===//
46
47MCSymbol *
48TargetLoweringObjectFileELF::getCFIPersonalitySymbol(const GlobalValue *GV,
49                                                     Mangler *Mang,
50                                                MachineModuleInfo *MMI) const {
51  unsigned Encoding = getPersonalityEncoding();
52  switch (Encoding & 0x70) {
53  default:
54    report_fatal_error("We do not support this DWARF encoding yet!");
55  case dwarf::DW_EH_PE_absptr:
56    return  Mang->getSymbol(GV);
57  case dwarf::DW_EH_PE_pcrel: {
58    return getContext().GetOrCreateSymbol(StringRef("DW.ref.") +
59                                          Mang->getSymbol(GV)->getName());
60  }
61  }
62}
63
64void TargetLoweringObjectFileELF::emitPersonalityValue(MCStreamer &Streamer,
65                                                       const TargetMachine &TM,
66                                                       const MCSymbol *Sym) const {
67  SmallString<64> NameData("DW.ref.");
68  NameData += Sym->getName();
69  MCSymbol *Label = getContext().GetOrCreateSymbol(NameData);
70  Streamer.EmitSymbolAttribute(Label, MCSA_Hidden);
71  Streamer.EmitSymbolAttribute(Label, MCSA_Weak);
72  StringRef Prefix = ".data.";
73  NameData.insert(NameData.begin(), Prefix.begin(), Prefix.end());
74  unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP;
75  const MCSection *Sec = getContext().getELFSection(NameData,
76                                                    ELF::SHT_PROGBITS,
77                                                    Flags,
78                                                    SectionKind::getDataRel(),
79                                                    0, Label->getName());
80  unsigned Size = TM.getTargetData()->getPointerSize();
81  Streamer.SwitchSection(Sec);
82  Streamer.EmitValueToAlignment(Size);
83  Streamer.EmitSymbolAttribute(Label, MCSA_ELF_TypeObject);
84  const MCExpr *E = MCConstantExpr::Create(Size, getContext());
85  Streamer.EmitELFSize(Label, E);
86  Streamer.EmitLabel(Label);
87
88  Streamer.EmitSymbolValue(Sym, Size);
89}
90
91static SectionKind
92getELFKindForNamedSection(StringRef Name, SectionKind K) {
93  // N.B.: The defaults used in here are no the same ones used in MC.
94  // We follow gcc, MC follows gas. For example, given ".section .eh_frame",
95  // both gas and MC will produce a section with no flags. Given
96  // section(".eh_frame") gcc will produce
97  // .section	.eh_frame,"a",@progbits
98  if (Name.empty() || Name[0] != '.') return K;
99
100  // Some lame default implementation based on some magic section names.
101  if (Name == ".bss" ||
102      Name.startswith(".bss.") ||
103      Name.startswith(".gnu.linkonce.b.") ||
104      Name.startswith(".llvm.linkonce.b.") ||
105      Name == ".sbss" ||
106      Name.startswith(".sbss.") ||
107      Name.startswith(".gnu.linkonce.sb.") ||
108      Name.startswith(".llvm.linkonce.sb."))
109    return SectionKind::getBSS();
110
111  if (Name == ".tdata" ||
112      Name.startswith(".tdata.") ||
113      Name.startswith(".gnu.linkonce.td.") ||
114      Name.startswith(".llvm.linkonce.td."))
115    return SectionKind::getThreadData();
116
117  if (Name == ".tbss" ||
118      Name.startswith(".tbss.") ||
119      Name.startswith(".gnu.linkonce.tb.") ||
120      Name.startswith(".llvm.linkonce.tb."))
121    return SectionKind::getThreadBSS();
122
123  return K;
124}
125
126
127static unsigned getELFSectionType(StringRef Name, SectionKind K) {
128
129  if (Name == ".init_array")
130    return ELF::SHT_INIT_ARRAY;
131
132  if (Name == ".fini_array")
133    return ELF::SHT_FINI_ARRAY;
134
135  if (Name == ".preinit_array")
136    return ELF::SHT_PREINIT_ARRAY;
137
138  if (K.isBSS() || K.isThreadBSS())
139    return ELF::SHT_NOBITS;
140
141  return ELF::SHT_PROGBITS;
142}
143
144
145static unsigned
146getELFSectionFlags(SectionKind K) {
147  unsigned Flags = 0;
148
149  if (!K.isMetadata())
150    Flags |= ELF::SHF_ALLOC;
151
152  if (K.isText())
153    Flags |= ELF::SHF_EXECINSTR;
154
155  if (K.isWriteable())
156    Flags |= ELF::SHF_WRITE;
157
158  if (K.isThreadLocal())
159    Flags |= ELF::SHF_TLS;
160
161  // K.isMergeableConst() is left out to honour PR4650
162  if (K.isMergeableCString() || K.isMergeableConst4() ||
163      K.isMergeableConst8() || K.isMergeableConst16())
164    Flags |= ELF::SHF_MERGE;
165
166  if (K.isMergeableCString())
167    Flags |= ELF::SHF_STRINGS;
168
169  return Flags;
170}
171
172
173const MCSection *TargetLoweringObjectFileELF::
174getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
175                         Mangler *Mang, const TargetMachine &TM) const {
176  StringRef SectionName = GV->getSection();
177
178  // Infer section flags from the section name if we can.
179  Kind = getELFKindForNamedSection(SectionName, Kind);
180
181  return getContext().getELFSection(SectionName,
182                                    getELFSectionType(SectionName, Kind),
183                                    getELFSectionFlags(Kind), Kind);
184}
185
186/// getSectionPrefixForGlobal - Return the section prefix name used by options
187/// FunctionsSections and DataSections.
188static const char *getSectionPrefixForGlobal(SectionKind Kind) {
189  if (Kind.isText())                 return ".text.";
190  if (Kind.isReadOnly())             return ".rodata.";
191
192  if (Kind.isThreadData())           return ".tdata.";
193  if (Kind.isThreadBSS())            return ".tbss.";
194
195  if (Kind.isDataNoRel())            return ".data.";
196  if (Kind.isDataRelLocal())         return ".data.rel.local.";
197  if (Kind.isDataRel())              return ".data.rel.";
198  if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local.";
199
200  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
201  return ".data.rel.ro.";
202}
203
204
205const MCSection *TargetLoweringObjectFileELF::
206SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
207                       Mangler *Mang, const TargetMachine &TM) const {
208  // If we have -ffunction-section or -fdata-section then we should emit the
209  // global value to a uniqued section specifically for it.
210  bool EmitUniquedSection;
211  if (Kind.isText())
212    EmitUniquedSection = TM.getFunctionSections();
213  else
214    EmitUniquedSection = TM.getDataSections();
215
216  // If this global is linkonce/weak and the target handles this by emitting it
217  // into a 'uniqued' section name, create and return the section now.
218  if ((GV->isWeakForLinker() || EmitUniquedSection) &&
219      !Kind.isCommon() && !Kind.isBSS()) {
220    const char *Prefix;
221    Prefix = getSectionPrefixForGlobal(Kind);
222
223    SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
224    MCSymbol *Sym = Mang->getSymbol(GV);
225    Name.append(Sym->getName().begin(), Sym->getName().end());
226    StringRef Group = "";
227    unsigned Flags = getELFSectionFlags(Kind);
228    if (GV->isWeakForLinker()) {
229      Group = Sym->getName();
230      Flags |= ELF::SHF_GROUP;
231    }
232
233    return getContext().getELFSection(Name.str(),
234                                      getELFSectionType(Name.str(), Kind),
235                                      Flags, Kind, 0, Group);
236  }
237
238  if (Kind.isText()) return TextSection;
239
240  if (Kind.isMergeable1ByteCString() ||
241      Kind.isMergeable2ByteCString() ||
242      Kind.isMergeable4ByteCString()) {
243
244    // We also need alignment here.
245    // FIXME: this is getting the alignment of the character, not the
246    // alignment of the global!
247    unsigned Align =
248      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
249
250    const char *SizeSpec = ".rodata.str1.";
251    if (Kind.isMergeable2ByteCString())
252      SizeSpec = ".rodata.str2.";
253    else if (Kind.isMergeable4ByteCString())
254      SizeSpec = ".rodata.str4.";
255    else
256      assert(Kind.isMergeable1ByteCString() && "unknown string width");
257
258
259    std::string Name = SizeSpec + utostr(Align);
260    return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
261                                      ELF::SHF_ALLOC |
262                                      ELF::SHF_MERGE |
263                                      ELF::SHF_STRINGS,
264                                      Kind);
265  }
266
267  if (Kind.isMergeableConst()) {
268    if (Kind.isMergeableConst4() && MergeableConst4Section)
269      return MergeableConst4Section;
270    if (Kind.isMergeableConst8() && MergeableConst8Section)
271      return MergeableConst8Section;
272    if (Kind.isMergeableConst16() && MergeableConst16Section)
273      return MergeableConst16Section;
274    return ReadOnlySection;  // .const
275  }
276
277  if (Kind.isReadOnly())             return ReadOnlySection;
278
279  if (Kind.isThreadData())           return TLSDataSection;
280  if (Kind.isThreadBSS())            return TLSBSSSection;
281
282  // Note: we claim that common symbols are put in BSSSection, but they are
283  // really emitted with the magic .comm directive, which creates a symbol table
284  // entry but not a section.
285  if (Kind.isBSS() || Kind.isCommon()) return BSSSection;
286
287  if (Kind.isDataNoRel())            return DataSection;
288  if (Kind.isDataRelLocal())         return DataRelLocalSection;
289  if (Kind.isDataRel())              return DataRelSection;
290  if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
291
292  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
293  return DataRelROSection;
294}
295
296/// getSectionForConstant - Given a mergeable constant with the
297/// specified size and relocation information, return a section that it
298/// should be placed in.
299const MCSection *TargetLoweringObjectFileELF::
300getSectionForConstant(SectionKind Kind) const {
301  if (Kind.isMergeableConst4() && MergeableConst4Section)
302    return MergeableConst4Section;
303  if (Kind.isMergeableConst8() && MergeableConst8Section)
304    return MergeableConst8Section;
305  if (Kind.isMergeableConst16() && MergeableConst16Section)
306    return MergeableConst16Section;
307  if (Kind.isReadOnly())
308    return ReadOnlySection;
309
310  if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
311  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
312  return DataRelROSection;
313}
314
315const MCExpr *TargetLoweringObjectFileELF::
316getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
317                               MachineModuleInfo *MMI,
318                               unsigned Encoding, MCStreamer &Streamer) const {
319
320  if (Encoding & dwarf::DW_EH_PE_indirect) {
321    MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
322
323    SmallString<128> Name;
324    Mang->getNameWithPrefix(Name, GV, true);
325    Name += ".DW.stub";
326
327    // Add information about the stub reference to ELFMMI so that the stub
328    // gets emitted by the asmprinter.
329    MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
330    MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
331    if (StubSym.getPointer() == 0) {
332      MCSymbol *Sym = Mang->getSymbol(GV);
333      StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
334    }
335
336    return TargetLoweringObjectFile::
337      getExprForDwarfReference(SSym, Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
338  }
339
340  return TargetLoweringObjectFile::
341    getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
342}
343
344const MCSection *
345TargetLoweringObjectFileELF::getStaticCtorSection(unsigned Priority) const {
346  // The default scheme is .ctor / .dtor, so we have to invert the priority
347  // numbering.
348  if (Priority == 65535)
349    return StaticCtorSection;
350
351  std::string Name = std::string(".ctors.") + utostr(65535 - Priority);
352  return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
353                                    ELF::SHF_ALLOC |ELF::SHF_WRITE,
354                                    SectionKind::getDataRel());
355}
356
357const MCSection *
358TargetLoweringObjectFileELF::getStaticDtorSection(unsigned Priority) const {
359  // The default scheme is .ctor / .dtor, so we have to invert the priority
360  // numbering.
361  if (Priority == 65535)
362    return StaticDtorSection;
363
364  std::string Name = std::string(".dtors.") + utostr(65535 - Priority);
365  return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
366                                    ELF::SHF_ALLOC |ELF::SHF_WRITE,
367                                    SectionKind::getDataRel());
368}
369
370//===----------------------------------------------------------------------===//
371//                                 MachO
372//===----------------------------------------------------------------------===//
373
374/// emitModuleFlags - Emit the module flags that specify the garbage collection
375/// information.
376void TargetLoweringObjectFileMachO::
377emitModuleFlags(MCStreamer &Streamer,
378                ArrayRef<Module::ModuleFlagEntry> ModuleFlags,
379                Mangler *Mang, const TargetMachine &TM) const {
380  unsigned VersionVal = 0;
381  unsigned GCFlags = 0;
382  StringRef SectionVal;
383
384  for (ArrayRef<Module::ModuleFlagEntry>::iterator
385         i = ModuleFlags.begin(), e = ModuleFlags.end(); i != e; ++i) {
386    const Module::ModuleFlagEntry &MFE = *i;
387
388    // Ignore flags with 'Require' behavior.
389    if (MFE.Behavior == Module::Require)
390      continue;
391
392    StringRef Key = MFE.Key->getString();
393    Value *Val = MFE.Val;
394
395    if (Key == "Objective-C Image Info Version")
396      VersionVal = cast<ConstantInt>(Val)->getZExtValue();
397    else if (Key == "Objective-C Garbage Collection" ||
398             Key == "Objective-C GC Only")
399      GCFlags |= cast<ConstantInt>(Val)->getZExtValue();
400    else if (Key == "Objective-C Image Info Section")
401      SectionVal = cast<MDString>(Val)->getString();
402  }
403
404  // The section is mandatory. If we don't have it, then we don't have GC info.
405  if (SectionVal.empty()) return;
406
407  StringRef Segment, Section;
408  unsigned TAA = 0, StubSize = 0;
409  bool TAAParsed;
410  std::string ErrorCode =
411    MCSectionMachO::ParseSectionSpecifier(SectionVal, Segment, Section,
412                                          TAA, TAAParsed, StubSize);
413  if (!ErrorCode.empty())
414    // If invalid, report the error with report_fatal_error.
415    report_fatal_error("Invalid section specifier '" + Section + "': " +
416                       ErrorCode + ".");
417
418  // Get the section.
419  const MCSectionMachO *S =
420    getContext().getMachOSection(Segment, Section, TAA, StubSize,
421                                 SectionKind::getDataNoRel());
422  Streamer.SwitchSection(S);
423  Streamer.EmitLabel(getContext().
424                     GetOrCreateSymbol(StringRef("L_OBJC_IMAGE_INFO")));
425  Streamer.EmitIntValue(VersionVal, 4);
426  Streamer.EmitIntValue(GCFlags, 4);
427  Streamer.AddBlankLine();
428}
429
430const MCSection *TargetLoweringObjectFileMachO::
431getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
432                         Mangler *Mang, const TargetMachine &TM) const {
433  // Parse the section specifier and create it if valid.
434  StringRef Segment, Section;
435  unsigned TAA = 0, StubSize = 0;
436  bool TAAParsed;
437  std::string ErrorCode =
438    MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
439                                          TAA, TAAParsed, StubSize);
440  if (!ErrorCode.empty()) {
441    // If invalid, report the error with report_fatal_error.
442    report_fatal_error("Global variable '" + GV->getName() +
443                       "' has an invalid section specifier '" +
444                       GV->getSection() + "': " + ErrorCode + ".");
445  }
446
447  // Get the section.
448  const MCSectionMachO *S =
449    getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
450
451  // If TAA wasn't set by ParseSectionSpecifier() above,
452  // use the value returned by getMachOSection() as a default.
453  if (!TAAParsed)
454    TAA = S->getTypeAndAttributes();
455
456  // Okay, now that we got the section, verify that the TAA & StubSize agree.
457  // If the user declared multiple globals with different section flags, we need
458  // to reject it here.
459  if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
460    // If invalid, report the error with report_fatal_error.
461    report_fatal_error("Global variable '" + GV->getName() +
462                       "' section type or attributes does not match previous"
463                       " section specifier");
464  }
465
466  return S;
467}
468
469const MCSection *TargetLoweringObjectFileMachO::
470SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
471                       Mangler *Mang, const TargetMachine &TM) const {
472
473  // Handle thread local data.
474  if (Kind.isThreadBSS()) return TLSBSSSection;
475  if (Kind.isThreadData()) return TLSDataSection;
476
477  if (Kind.isText())
478    return GV->isWeakForLinker() ? TextCoalSection : TextSection;
479
480  // If this is weak/linkonce, put this in a coalescable section, either in text
481  // or data depending on if it is writable.
482  if (GV->isWeakForLinker()) {
483    if (Kind.isReadOnly())
484      return ConstTextCoalSection;
485    return DataCoalSection;
486  }
487
488  // FIXME: Alignment check should be handled by section classifier.
489  if (Kind.isMergeable1ByteCString() &&
490      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
491    return CStringSection;
492
493  // Do not put 16-bit arrays in the UString section if they have an
494  // externally visible label, this runs into issues with certain linker
495  // versions.
496  if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
497      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
498    return UStringSection;
499
500  if (Kind.isMergeableConst()) {
501    if (Kind.isMergeableConst4())
502      return FourByteConstantSection;
503    if (Kind.isMergeableConst8())
504      return EightByteConstantSection;
505    if (Kind.isMergeableConst16() && SixteenByteConstantSection)
506      return SixteenByteConstantSection;
507  }
508
509  // Otherwise, if it is readonly, but not something we can specially optimize,
510  // just drop it in .const.
511  if (Kind.isReadOnly())
512    return ReadOnlySection;
513
514  // If this is marked const, put it into a const section.  But if the dynamic
515  // linker needs to write to it, put it in the data segment.
516  if (Kind.isReadOnlyWithRel())
517    return ConstDataSection;
518
519  // Put zero initialized globals with strong external linkage in the
520  // DATA, __common section with the .zerofill directive.
521  if (Kind.isBSSExtern())
522    return DataCommonSection;
523
524  // Put zero initialized globals with local linkage in __DATA,__bss directive
525  // with the .zerofill directive (aka .lcomm).
526  if (Kind.isBSSLocal())
527    return DataBSSSection;
528
529  // Otherwise, just drop the variable in the normal data section.
530  return DataSection;
531}
532
533const MCSection *
534TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
535  // If this constant requires a relocation, we have to put it in the data
536  // segment, not in the text segment.
537  if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
538    return ConstDataSection;
539
540  if (Kind.isMergeableConst4())
541    return FourByteConstantSection;
542  if (Kind.isMergeableConst8())
543    return EightByteConstantSection;
544  if (Kind.isMergeableConst16() && SixteenByteConstantSection)
545    return SixteenByteConstantSection;
546  return ReadOnlySection;  // .const
547}
548
549/// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
550/// not to emit the UsedDirective for some symbols in llvm.used.
551// FIXME: REMOVE this (rdar://7071300)
552bool TargetLoweringObjectFileMachO::
553shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
554  /// On Darwin, internally linked data beginning with "L" or "l" does not have
555  /// the directive emitted (this occurs in ObjC metadata).
556  if (!GV) return false;
557
558  // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
559  if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
560    // FIXME: ObjC metadata is currently emitted as internal symbols that have
561    // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
562    // this horrible hack can go away.
563    MCSymbol *Sym = Mang->getSymbol(GV);
564    if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
565      return false;
566  }
567
568  return true;
569}
570
571const MCExpr *TargetLoweringObjectFileMachO::
572getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
573                               MachineModuleInfo *MMI, unsigned Encoding,
574                               MCStreamer &Streamer) const {
575  // The mach-o version of this method defaults to returning a stub reference.
576
577  if (Encoding & DW_EH_PE_indirect) {
578    MachineModuleInfoMachO &MachOMMI =
579      MMI->getObjFileInfo<MachineModuleInfoMachO>();
580
581    SmallString<128> Name;
582    Mang->getNameWithPrefix(Name, GV, true);
583    Name += "$non_lazy_ptr";
584
585    // Add information about the stub reference to MachOMMI so that the stub
586    // gets emitted by the asmprinter.
587    MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
588    MachineModuleInfoImpl::StubValueTy &StubSym =
589      GV->hasHiddenVisibility() ? MachOMMI.getHiddenGVStubEntry(SSym) :
590                                  MachOMMI.getGVStubEntry(SSym);
591    if (StubSym.getPointer() == 0) {
592      MCSymbol *Sym = Mang->getSymbol(GV);
593      StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
594    }
595
596    return TargetLoweringObjectFile::
597      getExprForDwarfReference(SSym, Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
598  }
599
600  return TargetLoweringObjectFile::
601    getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
602}
603
604MCSymbol *TargetLoweringObjectFileMachO::
605getCFIPersonalitySymbol(const GlobalValue *GV, Mangler *Mang,
606                        MachineModuleInfo *MMI) const {
607  // The mach-o version of this method defaults to returning a stub reference.
608  MachineModuleInfoMachO &MachOMMI =
609    MMI->getObjFileInfo<MachineModuleInfoMachO>();
610
611  SmallString<128> Name;
612  Mang->getNameWithPrefix(Name, GV, true);
613  Name += "$non_lazy_ptr";
614
615  // Add information about the stub reference to MachOMMI so that the stub
616  // gets emitted by the asmprinter.
617  MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
618  MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
619  if (StubSym.getPointer() == 0) {
620    MCSymbol *Sym = Mang->getSymbol(GV);
621    StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
622  }
623
624  return SSym;
625}
626
627//===----------------------------------------------------------------------===//
628//                                  COFF
629//===----------------------------------------------------------------------===//
630
631static unsigned
632getCOFFSectionFlags(SectionKind K) {
633  unsigned Flags = 0;
634
635  if (K.isMetadata())
636    Flags |=
637      COFF::IMAGE_SCN_MEM_DISCARDABLE;
638  else if (K.isText())
639    Flags |=
640      COFF::IMAGE_SCN_MEM_EXECUTE |
641      COFF::IMAGE_SCN_MEM_READ |
642      COFF::IMAGE_SCN_CNT_CODE;
643  else if (K.isBSS ())
644    Flags |=
645      COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
646      COFF::IMAGE_SCN_MEM_READ |
647      COFF::IMAGE_SCN_MEM_WRITE;
648  else if (K.isThreadLocal())
649    Flags |=
650      COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
651      COFF::IMAGE_SCN_MEM_READ |
652      COFF::IMAGE_SCN_MEM_WRITE;
653  else if (K.isReadOnly())
654    Flags |=
655      COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
656      COFF::IMAGE_SCN_MEM_READ;
657  else if (K.isWriteable())
658    Flags |=
659      COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
660      COFF::IMAGE_SCN_MEM_READ |
661      COFF::IMAGE_SCN_MEM_WRITE;
662
663  return Flags;
664}
665
666const MCSection *TargetLoweringObjectFileCOFF::
667getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
668                         Mangler *Mang, const TargetMachine &TM) const {
669  return getContext().getCOFFSection(GV->getSection(),
670                                     getCOFFSectionFlags(Kind),
671                                     Kind);
672}
673
674static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
675  if (Kind.isText())
676    return ".text$";
677  if (Kind.isBSS ())
678    return ".bss$";
679  if (Kind.isThreadLocal())
680    return ".tls$";
681  if (Kind.isWriteable())
682    return ".data$";
683  return ".rdata$";
684}
685
686
687const MCSection *TargetLoweringObjectFileCOFF::
688SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
689                       Mangler *Mang, const TargetMachine &TM) const {
690
691  // If this global is linkonce/weak and the target handles this by emitting it
692  // into a 'uniqued' section name, create and return the section now.
693  if (GV->isWeakForLinker()) {
694    const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
695    SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
696    MCSymbol *Sym = Mang->getSymbol(GV);
697    Name.append(Sym->getName().begin() + 1, Sym->getName().end());
698
699    unsigned Characteristics = getCOFFSectionFlags(Kind);
700
701    Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
702
703    return getContext().getCOFFSection(Name.str(), Characteristics,
704                          COFF::IMAGE_COMDAT_SELECT_ANY, Kind);
705  }
706
707  if (Kind.isText())
708    return getTextSection();
709
710  if (Kind.isThreadLocal())
711    return getTLSDataSection();
712
713  return getDataSection();
714}
715
716