TargetLoweringObjectFileImpl.cpp revision 6e5ce287b0e53c264af0ba37169ad964e19b5bb7 
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/MCSectionCOFF.h"
26#include "llvm/MC/MCSymbol.h"
27#include "llvm/Target/Mangler.h"
28#include "llvm/Target/TargetData.h"
29#include "llvm/Target/TargetMachine.h"
30#include "llvm/Target/TargetOptions.h"
31#include "llvm/Support/Dwarf.h"
32#include "llvm/Support/ErrorHandling.h"
33#include "llvm/Support/raw_ostream.h"
34#include "llvm/ADT/SmallString.h"
35#include "llvm/ADT/StringExtras.h"
36using namespace llvm;
37using namespace dwarf;
38
39//===----------------------------------------------------------------------===//
40//                                  ELF
41//===----------------------------------------------------------------------===//
42
43void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
44                                             const TargetMachine &TM) {
45  TargetLoweringObjectFile::Initialize(Ctx, TM);
46
47  BSSSection =
48    getContext().getELFSection(".bss", MCSectionELF::SHT_NOBITS,
49                               MCSectionELF::SHF_WRITE |MCSectionELF::SHF_ALLOC,
50                               SectionKind::getBSS());
51
52  TextSection =
53    getContext().getELFSection(".text", MCSectionELF::SHT_PROGBITS,
54                               MCSectionELF::SHF_EXECINSTR |
55                               MCSectionELF::SHF_ALLOC,
56                               SectionKind::getText());
57
58  DataSection =
59    getContext().getELFSection(".data", MCSectionELF::SHT_PROGBITS,
60                               MCSectionELF::SHF_WRITE |MCSectionELF::SHF_ALLOC,
61                               SectionKind::getDataRel());
62
63  ReadOnlySection =
64    getContext().getELFSection(".rodata", MCSectionELF::SHT_PROGBITS,
65                               MCSectionELF::SHF_ALLOC,
66                               SectionKind::getReadOnly());
67
68  TLSDataSection =
69    getContext().getELFSection(".tdata", MCSectionELF::SHT_PROGBITS,
70                               MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
71                               MCSectionELF::SHF_WRITE,
72                               SectionKind::getThreadData());
73
74  TLSBSSSection =
75    getContext().getELFSection(".tbss", MCSectionELF::SHT_NOBITS,
76                               MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
77                               MCSectionELF::SHF_WRITE,
78                               SectionKind::getThreadBSS());
79
80  DataRelSection =
81    getContext().getELFSection(".data.rel", MCSectionELF::SHT_PROGBITS,
82                               MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE,
83                               SectionKind::getDataRel());
84
85  DataRelLocalSection =
86    getContext().getELFSection(".data.rel.local", MCSectionELF::SHT_PROGBITS,
87                               MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE,
88                               SectionKind::getDataRelLocal());
89
90  DataRelROSection =
91    getContext().getELFSection(".data.rel.ro", MCSectionELF::SHT_PROGBITS,
92                               MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE,
93                               SectionKind::getReadOnlyWithRel());
94
95  DataRelROLocalSection =
96    getContext().getELFSection(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS,
97                               MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE,
98                               SectionKind::getReadOnlyWithRelLocal());
99
100  MergeableConst4Section =
101    getContext().getELFSection(".rodata.cst4", MCSectionELF::SHT_PROGBITS,
102                               MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_MERGE,
103                               SectionKind::getMergeableConst4());
104
105  MergeableConst8Section =
106    getContext().getELFSection(".rodata.cst8", MCSectionELF::SHT_PROGBITS,
107                               MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_MERGE,
108                               SectionKind::getMergeableConst8());
109
110  MergeableConst16Section =
111    getContext().getELFSection(".rodata.cst16", MCSectionELF::SHT_PROGBITS,
112                               MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_MERGE,
113                               SectionKind::getMergeableConst16());
114
115  StaticCtorSection =
116    getContext().getELFSection(".ctors", MCSectionELF::SHT_PROGBITS,
117                               MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE,
118                               SectionKind::getDataRel());
119
120  StaticDtorSection =
121    getContext().getELFSection(".dtors", MCSectionELF::SHT_PROGBITS,
122                               MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE,
123                               SectionKind::getDataRel());
124
125  // Exception Handling Sections.
126
127  // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
128  // it contains relocatable pointers.  In PIC mode, this is probably a big
129  // runtime hit for C++ apps.  Either the contents of the LSDA need to be
130  // adjusted or this should be a data section.
131  LSDASection =
132    getContext().getELFSection(".gcc_except_table", MCSectionELF::SHT_PROGBITS,
133                               MCSectionELF::SHF_ALLOC,
134                               SectionKind::getReadOnly());
135  EHFrameSection =
136    getContext().getELFSection(".eh_frame", MCSectionELF::SHT_PROGBITS,
137                               MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE,
138                               SectionKind::getDataRel());
139
140  // Debug Info Sections.
141  DwarfAbbrevSection =
142    getContext().getELFSection(".debug_abbrev", MCSectionELF::SHT_PROGBITS, 0,
143                               SectionKind::getMetadata());
144  DwarfInfoSection =
145    getContext().getELFSection(".debug_info", MCSectionELF::SHT_PROGBITS, 0,
146                               SectionKind::getMetadata());
147  DwarfLineSection =
148    getContext().getELFSection(".debug_line", MCSectionELF::SHT_PROGBITS, 0,
149                               SectionKind::getMetadata());
150  DwarfFrameSection =
151    getContext().getELFSection(".debug_frame", MCSectionELF::SHT_PROGBITS, 0,
152                               SectionKind::getMetadata());
153  DwarfPubNamesSection =
154    getContext().getELFSection(".debug_pubnames", MCSectionELF::SHT_PROGBITS, 0,
155                               SectionKind::getMetadata());
156  DwarfPubTypesSection =
157    getContext().getELFSection(".debug_pubtypes", MCSectionELF::SHT_PROGBITS, 0,
158                               SectionKind::getMetadata());
159  DwarfStrSection =
160    getContext().getELFSection(".debug_str", MCSectionELF::SHT_PROGBITS, 0,
161                               SectionKind::getMetadata());
162  DwarfLocSection =
163    getContext().getELFSection(".debug_loc", MCSectionELF::SHT_PROGBITS, 0,
164                               SectionKind::getMetadata());
165  DwarfARangesSection =
166    getContext().getELFSection(".debug_aranges", MCSectionELF::SHT_PROGBITS, 0,
167                               SectionKind::getMetadata());
168  DwarfRangesSection =
169    getContext().getELFSection(".debug_ranges", MCSectionELF::SHT_PROGBITS, 0,
170                               SectionKind::getMetadata());
171  DwarfMacroInfoSection =
172    getContext().getELFSection(".debug_macinfo", MCSectionELF::SHT_PROGBITS, 0,
173                               SectionKind::getMetadata());
174}
175
176
177static SectionKind
178getELFKindForNamedSection(StringRef Name, SectionKind K) {
179  if (Name.empty() || Name[0] != '.') return K;
180
181  // Some lame default implementation based on some magic section names.
182  if (Name == ".bss" ||
183      Name.startswith(".bss.") ||
184      Name.startswith(".gnu.linkonce.b.") ||
185      Name.startswith(".llvm.linkonce.b.") ||
186      Name == ".sbss" ||
187      Name.startswith(".sbss.") ||
188      Name.startswith(".gnu.linkonce.sb.") ||
189      Name.startswith(".llvm.linkonce.sb."))
190    return SectionKind::getBSS();
191
192  if (Name == ".tdata" ||
193      Name.startswith(".tdata.") ||
194      Name.startswith(".gnu.linkonce.td.") ||
195      Name.startswith(".llvm.linkonce.td."))
196    return SectionKind::getThreadData();
197
198  if (Name == ".tbss" ||
199      Name.startswith(".tbss.") ||
200      Name.startswith(".gnu.linkonce.tb.") ||
201      Name.startswith(".llvm.linkonce.tb."))
202    return SectionKind::getThreadBSS();
203
204  return K;
205}
206
207
208static unsigned getELFSectionType(StringRef Name, SectionKind K) {
209
210  if (Name == ".init_array")
211    return MCSectionELF::SHT_INIT_ARRAY;
212
213  if (Name == ".fini_array")
214    return MCSectionELF::SHT_FINI_ARRAY;
215
216  if (Name == ".preinit_array")
217    return MCSectionELF::SHT_PREINIT_ARRAY;
218
219  if (K.isBSS() || K.isThreadBSS())
220    return MCSectionELF::SHT_NOBITS;
221
222  return MCSectionELF::SHT_PROGBITS;
223}
224
225
226static unsigned
227getELFSectionFlags(SectionKind K) {
228  unsigned Flags = 0;
229
230  if (!K.isMetadata())
231    Flags |= MCSectionELF::SHF_ALLOC;
232
233  if (K.isText())
234    Flags |= MCSectionELF::SHF_EXECINSTR;
235
236  if (K.isWriteable())
237    Flags |= MCSectionELF::SHF_WRITE;
238
239  if (K.isThreadLocal())
240    Flags |= MCSectionELF::SHF_TLS;
241
242  // K.isMergeableConst() is left out to honour PR4650
243  if (K.isMergeableCString() || K.isMergeableConst4() ||
244      K.isMergeableConst8() || K.isMergeableConst16())
245    Flags |= MCSectionELF::SHF_MERGE;
246
247  if (K.isMergeableCString())
248    Flags |= MCSectionELF::SHF_STRINGS;
249
250  return Flags;
251}
252
253
254const MCSection *TargetLoweringObjectFileELF::
255getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
256                         Mangler *Mang, const TargetMachine &TM) const {
257  StringRef SectionName = GV->getSection();
258
259  // Infer section flags from the section name if we can.
260  Kind = getELFKindForNamedSection(SectionName, Kind);
261
262  return getContext().getELFSection(SectionName,
263                                    getELFSectionType(SectionName, Kind),
264                                    getELFSectionFlags(Kind), Kind, true);
265}
266
267static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) {
268  if (Kind.isText())                 return ".gnu.linkonce.t.";
269  if (Kind.isReadOnly())             return ".gnu.linkonce.r.";
270
271  if (Kind.isThreadData())           return ".gnu.linkonce.td.";
272  if (Kind.isThreadBSS())            return ".gnu.linkonce.tb.";
273
274  if (Kind.isDataNoRel())            return ".gnu.linkonce.d.";
275  if (Kind.isDataRelLocal())         return ".gnu.linkonce.d.rel.local.";
276  if (Kind.isDataRel())              return ".gnu.linkonce.d.rel.";
277  if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local.";
278
279  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
280  return ".gnu.linkonce.d.rel.ro.";
281}
282
283/// getSectionPrefixForGlobal - Return the section prefix name used by options
284/// FunctionsSections and DataSections.
285static const char *getSectionPrefixForGlobal(SectionKind Kind) {
286  if (Kind.isText())                 return ".text.";
287  if (Kind.isReadOnly())             return ".rodata.";
288
289  if (Kind.isThreadData())           return ".tdata.";
290  if (Kind.isThreadBSS())            return ".tbss.";
291
292  if (Kind.isDataNoRel())            return ".data.";
293  if (Kind.isDataRelLocal())         return ".data.rel.local.";
294  if (Kind.isDataRel())              return ".data.rel.";
295  if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local.";
296
297  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
298  return ".data.rel.ro.";
299}
300
301
302const MCSection *TargetLoweringObjectFileELF::
303SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
304                       Mangler *Mang, const TargetMachine &TM) const {
305  // If we have -ffunction-section or -fdata-section then we should emit the
306  // global value to a uniqued section specifically for it.
307  bool EmitUniquedSection;
308  if (Kind.isText())
309    EmitUniquedSection = TM.getFunctionSections();
310  else
311    EmitUniquedSection = TM.getDataSections();
312
313  // If this global is linkonce/weak and the target handles this by emitting it
314  // into a 'uniqued' section name, create and return the section now.
315  if ((GV->isWeakForLinker() || EmitUniquedSection) &&
316      !Kind.isCommon() && !Kind.isBSS()) {
317    const char *Prefix;
318    if (GV->isWeakForLinker())
319      Prefix = getSectionPrefixForUniqueGlobal(Kind);
320    else {
321      assert(EmitUniquedSection);
322      Prefix = getSectionPrefixForGlobal(Kind);
323    }
324
325    SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
326    MCSymbol *Sym = Mang->getSymbol(GV);
327    Name.append(Sym->getName().begin(), Sym->getName().end());
328    return getContext().getELFSection(Name.str(),
329                                      getELFSectionType(Name.str(), Kind),
330                                      getELFSectionFlags(Kind), Kind);
331  }
332
333  if (Kind.isText()) return TextSection;
334
335  if (Kind.isMergeable1ByteCString() ||
336      Kind.isMergeable2ByteCString() ||
337      Kind.isMergeable4ByteCString()) {
338
339    // We also need alignment here.
340    // FIXME: this is getting the alignment of the character, not the
341    // alignment of the global!
342    unsigned Align =
343      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
344
345    const char *SizeSpec = ".rodata.str1.";
346    if (Kind.isMergeable2ByteCString())
347      SizeSpec = ".rodata.str2.";
348    else if (Kind.isMergeable4ByteCString())
349      SizeSpec = ".rodata.str4.";
350    else
351      assert(Kind.isMergeable1ByteCString() && "unknown string width");
352
353
354    std::string Name = SizeSpec + utostr(Align);
355    return getContext().getELFSection(Name, MCSectionELF::SHT_PROGBITS,
356                                      MCSectionELF::SHF_ALLOC |
357                                      MCSectionELF::SHF_MERGE |
358                                      MCSectionELF::SHF_STRINGS,
359                                      Kind);
360  }
361
362  if (Kind.isMergeableConst()) {
363    if (Kind.isMergeableConst4() && MergeableConst4Section)
364      return MergeableConst4Section;
365    if (Kind.isMergeableConst8() && MergeableConst8Section)
366      return MergeableConst8Section;
367    if (Kind.isMergeableConst16() && MergeableConst16Section)
368      return MergeableConst16Section;
369    return ReadOnlySection;  // .const
370  }
371
372  if (Kind.isReadOnly())             return ReadOnlySection;
373
374  if (Kind.isThreadData())           return TLSDataSection;
375  if (Kind.isThreadBSS())            return TLSBSSSection;
376
377  // Note: we claim that common symbols are put in BSSSection, but they are
378  // really emitted with the magic .comm directive, which creates a symbol table
379  // entry but not a section.
380  if (Kind.isBSS() || Kind.isCommon()) return BSSSection;
381
382  if (Kind.isDataNoRel())            return DataSection;
383  if (Kind.isDataRelLocal())         return DataRelLocalSection;
384  if (Kind.isDataRel())              return DataRelSection;
385  if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
386
387  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
388  return DataRelROSection;
389}
390
391/// getSectionForConstant - Given a mergeable constant with the
392/// specified size and relocation information, return a section that it
393/// should be placed in.
394const MCSection *TargetLoweringObjectFileELF::
395getSectionForConstant(SectionKind Kind) const {
396  if (Kind.isMergeableConst4() && MergeableConst4Section)
397    return MergeableConst4Section;
398  if (Kind.isMergeableConst8() && MergeableConst8Section)
399    return MergeableConst8Section;
400  if (Kind.isMergeableConst16() && MergeableConst16Section)
401    return MergeableConst16Section;
402  if (Kind.isReadOnly())
403    return ReadOnlySection;
404
405  if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
406  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
407  return DataRelROSection;
408}
409
410const MCExpr *TargetLoweringObjectFileELF::
411getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
412                               MachineModuleInfo *MMI,
413                               unsigned Encoding, MCStreamer &Streamer) const {
414
415  if (Encoding & dwarf::DW_EH_PE_indirect) {
416    MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
417
418    SmallString<128> Name;
419    Mang->getNameWithPrefix(Name, GV, true);
420    Name += ".DW.stub";
421
422    // Add information about the stub reference to ELFMMI so that the stub
423    // gets emitted by the asmprinter.
424    MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
425    MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
426    if (StubSym.getPointer() == 0) {
427      MCSymbol *Sym = Mang->getSymbol(GV);
428      StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
429    }
430
431    return TargetLoweringObjectFile::
432      getExprForDwarfReference(SSym, Mang, MMI,
433                               Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
434  }
435
436  return TargetLoweringObjectFile::
437    getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
438}
439
440//===----------------------------------------------------------------------===//
441//                                 MachO
442//===----------------------------------------------------------------------===//
443
444void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
445                                               const TargetMachine &TM) {
446  // _foo.eh symbols are currently always exported so that the linker knows
447  // about them.  This is not necessary on 10.6 and later, but it
448  // doesn't hurt anything.
449  // FIXME: I need to get this from Triple.
450  IsFunctionEHSymbolGlobal = true;
451  IsFunctionEHFrameSymbolPrivate = false;
452  SupportsWeakOmittedEHFrame = false;
453
454  TargetLoweringObjectFile::Initialize(Ctx, TM);
455
456  TextSection // .text
457    = getContext().getMachOSection("__TEXT", "__text",
458                                   MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
459                                   SectionKind::getText());
460  DataSection // .data
461    = getContext().getMachOSection("__DATA", "__data", 0,
462                                   SectionKind::getDataRel());
463
464  CStringSection // .cstring
465    = getContext().getMachOSection("__TEXT", "__cstring",
466                                   MCSectionMachO::S_CSTRING_LITERALS,
467                                   SectionKind::getMergeable1ByteCString());
468  UStringSection
469    = getContext().getMachOSection("__TEXT","__ustring", 0,
470                                   SectionKind::getMergeable2ByteCString());
471  FourByteConstantSection // .literal4
472    = getContext().getMachOSection("__TEXT", "__literal4",
473                                   MCSectionMachO::S_4BYTE_LITERALS,
474                                   SectionKind::getMergeableConst4());
475  EightByteConstantSection // .literal8
476    = getContext().getMachOSection("__TEXT", "__literal8",
477                                   MCSectionMachO::S_8BYTE_LITERALS,
478                                   SectionKind::getMergeableConst8());
479
480  // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
481  // to using it in -static mode.
482  SixteenByteConstantSection = 0;
483  if (TM.getRelocationModel() != Reloc::Static &&
484      TM.getTargetData()->getPointerSize() == 32)
485    SixteenByteConstantSection =   // .literal16
486      getContext().getMachOSection("__TEXT", "__literal16",
487                                   MCSectionMachO::S_16BYTE_LITERALS,
488                                   SectionKind::getMergeableConst16());
489
490  ReadOnlySection  // .const
491    = getContext().getMachOSection("__TEXT", "__const", 0,
492                                   SectionKind::getReadOnly());
493
494  TextCoalSection
495    = getContext().getMachOSection("__TEXT", "__textcoal_nt",
496                                   MCSectionMachO::S_COALESCED |
497                                   MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
498                                   SectionKind::getText());
499  ConstTextCoalSection
500    = getContext().getMachOSection("__TEXT", "__const_coal",
501                                   MCSectionMachO::S_COALESCED,
502                                   SectionKind::getText());
503  ConstDataCoalSection
504    = getContext().getMachOSection("__DATA","__const_coal",
505                                   MCSectionMachO::S_COALESCED,
506                                   SectionKind::getText());
507  ConstDataSection  // .const_data
508    = getContext().getMachOSection("__DATA", "__const", 0,
509                                   SectionKind::getReadOnlyWithRel());
510  DataCoalSection
511    = getContext().getMachOSection("__DATA","__datacoal_nt",
512                                   MCSectionMachO::S_COALESCED,
513                                   SectionKind::getDataRel());
514  DataCommonSection
515    = getContext().getMachOSection("__DATA","__common",
516                                   MCSectionMachO::S_ZEROFILL,
517                                   SectionKind::getBSS());
518  DataBSSSection
519    = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL,
520                                   SectionKind::getBSS());
521
522
523  LazySymbolPointerSection
524    = getContext().getMachOSection("__DATA", "__la_symbol_ptr",
525                                   MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
526                                   SectionKind::getMetadata());
527  NonLazySymbolPointerSection
528    = getContext().getMachOSection("__DATA", "__nl_symbol_ptr",
529                                   MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
530                                   SectionKind::getMetadata());
531
532  if (TM.getRelocationModel() == Reloc::Static) {
533    StaticCtorSection
534      = getContext().getMachOSection("__TEXT", "__constructor", 0,
535                                     SectionKind::getDataRel());
536    StaticDtorSection
537      = getContext().getMachOSection("__TEXT", "__destructor", 0,
538                                     SectionKind::getDataRel());
539  } else {
540    StaticCtorSection
541      = getContext().getMachOSection("__DATA", "__mod_init_func",
542                                     MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
543                                     SectionKind::getDataRel());
544    StaticDtorSection
545      = getContext().getMachOSection("__DATA", "__mod_term_func",
546                                     MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
547                                     SectionKind::getDataRel());
548  }
549
550  // Exception Handling.
551  LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0,
552                                             SectionKind::getReadOnlyWithRel());
553  EHFrameSection =
554    getContext().getMachOSection("__TEXT", "__eh_frame",
555                                 MCSectionMachO::S_COALESCED |
556                                 MCSectionMachO::S_ATTR_NO_TOC |
557                                 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
558                                 MCSectionMachO::S_ATTR_LIVE_SUPPORT,
559                                 SectionKind::getReadOnly());
560
561  // Debug Information.
562  DwarfAbbrevSection =
563    getContext().getMachOSection("__DWARF", "__debug_abbrev",
564                                 MCSectionMachO::S_ATTR_DEBUG,
565                                 SectionKind::getMetadata());
566  DwarfInfoSection =
567    getContext().getMachOSection("__DWARF", "__debug_info",
568                                 MCSectionMachO::S_ATTR_DEBUG,
569                                 SectionKind::getMetadata());
570  DwarfLineSection =
571    getContext().getMachOSection("__DWARF", "__debug_line",
572                                 MCSectionMachO::S_ATTR_DEBUG,
573                                 SectionKind::getMetadata());
574  DwarfFrameSection =
575    getContext().getMachOSection("__DWARF", "__debug_frame",
576                                 MCSectionMachO::S_ATTR_DEBUG,
577                                 SectionKind::getMetadata());
578  DwarfPubNamesSection =
579    getContext().getMachOSection("__DWARF", "__debug_pubnames",
580                                 MCSectionMachO::S_ATTR_DEBUG,
581                                 SectionKind::getMetadata());
582  DwarfPubTypesSection =
583    getContext().getMachOSection("__DWARF", "__debug_pubtypes",
584                                 MCSectionMachO::S_ATTR_DEBUG,
585                                 SectionKind::getMetadata());
586  DwarfStrSection =
587    getContext().getMachOSection("__DWARF", "__debug_str",
588                                 MCSectionMachO::S_ATTR_DEBUG,
589                                 SectionKind::getMetadata());
590  DwarfLocSection =
591    getContext().getMachOSection("__DWARF", "__debug_loc",
592                                 MCSectionMachO::S_ATTR_DEBUG,
593                                 SectionKind::getMetadata());
594  DwarfARangesSection =
595    getContext().getMachOSection("__DWARF", "__debug_aranges",
596                                 MCSectionMachO::S_ATTR_DEBUG,
597                                 SectionKind::getMetadata());
598  DwarfRangesSection =
599    getContext().getMachOSection("__DWARF", "__debug_ranges",
600                                 MCSectionMachO::S_ATTR_DEBUG,
601                                 SectionKind::getMetadata());
602  DwarfMacroInfoSection =
603    getContext().getMachOSection("__DWARF", "__debug_macinfo",
604                                 MCSectionMachO::S_ATTR_DEBUG,
605                                 SectionKind::getMetadata());
606  DwarfDebugInlineSection =
607    getContext().getMachOSection("__DWARF", "__debug_inlined",
608                                 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 report_fatal_error.
623    report_fatal_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    getContext().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 report_fatal_error.
639    report_fatal_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().GetOrCreateSymbol(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_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
792}
793
794//===----------------------------------------------------------------------===//
795//                                  COFF
796//===----------------------------------------------------------------------===//
797
798void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
799                                              const TargetMachine &TM) {
800  TargetLoweringObjectFile::Initialize(Ctx, TM);
801  TextSection =
802    getContext().getCOFFSection(".text",
803                                MCSectionCOFF::IMAGE_SCN_CNT_CODE |
804                                MCSectionCOFF::IMAGE_SCN_MEM_EXECUTE |
805                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
806                                SectionKind::getText());
807  DataSection =
808    getContext().getCOFFSection(".data",
809                                MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
810                                MCSectionCOFF::IMAGE_SCN_MEM_READ |
811                                MCSectionCOFF::IMAGE_SCN_MEM_WRITE,
812                                SectionKind::getDataRel());
813  ReadOnlySection =
814    getContext().getCOFFSection(".rdata",
815                                MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
816                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
817                                SectionKind::getReadOnly());
818  StaticCtorSection =
819    getContext().getCOFFSection(".ctors",
820                                MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
821                                MCSectionCOFF::IMAGE_SCN_MEM_READ |
822                                MCSectionCOFF::IMAGE_SCN_MEM_WRITE,
823                                SectionKind::getDataRel());
824  StaticDtorSection =
825    getContext().getCOFFSection(".dtors",
826                                MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
827                                MCSectionCOFF::IMAGE_SCN_MEM_READ |
828                                MCSectionCOFF::IMAGE_SCN_MEM_WRITE,
829                                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    getContext().getCOFFSection(".gcc_except_table",
837                                MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
838                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
839                                SectionKind::getReadOnly());
840  EHFrameSection =
841    getContext().getCOFFSection(".eh_frame",
842                                MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
843                                MCSectionCOFF::IMAGE_SCN_MEM_READ |
844                                MCSectionCOFF::IMAGE_SCN_MEM_WRITE,
845                                SectionKind::getDataRel());
846
847  // Debug info.
848  DwarfAbbrevSection =
849    getContext().getCOFFSection(".debug_abbrev",
850                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
851                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
852                                SectionKind::getMetadata());
853  DwarfInfoSection =
854    getContext().getCOFFSection(".debug_info",
855                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
856                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
857                                SectionKind::getMetadata());
858  DwarfLineSection =
859    getContext().getCOFFSection(".debug_line",
860                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
861                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
862                                SectionKind::getMetadata());
863  DwarfFrameSection =
864    getContext().getCOFFSection(".debug_frame",
865                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
866                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
867                                SectionKind::getMetadata());
868  DwarfPubNamesSection =
869    getContext().getCOFFSection(".debug_pubnames",
870                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
871                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
872                                SectionKind::getMetadata());
873  DwarfPubTypesSection =
874    getContext().getCOFFSection(".debug_pubtypes",
875                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
876                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
877                                SectionKind::getMetadata());
878  DwarfStrSection =
879    getContext().getCOFFSection(".debug_str",
880                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
881                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
882                                SectionKind::getMetadata());
883  DwarfLocSection =
884    getContext().getCOFFSection(".debug_loc",
885                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
886                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
887                                SectionKind::getMetadata());
888  DwarfARangesSection =
889    getContext().getCOFFSection(".debug_aranges",
890                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
891                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
892                                SectionKind::getMetadata());
893  DwarfRangesSection =
894    getContext().getCOFFSection(".debug_ranges",
895                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
896                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
897                                SectionKind::getMetadata());
898  DwarfMacroInfoSection =
899    getContext().getCOFFSection(".debug_macinfo",
900                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
901                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
902                                SectionKind::getMetadata());
903
904  DrectveSection =
905    getContext().getCOFFSection(".drectve",
906                                MCSectionCOFF::IMAGE_SCN_LNK_INFO,
907                                SectionKind::getMetadata());
908}
909
910static unsigned
911getCOFFSectionFlags(SectionKind K) {
912  unsigned Flags = 0;
913
914  if (!K.isMetadata())
915    Flags |=
916      MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE;
917  else if (K.isText())
918    Flags |=
919      MCSectionCOFF::IMAGE_SCN_MEM_EXECUTE |
920      MCSectionCOFF::IMAGE_SCN_CNT_CODE;
921  else if (K.isBSS ())
922    Flags |=
923      MCSectionCOFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
924      MCSectionCOFF::IMAGE_SCN_MEM_READ |
925      MCSectionCOFF::IMAGE_SCN_MEM_WRITE;
926  else if (K.isReadOnly())
927    Flags |=
928      MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
929      MCSectionCOFF::IMAGE_SCN_MEM_READ;
930  else if (K.isWriteable())
931    Flags |=
932      MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
933      MCSectionCOFF::IMAGE_SCN_MEM_READ |
934      MCSectionCOFF::IMAGE_SCN_MEM_WRITE;
935
936  return Flags;
937}
938
939const MCSection *TargetLoweringObjectFileCOFF::
940getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
941                         Mangler *Mang, const TargetMachine &TM) const {
942  return getContext().getCOFFSection(GV->getSection(),
943                                     getCOFFSectionFlags(Kind),
944                                     Kind);
945}
946
947static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
948  if (Kind.isText())
949    return ".text$linkonce";
950  if (Kind.isBSS ())
951    return ".bss$linkonce";
952  if (Kind.isWriteable())
953    return ".data$linkonce";
954  return ".rdata$linkonce";
955}
956
957
958const MCSection *TargetLoweringObjectFileCOFF::
959SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
960                       Mangler *Mang, const TargetMachine &TM) const {
961  assert(!Kind.isThreadLocal() && "Doesn't support TLS");
962
963  // If this global is linkonce/weak and the target handles this by emitting it
964  // into a 'uniqued' section name, create and return the section now.
965  if (GV->isWeakForLinker()) {
966    const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
967    SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
968    MCSymbol *Sym = Mang->getSymbol(GV);
969    Name.append(Sym->getName().begin(), Sym->getName().end());
970
971    unsigned Characteristics = getCOFFSectionFlags(Kind);
972
973    Characteristics |= MCSectionCOFF::IMAGE_SCN_LNK_COMDAT;
974
975    return getContext().getCOFFSection(Name.str(), Characteristics,
976                          MCSectionCOFF::IMAGE_COMDAT_SELECT_EXACT_MATCH, Kind);
977  }
978
979  if (Kind.isText())
980    return getTextSection();
981
982  return getDataSection();
983}
984
985