Iterating over sets of pointers in a heuristic was a bad idea. Switching
[oota-llvm.git] / lib / CodeGen / TargetLoweringObjectFileImpl.cpp
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"
36 using namespace llvm;
37 using namespace dwarf;
38
39 //===----------------------------------------------------------------------===//
40 //                                  ELF
41 //===----------------------------------------------------------------------===//
42
43 void 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
177 static SectionKind
178 getELFKindForNamedSection(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
208 static 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
226 static unsigned
227 getELFSectionFlags(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
254 const MCSection *TargetLoweringObjectFileELF::
255 getExplicitSectionGlobal(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
267 static 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.
285 static 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
302 const MCSection *TargetLoweringObjectFileELF::
303 SelectSectionForGlobal(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.
394 const MCSection *TargetLoweringObjectFileELF::
395 getSectionForConstant(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
410 const MCExpr *TargetLoweringObjectFileELF::
411 getExprForDwarfGlobalReference(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
444 void 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                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
523                                    SectionKind::getText());
524   ConstDataCoalSection
525     = getContext().getMachOSection("__DATA","__const_coal",
526                                    MCSectionMachO::S_COALESCED,
527                                    SectionKind::getReadOnly());
528   ConstDataSection  // .const_data
529     = getContext().getMachOSection("__DATA", "__const", 0,
530                                    SectionKind::getReadOnlyWithRel());
531   DataCoalSection
532     = getContext().getMachOSection("__DATA","__datacoal_nt", 
533                                    MCSectionMachO::S_COALESCED,
534                                    SectionKind::getDataRel());
535   DataCommonSection
536     = getContext().getMachOSection("__DATA","__common",
537                                    MCSectionMachO::S_ZEROFILL,
538                                    SectionKind::getBSS());
539   DataBSSSection
540     = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL,
541                                    SectionKind::getBSS());
542   
543
544   LazySymbolPointerSection
545     = getContext().getMachOSection("__DATA", "__la_symbol_ptr",
546                                    MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
547                                    SectionKind::getMetadata());
548   NonLazySymbolPointerSection
549     = getContext().getMachOSection("__DATA", "__nl_symbol_ptr",
550                                    MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
551                                    SectionKind::getMetadata());
552
553   if (TM.getRelocationModel() == Reloc::Static) {
554     StaticCtorSection
555       = getContext().getMachOSection("__TEXT", "__constructor", 0,
556                                      SectionKind::getDataRel());
557     StaticDtorSection
558       = getContext().getMachOSection("__TEXT", "__destructor", 0,
559                                      SectionKind::getDataRel());
560   } else {
561     StaticCtorSection
562       = getContext().getMachOSection("__DATA", "__mod_init_func",
563                                      MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
564                                      SectionKind::getDataRel());
565     StaticDtorSection
566       = getContext().getMachOSection("__DATA", "__mod_term_func",
567                                      MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
568                                      SectionKind::getDataRel());
569   }
570
571   // Exception Handling.
572   LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0,
573                                              SectionKind::getReadOnlyWithRel());
574   EHFrameSection =
575     getContext().getMachOSection("__TEXT", "__eh_frame",
576                                  MCSectionMachO::S_COALESCED |
577                                  MCSectionMachO::S_ATTR_NO_TOC |
578                                  MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
579                                  MCSectionMachO::S_ATTR_LIVE_SUPPORT,
580                                  SectionKind::getReadOnly());
581
582   // Debug Information.
583   DwarfAbbrevSection =
584     getContext().getMachOSection("__DWARF", "__debug_abbrev", 
585                                  MCSectionMachO::S_ATTR_DEBUG,
586                                  SectionKind::getMetadata());
587   DwarfInfoSection =
588     getContext().getMachOSection("__DWARF", "__debug_info",
589                                  MCSectionMachO::S_ATTR_DEBUG,
590                                  SectionKind::getMetadata());
591   DwarfLineSection =
592     getContext().getMachOSection("__DWARF", "__debug_line",
593                                  MCSectionMachO::S_ATTR_DEBUG,
594                                  SectionKind::getMetadata());
595   DwarfFrameSection =
596     getContext().getMachOSection("__DWARF", "__debug_frame",
597                                  MCSectionMachO::S_ATTR_DEBUG,
598                                  SectionKind::getMetadata());
599   DwarfPubNamesSection =
600     getContext().getMachOSection("__DWARF", "__debug_pubnames",
601                                  MCSectionMachO::S_ATTR_DEBUG,
602                                  SectionKind::getMetadata());
603   DwarfPubTypesSection =
604     getContext().getMachOSection("__DWARF", "__debug_pubtypes",
605                                  MCSectionMachO::S_ATTR_DEBUG,
606                                  SectionKind::getMetadata());
607   DwarfStrSection =
608     getContext().getMachOSection("__DWARF", "__debug_str",
609                                  MCSectionMachO::S_ATTR_DEBUG,
610                                  SectionKind::getMetadata());
611   DwarfLocSection =
612     getContext().getMachOSection("__DWARF", "__debug_loc",
613                                  MCSectionMachO::S_ATTR_DEBUG,
614                                  SectionKind::getMetadata());
615   DwarfARangesSection =
616     getContext().getMachOSection("__DWARF", "__debug_aranges",
617                                  MCSectionMachO::S_ATTR_DEBUG,
618                                  SectionKind::getMetadata());
619   DwarfRangesSection =
620     getContext().getMachOSection("__DWARF", "__debug_ranges",
621                                  MCSectionMachO::S_ATTR_DEBUG,
622                                  SectionKind::getMetadata());
623   DwarfMacroInfoSection =
624     getContext().getMachOSection("__DWARF", "__debug_macinfo",
625                                  MCSectionMachO::S_ATTR_DEBUG,
626                                  SectionKind::getMetadata());
627   DwarfDebugInlineSection =
628     getContext().getMachOSection("__DWARF", "__debug_inlined",
629                                  MCSectionMachO::S_ATTR_DEBUG,
630                                  SectionKind::getMetadata());
631                                  
632   TLSExtraDataSection = TLSTLVSection;
633 }
634
635 const MCSection *TargetLoweringObjectFileMachO::
636 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
637                          Mangler *Mang, const TargetMachine &TM) const {
638   // Parse the section specifier and create it if valid.
639   StringRef Segment, Section;
640   unsigned TAA, StubSize;
641   std::string ErrorCode =
642     MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
643                                           TAA, StubSize);
644   if (!ErrorCode.empty()) {
645     // If invalid, report the error with report_fatal_error.
646     report_fatal_error("Global variable '" + GV->getNameStr() +
647                       "' has an invalid section specifier '" + GV->getSection()+
648                       "': " + ErrorCode + ".");
649     // Fall back to dropping it into the data section.
650     return DataSection;
651   }
652
653   // Get the section.
654   const MCSectionMachO *S =
655     getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
656
657   // Okay, now that we got the section, verify that the TAA & StubSize agree.
658   // If the user declared multiple globals with different section flags, we need
659   // to reject it here.
660   if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
661     // If invalid, report the error with report_fatal_error.
662     report_fatal_error("Global variable '" + GV->getNameStr() +
663                       "' section type or attributes does not match previous"
664                       " section specifier");
665   }
666
667   return S;
668 }
669
670 const MCSection *TargetLoweringObjectFileMachO::
671 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
672                        Mangler *Mang, const TargetMachine &TM) const {
673   
674   // Handle thread local data.
675   if (Kind.isThreadBSS()) return TLSBSSSection;
676   if (Kind.isThreadData()) return TLSDataSection;
677
678   if (Kind.isText())
679     return GV->isWeakForLinker() ? TextCoalSection : TextSection;
680
681   // If this is weak/linkonce, put this in a coalescable section, either in text
682   // or data depending on if it is writable.
683   if (GV->isWeakForLinker()) {
684     if (Kind.isReadOnly())
685       return ConstTextCoalSection;
686     return DataCoalSection;
687   }
688
689   // FIXME: Alignment check should be handled by section classifier.
690   if (Kind.isMergeable1ByteCString() &&
691       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
692     return CStringSection;
693       
694   // Do not put 16-bit arrays in the UString section if they have an
695   // externally visible label, this runs into issues with certain linker
696   // versions.
697   if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
698       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
699     return UStringSection;
700
701   if (Kind.isMergeableConst()) {
702     if (Kind.isMergeableConst4())
703       return FourByteConstantSection;
704     if (Kind.isMergeableConst8())
705       return EightByteConstantSection;
706     if (Kind.isMergeableConst16() && SixteenByteConstantSection)
707       return SixteenByteConstantSection;
708   }
709
710   // Otherwise, if it is readonly, but not something we can specially optimize,
711   // just drop it in .const.
712   if (Kind.isReadOnly())
713     return ReadOnlySection;
714
715   // If this is marked const, put it into a const section.  But if the dynamic
716   // linker needs to write to it, put it in the data segment.
717   if (Kind.isReadOnlyWithRel())
718     return ConstDataSection;
719
720   // Put zero initialized globals with strong external linkage in the
721   // DATA, __common section with the .zerofill directive.
722   if (Kind.isBSSExtern())
723     return DataCommonSection;
724
725   // Put zero initialized globals with local linkage in __DATA,__bss directive
726   // with the .zerofill directive (aka .lcomm).
727   if (Kind.isBSSLocal())
728     return DataBSSSection;
729   
730   // Otherwise, just drop the variable in the normal data section.
731   return DataSection;
732 }
733
734 const MCSection *
735 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
736   // If this constant requires a relocation, we have to put it in the data
737   // segment, not in the text segment.
738   if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
739     return ConstDataSection;
740
741   if (Kind.isMergeableConst4())
742     return FourByteConstantSection;
743   if (Kind.isMergeableConst8())
744     return EightByteConstantSection;
745   if (Kind.isMergeableConst16() && SixteenByteConstantSection)
746     return SixteenByteConstantSection;
747   return ReadOnlySection;  // .const
748 }
749
750 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
751 /// not to emit the UsedDirective for some symbols in llvm.used.
752 // FIXME: REMOVE this (rdar://7071300)
753 bool TargetLoweringObjectFileMachO::
754 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
755   /// On Darwin, internally linked data beginning with "L" or "l" does not have
756   /// the directive emitted (this occurs in ObjC metadata).
757   if (!GV) return false;
758
759   // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
760   if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
761     // FIXME: ObjC metadata is currently emitted as internal symbols that have
762     // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
763     // this horrible hack can go away.
764     MCSymbol *Sym = Mang->getSymbol(GV);
765     if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
766       return false;
767   }
768
769   return true;
770 }
771
772 const MCExpr *TargetLoweringObjectFileMachO::
773 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
774                                MachineModuleInfo *MMI, unsigned Encoding,
775                                MCStreamer &Streamer) const {
776   // The mach-o version of this method defaults to returning a stub reference.
777
778   if (Encoding & DW_EH_PE_indirect) {
779     MachineModuleInfoMachO &MachOMMI =
780       MMI->getObjFileInfo<MachineModuleInfoMachO>();
781
782     SmallString<128> Name;
783     Mang->getNameWithPrefix(Name, GV, true);
784     Name += "$non_lazy_ptr";
785
786     // Add information about the stub reference to MachOMMI so that the stub
787     // gets emitted by the asmprinter.
788     MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
789     MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
790     if (StubSym.getPointer() == 0) {
791       MCSymbol *Sym = Mang->getSymbol(GV);
792       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
793     }
794
795     return TargetLoweringObjectFile::
796       getExprForDwarfReference(SSym, Mang, MMI,
797                                Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
798   }
799
800   return TargetLoweringObjectFile::
801     getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
802 }
803
804 unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const {
805   return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
806 }
807
808 unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const {
809   return DW_EH_PE_pcrel;
810 }
811
812 unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const {
813   return DW_EH_PE_pcrel;
814 }
815
816 unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const {
817   return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
818 }
819
820 //===----------------------------------------------------------------------===//
821 //                                  COFF
822 //===----------------------------------------------------------------------===//
823
824 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
825                                               const TargetMachine &TM) {
826   TargetLoweringObjectFile::Initialize(Ctx, TM);
827   TextSection =
828     getContext().getCOFFSection(".text",
829                                 COFF::IMAGE_SCN_CNT_CODE |
830                                 COFF::IMAGE_SCN_MEM_EXECUTE |
831                                 COFF::IMAGE_SCN_MEM_READ,
832                                 SectionKind::getText());
833   DataSection =
834     getContext().getCOFFSection(".data",
835                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
836                                 COFF::IMAGE_SCN_MEM_READ |
837                                 COFF::IMAGE_SCN_MEM_WRITE,
838                                 SectionKind::getDataRel());
839   ReadOnlySection =
840     getContext().getCOFFSection(".rdata",
841                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
842                                 COFF::IMAGE_SCN_MEM_READ,
843                                 SectionKind::getReadOnly());
844   StaticCtorSection =
845     getContext().getCOFFSection(".ctors",
846                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
847                                 COFF::IMAGE_SCN_MEM_READ |
848                                 COFF::IMAGE_SCN_MEM_WRITE,
849                                 SectionKind::getDataRel());
850   StaticDtorSection =
851     getContext().getCOFFSection(".dtors",
852                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
853                                 COFF::IMAGE_SCN_MEM_READ |
854                                 COFF::IMAGE_SCN_MEM_WRITE,
855                                 SectionKind::getDataRel());
856
857   // FIXME: We're emitting LSDA info into a readonly section on COFF, even
858   // though it contains relocatable pointers.  In PIC mode, this is probably a
859   // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
860   // adjusted or this should be a data section.
861   LSDASection =
862     getContext().getCOFFSection(".gcc_except_table",
863                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
864                                 COFF::IMAGE_SCN_MEM_READ,
865                                 SectionKind::getReadOnly());
866   EHFrameSection =
867     getContext().getCOFFSection(".eh_frame",
868                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
869                                 COFF::IMAGE_SCN_MEM_READ |
870                                 COFF::IMAGE_SCN_MEM_WRITE,
871                                 SectionKind::getDataRel());
872
873   // Debug info.
874   DwarfAbbrevSection =
875     getContext().getCOFFSection(".debug_abbrev",
876                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
877                                 COFF::IMAGE_SCN_MEM_READ,
878                                 SectionKind::getMetadata());
879   DwarfInfoSection =
880     getContext().getCOFFSection(".debug_info",
881                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
882                                 COFF::IMAGE_SCN_MEM_READ,
883                                 SectionKind::getMetadata());
884   DwarfLineSection =
885     getContext().getCOFFSection(".debug_line",
886                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
887                                 COFF::IMAGE_SCN_MEM_READ,
888                                 SectionKind::getMetadata());
889   DwarfFrameSection =
890     getContext().getCOFFSection(".debug_frame",
891                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
892                                 COFF::IMAGE_SCN_MEM_READ,
893                                 SectionKind::getMetadata());
894   DwarfPubNamesSection =
895     getContext().getCOFFSection(".debug_pubnames",
896                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
897                                 COFF::IMAGE_SCN_MEM_READ,
898                                 SectionKind::getMetadata());
899   DwarfPubTypesSection =
900     getContext().getCOFFSection(".debug_pubtypes",
901                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
902                                 COFF::IMAGE_SCN_MEM_READ,
903                                 SectionKind::getMetadata());
904   DwarfStrSection =
905     getContext().getCOFFSection(".debug_str",
906                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
907                                 COFF::IMAGE_SCN_MEM_READ,
908                                 SectionKind::getMetadata());
909   DwarfLocSection =
910     getContext().getCOFFSection(".debug_loc",
911                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
912                                 COFF::IMAGE_SCN_MEM_READ,
913                                 SectionKind::getMetadata());
914   DwarfARangesSection =
915     getContext().getCOFFSection(".debug_aranges",
916                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
917                                 COFF::IMAGE_SCN_MEM_READ,
918                                 SectionKind::getMetadata());
919   DwarfRangesSection =
920     getContext().getCOFFSection(".debug_ranges",
921                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
922                                 COFF::IMAGE_SCN_MEM_READ,
923                                 SectionKind::getMetadata());
924   DwarfMacroInfoSection =
925     getContext().getCOFFSection(".debug_macinfo",
926                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
927                                 COFF::IMAGE_SCN_MEM_READ,
928                                 SectionKind::getMetadata());
929
930   DrectveSection =
931     getContext().getCOFFSection(".drectve",
932                                 COFF::IMAGE_SCN_LNK_INFO,
933                                 SectionKind::getMetadata());
934 }
935
936 static unsigned
937 getCOFFSectionFlags(SectionKind K) {
938   unsigned Flags = 0;
939
940   if (K.isMetadata())
941     Flags |=
942       COFF::IMAGE_SCN_MEM_DISCARDABLE;
943   else if (K.isText())
944     Flags |=
945       COFF::IMAGE_SCN_MEM_EXECUTE |
946       COFF::IMAGE_SCN_CNT_CODE;
947   else if (K.isBSS ())
948     Flags |=
949       COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
950       COFF::IMAGE_SCN_MEM_READ |
951       COFF::IMAGE_SCN_MEM_WRITE;
952   else if (K.isReadOnly())
953     Flags |=
954       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
955       COFF::IMAGE_SCN_MEM_READ;
956   else if (K.isWriteable())
957     Flags |=
958       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
959       COFF::IMAGE_SCN_MEM_READ |
960       COFF::IMAGE_SCN_MEM_WRITE;
961
962   return Flags;
963 }
964
965 const MCSection *TargetLoweringObjectFileCOFF::
966 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
967                          Mangler *Mang, const TargetMachine &TM) const {
968   return getContext().getCOFFSection(GV->getSection(),
969                                      getCOFFSectionFlags(Kind),
970                                      Kind);
971 }
972
973 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
974   if (Kind.isText())
975     return ".text$linkonce";
976   if (Kind.isBSS ())
977     return ".bss$linkonce";
978   if (Kind.isWriteable())
979     return ".data$linkonce";
980   return ".rdata$linkonce";
981 }
982
983
984 const MCSection *TargetLoweringObjectFileCOFF::
985 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
986                        Mangler *Mang, const TargetMachine &TM) const {
987   assert(!Kind.isThreadLocal() && "Doesn't support TLS");
988
989   // If this global is linkonce/weak and the target handles this by emitting it
990   // into a 'uniqued' section name, create and return the section now.
991   if (GV->isWeakForLinker()) {
992     const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
993     SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
994     MCSymbol *Sym = Mang->getSymbol(GV);
995     Name.append(Sym->getName().begin(), Sym->getName().end());
996
997     unsigned Characteristics = getCOFFSectionFlags(Kind);
998
999     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
1000
1001     return getContext().getCOFFSection(Name.str(), Characteristics,
1002                           COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH, Kind);
1003   }
1004
1005   if (Kind.isText())
1006     return getTextSection();
1007
1008   return getDataSection();
1009 }
1010