TargetLoweringObjectFileImpl.cpp revision 30deafc84adf88f643cdc39dc97a37537155347f 
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/MCStreamer.h"
27#include "llvm/MC/MCSymbol.h"
28#include "llvm/Target/Mangler.h"
29#include "llvm/Target/TargetData.h"
30#include "llvm/Target/TargetMachine.h"
31#include "llvm/Target/TargetOptions.h"
32#include "llvm/Support/Dwarf.h"
33#include "llvm/Support/ELF.h"
34#include "llvm/Support/ErrorHandling.h"
35#include "llvm/Support/raw_ostream.h"
36#include "llvm/ADT/SmallString.h"
37#include "llvm/ADT/StringExtras.h"
38#include "llvm/ADT/Triple.h"
39using namespace llvm;
40using namespace dwarf;
41
42//===----------------------------------------------------------------------===//
43//                                  ELF
44//===----------------------------------------------------------------------===//
45
46void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
47                                             const TargetMachine &TM) {
48  TargetLoweringObjectFile::Initialize(Ctx, TM);
49
50  BSSSection =
51    getContext().getELFSection(".bss", ELF::SHT_NOBITS,
52                               ELF::SHF_WRITE |ELF::SHF_ALLOC,
53                               SectionKind::getBSS());
54
55  TextSection =
56    getContext().getELFSection(".text", ELF::SHT_PROGBITS,
57                               ELF::SHF_EXECINSTR |
58                               ELF::SHF_ALLOC,
59                               SectionKind::getText());
60
61  DataSection =
62    getContext().getELFSection(".data", ELF::SHT_PROGBITS,
63                               ELF::SHF_WRITE |ELF::SHF_ALLOC,
64                               SectionKind::getDataRel());
65
66  ReadOnlySection =
67    getContext().getELFSection(".rodata", ELF::SHT_PROGBITS,
68                               ELF::SHF_ALLOC,
69                               SectionKind::getReadOnly());
70
71  TLSDataSection =
72    getContext().getELFSection(".tdata", ELF::SHT_PROGBITS,
73                               ELF::SHF_ALLOC | ELF::SHF_TLS |
74                               ELF::SHF_WRITE,
75                               SectionKind::getThreadData());
76
77  TLSBSSSection =
78    getContext().getELFSection(".tbss", ELF::SHT_NOBITS,
79                               ELF::SHF_ALLOC | ELF::SHF_TLS |
80                               ELF::SHF_WRITE,
81                               SectionKind::getThreadBSS());
82
83  DataRelSection =
84    getContext().getELFSection(".data.rel", ELF::SHT_PROGBITS,
85                               ELF::SHF_ALLOC |ELF::SHF_WRITE,
86                               SectionKind::getDataRel());
87
88  DataRelLocalSection =
89    getContext().getELFSection(".data.rel.local", ELF::SHT_PROGBITS,
90                               ELF::SHF_ALLOC |ELF::SHF_WRITE,
91                               SectionKind::getDataRelLocal());
92
93  DataRelROSection =
94    getContext().getELFSection(".data.rel.ro", ELF::SHT_PROGBITS,
95                               ELF::SHF_ALLOC |ELF::SHF_WRITE,
96                               SectionKind::getReadOnlyWithRel());
97
98  DataRelROLocalSection =
99    getContext().getELFSection(".data.rel.ro.local", ELF::SHT_PROGBITS,
100                               ELF::SHF_ALLOC |ELF::SHF_WRITE,
101                               SectionKind::getReadOnlyWithRelLocal());
102
103  MergeableConst4Section =
104    getContext().getELFSection(".rodata.cst4", ELF::SHT_PROGBITS,
105                               ELF::SHF_ALLOC |ELF::SHF_MERGE,
106                               SectionKind::getMergeableConst4());
107
108  MergeableConst8Section =
109    getContext().getELFSection(".rodata.cst8", ELF::SHT_PROGBITS,
110                               ELF::SHF_ALLOC |ELF::SHF_MERGE,
111                               SectionKind::getMergeableConst8());
112
113  MergeableConst16Section =
114    getContext().getELFSection(".rodata.cst16", ELF::SHT_PROGBITS,
115                               ELF::SHF_ALLOC |ELF::SHF_MERGE,
116                               SectionKind::getMergeableConst16());
117
118  StaticCtorSection =
119    getContext().getELFSection(".ctors", ELF::SHT_PROGBITS,
120                               ELF::SHF_ALLOC |ELF::SHF_WRITE,
121                               SectionKind::getDataRel());
122
123  StaticDtorSection =
124    getContext().getELFSection(".dtors", ELF::SHT_PROGBITS,
125                               ELF::SHF_ALLOC |ELF::SHF_WRITE,
126                               SectionKind::getDataRel());
127
128  // Exception Handling Sections.
129
130  // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
131  // it contains relocatable pointers.  In PIC mode, this is probably a big
132  // runtime hit for C++ apps.  Either the contents of the LSDA need to be
133  // adjusted or this should be a data section.
134  LSDASection =
135    getContext().getELFSection(".gcc_except_table", ELF::SHT_PROGBITS,
136                               ELF::SHF_ALLOC,
137                               SectionKind::getReadOnly());
138  // Debug Info Sections.
139  DwarfAbbrevSection =
140    getContext().getELFSection(".debug_abbrev", ELF::SHT_PROGBITS, 0,
141                               SectionKind::getMetadata());
142  DwarfInfoSection =
143    getContext().getELFSection(".debug_info", ELF::SHT_PROGBITS, 0,
144                               SectionKind::getMetadata());
145  DwarfLineSection =
146    getContext().getELFSection(".debug_line", ELF::SHT_PROGBITS, 0,
147                               SectionKind::getMetadata());
148  DwarfFrameSection =
149    getContext().getELFSection(".debug_frame", ELF::SHT_PROGBITS, 0,
150                               SectionKind::getMetadata());
151  DwarfPubNamesSection =
152    getContext().getELFSection(".debug_pubnames", ELF::SHT_PROGBITS, 0,
153                               SectionKind::getMetadata());
154  DwarfPubTypesSection =
155    getContext().getELFSection(".debug_pubtypes", ELF::SHT_PROGBITS, 0,
156                               SectionKind::getMetadata());
157  DwarfStrSection =
158    getContext().getELFSection(".debug_str", ELF::SHT_PROGBITS, 0,
159                               SectionKind::getMetadata());
160  DwarfLocSection =
161    getContext().getELFSection(".debug_loc", ELF::SHT_PROGBITS, 0,
162                               SectionKind::getMetadata());
163  DwarfARangesSection =
164    getContext().getELFSection(".debug_aranges", ELF::SHT_PROGBITS, 0,
165                               SectionKind::getMetadata());
166  DwarfRangesSection =
167    getContext().getELFSection(".debug_ranges", ELF::SHT_PROGBITS, 0,
168                               SectionKind::getMetadata());
169  DwarfMacroInfoSection =
170    getContext().getELFSection(".debug_macinfo", ELF::SHT_PROGBITS, 0,
171                               SectionKind::getMetadata());
172}
173
174const MCSection *TargetLoweringObjectFileELF::getEHFrameSection() const {
175  return getContext().getELFSection(".eh_frame", ELF::SHT_PROGBITS,
176                                    ELF::SHF_ALLOC,
177                                    SectionKind::getDataRel());
178}
179
180MCSymbol *
181TargetLoweringObjectFileELF::getPersonalityPICSymbol(StringRef Name) const {
182  Twine FullName = StringRef("DW.ref.") + Name;
183  return getContext().GetOrCreateSymbol(FullName);
184}
185
186void TargetLoweringObjectFileELF::emitPersonalityValue(MCStreamer &Streamer,
187                                                       const TargetMachine &TM,
188                                                   const MCSymbol *Sym) const {
189    MCSymbol *Label = getPersonalityPICSymbol(Sym->getName());
190    Streamer.EmitSymbolAttribute(Label, MCSA_Hidden);
191    Streamer.EmitSymbolAttribute(Label, MCSA_Weak);
192    Twine SectionName = StringRef(".data.") + Label->getName();
193    SmallString<64> NameData;
194    SectionName.toVector(NameData);
195    unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP;
196    const MCSection *Sec = getContext().getELFSection(NameData,
197                                                      ELF::SHT_PROGBITS,
198                                                      Flags,
199                                                      SectionKind::getDataRel(),
200                                                      0, Label->getName());
201    Streamer.SwitchSection(Sec);
202    Streamer.EmitValueToAlignment(8);
203    Streamer.EmitSymbolAttribute(Label, MCSA_ELF_TypeObject);
204    const MCExpr *E = MCConstantExpr::Create(8, getContext());
205    Streamer.EmitELFSize(Label, E);
206    Streamer.EmitLabel(Label);
207
208    unsigned Size = TM.getTargetData()->getPointerSize();
209    Streamer.EmitSymbolValue(Sym, Size);
210}
211
212static SectionKind
213getELFKindForNamedSection(StringRef Name, SectionKind K) {
214  // FIXME: Why is this here? Codegen is should not be in the business
215  // of figuring section flags. If the user wrote section(".eh_frame"),
216  // we should just pass that to MC which will defer to the assembly
217  // or use its default if producing an object file.
218  if (Name.empty() || Name[0] != '.') return K;
219
220  // Some lame default implementation based on some magic section names.
221  if (Name == ".bss" ||
222      Name.startswith(".bss.") ||
223      Name.startswith(".gnu.linkonce.b.") ||
224      Name.startswith(".llvm.linkonce.b.") ||
225      Name == ".sbss" ||
226      Name.startswith(".sbss.") ||
227      Name.startswith(".gnu.linkonce.sb.") ||
228      Name.startswith(".llvm.linkonce.sb."))
229    return SectionKind::getBSS();
230
231  if (Name == ".tdata" ||
232      Name.startswith(".tdata.") ||
233      Name.startswith(".gnu.linkonce.td.") ||
234      Name.startswith(".llvm.linkonce.td."))
235    return SectionKind::getThreadData();
236
237  if (Name == ".tbss" ||
238      Name.startswith(".tbss.") ||
239      Name.startswith(".gnu.linkonce.tb.") ||
240      Name.startswith(".llvm.linkonce.tb."))
241    return SectionKind::getThreadBSS();
242
243  if (Name == ".eh_frame")
244    return SectionKind::getDataRel();
245
246  return K;
247}
248
249
250static unsigned getELFSectionType(StringRef Name, SectionKind K) {
251
252  if (Name == ".init_array")
253    return ELF::SHT_INIT_ARRAY;
254
255  if (Name == ".fini_array")
256    return ELF::SHT_FINI_ARRAY;
257
258  if (Name == ".preinit_array")
259    return ELF::SHT_PREINIT_ARRAY;
260
261  if (K.isBSS() || K.isThreadBSS())
262    return ELF::SHT_NOBITS;
263
264  return ELF::SHT_PROGBITS;
265}
266
267
268static unsigned
269getELFSectionFlags(SectionKind K) {
270  unsigned Flags = 0;
271
272  if (!K.isMetadata())
273    Flags |= ELF::SHF_ALLOC;
274
275  if (K.isText())
276    Flags |= ELF::SHF_EXECINSTR;
277
278  if (K.isWriteable())
279    Flags |= ELF::SHF_WRITE;
280
281  if (K.isThreadLocal())
282    Flags |= ELF::SHF_TLS;
283
284  // K.isMergeableConst() is left out to honour PR4650
285  if (K.isMergeableCString() || K.isMergeableConst4() ||
286      K.isMergeableConst8() || K.isMergeableConst16())
287    Flags |= ELF::SHF_MERGE;
288
289  if (K.isMergeableCString())
290    Flags |= ELF::SHF_STRINGS;
291
292  return Flags;
293}
294
295
296const MCSection *TargetLoweringObjectFileELF::
297getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
298                         Mangler *Mang, const TargetMachine &TM) const {
299  StringRef SectionName = GV->getSection();
300
301  // Infer section flags from the section name if we can.
302  Kind = getELFKindForNamedSection(SectionName, Kind);
303
304  return getContext().getELFSection(SectionName,
305                                    getELFSectionType(SectionName, Kind),
306                                    getELFSectionFlags(Kind), Kind);
307}
308
309/// getSectionPrefixForGlobal - Return the section prefix name used by options
310/// FunctionsSections and DataSections.
311static const char *getSectionPrefixForGlobal(SectionKind Kind) {
312  if (Kind.isText())                 return ".text.";
313  if (Kind.isReadOnly())             return ".rodata.";
314
315  if (Kind.isThreadData())           return ".tdata.";
316  if (Kind.isThreadBSS())            return ".tbss.";
317
318  if (Kind.isDataNoRel())            return ".data.";
319  if (Kind.isDataRelLocal())         return ".data.rel.local.";
320  if (Kind.isDataRel())              return ".data.rel.";
321  if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local.";
322
323  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
324  return ".data.rel.ro.";
325}
326
327
328const MCSection *TargetLoweringObjectFileELF::
329SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
330                       Mangler *Mang, const TargetMachine &TM) const {
331  // If we have -ffunction-section or -fdata-section then we should emit the
332  // global value to a uniqued section specifically for it.
333  bool EmitUniquedSection;
334  if (Kind.isText())
335    EmitUniquedSection = TM.getFunctionSections();
336  else
337    EmitUniquedSection = TM.getDataSections();
338
339  // If this global is linkonce/weak and the target handles this by emitting it
340  // into a 'uniqued' section name, create and return the section now.
341  if ((GV->isWeakForLinker() || EmitUniquedSection) &&
342      !Kind.isCommon() && !Kind.isBSS()) {
343    const char *Prefix;
344    Prefix = getSectionPrefixForGlobal(Kind);
345
346    SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
347    MCSymbol *Sym = Mang->getSymbol(GV);
348    Name.append(Sym->getName().begin(), Sym->getName().end());
349    StringRef Group = "";
350    unsigned Flags = getELFSectionFlags(Kind);
351    if (GV->isWeakForLinker()) {
352      Group = Sym->getName();
353      Flags |= ELF::SHF_GROUP;
354    }
355
356    return getContext().getELFSection(Name.str(),
357                                      getELFSectionType(Name.str(), Kind),
358                                      Flags, Kind, 0, Group);
359  }
360
361  if (Kind.isText()) return TextSection;
362
363  if (Kind.isMergeable1ByteCString() ||
364      Kind.isMergeable2ByteCString() ||
365      Kind.isMergeable4ByteCString()) {
366
367    // We also need alignment here.
368    // FIXME: this is getting the alignment of the character, not the
369    // alignment of the global!
370    unsigned Align =
371      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
372
373    const char *SizeSpec = ".rodata.str1.";
374    if (Kind.isMergeable2ByteCString())
375      SizeSpec = ".rodata.str2.";
376    else if (Kind.isMergeable4ByteCString())
377      SizeSpec = ".rodata.str4.";
378    else
379      assert(Kind.isMergeable1ByteCString() && "unknown string width");
380
381
382    std::string Name = SizeSpec + utostr(Align);
383    return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
384                                      ELF::SHF_ALLOC |
385                                      ELF::SHF_MERGE |
386                                      ELF::SHF_STRINGS,
387                                      Kind);
388  }
389
390  if (Kind.isMergeableConst()) {
391    if (Kind.isMergeableConst4() && MergeableConst4Section)
392      return MergeableConst4Section;
393    if (Kind.isMergeableConst8() && MergeableConst8Section)
394      return MergeableConst8Section;
395    if (Kind.isMergeableConst16() && MergeableConst16Section)
396      return MergeableConst16Section;
397    return ReadOnlySection;  // .const
398  }
399
400  if (Kind.isReadOnly())             return ReadOnlySection;
401
402  if (Kind.isThreadData())           return TLSDataSection;
403  if (Kind.isThreadBSS())            return TLSBSSSection;
404
405  // Note: we claim that common symbols are put in BSSSection, but they are
406  // really emitted with the magic .comm directive, which creates a symbol table
407  // entry but not a section.
408  if (Kind.isBSS() || Kind.isCommon()) return BSSSection;
409
410  if (Kind.isDataNoRel())            return DataSection;
411  if (Kind.isDataRelLocal())         return DataRelLocalSection;
412  if (Kind.isDataRel())              return DataRelSection;
413  if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
414
415  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
416  return DataRelROSection;
417}
418
419/// getSectionForConstant - Given a mergeable constant with the
420/// specified size and relocation information, return a section that it
421/// should be placed in.
422const MCSection *TargetLoweringObjectFileELF::
423getSectionForConstant(SectionKind Kind) const {
424  if (Kind.isMergeableConst4() && MergeableConst4Section)
425    return MergeableConst4Section;
426  if (Kind.isMergeableConst8() && MergeableConst8Section)
427    return MergeableConst8Section;
428  if (Kind.isMergeableConst16() && MergeableConst16Section)
429    return MergeableConst16Section;
430  if (Kind.isReadOnly())
431    return ReadOnlySection;
432
433  if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
434  assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
435  return DataRelROSection;
436}
437
438const MCExpr *TargetLoweringObjectFileELF::
439getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
440                               MachineModuleInfo *MMI,
441                               unsigned Encoding, MCStreamer &Streamer) const {
442
443  if (Encoding & dwarf::DW_EH_PE_indirect) {
444    MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
445
446    SmallString<128> Name;
447    Mang->getNameWithPrefix(Name, GV, true);
448    Name += ".DW.stub";
449
450    // Add information about the stub reference to ELFMMI so that the stub
451    // gets emitted by the asmprinter.
452    MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
453    MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
454    if (StubSym.getPointer() == 0) {
455      MCSymbol *Sym = Mang->getSymbol(GV);
456      StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
457    }
458
459    return TargetLoweringObjectFile::
460      getExprForDwarfReference(SSym, Mang, MMI,
461                               Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
462  }
463
464  return TargetLoweringObjectFile::
465    getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
466}
467
468//===----------------------------------------------------------------------===//
469//                                 MachO
470//===----------------------------------------------------------------------===//
471
472void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
473                                               const TargetMachine &TM) {
474  // _foo.eh symbols are currently always exported so that the linker knows
475  // about them.  This is not necessary on 10.6 and later, but it
476  // doesn't hurt anything.
477  // FIXME: I need to get this from Triple.
478  IsFunctionEHSymbolGlobal = true;
479  IsFunctionEHFrameSymbolPrivate = false;
480  SupportsWeakOmittedEHFrame = false;
481
482  Triple T(((LLVMTargetMachine&)TM).getTargetTriple());
483  if (T.getOS() == Triple::Darwin) {
484    switch (T.getDarwinMajorNumber()) {
485    case 7:  // 10.3 Panther.
486    case 8:  // 10.4 Tiger.
487      CommDirectiveSupportsAlignment = false;
488      break;
489    case 9:   // 10.5 Leopard.
490    case 10:  // 10.6 SnowLeopard.
491      break;
492    }
493  }
494
495  TargetLoweringObjectFile::Initialize(Ctx, TM);
496
497  TextSection // .text
498    = getContext().getMachOSection("__TEXT", "__text",
499                                   MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
500                                   SectionKind::getText());
501  DataSection // .data
502    = getContext().getMachOSection("__DATA", "__data", 0,
503                                   SectionKind::getDataRel());
504
505  TLSDataSection // .tdata
506    = getContext().getMachOSection("__DATA", "__thread_data",
507                                   MCSectionMachO::S_THREAD_LOCAL_REGULAR,
508                                   SectionKind::getDataRel());
509  TLSBSSSection // .tbss
510    = getContext().getMachOSection("__DATA", "__thread_bss",
511                                   MCSectionMachO::S_THREAD_LOCAL_ZEROFILL,
512                                   SectionKind::getThreadBSS());
513
514  // TODO: Verify datarel below.
515  TLSTLVSection // .tlv
516    = getContext().getMachOSection("__DATA", "__thread_vars",
517                                   MCSectionMachO::S_THREAD_LOCAL_VARIABLES,
518                                   SectionKind::getDataRel());
519
520  TLSThreadInitSection
521    = getContext().getMachOSection("__DATA", "__thread_init",
522                          MCSectionMachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
523                          SectionKind::getDataRel());
524
525  CStringSection // .cstring
526    = getContext().getMachOSection("__TEXT", "__cstring",
527                                   MCSectionMachO::S_CSTRING_LITERALS,
528                                   SectionKind::getMergeable1ByteCString());
529  UStringSection
530    = getContext().getMachOSection("__TEXT","__ustring", 0,
531                                   SectionKind::getMergeable2ByteCString());
532  FourByteConstantSection // .literal4
533    = getContext().getMachOSection("__TEXT", "__literal4",
534                                   MCSectionMachO::S_4BYTE_LITERALS,
535                                   SectionKind::getMergeableConst4());
536  EightByteConstantSection // .literal8
537    = getContext().getMachOSection("__TEXT", "__literal8",
538                                   MCSectionMachO::S_8BYTE_LITERALS,
539                                   SectionKind::getMergeableConst8());
540
541  // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
542  // to using it in -static mode.
543  SixteenByteConstantSection = 0;
544  if (TM.getRelocationModel() != Reloc::Static &&
545      TM.getTargetData()->getPointerSize() == 32)
546    SixteenByteConstantSection =   // .literal16
547      getContext().getMachOSection("__TEXT", "__literal16",
548                                   MCSectionMachO::S_16BYTE_LITERALS,
549                                   SectionKind::getMergeableConst16());
550
551  ReadOnlySection  // .const
552    = getContext().getMachOSection("__TEXT", "__const", 0,
553                                   SectionKind::getReadOnly());
554
555  TextCoalSection
556    = getContext().getMachOSection("__TEXT", "__textcoal_nt",
557                                   MCSectionMachO::S_COALESCED |
558                                   MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
559                                   SectionKind::getText());
560  ConstTextCoalSection
561    = getContext().getMachOSection("__TEXT", "__const_coal",
562                                   MCSectionMachO::S_COALESCED,
563                                   SectionKind::getReadOnly());
564  ConstDataSection  // .const_data
565    = getContext().getMachOSection("__DATA", "__const", 0,
566                                   SectionKind::getReadOnlyWithRel());
567  DataCoalSection
568    = getContext().getMachOSection("__DATA","__datacoal_nt",
569                                   MCSectionMachO::S_COALESCED,
570                                   SectionKind::getDataRel());
571  DataCommonSection
572    = getContext().getMachOSection("__DATA","__common",
573                                   MCSectionMachO::S_ZEROFILL,
574                                   SectionKind::getBSS());
575  DataBSSSection
576    = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL,
577                                   SectionKind::getBSS());
578
579
580  LazySymbolPointerSection
581    = getContext().getMachOSection("__DATA", "__la_symbol_ptr",
582                                   MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
583                                   SectionKind::getMetadata());
584  NonLazySymbolPointerSection
585    = getContext().getMachOSection("__DATA", "__nl_symbol_ptr",
586                                   MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
587                                   SectionKind::getMetadata());
588
589  if (TM.getRelocationModel() == Reloc::Static) {
590    StaticCtorSection
591      = getContext().getMachOSection("__TEXT", "__constructor", 0,
592                                     SectionKind::getDataRel());
593    StaticDtorSection
594      = getContext().getMachOSection("__TEXT", "__destructor", 0,
595                                     SectionKind::getDataRel());
596  } else {
597    StaticCtorSection
598      = getContext().getMachOSection("__DATA", "__mod_init_func",
599                                     MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
600                                     SectionKind::getDataRel());
601    StaticDtorSection
602      = getContext().getMachOSection("__DATA", "__mod_term_func",
603                                     MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
604                                     SectionKind::getDataRel());
605  }
606
607  // Exception Handling.
608  LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0,
609                                             SectionKind::getReadOnlyWithRel());
610  // Debug Information.
611  DwarfAbbrevSection =
612    getContext().getMachOSection("__DWARF", "__debug_abbrev",
613                                 MCSectionMachO::S_ATTR_DEBUG,
614                                 SectionKind::getMetadata());
615  DwarfInfoSection =
616    getContext().getMachOSection("__DWARF", "__debug_info",
617                                 MCSectionMachO::S_ATTR_DEBUG,
618                                 SectionKind::getMetadata());
619  DwarfLineSection =
620    getContext().getMachOSection("__DWARF", "__debug_line",
621                                 MCSectionMachO::S_ATTR_DEBUG,
622                                 SectionKind::getMetadata());
623  DwarfFrameSection =
624    getContext().getMachOSection("__DWARF", "__debug_frame",
625                                 MCSectionMachO::S_ATTR_DEBUG,
626                                 SectionKind::getMetadata());
627  DwarfPubNamesSection =
628    getContext().getMachOSection("__DWARF", "__debug_pubnames",
629                                 MCSectionMachO::S_ATTR_DEBUG,
630                                 SectionKind::getMetadata());
631  DwarfPubTypesSection =
632    getContext().getMachOSection("__DWARF", "__debug_pubtypes",
633                                 MCSectionMachO::S_ATTR_DEBUG,
634                                 SectionKind::getMetadata());
635  DwarfStrSection =
636    getContext().getMachOSection("__DWARF", "__debug_str",
637                                 MCSectionMachO::S_ATTR_DEBUG,
638                                 SectionKind::getMetadata());
639  DwarfLocSection =
640    getContext().getMachOSection("__DWARF", "__debug_loc",
641                                 MCSectionMachO::S_ATTR_DEBUG,
642                                 SectionKind::getMetadata());
643  DwarfARangesSection =
644    getContext().getMachOSection("__DWARF", "__debug_aranges",
645                                 MCSectionMachO::S_ATTR_DEBUG,
646                                 SectionKind::getMetadata());
647  DwarfRangesSection =
648    getContext().getMachOSection("__DWARF", "__debug_ranges",
649                                 MCSectionMachO::S_ATTR_DEBUG,
650                                 SectionKind::getMetadata());
651  DwarfMacroInfoSection =
652    getContext().getMachOSection("__DWARF", "__debug_macinfo",
653                                 MCSectionMachO::S_ATTR_DEBUG,
654                                 SectionKind::getMetadata());
655  DwarfDebugInlineSection =
656    getContext().getMachOSection("__DWARF", "__debug_inlined",
657                                 MCSectionMachO::S_ATTR_DEBUG,
658                                 SectionKind::getMetadata());
659
660  TLSExtraDataSection = TLSTLVSection;
661}
662
663const MCSection *TargetLoweringObjectFileMachO::getEHFrameSection() const {
664  return getContext().getMachOSection("__TEXT", "__eh_frame",
665                                      MCSectionMachO::S_COALESCED |
666                                      MCSectionMachO::S_ATTR_NO_TOC |
667                                      MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
668                                      MCSectionMachO::S_ATTR_LIVE_SUPPORT,
669                                      SectionKind::getReadOnly());
670}
671
672const MCSection *TargetLoweringObjectFileMachO::
673getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
674                         Mangler *Mang, const TargetMachine &TM) const {
675  // Parse the section specifier and create it if valid.
676  StringRef Segment, Section;
677  unsigned TAA = 0, StubSize = 0;
678  bool TAAParsed;
679  std::string ErrorCode =
680    MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
681                                          TAA, TAAParsed, StubSize);
682  if (!ErrorCode.empty()) {
683    // If invalid, report the error with report_fatal_error.
684    report_fatal_error("Global variable '" + GV->getNameStr() +
685                      "' has an invalid section specifier '" + GV->getSection()+
686                      "': " + ErrorCode + ".");
687    // Fall back to dropping it into the data section.
688    return DataSection;
689  }
690
691  // Get the section.
692  const MCSectionMachO *S =
693    getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
694
695  // If TAA wasn't set by ParseSectionSpecifier() above,
696  // use the value returned by getMachOSection() as a default.
697  if (!TAAParsed)
698    TAA = S->getTypeAndAttributes();
699
700  // Okay, now that we got the section, verify that the TAA & StubSize agree.
701  // If the user declared multiple globals with different section flags, we need
702  // to reject it here.
703  if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
704    // If invalid, report the error with report_fatal_error.
705    report_fatal_error("Global variable '" + GV->getNameStr() +
706                      "' section type or attributes does not match previous"
707                      " section specifier");
708  }
709
710  return S;
711}
712
713const MCSection *TargetLoweringObjectFileMachO::
714SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
715                       Mangler *Mang, const TargetMachine &TM) const {
716
717  // Handle thread local data.
718  if (Kind.isThreadBSS()) return TLSBSSSection;
719  if (Kind.isThreadData()) return TLSDataSection;
720
721  if (Kind.isText())
722    return GV->isWeakForLinker() ? TextCoalSection : TextSection;
723
724  // If this is weak/linkonce, put this in a coalescable section, either in text
725  // or data depending on if it is writable.
726  if (GV->isWeakForLinker()) {
727    if (Kind.isReadOnly())
728      return ConstTextCoalSection;
729    return DataCoalSection;
730  }
731
732  // FIXME: Alignment check should be handled by section classifier.
733  if (Kind.isMergeable1ByteCString() &&
734      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
735    return CStringSection;
736
737  // Do not put 16-bit arrays in the UString section if they have an
738  // externally visible label, this runs into issues with certain linker
739  // versions.
740  if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
741      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
742    return UStringSection;
743
744  if (Kind.isMergeableConst()) {
745    if (Kind.isMergeableConst4())
746      return FourByteConstantSection;
747    if (Kind.isMergeableConst8())
748      return EightByteConstantSection;
749    if (Kind.isMergeableConst16() && SixteenByteConstantSection)
750      return SixteenByteConstantSection;
751  }
752
753  // Otherwise, if it is readonly, but not something we can specially optimize,
754  // just drop it in .const.
755  if (Kind.isReadOnly())
756    return ReadOnlySection;
757
758  // If this is marked const, put it into a const section.  But if the dynamic
759  // linker needs to write to it, put it in the data segment.
760  if (Kind.isReadOnlyWithRel())
761    return ConstDataSection;
762
763  // Put zero initialized globals with strong external linkage in the
764  // DATA, __common section with the .zerofill directive.
765  if (Kind.isBSSExtern())
766    return DataCommonSection;
767
768  // Put zero initialized globals with local linkage in __DATA,__bss directive
769  // with the .zerofill directive (aka .lcomm).
770  if (Kind.isBSSLocal())
771    return DataBSSSection;
772
773  // Otherwise, just drop the variable in the normal data section.
774  return DataSection;
775}
776
777const MCSection *
778TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
779  // If this constant requires a relocation, we have to put it in the data
780  // segment, not in the text segment.
781  if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
782    return ConstDataSection;
783
784  if (Kind.isMergeableConst4())
785    return FourByteConstantSection;
786  if (Kind.isMergeableConst8())
787    return EightByteConstantSection;
788  if (Kind.isMergeableConst16() && SixteenByteConstantSection)
789    return SixteenByteConstantSection;
790  return ReadOnlySection;  // .const
791}
792
793/// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
794/// not to emit the UsedDirective for some symbols in llvm.used.
795// FIXME: REMOVE this (rdar://7071300)
796bool TargetLoweringObjectFileMachO::
797shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
798  /// On Darwin, internally linked data beginning with "L" or "l" does not have
799  /// the directive emitted (this occurs in ObjC metadata).
800  if (!GV) return false;
801
802  // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
803  if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
804    // FIXME: ObjC metadata is currently emitted as internal symbols that have
805    // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
806    // this horrible hack can go away.
807    MCSymbol *Sym = Mang->getSymbol(GV);
808    if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
809      return false;
810  }
811
812  return true;
813}
814
815const MCExpr *TargetLoweringObjectFileMachO::
816getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
817                               MachineModuleInfo *MMI, unsigned Encoding,
818                               MCStreamer &Streamer) const {
819  // The mach-o version of this method defaults to returning a stub reference.
820
821  if (Encoding & DW_EH_PE_indirect) {
822    MachineModuleInfoMachO &MachOMMI =
823      MMI->getObjFileInfo<MachineModuleInfoMachO>();
824
825    SmallString<128> Name;
826    Mang->getNameWithPrefix(Name, GV, true);
827    Name += "$non_lazy_ptr";
828
829    // Add information about the stub reference to MachOMMI so that the stub
830    // gets emitted by the asmprinter.
831    MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
832    MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
833    if (StubSym.getPointer() == 0) {
834      MCSymbol *Sym = Mang->getSymbol(GV);
835      StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
836    }
837
838    return TargetLoweringObjectFile::
839      getExprForDwarfReference(SSym, Mang, MMI,
840                               Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
841  }
842
843  return TargetLoweringObjectFile::
844    getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
845}
846
847unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const {
848  return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
849}
850
851unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const {
852  return DW_EH_PE_pcrel;
853}
854
855unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const {
856  return DW_EH_PE_pcrel;
857}
858
859unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const {
860  return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
861}
862
863//===----------------------------------------------------------------------===//
864//                                  COFF
865//===----------------------------------------------------------------------===//
866
867void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
868                                              const TargetMachine &TM) {
869  TargetLoweringObjectFile::Initialize(Ctx, TM);
870  TextSection =
871    getContext().getCOFFSection(".text",
872                                COFF::IMAGE_SCN_CNT_CODE |
873                                COFF::IMAGE_SCN_MEM_EXECUTE |
874                                COFF::IMAGE_SCN_MEM_READ,
875                                SectionKind::getText());
876  DataSection =
877    getContext().getCOFFSection(".data",
878                                COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
879                                COFF::IMAGE_SCN_MEM_READ |
880                                COFF::IMAGE_SCN_MEM_WRITE,
881                                SectionKind::getDataRel());
882  ReadOnlySection =
883    getContext().getCOFFSection(".rdata",
884                                COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
885                                COFF::IMAGE_SCN_MEM_READ,
886                                SectionKind::getReadOnly());
887  StaticCtorSection =
888    getContext().getCOFFSection(".ctors",
889                                COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
890                                COFF::IMAGE_SCN_MEM_READ |
891                                COFF::IMAGE_SCN_MEM_WRITE,
892                                SectionKind::getDataRel());
893  StaticDtorSection =
894    getContext().getCOFFSection(".dtors",
895                                COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
896                                COFF::IMAGE_SCN_MEM_READ |
897                                COFF::IMAGE_SCN_MEM_WRITE,
898                                SectionKind::getDataRel());
899
900  // FIXME: We're emitting LSDA info into a readonly section on COFF, even
901  // though it contains relocatable pointers.  In PIC mode, this is probably a
902  // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
903  // adjusted or this should be a data section.
904  LSDASection =
905    getContext().getCOFFSection(".gcc_except_table",
906                                COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
907                                COFF::IMAGE_SCN_MEM_READ,
908                                SectionKind::getReadOnly());
909  // Debug info.
910  DwarfAbbrevSection =
911    getContext().getCOFFSection(".debug_abbrev",
912                                COFF::IMAGE_SCN_MEM_DISCARDABLE |
913                                COFF::IMAGE_SCN_MEM_READ,
914                                SectionKind::getMetadata());
915  DwarfInfoSection =
916    getContext().getCOFFSection(".debug_info",
917                                COFF::IMAGE_SCN_MEM_DISCARDABLE |
918                                COFF::IMAGE_SCN_MEM_READ,
919                                SectionKind::getMetadata());
920  DwarfLineSection =
921    getContext().getCOFFSection(".debug_line",
922                                COFF::IMAGE_SCN_MEM_DISCARDABLE |
923                                COFF::IMAGE_SCN_MEM_READ,
924                                SectionKind::getMetadata());
925  DwarfFrameSection =
926    getContext().getCOFFSection(".debug_frame",
927                                COFF::IMAGE_SCN_MEM_DISCARDABLE |
928                                COFF::IMAGE_SCN_MEM_READ,
929                                SectionKind::getMetadata());
930  DwarfPubNamesSection =
931    getContext().getCOFFSection(".debug_pubnames",
932                                COFF::IMAGE_SCN_MEM_DISCARDABLE |
933                                COFF::IMAGE_SCN_MEM_READ,
934                                SectionKind::getMetadata());
935  DwarfPubTypesSection =
936    getContext().getCOFFSection(".debug_pubtypes",
937                                COFF::IMAGE_SCN_MEM_DISCARDABLE |
938                                COFF::IMAGE_SCN_MEM_READ,
939                                SectionKind::getMetadata());
940  DwarfStrSection =
941    getContext().getCOFFSection(".debug_str",
942                                COFF::IMAGE_SCN_MEM_DISCARDABLE |
943                                COFF::IMAGE_SCN_MEM_READ,
944                                SectionKind::getMetadata());
945  DwarfLocSection =
946    getContext().getCOFFSection(".debug_loc",
947                                COFF::IMAGE_SCN_MEM_DISCARDABLE |
948                                COFF::IMAGE_SCN_MEM_READ,
949                                SectionKind::getMetadata());
950  DwarfARangesSection =
951    getContext().getCOFFSection(".debug_aranges",
952                                COFF::IMAGE_SCN_MEM_DISCARDABLE |
953                                COFF::IMAGE_SCN_MEM_READ,
954                                SectionKind::getMetadata());
955  DwarfRangesSection =
956    getContext().getCOFFSection(".debug_ranges",
957                                COFF::IMAGE_SCN_MEM_DISCARDABLE |
958                                COFF::IMAGE_SCN_MEM_READ,
959                                SectionKind::getMetadata());
960  DwarfMacroInfoSection =
961    getContext().getCOFFSection(".debug_macinfo",
962                                COFF::IMAGE_SCN_MEM_DISCARDABLE |
963                                COFF::IMAGE_SCN_MEM_READ,
964                                SectionKind::getMetadata());
965
966  DrectveSection =
967    getContext().getCOFFSection(".drectve",
968                                COFF::IMAGE_SCN_LNK_INFO,
969                                SectionKind::getMetadata());
970}
971
972const MCSection *TargetLoweringObjectFileCOFF::getEHFrameSection() const {
973  return getContext().getCOFFSection(".eh_frame",
974                                     COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
975                                     COFF::IMAGE_SCN_MEM_READ |
976                                     COFF::IMAGE_SCN_MEM_WRITE,
977                                     SectionKind::getDataRel());
978}
979
980
981static unsigned
982getCOFFSectionFlags(SectionKind K) {
983  unsigned Flags = 0;
984
985  if (K.isMetadata())
986    Flags |=
987      COFF::IMAGE_SCN_MEM_DISCARDABLE;
988  else if (K.isText())
989    Flags |=
990      COFF::IMAGE_SCN_MEM_EXECUTE |
991      COFF::IMAGE_SCN_MEM_READ |
992      COFF::IMAGE_SCN_CNT_CODE;
993  else if (K.isBSS ())
994    Flags |=
995      COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
996      COFF::IMAGE_SCN_MEM_READ |
997      COFF::IMAGE_SCN_MEM_WRITE;
998  else if (K.isReadOnly())
999    Flags |=
1000      COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1001      COFF::IMAGE_SCN_MEM_READ;
1002  else if (K.isWriteable())
1003    Flags |=
1004      COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1005      COFF::IMAGE_SCN_MEM_READ |
1006      COFF::IMAGE_SCN_MEM_WRITE;
1007
1008  return Flags;
1009}
1010
1011const MCSection *TargetLoweringObjectFileCOFF::
1012getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
1013                         Mangler *Mang, const TargetMachine &TM) const {
1014  return getContext().getCOFFSection(GV->getSection(),
1015                                     getCOFFSectionFlags(Kind),
1016                                     Kind);
1017}
1018
1019static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
1020  if (Kind.isText())
1021    return ".text$";
1022  if (Kind.isBSS ())
1023    return ".bss$";
1024  if (Kind.isWriteable())
1025    return ".data$";
1026  return ".rdata$";
1027}
1028
1029
1030const MCSection *TargetLoweringObjectFileCOFF::
1031SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
1032                       Mangler *Mang, const TargetMachine &TM) const {
1033  assert(!Kind.isThreadLocal() && "Doesn't support TLS");
1034
1035  // If this global is linkonce/weak and the target handles this by emitting it
1036  // into a 'uniqued' section name, create and return the section now.
1037  if (GV->isWeakForLinker()) {
1038    const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
1039    SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
1040    MCSymbol *Sym = Mang->getSymbol(GV);
1041    Name.append(Sym->getName().begin() + 1, Sym->getName().end());
1042
1043    unsigned Characteristics = getCOFFSectionFlags(Kind);
1044
1045    Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
1046
1047    return getContext().getCOFFSection(Name.str(), Characteristics,
1048                          COFF::IMAGE_COMDAT_SELECT_ANY, Kind);
1049  }
1050
1051  if (Kind.isText())
1052    return getTextSection();
1053
1054  return getDataSection();
1055}
1056
1057