1 //===-- llvm/CodeGen/TargetLoweringObjectFileImpl.cpp - Object File Info --===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements classes used to handle lowerings specific to common 11 // object file formats. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h" 16 #include "llvm/Constants.h" 17 #include "llvm/DerivedTypes.h" 18 #include "llvm/Function.h" 19 #include "llvm/GlobalVariable.h" 20 #include "llvm/CodeGen/MachineModuleInfoImpls.h" 21 #include "llvm/MC/MCContext.h" 22 #include "llvm/MC/MCExpr.h" 23 #include "llvm/MC/MCSectionMachO.h" 24 #include "llvm/MC/MCSectionELF.h" 25 #include "llvm/MC/MCSymbol.h" 26 #include "llvm/Target/Mangler.h" 27 #include "llvm/Target/TargetData.h" 28 #include "llvm/Target/TargetMachine.h" 29 #include "llvm/Target/TargetOptions.h" 30 #include "llvm/Support/Dwarf.h" 31 #include "llvm/Support/ErrorHandling.h" 32 #include "llvm/Support/raw_ostream.h" 33 #include "llvm/ADT/SmallString.h" 34 #include "llvm/ADT/StringExtras.h" 35 using namespace llvm; 36 using namespace dwarf; 37 38 //===----------------------------------------------------------------------===// 39 // ELF 40 //===----------------------------------------------------------------------===// 41 typedef StringMap<const MCSectionELF*> ELFUniqueMapTy; 42 43 TargetLoweringObjectFileELF::~TargetLoweringObjectFileELF() { 44 // If we have the section uniquing map, free it. 45 delete (ELFUniqueMapTy*)UniquingMap; 46 } 47 48 const MCSection *TargetLoweringObjectFileELF:: 49 getELFSection(StringRef Section, unsigned Type, unsigned Flags, 50 SectionKind Kind, bool IsExplicit) const { 51 if (UniquingMap == 0) 52 UniquingMap = new ELFUniqueMapTy(); 53 ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)UniquingMap; 54 55 // Do the lookup, if we have a hit, return it. 56 const MCSectionELF *&Entry = Map[Section]; 57 if (Entry) return Entry; 58 59 return Entry = MCSectionELF::Create(Section, Type, Flags, Kind, IsExplicit, 60 getContext()); 61 } 62 63 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx, 64 const TargetMachine &TM) { 65 if (UniquingMap != 0) 66 ((ELFUniqueMapTy*)UniquingMap)->clear(); 67 TargetLoweringObjectFile::Initialize(Ctx, TM); 68 69 BSSSection = 70 getELFSection(".bss", MCSectionELF::SHT_NOBITS, 71 MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC, 72 SectionKind::getBSS()); 73 74 TextSection = 75 getELFSection(".text", MCSectionELF::SHT_PROGBITS, 76 MCSectionELF::SHF_EXECINSTR | MCSectionELF::SHF_ALLOC, 77 SectionKind::getText()); 78 79 DataSection = 80 getELFSection(".data", MCSectionELF::SHT_PROGBITS, 81 MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC, 82 SectionKind::getDataRel()); 83 84 ReadOnlySection = 85 getELFSection(".rodata", MCSectionELF::SHT_PROGBITS, 86 MCSectionELF::SHF_ALLOC, 87 SectionKind::getReadOnly()); 88 89 TLSDataSection = 90 getELFSection(".tdata", MCSectionELF::SHT_PROGBITS, 91 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS | 92 MCSectionELF::SHF_WRITE, SectionKind::getThreadData()); 93 94 TLSBSSSection = 95 getELFSection(".tbss", MCSectionELF::SHT_NOBITS, 96 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS | 97 MCSectionELF::SHF_WRITE, SectionKind::getThreadBSS()); 98 99 DataRelSection = 100 getELFSection(".data.rel", MCSectionELF::SHT_PROGBITS, 101 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, 102 SectionKind::getDataRel()); 103 104 DataRelLocalSection = 105 getELFSection(".data.rel.local", MCSectionELF::SHT_PROGBITS, 106 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, 107 SectionKind::getDataRelLocal()); 108 109 DataRelROSection = 110 getELFSection(".data.rel.ro", MCSectionELF::SHT_PROGBITS, 111 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, 112 SectionKind::getReadOnlyWithRel()); 113 114 DataRelROLocalSection = 115 getELFSection(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS, 116 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, 117 SectionKind::getReadOnlyWithRelLocal()); 118 119 MergeableConst4Section = 120 getELFSection(".rodata.cst4", MCSectionELF::SHT_PROGBITS, 121 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE, 122 SectionKind::getMergeableConst4()); 123 124 MergeableConst8Section = 125 getELFSection(".rodata.cst8", MCSectionELF::SHT_PROGBITS, 126 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE, 127 SectionKind::getMergeableConst8()); 128 129 MergeableConst16Section = 130 getELFSection(".rodata.cst16", MCSectionELF::SHT_PROGBITS, 131 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE, 132 SectionKind::getMergeableConst16()); 133 134 StaticCtorSection = 135 getELFSection(".ctors", MCSectionELF::SHT_PROGBITS, 136 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, 137 SectionKind::getDataRel()); 138 139 StaticDtorSection = 140 getELFSection(".dtors", MCSectionELF::SHT_PROGBITS, 141 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, 142 SectionKind::getDataRel()); 143 144 // Exception Handling Sections. 145 146 // FIXME: We're emitting LSDA info into a readonly section on ELF, even though 147 // it contains relocatable pointers. In PIC mode, this is probably a big 148 // runtime hit for C++ apps. Either the contents of the LSDA need to be 149 // adjusted or this should be a data section. 150 LSDASection = 151 getELFSection(".gcc_except_table", MCSectionELF::SHT_PROGBITS, 152 MCSectionELF::SHF_ALLOC, SectionKind::getReadOnly()); 153 EHFrameSection = 154 getELFSection(".eh_frame", MCSectionELF::SHT_PROGBITS, 155 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, 156 SectionKind::getDataRel()); 157 158 // Debug Info Sections. 159 DwarfAbbrevSection = 160 getELFSection(".debug_abbrev", MCSectionELF::SHT_PROGBITS, 0, 161 SectionKind::getMetadata()); 162 DwarfInfoSection = 163 getELFSection(".debug_info", MCSectionELF::SHT_PROGBITS, 0, 164 SectionKind::getMetadata()); 165 DwarfLineSection = 166 getELFSection(".debug_line", MCSectionELF::SHT_PROGBITS, 0, 167 SectionKind::getMetadata()); 168 DwarfFrameSection = 169 getELFSection(".debug_frame", MCSectionELF::SHT_PROGBITS, 0, 170 SectionKind::getMetadata()); 171 DwarfPubNamesSection = 172 getELFSection(".debug_pubnames", MCSectionELF::SHT_PROGBITS, 0, 173 SectionKind::getMetadata()); 174 DwarfPubTypesSection = 175 getELFSection(".debug_pubtypes", MCSectionELF::SHT_PROGBITS, 0, 176 SectionKind::getMetadata()); 177 DwarfStrSection = 178 getELFSection(".debug_str", MCSectionELF::SHT_PROGBITS, 0, 179 SectionKind::getMetadata()); 180 DwarfLocSection = 181 getELFSection(".debug_loc", MCSectionELF::SHT_PROGBITS, 0, 182 SectionKind::getMetadata()); 183 DwarfARangesSection = 184 getELFSection(".debug_aranges", MCSectionELF::SHT_PROGBITS, 0, 185 SectionKind::getMetadata()); 186 DwarfRangesSection = 187 getELFSection(".debug_ranges", MCSectionELF::SHT_PROGBITS, 0, 188 SectionKind::getMetadata()); 189 DwarfMacroInfoSection = 190 getELFSection(".debug_macinfo", MCSectionELF::SHT_PROGBITS, 0, 191 SectionKind::getMetadata()); 192 } 193 194 195 static SectionKind 196 getELFKindForNamedSection(StringRef Name, SectionKind K) { 197 if (Name.empty() || Name[0] != '.') return K; 198 199 // Some lame default implementation based on some magic section names. 200 if (Name == ".bss" || 201 Name.startswith(".bss.") || 202 Name.startswith(".gnu.linkonce.b.") || 203 Name.startswith(".llvm.linkonce.b.") || 204 Name == ".sbss" || 205 Name.startswith(".sbss.") || 206 Name.startswith(".gnu.linkonce.sb.") || 207 Name.startswith(".llvm.linkonce.sb.")) 208 return SectionKind::getBSS(); 209 210 if (Name == ".tdata" || 211 Name.startswith(".tdata.") || 212 Name.startswith(".gnu.linkonce.td.") || 213 Name.startswith(".llvm.linkonce.td.")) 214 return SectionKind::getThreadData(); 215 216 if (Name == ".tbss" || 217 Name.startswith(".tbss.") || 218 Name.startswith(".gnu.linkonce.tb.") || 219 Name.startswith(".llvm.linkonce.tb.")) 220 return SectionKind::getThreadBSS(); 221 222 return K; 223 } 224 225 226 static unsigned getELFSectionType(StringRef Name, SectionKind K) { 227 228 if (Name == ".init_array") 229 return MCSectionELF::SHT_INIT_ARRAY; 230 231 if (Name == ".fini_array") 232 return MCSectionELF::SHT_FINI_ARRAY; 233 234 if (Name == ".preinit_array") 235 return MCSectionELF::SHT_PREINIT_ARRAY; 236 237 if (K.isBSS() || K.isThreadBSS()) 238 return MCSectionELF::SHT_NOBITS; 239 240 return MCSectionELF::SHT_PROGBITS; 241 } 242 243 244 static unsigned 245 getELFSectionFlags(SectionKind K) { 246 unsigned Flags = 0; 247 248 if (!K.isMetadata()) 249 Flags |= MCSectionELF::SHF_ALLOC; 250 251 if (K.isText()) 252 Flags |= MCSectionELF::SHF_EXECINSTR; 253 254 if (K.isWriteable()) 255 Flags |= MCSectionELF::SHF_WRITE; 256 257 if (K.isThreadLocal()) 258 Flags |= MCSectionELF::SHF_TLS; 259 260 // K.isMergeableConst() is left out to honour PR4650 261 if (K.isMergeableCString() || K.isMergeableConst4() || 262 K.isMergeableConst8() || K.isMergeableConst16()) 263 Flags |= MCSectionELF::SHF_MERGE; 264 265 if (K.isMergeableCString()) 266 Flags |= MCSectionELF::SHF_STRINGS; 267 268 return Flags; 269 } 270 271 272 const MCSection *TargetLoweringObjectFileELF:: 273 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 274 Mangler *Mang, const TargetMachine &TM) const { 275 StringRef SectionName = GV->getSection(); 276 277 // Infer section flags from the section name if we can. 278 Kind = getELFKindForNamedSection(SectionName, Kind); 279 280 return getELFSection(SectionName, 281 getELFSectionType(SectionName, Kind), 282 getELFSectionFlags(Kind), Kind, true); 283 } 284 285 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) { 286 if (Kind.isText()) return ".gnu.linkonce.t."; 287 if (Kind.isReadOnly()) return ".gnu.linkonce.r."; 288 289 if (Kind.isThreadData()) return ".gnu.linkonce.td."; 290 if (Kind.isThreadBSS()) return ".gnu.linkonce.tb."; 291 292 if (Kind.isDataNoRel()) return ".gnu.linkonce.d."; 293 if (Kind.isDataRelLocal()) return ".gnu.linkonce.d.rel.local."; 294 if (Kind.isDataRel()) return ".gnu.linkonce.d.rel."; 295 if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local."; 296 297 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 298 return ".gnu.linkonce.d.rel.ro."; 299 } 300 301 const MCSection *TargetLoweringObjectFileELF:: 302 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 303 Mangler *Mang, const TargetMachine &TM) const { 304 305 // If this global is linkonce/weak and the target handles this by emitting it 306 // into a 'uniqued' section name, create and return the section now. 307 if (GV->isWeakForLinker() && !Kind.isCommon() && !Kind.isBSS()) { 308 const char *Prefix = getSectionPrefixForUniqueGlobal(Kind); 309 SmallString<128> Name; 310 Name.append(Prefix, Prefix+strlen(Prefix)); 311 Mang->getNameWithPrefix(Name, GV, false); 312 return getELFSection(Name.str(), getELFSectionType(Name.str(), Kind), 313 getELFSectionFlags(Kind), Kind); 314 } 315 316 if (Kind.isText()) return TextSection; 317 318 if (Kind.isMergeable1ByteCString() || 319 Kind.isMergeable2ByteCString() || 320 Kind.isMergeable4ByteCString()) { 321 322 // We also need alignment here. 323 // FIXME: this is getting the alignment of the character, not the 324 // alignment of the global! 325 unsigned Align = 326 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)); 327 328 const char *SizeSpec = ".rodata.str1."; 329 if (Kind.isMergeable2ByteCString()) 330 SizeSpec = ".rodata.str2."; 331 else if (Kind.isMergeable4ByteCString()) 332 SizeSpec = ".rodata.str4."; 333 else 334 assert(Kind.isMergeable1ByteCString() && "unknown string width"); 335 336 337 std::string Name = SizeSpec + utostr(Align); 338 return getELFSection(Name, MCSectionELF::SHT_PROGBITS, 339 MCSectionELF::SHF_ALLOC | 340 MCSectionELF::SHF_MERGE | 341 MCSectionELF::SHF_STRINGS, 342 Kind); 343 } 344 345 if (Kind.isMergeableConst()) { 346 if (Kind.isMergeableConst4() && MergeableConst4Section) 347 return MergeableConst4Section; 348 if (Kind.isMergeableConst8() && MergeableConst8Section) 349 return MergeableConst8Section; 350 if (Kind.isMergeableConst16() && MergeableConst16Section) 351 return MergeableConst16Section; 352 return ReadOnlySection; // .const 353 } 354 355 if (Kind.isReadOnly()) return ReadOnlySection; 356 357 if (Kind.isThreadData()) return TLSDataSection; 358 if (Kind.isThreadBSS()) return TLSBSSSection; 359 360 // Note: we claim that common symbols are put in BSSSection, but they are 361 // really emitted with the magic .comm directive, which creates a symbol table 362 // entry but not a section. 363 if (Kind.isBSS() || Kind.isCommon()) return BSSSection; 364 365 if (Kind.isDataNoRel()) return DataSection; 366 if (Kind.isDataRelLocal()) return DataRelLocalSection; 367 if (Kind.isDataRel()) return DataRelSection; 368 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 369 370 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 371 return DataRelROSection; 372 } 373 374 /// getSectionForConstant - Given a mergeable constant with the 375 /// specified size and relocation information, return a section that it 376 /// should be placed in. 377 const MCSection *TargetLoweringObjectFileELF:: 378 getSectionForConstant(SectionKind Kind) const { 379 if (Kind.isMergeableConst4() && MergeableConst4Section) 380 return MergeableConst4Section; 381 if (Kind.isMergeableConst8() && MergeableConst8Section) 382 return MergeableConst8Section; 383 if (Kind.isMergeableConst16() && MergeableConst16Section) 384 return MergeableConst16Section; 385 if (Kind.isReadOnly()) 386 return ReadOnlySection; 387 388 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 389 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 390 return DataRelROSection; 391 } 392 393 const MCExpr *TargetLoweringObjectFileELF:: 394 getSymbolForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 395 MachineModuleInfo *MMI, unsigned Encoding) const { 396 397 if (Encoding & dwarf::DW_EH_PE_indirect) { 398 MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>(); 399 400 SmallString<128> Name; 401 Mang->getNameWithPrefix(Name, GV, true); 402 Name += ".DW.stub"; 403 404 // Add information about the stub reference to ELFMMI so that the stub 405 // gets emitted by the asmprinter. 406 MCSymbol *Sym = getContext().GetOrCreateTemporarySymbol(Name.str()); 407 MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(Sym); 408 if (StubSym.getPointer() == 0) { 409 Name.clear(); 410 Mang->getNameWithPrefix(Name, GV, false); 411 412 if (GV->hasPrivateLinkage()) 413 StubSym = MachineModuleInfoImpl:: 414 StubValueTy(getContext().GetOrCreateTemporarySymbol(Name.str()), 415 false); 416 else 417 StubSym = MachineModuleInfoImpl:: 418 StubValueTy(getContext().GetOrCreateSymbol(Name.str()), 419 !GV->hasInternalLinkage()); 420 } 421 422 return TargetLoweringObjectFile:: 423 getSymbolForDwarfReference(Sym, MMI, 424 Encoding & ~dwarf::DW_EH_PE_indirect); 425 } 426 427 return TargetLoweringObjectFile:: 428 getSymbolForDwarfGlobalReference(GV, Mang, MMI, Encoding); 429 } 430 431 //===----------------------------------------------------------------------===// 432 // MachO 433 //===----------------------------------------------------------------------===// 434 435 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy; 436 437 TargetLoweringObjectFileMachO::~TargetLoweringObjectFileMachO() { 438 // If we have the MachO uniquing map, free it. 439 delete (MachOUniqueMapTy*)UniquingMap; 440 } 441 442 443 const MCSectionMachO *TargetLoweringObjectFileMachO:: 444 getMachOSection(StringRef Segment, StringRef Section, 445 unsigned TypeAndAttributes, 446 unsigned Reserved2, SectionKind Kind) const { 447 // We unique sections by their segment/section pair. The returned section 448 // may not have the same flags as the requested section, if so this should be 449 // diagnosed by the client as an error. 450 451 // Create the map if it doesn't already exist. 452 if (UniquingMap == 0) 453 UniquingMap = new MachOUniqueMapTy(); 454 MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)UniquingMap; 455 456 // Form the name to look up. 457 SmallString<64> Name; 458 Name += Segment; 459 Name.push_back(','); 460 Name += Section; 461 462 // Do the lookup, if we have a hit, return it. 463 const MCSectionMachO *&Entry = Map[Name.str()]; 464 if (Entry) return Entry; 465 466 // Otherwise, return a new section. 467 return Entry = MCSectionMachO::Create(Segment, Section, TypeAndAttributes, 468 Reserved2, Kind, getContext()); 469 } 470 471 472 void 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 if (UniquingMap != 0) 483 ((MachOUniqueMapTy*)UniquingMap)->clear(); 484 TargetLoweringObjectFile::Initialize(Ctx, TM); 485 486 TextSection // .text 487 = getMachOSection("__TEXT", "__text", 488 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 489 SectionKind::getText()); 490 DataSection // .data 491 = getMachOSection("__DATA", "__data", 0, SectionKind::getDataRel()); 492 493 CStringSection // .cstring 494 = getMachOSection("__TEXT", "__cstring", MCSectionMachO::S_CSTRING_LITERALS, 495 SectionKind::getMergeable1ByteCString()); 496 UStringSection 497 = getMachOSection("__TEXT","__ustring", 0, 498 SectionKind::getMergeable2ByteCString()); 499 FourByteConstantSection // .literal4 500 = getMachOSection("__TEXT", "__literal4", MCSectionMachO::S_4BYTE_LITERALS, 501 SectionKind::getMergeableConst4()); 502 EightByteConstantSection // .literal8 503 = getMachOSection("__TEXT", "__literal8", MCSectionMachO::S_8BYTE_LITERALS, 504 SectionKind::getMergeableConst8()); 505 506 // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back 507 // to using it in -static mode. 508 SixteenByteConstantSection = 0; 509 if (TM.getRelocationModel() != Reloc::Static && 510 TM.getTargetData()->getPointerSize() == 32) 511 SixteenByteConstantSection = // .literal16 512 getMachOSection("__TEXT", "__literal16",MCSectionMachO::S_16BYTE_LITERALS, 513 SectionKind::getMergeableConst16()); 514 515 ReadOnlySection // .const 516 = getMachOSection("__TEXT", "__const", 0, SectionKind::getReadOnly()); 517 518 TextCoalSection 519 = getMachOSection("__TEXT", "__textcoal_nt", 520 MCSectionMachO::S_COALESCED | 521 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 522 SectionKind::getText()); 523 ConstTextCoalSection 524 = getMachOSection("__TEXT", "__const_coal", MCSectionMachO::S_COALESCED, 525 SectionKind::getText()); 526 ConstDataCoalSection 527 = getMachOSection("__DATA","__const_coal", MCSectionMachO::S_COALESCED, 528 SectionKind::getText()); 529 ConstDataSection // .const_data 530 = getMachOSection("__DATA", "__const", 0, 531 SectionKind::getReadOnlyWithRel()); 532 DataCoalSection 533 = getMachOSection("__DATA","__datacoal_nt", MCSectionMachO::S_COALESCED, 534 SectionKind::getDataRel()); 535 DataCommonSection 536 = getMachOSection("__DATA","__common", MCSectionMachO::S_ZEROFILL, 537 SectionKind::getBSS()); 538 DataBSSSection 539 = getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL, 540 SectionKind::getBSS()); 541 542 543 LazySymbolPointerSection 544 = getMachOSection("__DATA", "__la_symbol_ptr", 545 MCSectionMachO::S_LAZY_SYMBOL_POINTERS, 546 SectionKind::getMetadata()); 547 NonLazySymbolPointerSection 548 = 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 = getMachOSection("__TEXT", "__constructor", 0,SectionKind::getDataRel()); 555 StaticDtorSection 556 = getMachOSection("__TEXT", "__destructor", 0, SectionKind::getDataRel()); 557 } else { 558 StaticCtorSection 559 = getMachOSection("__DATA", "__mod_init_func", 560 MCSectionMachO::S_MOD_INIT_FUNC_POINTERS, 561 SectionKind::getDataRel()); 562 StaticDtorSection 563 = getMachOSection("__DATA", "__mod_term_func", 564 MCSectionMachO::S_MOD_TERM_FUNC_POINTERS, 565 SectionKind::getDataRel()); 566 } 567 568 // Exception Handling. 569 LSDASection = getMachOSection("__DATA", "__gcc_except_tab", 0, 570 SectionKind::getDataRel()); 571 EHFrameSection = 572 getMachOSection("__TEXT", "__eh_frame", 573 MCSectionMachO::S_COALESCED | 574 MCSectionMachO::S_ATTR_NO_TOC | 575 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS | 576 MCSectionMachO::S_ATTR_LIVE_SUPPORT, 577 SectionKind::getReadOnly()); 578 579 // Debug Information. 580 DwarfAbbrevSection = 581 getMachOSection("__DWARF", "__debug_abbrev", MCSectionMachO::S_ATTR_DEBUG, 582 SectionKind::getMetadata()); 583 DwarfInfoSection = 584 getMachOSection("__DWARF", "__debug_info", MCSectionMachO::S_ATTR_DEBUG, 585 SectionKind::getMetadata()); 586 DwarfLineSection = 587 getMachOSection("__DWARF", "__debug_line", MCSectionMachO::S_ATTR_DEBUG, 588 SectionKind::getMetadata()); 589 DwarfFrameSection = 590 getMachOSection("__DWARF", "__debug_frame", MCSectionMachO::S_ATTR_DEBUG, 591 SectionKind::getMetadata()); 592 DwarfPubNamesSection = 593 getMachOSection("__DWARF", "__debug_pubnames", MCSectionMachO::S_ATTR_DEBUG, 594 SectionKind::getMetadata()); 595 DwarfPubTypesSection = 596 getMachOSection("__DWARF", "__debug_pubtypes", MCSectionMachO::S_ATTR_DEBUG, 597 SectionKind::getMetadata()); 598 DwarfStrSection = 599 getMachOSection("__DWARF", "__debug_str", MCSectionMachO::S_ATTR_DEBUG, 600 SectionKind::getMetadata()); 601 DwarfLocSection = 602 getMachOSection("__DWARF", "__debug_loc", MCSectionMachO::S_ATTR_DEBUG, 603 SectionKind::getMetadata()); 604 DwarfARangesSection = 605 getMachOSection("__DWARF", "__debug_aranges", MCSectionMachO::S_ATTR_DEBUG, 606 SectionKind::getMetadata()); 607 DwarfRangesSection = 608 getMachOSection("__DWARF", "__debug_ranges", MCSectionMachO::S_ATTR_DEBUG, 609 SectionKind::getMetadata()); 610 DwarfMacroInfoSection = 611 getMachOSection("__DWARF", "__debug_macinfo", MCSectionMachO::S_ATTR_DEBUG, 612 SectionKind::getMetadata()); 613 DwarfDebugInlineSection = 614 getMachOSection("__DWARF", "__debug_inlined", MCSectionMachO::S_ATTR_DEBUG, 615 SectionKind::getMetadata()); 616 } 617 618 const MCSection *TargetLoweringObjectFileMachO:: 619 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 620 Mangler *Mang, const TargetMachine &TM) const { 621 // Parse the section specifier and create it if valid. 622 StringRef Segment, Section; 623 unsigned TAA, StubSize; 624 std::string ErrorCode = 625 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section, 626 TAA, StubSize); 627 if (!ErrorCode.empty()) { 628 // If invalid, report the error with llvm_report_error. 629 llvm_report_error("Global variable '" + GV->getNameStr() + 630 "' has an invalid section specifier '" + GV->getSection()+ 631 "': " + ErrorCode + "."); 632 // Fall back to dropping it into the data section. 633 return DataSection; 634 } 635 636 // Get the section. 637 const MCSectionMachO *S = 638 getMachOSection(Segment, Section, TAA, StubSize, Kind); 639 640 // Okay, now that we got the section, verify that the TAA & StubSize agree. 641 // If the user declared multiple globals with different section flags, we need 642 // to reject it here. 643 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) { 644 // If invalid, report the error with llvm_report_error. 645 llvm_report_error("Global variable '" + GV->getNameStr() + 646 "' section type or attributes does not match previous" 647 " section specifier"); 648 } 649 650 return S; 651 } 652 653 const MCSection *TargetLoweringObjectFileMachO:: 654 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 655 Mangler *Mang, const TargetMachine &TM) const { 656 assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS"); 657 658 if (Kind.isText()) 659 return GV->isWeakForLinker() ? TextCoalSection : TextSection; 660 661 // If this is weak/linkonce, put this in a coalescable section, either in text 662 // or data depending on if it is writable. 663 if (GV->isWeakForLinker()) { 664 if (Kind.isReadOnly()) 665 return ConstTextCoalSection; 666 return DataCoalSection; 667 } 668 669 // FIXME: Alignment check should be handled by section classifier. 670 if (Kind.isMergeable1ByteCString() && 671 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 672 return CStringSection; 673 674 // Do not put 16-bit arrays in the UString section if they have an 675 // externally visible label, this runs into issues with certain linker 676 // versions. 677 if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() && 678 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 679 return UStringSection; 680 681 if (Kind.isMergeableConst()) { 682 if (Kind.isMergeableConst4()) 683 return FourByteConstantSection; 684 if (Kind.isMergeableConst8()) 685 return EightByteConstantSection; 686 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 687 return SixteenByteConstantSection; 688 } 689 690 // Otherwise, if it is readonly, but not something we can specially optimize, 691 // just drop it in .const. 692 if (Kind.isReadOnly()) 693 return ReadOnlySection; 694 695 // If this is marked const, put it into a const section. But if the dynamic 696 // linker needs to write to it, put it in the data segment. 697 if (Kind.isReadOnlyWithRel()) 698 return ConstDataSection; 699 700 // Put zero initialized globals with strong external linkage in the 701 // DATA, __common section with the .zerofill directive. 702 if (Kind.isBSSExtern()) 703 return DataCommonSection; 704 705 // Put zero initialized globals with local linkage in __DATA,__bss directive 706 // with the .zerofill directive (aka .lcomm). 707 if (Kind.isBSSLocal()) 708 return DataBSSSection; 709 710 // Otherwise, just drop the variable in the normal data section. 711 return DataSection; 712 } 713 714 const MCSection * 715 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { 716 // If this constant requires a relocation, we have to put it in the data 717 // segment, not in the text segment. 718 if (Kind.isDataRel() || Kind.isReadOnlyWithRel()) 719 return ConstDataSection; 720 721 if (Kind.isMergeableConst4()) 722 return FourByteConstantSection; 723 if (Kind.isMergeableConst8()) 724 return EightByteConstantSection; 725 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 726 return SixteenByteConstantSection; 727 return ReadOnlySection; // .const 728 } 729 730 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide 731 /// not to emit the UsedDirective for some symbols in llvm.used. 732 // FIXME: REMOVE this (rdar://7071300) 733 bool TargetLoweringObjectFileMachO:: 734 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { 735 /// On Darwin, internally linked data beginning with "L" or "l" does not have 736 /// the directive emitted (this occurs in ObjC metadata). 737 if (!GV) return false; 738 739 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. 740 if (GV->hasLocalLinkage() && !isa<Function>(GV)) { 741 // FIXME: ObjC metadata is currently emitted as internal symbols that have 742 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and 743 // this horrible hack can go away. 744 SmallString<64> Name; 745 Mang->getNameWithPrefix(Name, GV, false); 746 if (Name[0] == 'L' || Name[0] == 'l') 747 return false; 748 } 749 750 return true; 751 } 752 753 const MCExpr *TargetLoweringObjectFileMachO:: 754 getSymbolForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 755 MachineModuleInfo *MMI, unsigned Encoding) const { 756 // The mach-o version of this method defaults to returning a stub reference. 757 758 if (Encoding & DW_EH_PE_indirect) { 759 MachineModuleInfoMachO &MachOMMI = 760 MMI->getObjFileInfo<MachineModuleInfoMachO>(); 761 762 SmallString<128> Name; 763 Mang->getNameWithPrefix(Name, GV, true); 764 Name += "$non_lazy_ptr"; 765 766 // Add information about the stub reference to MachOMMI so that the stub 767 // gets emitted by the asmprinter. 768 MCSymbol *Sym = getContext().GetOrCreateTemporarySymbol(Name.str()); 769 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(Sym); 770 if (StubSym.getPointer() == 0) { 771 Name.clear(); 772 Mang->getNameWithPrefix(Name, GV, false); 773 774 if (GV->hasPrivateLinkage()) 775 StubSym = MachineModuleInfoImpl:: 776 StubValueTy(getContext().GetOrCreateTemporarySymbol(Name.str()), 777 false); 778 else 779 StubSym = MachineModuleInfoImpl:: 780 StubValueTy(getContext().GetOrCreateSymbol(Name.str()), 781 !GV->hasInternalLinkage()); 782 } 783 784 return TargetLoweringObjectFile:: 785 getSymbolForDwarfReference(Sym, MMI, 786 Encoding & ~dwarf::DW_EH_PE_indirect); 787 } 788 789 return TargetLoweringObjectFile:: 790 getSymbolForDwarfGlobalReference(GV, Mang, MMI, Encoding); 791 } 792 793 unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const { 794 return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4; 795 } 796 797 unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const { 798 return DW_EH_PE_pcrel; 799 } 800 801 unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const { 802 return DW_EH_PE_pcrel; 803 } 804 805 unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const { 806 return DW_EH_PE_absptr; 807 } 808 809 //===----------------------------------------------------------------------===// 810 // COFF 811 //===----------------------------------------------------------------------===// 812 813 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy; 814 815 TargetLoweringObjectFileCOFF::~TargetLoweringObjectFileCOFF() { 816 delete (COFFUniqueMapTy*)UniquingMap; 817 } 818 819 820 const MCSection *TargetLoweringObjectFileCOFF:: 821 getCOFFSection(StringRef Name, bool isDirective, SectionKind Kind) const { 822 // Create the map if it doesn't already exist. 823 if (UniquingMap == 0) 824 UniquingMap = new MachOUniqueMapTy(); 825 COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)UniquingMap; 826 827 // Do the lookup, if we have a hit, return it. 828 const MCSectionCOFF *&Entry = Map[Name]; 829 if (Entry) return Entry; 830 831 return Entry = MCSectionCOFF::Create(Name, isDirective, Kind, getContext()); 832 } 833 834 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx, 835 const TargetMachine &TM) { 836 if (UniquingMap != 0) 837 ((COFFUniqueMapTy*)UniquingMap)->clear(); 838 TargetLoweringObjectFile::Initialize(Ctx, TM); 839 TextSection = getCOFFSection("\t.text", true, SectionKind::getText()); 840 DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel()); 841 StaticCtorSection = 842 getCOFFSection(".ctors", false, SectionKind::getDataRel()); 843 StaticDtorSection = 844 getCOFFSection(".dtors", false, SectionKind::getDataRel()); 845 846 // FIXME: We're emitting LSDA info into a readonly section on COFF, even 847 // though it contains relocatable pointers. In PIC mode, this is probably a 848 // big runtime hit for C++ apps. Either the contents of the LSDA need to be 849 // adjusted or this should be a data section. 850 LSDASection = 851 getCOFFSection(".gcc_except_table", false, SectionKind::getReadOnly()); 852 EHFrameSection = 853 getCOFFSection(".eh_frame", false, SectionKind::getDataRel()); 854 855 // Debug info. 856 // FIXME: Don't use 'directive' mode here. 857 DwarfAbbrevSection = 858 getCOFFSection("\t.section\t.debug_abbrev,\"dr\"", 859 true, SectionKind::getMetadata()); 860 DwarfInfoSection = 861 getCOFFSection("\t.section\t.debug_info,\"dr\"", 862 true, SectionKind::getMetadata()); 863 DwarfLineSection = 864 getCOFFSection("\t.section\t.debug_line,\"dr\"", 865 true, SectionKind::getMetadata()); 866 DwarfFrameSection = 867 getCOFFSection("\t.section\t.debug_frame,\"dr\"", 868 true, SectionKind::getMetadata()); 869 DwarfPubNamesSection = 870 getCOFFSection("\t.section\t.debug_pubnames,\"dr\"", 871 true, SectionKind::getMetadata()); 872 DwarfPubTypesSection = 873 getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"", 874 true, SectionKind::getMetadata()); 875 DwarfStrSection = 876 getCOFFSection("\t.section\t.debug_str,\"dr\"", 877 true, SectionKind::getMetadata()); 878 DwarfLocSection = 879 getCOFFSection("\t.section\t.debug_loc,\"dr\"", 880 true, SectionKind::getMetadata()); 881 DwarfARangesSection = 882 getCOFFSection("\t.section\t.debug_aranges,\"dr\"", 883 true, SectionKind::getMetadata()); 884 DwarfRangesSection = 885 getCOFFSection("\t.section\t.debug_ranges,\"dr\"", 886 true, SectionKind::getMetadata()); 887 DwarfMacroInfoSection = 888 getCOFFSection("\t.section\t.debug_macinfo,\"dr\"", 889 true, SectionKind::getMetadata()); 890 } 891 892 const MCSection *TargetLoweringObjectFileCOFF:: 893 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 894 Mangler *Mang, const TargetMachine &TM) const { 895 return getCOFFSection(GV->getSection(), false, Kind); 896 } 897 898 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) { 899 if (Kind.isText()) 900 return ".text$linkonce"; 901 if (Kind.isWriteable()) 902 return ".data$linkonce"; 903 return ".rdata$linkonce"; 904 } 905 906 907 const MCSection *TargetLoweringObjectFileCOFF:: 908 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 909 Mangler *Mang, const TargetMachine &TM) const { 910 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 911 912 // If this global is linkonce/weak and the target handles this by emitting it 913 // into a 'uniqued' section name, create and return the section now. 914 if (GV->isWeakForLinker()) { 915 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind); 916 SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); 917 Mang->getNameWithPrefix(Name, GV, false); 918 return getCOFFSection(Name.str(), false, Kind); 919 } 920 921 if (Kind.isText()) 922 return getTextSection(); 923 924 return getDataSection(); 925 } 926 927