TargetLoweringObjectFileImpl.cpp revision f0e7c87e56df43b012667762e2fb3e1b9edb766d 
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  const MCSectionELF *&Entry = Map[Section];
57  if (Entry) return Entry;
58
59  return Entry = MCSectionELF::Create(Section, Type, Flags, Kind, IsExplicit,
60                                      getContext());
61}
62
63void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
64                                             const TargetMachine &TM) {
65  if (UniquingMap != 0)
66    ((ELFUniqueMapTy*)UniquingMap)->clear();
67  TargetLoweringObjectFile::Initialize(Ctx, TM);
68
69  BSSSection =
70    getELFSection(".bss", MCSectionELF::SHT_NOBITS,
71                  MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
72                  SectionKind::getBSS());
73
74  TextSection =
75    getELFSection(".text", MCSectionELF::SHT_PROGBITS,
76                  MCSectionELF::SHF_EXECINSTR | MCSectionELF::SHF_ALLOC,
77                  SectionKind::getText());
78
79  DataSection =
80    getELFSection(".data", MCSectionELF::SHT_PROGBITS,
81                  MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
82                  SectionKind::getDataRel());
83
84  ReadOnlySection =
85    getELFSection(".rodata", MCSectionELF::SHT_PROGBITS,
86                  MCSectionELF::SHF_ALLOC,
87                  SectionKind::getReadOnly());
88
89  TLSDataSection =
90    getELFSection(".tdata", MCSectionELF::SHT_PROGBITS,
91                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
92                  MCSectionELF::SHF_WRITE, SectionKind::getThreadData());
93
94  TLSBSSSection =
95    getELFSection(".tbss", MCSectionELF::SHT_NOBITS,
96                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
97                  MCSectionELF::SHF_WRITE, SectionKind::getThreadBSS());
98
99  DataRelSection =
100    getELFSection(".data.rel", MCSectionELF::SHT_PROGBITS,
101                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
102                  SectionKind::getDataRel());
103
104  DataRelLocalSection =
105    getELFSection(".data.rel.local", MCSectionELF::SHT_PROGBITS,
106                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
107                  SectionKind::getDataRelLocal());
108
109  DataRelROSection =
110    getELFSection(".data.rel.ro", MCSectionELF::SHT_PROGBITS,
111                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
112                  SectionKind::getReadOnlyWithRel());
113
114  DataRelROLocalSection =
115    getELFSection(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS,
116                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
117                  SectionKind::getReadOnlyWithRelLocal());
118
119  MergeableConst4Section =
120    getELFSection(".rodata.cst4", MCSectionELF::SHT_PROGBITS,
121                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
122                  SectionKind::getMergeableConst4());
123
124  MergeableConst8Section =
125    getELFSection(".rodata.cst8", MCSectionELF::SHT_PROGBITS,
126                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
127                  SectionKind::getMergeableConst8());
128
129  MergeableConst16Section =
130    getELFSection(".rodata.cst16", MCSectionELF::SHT_PROGBITS,
131                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
132                  SectionKind::getMergeableConst16());
133
134  StaticCtorSection =
135    getELFSection(".ctors", MCSectionELF::SHT_PROGBITS,
136                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
137                  SectionKind::getDataRel());
138
139  StaticDtorSection =
140    getELFSection(".dtors", MCSectionELF::SHT_PROGBITS,
141                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
142                  SectionKind::getDataRel());
143
144  // Exception Handling Sections.
145
146  // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
147  // it contains relocatable pointers.  In PIC mode, this is probably a big
148  // runtime hit for C++ apps.  Either the contents of the LSDA need to be
149  // adjusted or this should be a data section.
150  LSDASection =
151    getELFSection(".gcc_except_table", MCSectionELF::SHT_PROGBITS,
152                  MCSectionELF::SHF_ALLOC, SectionKind::getReadOnly());
153  EHFrameSection =
154    getELFSection(".eh_frame", MCSectionELF::SHT_PROGBITS,
155                  MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
156                  SectionKind::getDataRel());
157
158  // Debug Info Sections.
159  DwarfAbbrevSection =
160    getELFSection(".debug_abbrev", MCSectionELF::SHT_PROGBITS, 0,
161                  SectionKind::getMetadata());
162  DwarfInfoSection =
163    getELFSection(".debug_info", MCSectionELF::SHT_PROGBITS, 0,
164                  SectionKind::getMetadata());
165  DwarfLineSection =
166    getELFSection(".debug_line", MCSectionELF::SHT_PROGBITS, 0,
167                  SectionKind::getMetadata());
168  DwarfFrameSection =
169    getELFSection(".debug_frame", MCSectionELF::SHT_PROGBITS, 0,
170                  SectionKind::getMetadata());
171  DwarfPubNamesSection =
172    getELFSection(".debug_pubnames", MCSectionELF::SHT_PROGBITS, 0,
173                  SectionKind::getMetadata());
174  DwarfPubTypesSection =
175    getELFSection(".debug_pubtypes", MCSectionELF::SHT_PROGBITS, 0,
176                  SectionKind::getMetadata());
177  DwarfStrSection =
178    getELFSection(".debug_str", MCSectionELF::SHT_PROGBITS, 0,
179                  SectionKind::getMetadata());
180  DwarfLocSection =
181    getELFSection(".debug_loc", MCSectionELF::SHT_PROGBITS, 0,
182                  SectionKind::getMetadata());
183  DwarfARangesSection =
184    getELFSection(".debug_aranges", MCSectionELF::SHT_PROGBITS, 0,
185                  SectionKind::getMetadata());
186  DwarfRangesSection =
187    getELFSection(".debug_ranges", MCSectionELF::SHT_PROGBITS, 0,
188                  SectionKind::getMetadata());
189  DwarfMacroInfoSection =
190    getELFSection(".debug_macinfo", MCSectionELF::SHT_PROGBITS, 0,
191                  SectionKind::getMetadata());
192}
193
194
195static SectionKind
196getELFKindForNamedSection(StringRef Name, SectionKind K) {
197  if (Name.empty() || Name[0] != '.') return K;
198
199  // Some lame default implementation based on some magic section names.
200  if (Name == ".bss" ||
201      Name.startswith(".bss.") ||
202      Name.startswith(".gnu.linkonce.b.") ||
203      Name.startswith(".llvm.linkonce.b.") ||
204      Name == ".sbss" ||
205      Name.startswith(".sbss.") ||
206      Name.startswith(".gnu.linkonce.sb.") ||
207      Name.startswith(".llvm.linkonce.sb."))
208    return SectionKind::getBSS();
209
210  if (Name == ".tdata" ||
211      Name.startswith(".tdata.") ||
212      Name.startswith(".gnu.linkonce.td.") ||
213      Name.startswith(".llvm.linkonce.td."))
214    return SectionKind::getThreadData();
215
216  if (Name == ".tbss" ||
217      Name.startswith(".tbss.") ||
218      Name.startswith(".gnu.linkonce.tb.") ||
219      Name.startswith(".llvm.linkonce.tb."))
220    return SectionKind::getThreadBSS();
221
222  return K;
223}
224
225
226static unsigned getELFSectionType(StringRef Name, SectionKind K) {
227
228  if (Name == ".init_array")
229    return MCSectionELF::SHT_INIT_ARRAY;
230
231  if (Name == ".fini_array")
232    return MCSectionELF::SHT_FINI_ARRAY;
233
234  if (Name == ".preinit_array")
235    return MCSectionELF::SHT_PREINIT_ARRAY;
236
237  if (K.isBSS() || K.isThreadBSS())
238    return MCSectionELF::SHT_NOBITS;
239
240  return MCSectionELF::SHT_PROGBITS;
241}
242
243
244static unsigned
245getELFSectionFlags(SectionKind K) {
246  unsigned Flags = 0;
247
248  if (!K.isMetadata())
249    Flags |= MCSectionELF::SHF_ALLOC;
250
251  if (K.isText())
252    Flags |= MCSectionELF::SHF_EXECINSTR;
253
254  if (K.isWriteable())
255    Flags |= MCSectionELF::SHF_WRITE;
256
257  if (K.isThreadLocal())
258    Flags |= MCSectionELF::SHF_TLS;
259
260  // K.isMergeableConst() is left out to honour PR4650
261  if (K.isMergeableCString() || K.isMergeableConst4() ||
262      K.isMergeableConst8() || K.isMergeableConst16())
263    Flags |= MCSectionELF::SHF_MERGE;
264
265  if (K.isMergeableCString())
266    Flags |= MCSectionELF::SHF_STRINGS;
267
268  return Flags;
269}
270
271
272const MCSection *TargetLoweringObjectFileELF::
273getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
274                         Mangler *Mang, const TargetMachine &TM) const {
275  StringRef SectionName = GV->getSection();
276
277  // Infer section flags from the section name if we can.
278  Kind = getELFKindForNamedSection(SectionName, Kind);
279
280  return getELFSection(SectionName,
281                       getELFSectionType(SectionName, Kind),
282                       getELFSectionFlags(Kind), Kind, true);
283}
284
285static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) {
286  if (Kind.isText())                 return ".gnu.linkonce.t.";
287  if (Kind.isReadOnly())             return ".gnu.linkonce.r.";
288
289  if (Kind.isThreadData())           return ".gnu.linkonce.td.";
290  if (Kind.isThreadBSS())            return ".gnu.linkonce.tb.";
291
292  if (Kind.isDataNoRel())            return ".gnu.linkonce.d.";
293  if (Kind.isDataRelLocal())         return ".gnu.linkonce.d.rel.local.";
294  if (Kind.isDataRel())              return ".gnu.linkonce.d.rel.";
295  if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local.";
296
297  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
298  return ".gnu.linkonce.d.rel.ro.";
299}
300
301const MCSection *TargetLoweringObjectFileELF::
302SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
303                       Mangler *Mang, const TargetMachine &TM) const {
304
305  // If this global is linkonce/weak and the target handles this by emitting it
306  // into a 'uniqued' section name, create and return the section now.
307  if (GV->isWeakForLinker() && !Kind.isCommon() && !Kind.isBSS()) {
308    const char *Prefix = getSectionPrefixForUniqueGlobal(Kind);
309    SmallString<128> Name;
310    Name.append(Prefix, Prefix+strlen(Prefix));
311    Mang->getNameWithPrefix(Name, GV, false);
312    return getELFSection(Name.str(), getELFSectionType(Name.str(), Kind),
313                         getELFSectionFlags(Kind), Kind);
314  }
315
316  if (Kind.isText()) return TextSection;
317
318  if (Kind.isMergeable1ByteCString() ||
319      Kind.isMergeable2ByteCString() ||
320      Kind.isMergeable4ByteCString()) {
321
322    // We also need alignment here.
323    // FIXME: this is getting the alignment of the character, not the
324    // alignment of the global!
325    unsigned Align =
326      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
327
328    const char *SizeSpec = ".rodata.str1.";
329    if (Kind.isMergeable2ByteCString())
330      SizeSpec = ".rodata.str2.";
331    else if (Kind.isMergeable4ByteCString())
332      SizeSpec = ".rodata.str4.";
333    else
334      assert(Kind.isMergeable1ByteCString() && "unknown string width");
335
336
337    std::string Name = SizeSpec + utostr(Align);
338    return getELFSection(Name, MCSectionELF::SHT_PROGBITS,
339                         MCSectionELF::SHF_ALLOC |
340                         MCSectionELF::SHF_MERGE |
341                         MCSectionELF::SHF_STRINGS,
342                         Kind);
343  }
344
345  if (Kind.isMergeableConst()) {
346    if (Kind.isMergeableConst4() && MergeableConst4Section)
347      return MergeableConst4Section;
348    if (Kind.isMergeableConst8() && MergeableConst8Section)
349      return MergeableConst8Section;
350    if (Kind.isMergeableConst16() && MergeableConst16Section)
351      return MergeableConst16Section;
352    return ReadOnlySection;  // .const
353  }
354
355  if (Kind.isReadOnly())             return ReadOnlySection;
356
357  if (Kind.isThreadData())           return TLSDataSection;
358  if (Kind.isThreadBSS())            return TLSBSSSection;
359
360  // Note: we claim that common symbols are put in BSSSection, but they are
361  // really emitted with the magic .comm directive, which creates a symbol table
362  // entry but not a section.
363  if (Kind.isBSS() || Kind.isCommon()) return BSSSection;
364
365  if (Kind.isDataNoRel())            return DataSection;
366  if (Kind.isDataRelLocal())         return DataRelLocalSection;
367  if (Kind.isDataRel())              return DataRelSection;
368  if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
369
370  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
371  return DataRelROSection;
372}
373
374/// getSectionForConstant - Given a mergeable constant with the
375/// specified size and relocation information, return a section that it
376/// should be placed in.
377const MCSection *TargetLoweringObjectFileELF::
378getSectionForConstant(SectionKind Kind) const {
379  if (Kind.isMergeableConst4() && MergeableConst4Section)
380    return MergeableConst4Section;
381  if (Kind.isMergeableConst8() && MergeableConst8Section)
382    return MergeableConst8Section;
383  if (Kind.isMergeableConst16() && MergeableConst16Section)
384    return MergeableConst16Section;
385  if (Kind.isReadOnly())
386    return ReadOnlySection;
387
388  if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
389  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
390  return DataRelROSection;
391}
392
393const MCExpr *TargetLoweringObjectFileELF::
394getSymbolForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
395                             MachineModuleInfo *MMI, unsigned Encoding) const {
396
397  if (Encoding & dwarf::DW_EH_PE_indirect) {
398    MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
399
400    SmallString<128> Name;
401    Mang->getNameWithPrefix(Name, GV, true);
402    Name += ".DW.stub";
403
404    // Add information about the stub reference to ELFMMI so that the stub
405    // gets emitted by the asmprinter.
406    MCSymbol *Sym = getContext().GetOrCreateSymbol(Name.str());
407    MCSymbol *&StubSym = ELFMMI.getGVStubEntry(Sym);
408    if (StubSym == 0) {
409      Name.clear();
410      Mang->getNameWithPrefix(Name, GV, false);
411      StubSym = getContext().GetOrCreateSymbol(Name.str());
412    }
413
414    return TargetLoweringObjectFile::
415      getSymbolForDwarfReference(Sym, MMI,
416                                 Encoding & ~dwarf::DW_EH_PE_indirect);
417  }
418
419  return TargetLoweringObjectFile::
420    getSymbolForDwarfGlobalReference(GV, Mang, MMI, Encoding);
421}
422
423//===----------------------------------------------------------------------===//
424//                                 MachO
425//===----------------------------------------------------------------------===//
426
427typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
428
429TargetLoweringObjectFileMachO::~TargetLoweringObjectFileMachO() {
430  // If we have the MachO uniquing map, free it.
431  delete (MachOUniqueMapTy*)UniquingMap;
432}
433
434
435const MCSectionMachO *TargetLoweringObjectFileMachO::
436getMachOSection(StringRef Segment, StringRef Section,
437                unsigned TypeAndAttributes,
438                unsigned Reserved2, SectionKind Kind) const {
439  // We unique sections by their segment/section pair.  The returned section
440  // may not have the same flags as the requested section, if so this should be
441  // diagnosed by the client as an error.
442
443  // Create the map if it doesn't already exist.
444  if (UniquingMap == 0)
445    UniquingMap = new MachOUniqueMapTy();
446  MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)UniquingMap;
447
448  // Form the name to look up.
449  SmallString<64> Name;
450  Name += Segment;
451  Name.push_back(',');
452  Name += Section;
453
454  // Do the lookup, if we have a hit, return it.
455  const MCSectionMachO *&Entry = Map[Name.str()];
456  if (Entry) return Entry;
457
458  // Otherwise, return a new section.
459  return Entry = MCSectionMachO::Create(Segment, Section, TypeAndAttributes,
460                                        Reserved2, Kind, getContext());
461}
462
463
464void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
465                                               const TargetMachine &TM) {
466  if (UniquingMap != 0)
467    ((MachOUniqueMapTy*)UniquingMap)->clear();
468  TargetLoweringObjectFile::Initialize(Ctx, TM);
469
470  TextSection // .text
471    = getMachOSection("__TEXT", "__text",
472                      MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
473                      SectionKind::getText());
474  DataSection // .data
475    = getMachOSection("__DATA", "__data", 0, SectionKind::getDataRel());
476
477  CStringSection // .cstring
478    = getMachOSection("__TEXT", "__cstring", MCSectionMachO::S_CSTRING_LITERALS,
479                      SectionKind::getMergeable1ByteCString());
480  UStringSection
481    = getMachOSection("__TEXT","__ustring", 0,
482                      SectionKind::getMergeable2ByteCString());
483  FourByteConstantSection // .literal4
484    = getMachOSection("__TEXT", "__literal4", MCSectionMachO::S_4BYTE_LITERALS,
485                      SectionKind::getMergeableConst4());
486  EightByteConstantSection // .literal8
487    = getMachOSection("__TEXT", "__literal8", MCSectionMachO::S_8BYTE_LITERALS,
488                      SectionKind::getMergeableConst8());
489
490  // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
491  // to using it in -static mode.
492  SixteenByteConstantSection = 0;
493  if (TM.getRelocationModel() != Reloc::Static &&
494      TM.getTargetData()->getPointerSize() == 32)
495    SixteenByteConstantSection =   // .literal16
496      getMachOSection("__TEXT", "__literal16",MCSectionMachO::S_16BYTE_LITERALS,
497                      SectionKind::getMergeableConst16());
498
499  ReadOnlySection  // .const
500    = getMachOSection("__TEXT", "__const", 0, SectionKind::getReadOnly());
501
502  TextCoalSection
503    = getMachOSection("__TEXT", "__textcoal_nt",
504                      MCSectionMachO::S_COALESCED |
505                      MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
506                      SectionKind::getText());
507  ConstTextCoalSection
508    = getMachOSection("__TEXT", "__const_coal", MCSectionMachO::S_COALESCED,
509                      SectionKind::getText());
510  ConstDataCoalSection
511    = getMachOSection("__DATA","__const_coal", MCSectionMachO::S_COALESCED,
512                      SectionKind::getText());
513  ConstDataSection  // .const_data
514    = getMachOSection("__DATA", "__const", 0,
515                      SectionKind::getReadOnlyWithRel());
516  DataCoalSection
517    = getMachOSection("__DATA","__datacoal_nt", MCSectionMachO::S_COALESCED,
518                      SectionKind::getDataRel());
519  DataCommonSection
520    = getMachOSection("__DATA","__common", MCSectionMachO::S_ZEROFILL,
521                      SectionKind::getBSS());
522  DataBSSSection
523    = getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL,
524                    SectionKind::getBSS());
525
526
527  LazySymbolPointerSection
528    = getMachOSection("__DATA", "__la_symbol_ptr",
529                      MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
530                      SectionKind::getMetadata());
531  NonLazySymbolPointerSection
532    = getMachOSection("__DATA", "__nl_symbol_ptr",
533                      MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
534                      SectionKind::getMetadata());
535
536  if (TM.getRelocationModel() == Reloc::Static) {
537    StaticCtorSection
538      = getMachOSection("__TEXT", "__constructor", 0,SectionKind::getDataRel());
539    StaticDtorSection
540      = getMachOSection("__TEXT", "__destructor", 0, SectionKind::getDataRel());
541  } else {
542    StaticCtorSection
543      = getMachOSection("__DATA", "__mod_init_func",
544                        MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
545                        SectionKind::getDataRel());
546    StaticDtorSection
547      = getMachOSection("__DATA", "__mod_term_func",
548                        MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
549                        SectionKind::getDataRel());
550  }
551
552  // Exception Handling.
553  LSDASection = getMachOSection("__DATA", "__gcc_except_tab", 0,
554                                SectionKind::getDataRel());
555  EHFrameSection =
556    getMachOSection("__TEXT", "__eh_frame",
557                    MCSectionMachO::S_COALESCED |
558                    MCSectionMachO::S_ATTR_NO_TOC |
559                    MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
560                    MCSectionMachO::S_ATTR_LIVE_SUPPORT,
561                    SectionKind::getReadOnly());
562
563  // Debug Information.
564  DwarfAbbrevSection =
565    getMachOSection("__DWARF", "__debug_abbrev", MCSectionMachO::S_ATTR_DEBUG,
566                    SectionKind::getMetadata());
567  DwarfInfoSection =
568    getMachOSection("__DWARF", "__debug_info", MCSectionMachO::S_ATTR_DEBUG,
569                    SectionKind::getMetadata());
570  DwarfLineSection =
571    getMachOSection("__DWARF", "__debug_line", MCSectionMachO::S_ATTR_DEBUG,
572                    SectionKind::getMetadata());
573  DwarfFrameSection =
574    getMachOSection("__DWARF", "__debug_frame", MCSectionMachO::S_ATTR_DEBUG,
575                    SectionKind::getMetadata());
576  DwarfPubNamesSection =
577    getMachOSection("__DWARF", "__debug_pubnames", MCSectionMachO::S_ATTR_DEBUG,
578                    SectionKind::getMetadata());
579  DwarfPubTypesSection =
580    getMachOSection("__DWARF", "__debug_pubtypes", MCSectionMachO::S_ATTR_DEBUG,
581                    SectionKind::getMetadata());
582  DwarfStrSection =
583    getMachOSection("__DWARF", "__debug_str", MCSectionMachO::S_ATTR_DEBUG,
584                    SectionKind::getMetadata());
585  DwarfLocSection =
586    getMachOSection("__DWARF", "__debug_loc", MCSectionMachO::S_ATTR_DEBUG,
587                    SectionKind::getMetadata());
588  DwarfARangesSection =
589    getMachOSection("__DWARF", "__debug_aranges", MCSectionMachO::S_ATTR_DEBUG,
590                    SectionKind::getMetadata());
591  DwarfRangesSection =
592    getMachOSection("__DWARF", "__debug_ranges", MCSectionMachO::S_ATTR_DEBUG,
593                    SectionKind::getMetadata());
594  DwarfMacroInfoSection =
595    getMachOSection("__DWARF", "__debug_macinfo", MCSectionMachO::S_ATTR_DEBUG,
596                    SectionKind::getMetadata());
597  DwarfDebugInlineSection =
598    getMachOSection("__DWARF", "__debug_inlined", MCSectionMachO::S_ATTR_DEBUG,
599                    SectionKind::getMetadata());
600}
601
602const MCSection *TargetLoweringObjectFileMachO::
603getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
604                         Mangler *Mang, const TargetMachine &TM) const {
605  // Parse the section specifier and create it if valid.
606  StringRef Segment, Section;
607  unsigned TAA, StubSize;
608  std::string ErrorCode =
609    MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
610                                          TAA, StubSize);
611  if (!ErrorCode.empty()) {
612    // If invalid, report the error with llvm_report_error.
613    llvm_report_error("Global variable '" + GV->getNameStr() +
614                      "' has an invalid section specifier '" + GV->getSection()+
615                      "': " + ErrorCode + ".");
616    // Fall back to dropping it into the data section.
617    return DataSection;
618  }
619
620  // Get the section.
621  const MCSectionMachO *S =
622    getMachOSection(Segment, Section, TAA, StubSize, Kind);
623
624  // Okay, now that we got the section, verify that the TAA & StubSize agree.
625  // If the user declared multiple globals with different section flags, we need
626  // to reject it here.
627  if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
628    // If invalid, report the error with llvm_report_error.
629    llvm_report_error("Global variable '" + GV->getNameStr() +
630                      "' section type or attributes does not match previous"
631                      " section specifier");
632  }
633
634  return S;
635}
636
637const MCSection *TargetLoweringObjectFileMachO::
638SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
639                       Mangler *Mang, const TargetMachine &TM) const {
640  assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS");
641
642  if (Kind.isText())
643    return GV->isWeakForLinker() ? TextCoalSection : TextSection;
644
645  // If this is weak/linkonce, put this in a coalescable section, either in text
646  // or data depending on if it is writable.
647  if (GV->isWeakForLinker()) {
648    if (Kind.isReadOnly())
649      return ConstTextCoalSection;
650    return DataCoalSection;
651  }
652
653  // FIXME: Alignment check should be handled by section classifier.
654  if (Kind.isMergeable1ByteCString() ||
655      Kind.isMergeable2ByteCString()) {
656    if (TM.getTargetData()->getPreferredAlignment(
657                                              cast<GlobalVariable>(GV)) < 32) {
658      if (Kind.isMergeable1ByteCString())
659        return CStringSection;
660      assert(Kind.isMergeable2ByteCString());
661      return UStringSection;
662    }
663  }
664
665  if (Kind.isMergeableConst()) {
666    if (Kind.isMergeableConst4())
667      return FourByteConstantSection;
668    if (Kind.isMergeableConst8())
669      return EightByteConstantSection;
670    if (Kind.isMergeableConst16() && SixteenByteConstantSection)
671      return SixteenByteConstantSection;
672  }
673
674  // Otherwise, if it is readonly, but not something we can specially optimize,
675  // just drop it in .const.
676  if (Kind.isReadOnly())
677    return ReadOnlySection;
678
679  // If this is marked const, put it into a const section.  But if the dynamic
680  // linker needs to write to it, put it in the data segment.
681  if (Kind.isReadOnlyWithRel())
682    return ConstDataSection;
683
684  // Put zero initialized globals with strong external linkage in the
685  // DATA, __common section with the .zerofill directive.
686  if (Kind.isBSSExtern())
687    return DataCommonSection;
688
689  // Put zero initialized globals with local linkage in __DATA,__bss directive
690  // with the .zerofill directive (aka .lcomm).
691  if (Kind.isBSSLocal())
692    return DataBSSSection;
693
694  // Otherwise, just drop the variable in the normal data section.
695  return DataSection;
696}
697
698const MCSection *
699TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
700  // If this constant requires a relocation, we have to put it in the data
701  // segment, not in the text segment.
702  if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
703    return ConstDataSection;
704
705  if (Kind.isMergeableConst4())
706    return FourByteConstantSection;
707  if (Kind.isMergeableConst8())
708    return EightByteConstantSection;
709  if (Kind.isMergeableConst16() && SixteenByteConstantSection)
710    return SixteenByteConstantSection;
711  return ReadOnlySection;  // .const
712}
713
714/// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
715/// not to emit the UsedDirective for some symbols in llvm.used.
716// FIXME: REMOVE this (rdar://7071300)
717bool TargetLoweringObjectFileMachO::
718shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
719  /// On Darwin, internally linked data beginning with "L" or "l" does not have
720  /// the directive emitted (this occurs in ObjC metadata).
721  if (!GV) return false;
722
723  // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
724  if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
725    // FIXME: ObjC metadata is currently emitted as internal symbols that have
726    // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
727    // this horrible hack can go away.
728    SmallString<64> Name;
729    Mang->getNameWithPrefix(Name, GV, false);
730    if (Name[0] == 'L' || Name[0] == 'l')
731      return false;
732  }
733
734  return true;
735}
736
737const MCExpr *TargetLoweringObjectFileMachO::
738getSymbolForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
739                             MachineModuleInfo *MMI, unsigned Encoding) const {
740  // The mach-o version of this method defaults to returning a stub reference.
741
742  if (Encoding & dwarf::DW_EH_PE_indirect) {
743    SmallString<128> Name;
744    Mang->getNameWithPrefix(Name, GV, true);
745    Name += "$non_lazy_ptr";
746    MCSymbol *Sym = getContext().GetOrCreateSymbol(Name.str());
747
748    return TargetLoweringObjectFile::
749      getSymbolForDwarfReference(Sym, MMI,
750                                 Encoding & ~dwarf::DW_EH_PE_indirect);
751  }
752
753  return TargetLoweringObjectFile::
754    getSymbolForDwarfGlobalReference(GV, Mang, MMI, Encoding);
755}
756
757
758unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const {
759  return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
760}
761
762unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const {
763  return DW_EH_PE_pcrel;
764}
765
766unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const {
767  return DW_EH_PE_pcrel;
768}
769
770unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const {
771  return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
772}
773
774//===----------------------------------------------------------------------===//
775//                                  COFF
776//===----------------------------------------------------------------------===//
777
778typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
779
780TargetLoweringObjectFileCOFF::~TargetLoweringObjectFileCOFF() {
781  delete (COFFUniqueMapTy*)UniquingMap;
782}
783
784
785const MCSection *TargetLoweringObjectFileCOFF::
786getCOFFSection(StringRef Name, bool isDirective, SectionKind Kind) const {
787  // Create the map if it doesn't already exist.
788  if (UniquingMap == 0)
789    UniquingMap = new MachOUniqueMapTy();
790  COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)UniquingMap;
791
792  // Do the lookup, if we have a hit, return it.
793  const MCSectionCOFF *&Entry = Map[Name];
794  if (Entry) return Entry;
795
796  return Entry = MCSectionCOFF::Create(Name, isDirective, Kind, getContext());
797}
798
799void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
800                                              const TargetMachine &TM) {
801  if (UniquingMap != 0)
802    ((COFFUniqueMapTy*)UniquingMap)->clear();
803  TargetLoweringObjectFile::Initialize(Ctx, TM);
804  TextSection = getCOFFSection("\t.text", true, SectionKind::getText());
805  DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel());
806  StaticCtorSection =
807    getCOFFSection(".ctors", false, SectionKind::getDataRel());
808  StaticDtorSection =
809    getCOFFSection(".dtors", false, SectionKind::getDataRel());
810
811  // FIXME: We're emitting LSDA info into a readonly section on COFF, even
812  // though it contains relocatable pointers.  In PIC mode, this is probably a
813  // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
814  // adjusted or this should be a data section.
815  LSDASection =
816    getCOFFSection(".gcc_except_table", false, SectionKind::getReadOnly());
817  EHFrameSection =
818    getCOFFSection(".eh_frame", false, SectionKind::getDataRel());
819
820  // Debug info.
821  // FIXME: Don't use 'directive' mode here.
822  DwarfAbbrevSection =
823    getCOFFSection("\t.section\t.debug_abbrev,\"dr\"",
824                   true, SectionKind::getMetadata());
825  DwarfInfoSection =
826    getCOFFSection("\t.section\t.debug_info,\"dr\"",
827                   true, SectionKind::getMetadata());
828  DwarfLineSection =
829    getCOFFSection("\t.section\t.debug_line,\"dr\"",
830                   true, SectionKind::getMetadata());
831  DwarfFrameSection =
832    getCOFFSection("\t.section\t.debug_frame,\"dr\"",
833                   true, SectionKind::getMetadata());
834  DwarfPubNamesSection =
835    getCOFFSection("\t.section\t.debug_pubnames,\"dr\"",
836                   true, SectionKind::getMetadata());
837  DwarfPubTypesSection =
838    getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"",
839                   true, SectionKind::getMetadata());
840  DwarfStrSection =
841    getCOFFSection("\t.section\t.debug_str,\"dr\"",
842                   true, SectionKind::getMetadata());
843  DwarfLocSection =
844    getCOFFSection("\t.section\t.debug_loc,\"dr\"",
845                   true, SectionKind::getMetadata());
846  DwarfARangesSection =
847    getCOFFSection("\t.section\t.debug_aranges,\"dr\"",
848                   true, SectionKind::getMetadata());
849  DwarfRangesSection =
850    getCOFFSection("\t.section\t.debug_ranges,\"dr\"",
851                   true, SectionKind::getMetadata());
852  DwarfMacroInfoSection =
853    getCOFFSection("\t.section\t.debug_macinfo,\"dr\"",
854                   true, SectionKind::getMetadata());
855}
856
857const MCSection *TargetLoweringObjectFileCOFF::
858getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
859                         Mangler *Mang, const TargetMachine &TM) const {
860  return getCOFFSection(GV->getSection(), false, Kind);
861}
862
863static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
864  if (Kind.isText())
865    return ".text$linkonce";
866  if (Kind.isWriteable())
867    return ".data$linkonce";
868  return ".rdata$linkonce";
869}
870
871
872const MCSection *TargetLoweringObjectFileCOFF::
873SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
874                       Mangler *Mang, const TargetMachine &TM) const {
875  assert(!Kind.isThreadLocal() && "Doesn't support TLS");
876
877  // If this global is linkonce/weak and the target handles this by emitting it
878  // into a 'uniqued' section name, create and return the section now.
879  if (GV->isWeakForLinker()) {
880    const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
881    SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
882    Mang->getNameWithPrefix(Name, GV, false);
883    return getCOFFSection(Name.str(), false, Kind);
884  }
885
886  if (Kind.isText())
887    return getTextSection();
888
889  return getDataSection();
890}
891
892