TargetLoweringObjectFileImpl.cpp revision c6177a4531a5d7e2207a3184cc8a4f1792073a7d 
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  TLSDataSection // .tdata
465    = getContext().getMachOSection("__DATA", "__thread_data",
466                                   MCSectionMachO::S_THREAD_LOCAL_REGULAR,
467                                   SectionKind::getDataRel());
468  TLSBSSSection // .tbss
469    = getContext().getMachOSection("__DATA", "__thread_bss",
470                                   MCSectionMachO::S_THREAD_LOCAL_ZEROFILL,
471                                   SectionKind::getThreadBSS());
472
473  // TODO: Verify datarel below.
474  TLSTLVSection // .tlv
475    = getContext().getMachOSection("__DATA", "__thread_vars",
476                                   MCSectionMachO::S_THREAD_LOCAL_VARIABLES,
477                                   SectionKind::getDataRel());
478
479  TLSThreadInitSection
480    = getContext().getMachOSection("__DATA", "__thread_init",
481                          MCSectionMachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
482                          SectionKind::getDataRel());
483
484  CStringSection // .cstring
485    = getContext().getMachOSection("__TEXT", "__cstring",
486                                   MCSectionMachO::S_CSTRING_LITERALS,
487                                   SectionKind::getMergeable1ByteCString());
488  UStringSection
489    = getContext().getMachOSection("__TEXT","__ustring", 0,
490                                   SectionKind::getMergeable2ByteCString());
491  FourByteConstantSection // .literal4
492    = getContext().getMachOSection("__TEXT", "__literal4",
493                                   MCSectionMachO::S_4BYTE_LITERALS,
494                                   SectionKind::getMergeableConst4());
495  EightByteConstantSection // .literal8
496    = getContext().getMachOSection("__TEXT", "__literal8",
497                                   MCSectionMachO::S_8BYTE_LITERALS,
498                                   SectionKind::getMergeableConst8());
499
500  // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
501  // to using it in -static mode.
502  SixteenByteConstantSection = 0;
503  if (TM.getRelocationModel() != Reloc::Static &&
504      TM.getTargetData()->getPointerSize() == 32)
505    SixteenByteConstantSection =   // .literal16
506      getContext().getMachOSection("__TEXT", "__literal16",
507                                   MCSectionMachO::S_16BYTE_LITERALS,
508                                   SectionKind::getMergeableConst16());
509
510  ReadOnlySection  // .const
511    = getContext().getMachOSection("__TEXT", "__const", 0,
512                                   SectionKind::getReadOnly());
513
514  TextCoalSection
515    = getContext().getMachOSection("__TEXT", "__textcoal_nt",
516                                   MCSectionMachO::S_COALESCED |
517                                   MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
518                                   SectionKind::getText());
519  ConstTextCoalSection
520    = getContext().getMachOSection("__TEXT", "__const_coal",
521                                   MCSectionMachO::S_COALESCED,
522                                   SectionKind::getText());
523  ConstDataCoalSection
524    = getContext().getMachOSection("__DATA","__const_coal",
525                                   MCSectionMachO::S_COALESCED,
526                                   SectionKind::getText());
527  ConstDataSection  // .const_data
528    = getContext().getMachOSection("__DATA", "__const", 0,
529                                   SectionKind::getReadOnlyWithRel());
530  DataCoalSection
531    = getContext().getMachOSection("__DATA","__datacoal_nt",
532                                   MCSectionMachO::S_COALESCED,
533                                   SectionKind::getDataRel());
534  DataCommonSection
535    = getContext().getMachOSection("__DATA","__common",
536                                   MCSectionMachO::S_ZEROFILL,
537                                   SectionKind::getBSS());
538  DataBSSSection
539    = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL,
540                                   SectionKind::getBSS());
541
542
543  LazySymbolPointerSection
544    = getContext().getMachOSection("__DATA", "__la_symbol_ptr",
545                                   MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
546                                   SectionKind::getMetadata());
547  NonLazySymbolPointerSection
548    = getContext().getMachOSection("__DATA", "__nl_symbol_ptr",
549                                   MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
550                                   SectionKind::getMetadata());
551
552  if (TM.getRelocationModel() == Reloc::Static) {
553    StaticCtorSection
554      = getContext().getMachOSection("__TEXT", "__constructor", 0,
555                                     SectionKind::getDataRel());
556    StaticDtorSection
557      = getContext().getMachOSection("__TEXT", "__destructor", 0,
558                                     SectionKind::getDataRel());
559  } else {
560    StaticCtorSection
561      = getContext().getMachOSection("__DATA", "__mod_init_func",
562                                     MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
563                                     SectionKind::getDataRel());
564    StaticDtorSection
565      = getContext().getMachOSection("__DATA", "__mod_term_func",
566                                     MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
567                                     SectionKind::getDataRel());
568  }
569
570  // Exception Handling.
571  LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0,
572                                             SectionKind::getReadOnlyWithRel());
573  EHFrameSection =
574    getContext().getMachOSection("__TEXT", "__eh_frame",
575                                 MCSectionMachO::S_COALESCED |
576                                 MCSectionMachO::S_ATTR_NO_TOC |
577                                 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
578                                 MCSectionMachO::S_ATTR_LIVE_SUPPORT,
579                                 SectionKind::getReadOnly());
580
581  // Debug Information.
582  DwarfAbbrevSection =
583    getContext().getMachOSection("__DWARF", "__debug_abbrev",
584                                 MCSectionMachO::S_ATTR_DEBUG,
585                                 SectionKind::getMetadata());
586  DwarfInfoSection =
587    getContext().getMachOSection("__DWARF", "__debug_info",
588                                 MCSectionMachO::S_ATTR_DEBUG,
589                                 SectionKind::getMetadata());
590  DwarfLineSection =
591    getContext().getMachOSection("__DWARF", "__debug_line",
592                                 MCSectionMachO::S_ATTR_DEBUG,
593                                 SectionKind::getMetadata());
594  DwarfFrameSection =
595    getContext().getMachOSection("__DWARF", "__debug_frame",
596                                 MCSectionMachO::S_ATTR_DEBUG,
597                                 SectionKind::getMetadata());
598  DwarfPubNamesSection =
599    getContext().getMachOSection("__DWARF", "__debug_pubnames",
600                                 MCSectionMachO::S_ATTR_DEBUG,
601                                 SectionKind::getMetadata());
602  DwarfPubTypesSection =
603    getContext().getMachOSection("__DWARF", "__debug_pubtypes",
604                                 MCSectionMachO::S_ATTR_DEBUG,
605                                 SectionKind::getMetadata());
606  DwarfStrSection =
607    getContext().getMachOSection("__DWARF", "__debug_str",
608                                 MCSectionMachO::S_ATTR_DEBUG,
609                                 SectionKind::getMetadata());
610  DwarfLocSection =
611    getContext().getMachOSection("__DWARF", "__debug_loc",
612                                 MCSectionMachO::S_ATTR_DEBUG,
613                                 SectionKind::getMetadata());
614  DwarfARangesSection =
615    getContext().getMachOSection("__DWARF", "__debug_aranges",
616                                 MCSectionMachO::S_ATTR_DEBUG,
617                                 SectionKind::getMetadata());
618  DwarfRangesSection =
619    getContext().getMachOSection("__DWARF", "__debug_ranges",
620                                 MCSectionMachO::S_ATTR_DEBUG,
621                                 SectionKind::getMetadata());
622  DwarfMacroInfoSection =
623    getContext().getMachOSection("__DWARF", "__debug_macinfo",
624                                 MCSectionMachO::S_ATTR_DEBUG,
625                                 SectionKind::getMetadata());
626  DwarfDebugInlineSection =
627    getContext().getMachOSection("__DWARF", "__debug_inlined",
628                                 MCSectionMachO::S_ATTR_DEBUG,
629                                 SectionKind::getMetadata());
630}
631
632const MCSection *TargetLoweringObjectFileMachO::
633getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
634                         Mangler *Mang, const TargetMachine &TM) const {
635  // Parse the section specifier and create it if valid.
636  StringRef Segment, Section;
637  unsigned TAA, StubSize;
638  std::string ErrorCode =
639    MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
640                                          TAA, StubSize);
641  if (!ErrorCode.empty()) {
642    // If invalid, report the error with report_fatal_error.
643    report_fatal_error("Global variable '" + GV->getNameStr() +
644                      "' has an invalid section specifier '" + GV->getSection()+
645                      "': " + ErrorCode + ".");
646    // Fall back to dropping it into the data section.
647    return DataSection;
648  }
649
650  // Get the section.
651  const MCSectionMachO *S =
652    getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
653
654  // Okay, now that we got the section, verify that the TAA & StubSize agree.
655  // If the user declared multiple globals with different section flags, we need
656  // to reject it here.
657  if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
658    // If invalid, report the error with report_fatal_error.
659    report_fatal_error("Global variable '" + GV->getNameStr() +
660                      "' section type or attributes does not match previous"
661                      " section specifier");
662  }
663
664  return S;
665}
666
667const MCSection *TargetLoweringObjectFileMachO::
668SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
669                       Mangler *Mang, const TargetMachine &TM) const {
670  assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS");
671
672  if (Kind.isText())
673    return GV->isWeakForLinker() ? TextCoalSection : TextSection;
674
675  // If this is weak/linkonce, put this in a coalescable section, either in text
676  // or data depending on if it is writable.
677  if (GV->isWeakForLinker()) {
678    if (Kind.isReadOnly())
679      return ConstTextCoalSection;
680    return DataCoalSection;
681  }
682
683  // FIXME: Alignment check should be handled by section classifier.
684  if (Kind.isMergeable1ByteCString() &&
685      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
686    return CStringSection;
687
688  // Do not put 16-bit arrays in the UString section if they have an
689  // externally visible label, this runs into issues with certain linker
690  // versions.
691  if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
692      TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
693    return UStringSection;
694
695  if (Kind.isMergeableConst()) {
696    if (Kind.isMergeableConst4())
697      return FourByteConstantSection;
698    if (Kind.isMergeableConst8())
699      return EightByteConstantSection;
700    if (Kind.isMergeableConst16() && SixteenByteConstantSection)
701      return SixteenByteConstantSection;
702  }
703
704  // Otherwise, if it is readonly, but not something we can specially optimize,
705  // just drop it in .const.
706  if (Kind.isReadOnly())
707    return ReadOnlySection;
708
709  // If this is marked const, put it into a const section.  But if the dynamic
710  // linker needs to write to it, put it in the data segment.
711  if (Kind.isReadOnlyWithRel())
712    return ConstDataSection;
713
714  // Put zero initialized globals with strong external linkage in the
715  // DATA, __common section with the .zerofill directive.
716  if (Kind.isBSSExtern())
717    return DataCommonSection;
718
719  // Put zero initialized globals with local linkage in __DATA,__bss directive
720  // with the .zerofill directive (aka .lcomm).
721  if (Kind.isBSSLocal())
722    return DataBSSSection;
723
724  // Otherwise, just drop the variable in the normal data section.
725  return DataSection;
726}
727
728const MCSection *
729TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
730  // If this constant requires a relocation, we have to put it in the data
731  // segment, not in the text segment.
732  if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
733    return ConstDataSection;
734
735  if (Kind.isMergeableConst4())
736    return FourByteConstantSection;
737  if (Kind.isMergeableConst8())
738    return EightByteConstantSection;
739  if (Kind.isMergeableConst16() && SixteenByteConstantSection)
740    return SixteenByteConstantSection;
741  return ReadOnlySection;  // .const
742}
743
744/// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
745/// not to emit the UsedDirective for some symbols in llvm.used.
746// FIXME: REMOVE this (rdar://7071300)
747bool TargetLoweringObjectFileMachO::
748shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
749  /// On Darwin, internally linked data beginning with "L" or "l" does not have
750  /// the directive emitted (this occurs in ObjC metadata).
751  if (!GV) return false;
752
753  // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
754  if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
755    // FIXME: ObjC metadata is currently emitted as internal symbols that have
756    // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
757    // this horrible hack can go away.
758    MCSymbol *Sym = Mang->getSymbol(GV);
759    if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
760      return false;
761  }
762
763  return true;
764}
765
766const MCExpr *TargetLoweringObjectFileMachO::
767getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
768                               MachineModuleInfo *MMI, unsigned Encoding,
769                               MCStreamer &Streamer) const {
770  // The mach-o version of this method defaults to returning a stub reference.
771
772  if (Encoding & DW_EH_PE_indirect) {
773    MachineModuleInfoMachO &MachOMMI =
774      MMI->getObjFileInfo<MachineModuleInfoMachO>();
775
776    SmallString<128> Name;
777    Mang->getNameWithPrefix(Name, GV, true);
778    Name += "$non_lazy_ptr";
779
780    // Add information about the stub reference to MachOMMI so that the stub
781    // gets emitted by the asmprinter.
782    MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
783    MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
784    if (StubSym.getPointer() == 0) {
785      MCSymbol *Sym = Mang->getSymbol(GV);
786      StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
787    }
788
789    return TargetLoweringObjectFile::
790      getExprForDwarfReference(SSym, Mang, MMI,
791                               Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
792  }
793
794  return TargetLoweringObjectFile::
795    getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
796}
797
798unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const {
799  return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
800}
801
802unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const {
803  return DW_EH_PE_pcrel;
804}
805
806unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const {
807  return DW_EH_PE_pcrel;
808}
809
810unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const {
811  return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
812}
813
814//===----------------------------------------------------------------------===//
815//                                  COFF
816//===----------------------------------------------------------------------===//
817
818void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
819                                              const TargetMachine &TM) {
820  TargetLoweringObjectFile::Initialize(Ctx, TM);
821  TextSection =
822    getContext().getCOFFSection(".text",
823                                MCSectionCOFF::IMAGE_SCN_CNT_CODE |
824                                MCSectionCOFF::IMAGE_SCN_MEM_EXECUTE |
825                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
826                                SectionKind::getText());
827  DataSection =
828    getContext().getCOFFSection(".data",
829                                MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
830                                MCSectionCOFF::IMAGE_SCN_MEM_READ |
831                                MCSectionCOFF::IMAGE_SCN_MEM_WRITE,
832                                SectionKind::getDataRel());
833  ReadOnlySection =
834    getContext().getCOFFSection(".rdata",
835                                MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
836                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
837                                SectionKind::getReadOnly());
838  StaticCtorSection =
839    getContext().getCOFFSection(".ctors",
840                                MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
841                                MCSectionCOFF::IMAGE_SCN_MEM_READ |
842                                MCSectionCOFF::IMAGE_SCN_MEM_WRITE,
843                                SectionKind::getDataRel());
844  StaticDtorSection =
845    getContext().getCOFFSection(".dtors",
846                                MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
847                                MCSectionCOFF::IMAGE_SCN_MEM_READ |
848                                MCSectionCOFF::IMAGE_SCN_MEM_WRITE,
849                                SectionKind::getDataRel());
850
851  // FIXME: We're emitting LSDA info into a readonly section on COFF, even
852  // though it contains relocatable pointers.  In PIC mode, this is probably a
853  // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
854  // adjusted or this should be a data section.
855  LSDASection =
856    getContext().getCOFFSection(".gcc_except_table",
857                                MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
858                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
859                                SectionKind::getReadOnly());
860  EHFrameSection =
861    getContext().getCOFFSection(".eh_frame",
862                                MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
863                                MCSectionCOFF::IMAGE_SCN_MEM_READ |
864                                MCSectionCOFF::IMAGE_SCN_MEM_WRITE,
865                                SectionKind::getDataRel());
866
867  // Debug info.
868  DwarfAbbrevSection =
869    getContext().getCOFFSection(".debug_abbrev",
870                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
871                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
872                                SectionKind::getMetadata());
873  DwarfInfoSection =
874    getContext().getCOFFSection(".debug_info",
875                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
876                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
877                                SectionKind::getMetadata());
878  DwarfLineSection =
879    getContext().getCOFFSection(".debug_line",
880                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
881                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
882                                SectionKind::getMetadata());
883  DwarfFrameSection =
884    getContext().getCOFFSection(".debug_frame",
885                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
886                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
887                                SectionKind::getMetadata());
888  DwarfPubNamesSection =
889    getContext().getCOFFSection(".debug_pubnames",
890                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
891                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
892                                SectionKind::getMetadata());
893  DwarfPubTypesSection =
894    getContext().getCOFFSection(".debug_pubtypes",
895                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
896                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
897                                SectionKind::getMetadata());
898  DwarfStrSection =
899    getContext().getCOFFSection(".debug_str",
900                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
901                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
902                                SectionKind::getMetadata());
903  DwarfLocSection =
904    getContext().getCOFFSection(".debug_loc",
905                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
906                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
907                                SectionKind::getMetadata());
908  DwarfARangesSection =
909    getContext().getCOFFSection(".debug_aranges",
910                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
911                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
912                                SectionKind::getMetadata());
913  DwarfRangesSection =
914    getContext().getCOFFSection(".debug_ranges",
915                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
916                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
917                                SectionKind::getMetadata());
918  DwarfMacroInfoSection =
919    getContext().getCOFFSection(".debug_macinfo",
920                                MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE |
921                                MCSectionCOFF::IMAGE_SCN_MEM_READ,
922                                SectionKind::getMetadata());
923
924  DrectveSection =
925    getContext().getCOFFSection(".drectve",
926                                MCSectionCOFF::IMAGE_SCN_LNK_INFO,
927                                SectionKind::getMetadata());
928}
929
930static unsigned
931getCOFFSectionFlags(SectionKind K) {
932  unsigned Flags = 0;
933
934  if (!K.isMetadata())
935    Flags |=
936      MCSectionCOFF::IMAGE_SCN_MEM_DISCARDABLE;
937  else if (K.isText())
938    Flags |=
939      MCSectionCOFF::IMAGE_SCN_MEM_EXECUTE |
940      MCSectionCOFF::IMAGE_SCN_CNT_CODE;
941  else if (K.isBSS ())
942    Flags |=
943      MCSectionCOFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
944      MCSectionCOFF::IMAGE_SCN_MEM_READ |
945      MCSectionCOFF::IMAGE_SCN_MEM_WRITE;
946  else if (K.isReadOnly())
947    Flags |=
948      MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
949      MCSectionCOFF::IMAGE_SCN_MEM_READ;
950  else if (K.isWriteable())
951    Flags |=
952      MCSectionCOFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
953      MCSectionCOFF::IMAGE_SCN_MEM_READ |
954      MCSectionCOFF::IMAGE_SCN_MEM_WRITE;
955
956  return Flags;
957}
958
959const MCSection *TargetLoweringObjectFileCOFF::
960getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
961                         Mangler *Mang, const TargetMachine &TM) const {
962  return getContext().getCOFFSection(GV->getSection(),
963                                     getCOFFSectionFlags(Kind),
964                                     Kind);
965}
966
967static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
968  if (Kind.isText())
969    return ".text$linkonce";
970  if (Kind.isBSS ())
971    return ".bss$linkonce";
972  if (Kind.isWriteable())
973    return ".data$linkonce";
974  return ".rdata$linkonce";
975}
976
977
978const MCSection *TargetLoweringObjectFileCOFF::
979SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
980                       Mangler *Mang, const TargetMachine &TM) const {
981  assert(!Kind.isThreadLocal() && "Doesn't support TLS");
982
983  // If this global is linkonce/weak and the target handles this by emitting it
984  // into a 'uniqued' section name, create and return the section now.
985  if (GV->isWeakForLinker()) {
986    const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
987    SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
988    MCSymbol *Sym = Mang->getSymbol(GV);
989    Name.append(Sym->getName().begin(), Sym->getName().end());
990
991    unsigned Characteristics = getCOFFSectionFlags(Kind);
992
993    Characteristics |= MCSectionCOFF::IMAGE_SCN_LNK_COMDAT;
994
995    return getContext().getCOFFSection(Name.str(), Characteristics,
996                          MCSectionCOFF::IMAGE_COMDAT_SELECT_EXACT_MATCH, Kind);
997  }
998
999  if (Kind.isText())
1000    return getTextSection();
1001
1002  return getDataSection();
1003}
1004
1005