TargetLoweringObjectFileImpl.cpp revision 22772214de79aa1c5ca38c4fb1da137d8fb30a05 
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().GetOrCreateSymbol(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
429void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
430                                               const TargetMachine &TM) {
431  // _foo.eh symbols are currently always exported so that the linker knows
432  // about them.  This is not necessary on 10.6 and later, but it
433  // doesn't hurt anything.
434  // FIXME: I need to get this from Triple.
435  IsFunctionEHSymbolGlobal = true;
436  IsFunctionEHFrameSymbolPrivate = false;
437  SupportsWeakOmittedEHFrame = false;
438
439  TargetLoweringObjectFile::Initialize(Ctx, TM);
440
441  TextSection // .text
442    = getContext().getMachOSection("__TEXT", "__text",
443                                   MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
444                                   SectionKind::getText());
445  DataSection // .data
446    = getContext().getMachOSection("__DATA", "__data", 0,
447                                   SectionKind::getDataRel());
448
449  CStringSection // .cstring
450    = getContext().getMachOSection("__TEXT", "__cstring",
451                                   MCSectionMachO::S_CSTRING_LITERALS,
452                                   SectionKind::getMergeable1ByteCString());
453  UStringSection
454    = getContext().getMachOSection("__TEXT","__ustring", 0,
455                                   SectionKind::getMergeable2ByteCString());
456  FourByteConstantSection // .literal4
457    = getContext().getMachOSection("__TEXT", "__literal4",
458                                   MCSectionMachO::S_4BYTE_LITERALS,
459                                   SectionKind::getMergeableConst4());
460  EightByteConstantSection // .literal8
461    = getContext().getMachOSection("__TEXT", "__literal8",
462                                   MCSectionMachO::S_8BYTE_LITERALS,
463                                   SectionKind::getMergeableConst8());
464
465  // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
466  // to using it in -static mode.
467  SixteenByteConstantSection = 0;
468  if (TM.getRelocationModel() != Reloc::Static &&
469      TM.getTargetData()->getPointerSize() == 32)
470    SixteenByteConstantSection =   // .literal16
471      getContext().getMachOSection("__TEXT", "__literal16",
472                                   MCSectionMachO::S_16BYTE_LITERALS,
473                                   SectionKind::getMergeableConst16());
474
475  ReadOnlySection  // .const
476    = getContext().getMachOSection("__TEXT", "__const", 0,
477                                   SectionKind::getReadOnly());
478
479  TextCoalSection
480    = getContext().getMachOSection("__TEXT", "__textcoal_nt",
481                                   MCSectionMachO::S_COALESCED |
482                                   MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
483                                   SectionKind::getText());
484  ConstTextCoalSection
485    = getContext().getMachOSection("__TEXT", "__const_coal",
486                                   MCSectionMachO::S_COALESCED,
487                                   SectionKind::getText());
488  ConstDataCoalSection
489    = getContext().getMachOSection("__DATA","__const_coal",
490                                   MCSectionMachO::S_COALESCED,
491                                   SectionKind::getText());
492  ConstDataSection  // .const_data
493    = getContext().getMachOSection("__DATA", "__const", 0,
494                                   SectionKind::getReadOnlyWithRel());
495  DataCoalSection
496    = getContext().getMachOSection("__DATA","__datacoal_nt",
497                                   MCSectionMachO::S_COALESCED,
498                                   SectionKind::getDataRel());
499  DataCommonSection
500    = getContext().getMachOSection("__DATA","__common",
501                                   MCSectionMachO::S_ZEROFILL,
502                                   SectionKind::getBSS());
503  DataBSSSection
504    = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL,
505                                   SectionKind::getBSS());
506
507
508  LazySymbolPointerSection
509    = getContext().getMachOSection("__DATA", "__la_symbol_ptr",
510                                   MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
511                                   SectionKind::getMetadata());
512  NonLazySymbolPointerSection
513    = getContext().getMachOSection("__DATA", "__nl_symbol_ptr",
514                                   MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
515                                   SectionKind::getMetadata());
516
517  if (TM.getRelocationModel() == Reloc::Static) {
518    StaticCtorSection
519      = getContext().getMachOSection("__TEXT", "__constructor", 0,
520                                     SectionKind::getDataRel());
521    StaticDtorSection
522      = getContext().getMachOSection("__TEXT", "__destructor", 0,
523                                     SectionKind::getDataRel());
524  } else {
525    StaticCtorSection
526      = getContext().getMachOSection("__DATA", "__mod_init_func",
527                                     MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
528                                     SectionKind::getDataRel());
529    StaticDtorSection
530      = getContext().getMachOSection("__DATA", "__mod_term_func",
531                                     MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
532                                     SectionKind::getDataRel());
533  }
534
535  // Exception Handling.
536  LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0,
537                                             SectionKind::getReadOnlyWithRel());
538  EHFrameSection =
539    getContext().getMachOSection("__TEXT", "__eh_frame",
540                                 MCSectionMachO::S_COALESCED |
541                                 MCSectionMachO::S_ATTR_NO_TOC |
542                                 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
543                                 MCSectionMachO::S_ATTR_LIVE_SUPPORT,
544                                 SectionKind::getReadOnly());
545
546  // Debug Information.
547  DwarfAbbrevSection =
548    getContext().getMachOSection("__DWARF", "__debug_abbrev",
549                                 MCSectionMachO::S_ATTR_DEBUG,
550                                 SectionKind::getMetadata());
551  DwarfInfoSection =
552    getContext().getMachOSection("__DWARF", "__debug_info",
553                                 MCSectionMachO::S_ATTR_DEBUG,
554                                 SectionKind::getMetadata());
555  DwarfLineSection =
556    getContext().getMachOSection("__DWARF", "__debug_line",
557                                 MCSectionMachO::S_ATTR_DEBUG,
558                                 SectionKind::getMetadata());
559  DwarfFrameSection =
560    getContext().getMachOSection("__DWARF", "__debug_frame",
561                                 MCSectionMachO::S_ATTR_DEBUG,
562                                 SectionKind::getMetadata());
563  DwarfPubNamesSection =
564    getContext().getMachOSection("__DWARF", "__debug_pubnames",
565                                 MCSectionMachO::S_ATTR_DEBUG,
566                                 SectionKind::getMetadata());
567  DwarfPubTypesSection =
568    getContext().getMachOSection("__DWARF", "__debug_pubtypes",
569                                 MCSectionMachO::S_ATTR_DEBUG,
570                                 SectionKind::getMetadata());
571  DwarfStrSection =
572    getContext().getMachOSection("__DWARF", "__debug_str",
573                                 MCSectionMachO::S_ATTR_DEBUG,
574                                 SectionKind::getMetadata());
575  DwarfLocSection =
576    getContext().getMachOSection("__DWARF", "__debug_loc",
577                                 MCSectionMachO::S_ATTR_DEBUG,
578                                 SectionKind::getMetadata());
579  DwarfARangesSection =
580    getContext().getMachOSection("__DWARF", "__debug_aranges",
581                                 MCSectionMachO::S_ATTR_DEBUG,
582                                 SectionKind::getMetadata());
583  DwarfRangesSection =
584    getContext().getMachOSection("__DWARF", "__debug_ranges",
585                                 MCSectionMachO::S_ATTR_DEBUG,
586                                 SectionKind::getMetadata());
587  DwarfMacroInfoSection =
588    getContext().getMachOSection("__DWARF", "__debug_macinfo",
589                                 MCSectionMachO::S_ATTR_DEBUG,
590                                 SectionKind::getMetadata());
591  DwarfDebugInlineSection =
592    getContext().getMachOSection("__DWARF", "__debug_inlined",
593                                 MCSectionMachO::S_ATTR_DEBUG,
594                                 SectionKind::getMetadata());
595}
596
597const MCSection *TargetLoweringObjectFileMachO::
598getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
599                         Mangler *Mang, const TargetMachine &TM) const {
600  // Parse the section specifier and create it if valid.
601  StringRef Segment, Section;
602  unsigned TAA, StubSize;
603  std::string ErrorCode =
604    MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
605                                          TAA, StubSize);
606  if (!ErrorCode.empty()) {
607    // If invalid, report the error with report_fatal_error.
608    report_fatal_error("Global variable '" + GV->getNameStr() +
609                      "' has an invalid section specifier '" + GV->getSection()+
610                      "': " + ErrorCode + ".");
611    // Fall back to dropping it into the data section.
612    return DataSection;
613  }
614
615  // Get the section.
616  const MCSectionMachO *S =
617    getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
618
619  // Okay, now that we got the section, verify that the TAA & StubSize agree.
620  // If the user declared multiple globals with different section flags, we need
621  // to reject it here.
622  if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
623    // If invalid, report the error with report_fatal_error.
624    report_fatal_error("Global variable '" + GV->getNameStr() +
625                      "' section type or attributes does not match previous"
626                      " section specifier");
627  }
628
629  return S;
630}
631
632const MCSection *TargetLoweringObjectFileMachO::
633SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
634                       Mangler *Mang, const TargetMachine &TM) const {
635  assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS");
636
637  if (Kind.isText())
638    return GV->isWeakForLinker() ? TextCoalSection : TextSection;
639
640  // If this is weak/linkonce, put this in a coalescable section, either in text
641  // or data depending on if it is writable.
642  if (GV->isWeakForLinker()) {
643    if (Kind.isReadOnly())
644      return ConstTextCoalSection;
645    return DataCoalSection;
646  }
647
648  // FIXME: Alignment check should be handled by section classifier.
649  if (Kind.isMergeable1ByteCString() &&
650      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
651    return CStringSection;
652
653  // Do not put 16-bit arrays in the UString section if they have an
654  // externally visible label, this runs into issues with certain linker
655  // versions.
656  if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
657      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
658    return UStringSection;
659
660  if (Kind.isMergeableConst()) {
661    if (Kind.isMergeableConst4())
662      return FourByteConstantSection;
663    if (Kind.isMergeableConst8())
664      return EightByteConstantSection;
665    if (Kind.isMergeableConst16() && SixteenByteConstantSection)
666      return SixteenByteConstantSection;
667  }
668
669  // Otherwise, if it is readonly, but not something we can specially optimize,
670  // just drop it in .const.
671  if (Kind.isReadOnly())
672    return ReadOnlySection;
673
674  // If this is marked const, put it into a const section.  But if the dynamic
675  // linker needs to write to it, put it in the data segment.
676  if (Kind.isReadOnlyWithRel())
677    return ConstDataSection;
678
679  // Put zero initialized globals with strong external linkage in the
680  // DATA, __common section with the .zerofill directive.
681  if (Kind.isBSSExtern())
682    return DataCommonSection;
683
684  // Put zero initialized globals with local linkage in __DATA,__bss directive
685  // with the .zerofill directive (aka .lcomm).
686  if (Kind.isBSSLocal())
687    return DataBSSSection;
688
689  // Otherwise, just drop the variable in the normal data section.
690  return DataSection;
691}
692
693const MCSection *
694TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
695  // If this constant requires a relocation, we have to put it in the data
696  // segment, not in the text segment.
697  if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
698    return ConstDataSection;
699
700  if (Kind.isMergeableConst4())
701    return FourByteConstantSection;
702  if (Kind.isMergeableConst8())
703    return EightByteConstantSection;
704  if (Kind.isMergeableConst16() && SixteenByteConstantSection)
705    return SixteenByteConstantSection;
706  return ReadOnlySection;  // .const
707}
708
709/// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
710/// not to emit the UsedDirective for some symbols in llvm.used.
711// FIXME: REMOVE this (rdar://7071300)
712bool TargetLoweringObjectFileMachO::
713shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
714  /// On Darwin, internally linked data beginning with "L" or "l" does not have
715  /// the directive emitted (this occurs in ObjC metadata).
716  if (!GV) return false;
717
718  // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
719  if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
720    // FIXME: ObjC metadata is currently emitted as internal symbols that have
721    // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
722    // this horrible hack can go away.
723    MCSymbol *Sym = Mang->getSymbol(GV);
724    if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
725      return false;
726  }
727
728  return true;
729}
730
731const MCExpr *TargetLoweringObjectFileMachO::
732getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
733                               MachineModuleInfo *MMI, unsigned Encoding,
734                               MCStreamer &Streamer) const {
735  // The mach-o version of this method defaults to returning a stub reference.
736
737  if (Encoding & DW_EH_PE_indirect) {
738    MachineModuleInfoMachO &MachOMMI =
739      MMI->getObjFileInfo<MachineModuleInfoMachO>();
740
741    SmallString<128> Name;
742    Mang->getNameWithPrefix(Name, GV, true);
743    Name += "$non_lazy_ptr";
744
745    // Add information about the stub reference to MachOMMI so that the stub
746    // gets emitted by the asmprinter.
747    MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
748    MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
749    if (StubSym.getPointer() == 0) {
750      MCSymbol *Sym = Mang->getSymbol(GV);
751      StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
752    }
753
754    return TargetLoweringObjectFile::
755      getExprForDwarfReference(SSym, Mang, MMI,
756                               Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
757  }
758
759  return TargetLoweringObjectFile::
760    getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
761}
762
763unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const {
764  return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
765}
766
767unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const {
768  return DW_EH_PE_pcrel;
769}
770
771unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const {
772  return DW_EH_PE_pcrel;
773}
774
775unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const {
776  return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
777}
778
779//===----------------------------------------------------------------------===//
780//                                  COFF
781//===----------------------------------------------------------------------===//
782
783typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
784
785TargetLoweringObjectFileCOFF::~TargetLoweringObjectFileCOFF() {
786  delete (COFFUniqueMapTy*)UniquingMap;
787}
788
789
790const MCSection *TargetLoweringObjectFileCOFF::
791getCOFFSection(StringRef Name, bool isDirective, SectionKind Kind) const {
792  // Create the map if it doesn't already exist.
793  if (UniquingMap == 0)
794    UniquingMap = new COFFUniqueMapTy();
795  COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)UniquingMap;
796
797  // Do the lookup, if we have a hit, return it.
798  const MCSectionCOFF *&Entry = Map[Name];
799  if (Entry) return Entry;
800
801  return Entry = MCSectionCOFF::Create(Name, isDirective, Kind, getContext());
802}
803
804void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
805                                              const TargetMachine &TM) {
806  if (UniquingMap != 0)
807    ((COFFUniqueMapTy*)UniquingMap)->clear();
808  TargetLoweringObjectFile::Initialize(Ctx, TM);
809  TextSection = getCOFFSection("\t.text", true, SectionKind::getText());
810  DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel());
811  StaticCtorSection =
812    getCOFFSection(".ctors", false, SectionKind::getDataRel());
813  StaticDtorSection =
814    getCOFFSection(".dtors", false, SectionKind::getDataRel());
815
816  // FIXME: We're emitting LSDA info into a readonly section on COFF, even
817  // though it contains relocatable pointers.  In PIC mode, this is probably a
818  // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
819  // adjusted or this should be a data section.
820  LSDASection =
821    getCOFFSection(".gcc_except_table", false, SectionKind::getReadOnly());
822  EHFrameSection =
823    getCOFFSection(".eh_frame", false, SectionKind::getDataRel());
824
825  // Debug info.
826  // FIXME: Don't use 'directive' mode here.
827  DwarfAbbrevSection =
828    getCOFFSection("\t.section\t.debug_abbrev,\"dr\"",
829                   true, SectionKind::getMetadata());
830  DwarfInfoSection =
831    getCOFFSection("\t.section\t.debug_info,\"dr\"",
832                   true, SectionKind::getMetadata());
833  DwarfLineSection =
834    getCOFFSection("\t.section\t.debug_line,\"dr\"",
835                   true, SectionKind::getMetadata());
836  DwarfFrameSection =
837    getCOFFSection("\t.section\t.debug_frame,\"dr\"",
838                   true, SectionKind::getMetadata());
839  DwarfPubNamesSection =
840    getCOFFSection("\t.section\t.debug_pubnames,\"dr\"",
841                   true, SectionKind::getMetadata());
842  DwarfPubTypesSection =
843    getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"",
844                   true, SectionKind::getMetadata());
845  DwarfStrSection =
846    getCOFFSection("\t.section\t.debug_str,\"dr\"",
847                   true, SectionKind::getMetadata());
848  DwarfLocSection =
849    getCOFFSection("\t.section\t.debug_loc,\"dr\"",
850                   true, SectionKind::getMetadata());
851  DwarfARangesSection =
852    getCOFFSection("\t.section\t.debug_aranges,\"dr\"",
853                   true, SectionKind::getMetadata());
854  DwarfRangesSection =
855    getCOFFSection("\t.section\t.debug_ranges,\"dr\"",
856                   true, SectionKind::getMetadata());
857  DwarfMacroInfoSection =
858    getCOFFSection("\t.section\t.debug_macinfo,\"dr\"",
859                   true, SectionKind::getMetadata());
860}
861
862const MCSection *TargetLoweringObjectFileCOFF::
863getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
864                         Mangler *Mang, const TargetMachine &TM) const {
865  return getCOFFSection(GV->getSection(), false, Kind);
866}
867
868static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
869  if (Kind.isText())
870    return ".text$linkonce";
871  if (Kind.isWriteable())
872    return ".data$linkonce";
873  return ".rdata$linkonce";
874}
875
876
877const MCSection *TargetLoweringObjectFileCOFF::
878SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
879                       Mangler *Mang, const TargetMachine &TM) const {
880  assert(!Kind.isThreadLocal() && "Doesn't support TLS");
881
882  // If this global is linkonce/weak and the target handles this by emitting it
883  // into a 'uniqued' section name, create and return the section now.
884  if (GV->isWeakForLinker()) {
885    const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
886    SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
887    MCSymbol *Sym = Mang->getSymbol(GV);
888    Name.append(Sym->getName().begin(), Sym->getName().end());
889    return getCOFFSection(Name.str(), false, Kind);
890  }
891
892  if (Kind.isText())
893    return getTextSection();
894
895  return getDataSection();
896}
897
898