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 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 395 MachineModuleInfo *MMI, 396 unsigned Encoding, MCStreamer &Streamer) const { 397 398 if (Encoding & dwarf::DW_EH_PE_indirect) { 399 MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>(); 400 401 SmallString<128> Name; 402 Mang->getNameWithPrefix(Name, GV, true); 403 Name += ".DW.stub"; 404 405 // Add information about the stub reference to ELFMMI so that the stub 406 // gets emitted by the asmprinter. 407 MCSymbol *Sym = getContext().GetOrCreateTemporarySymbol(Name.str()); 408 MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(Sym); 409 if (StubSym.getPointer() == 0) { 410 Name.clear(); 411 Mang->getNameWithPrefix(Name, GV, false); 412 413 if (GV->hasPrivateLinkage()) 414 StubSym = MachineModuleInfoImpl:: 415 StubValueTy(getContext().GetOrCreateTemporarySymbol(Name.str()), 416 false); 417 else 418 StubSym = MachineModuleInfoImpl:: 419 StubValueTy(getContext().GetOrCreateSymbol(Name.str()), 420 !GV->hasInternalLinkage()); 421 } 422 423 return TargetLoweringObjectFile:: 424 getExprForDwarfReference(Sym, Mang, MMI, 425 Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); 426 } 427 428 return TargetLoweringObjectFile:: 429 getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer); 430 } 431 432 //===----------------------------------------------------------------------===// 433 // MachO 434 //===----------------------------------------------------------------------===// 435 436 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy; 437 438 TargetLoweringObjectFileMachO::~TargetLoweringObjectFileMachO() { 439 // If we have the MachO uniquing map, free it. 440 delete (MachOUniqueMapTy*)UniquingMap; 441 } 442 443 444 const MCSectionMachO *TargetLoweringObjectFileMachO:: 445 getMachOSection(StringRef Segment, StringRef Section, 446 unsigned TypeAndAttributes, 447 unsigned Reserved2, SectionKind Kind) const { 448 // We unique sections by their segment/section pair. The returned section 449 // may not have the same flags as the requested section, if so this should be 450 // diagnosed by the client as an error. 451 452 // Create the map if it doesn't already exist. 453 if (UniquingMap == 0) 454 UniquingMap = new MachOUniqueMapTy(); 455 MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)UniquingMap; 456 457 // Form the name to look up. 458 SmallString<64> Name; 459 Name += Segment; 460 Name.push_back(','); 461 Name += Section; 462 463 // Do the lookup, if we have a hit, return it. 464 const MCSectionMachO *&Entry = Map[Name.str()]; 465 if (Entry) return Entry; 466 467 // Otherwise, return a new section. 468 return Entry = MCSectionMachO::Create(Segment, Section, TypeAndAttributes, 469 Reserved2, Kind, getContext()); 470 } 471 472 473 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx, 474 const TargetMachine &TM) { 475 // _foo.eh symbols are currently always exported so that the linker knows 476 // about them. This is not necessary on 10.6 and later, but it 477 // doesn't hurt anything. 478 // FIXME: I need to get this from Triple. 479 IsFunctionEHSymbolGlobal = true; 480 IsFunctionEHFrameSymbolPrivate = false; 481 SupportsWeakOmittedEHFrame = false; 482 483 if (UniquingMap != 0) 484 ((MachOUniqueMapTy*)UniquingMap)->clear(); 485 TargetLoweringObjectFile::Initialize(Ctx, TM); 486 487 TextSection // .text 488 = getMachOSection("__TEXT", "__text", 489 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 490 SectionKind::getText()); 491 DataSection // .data 492 = getMachOSection("__DATA", "__data", 0, SectionKind::getDataRel()); 493 494 CStringSection // .cstring 495 = getMachOSection("__TEXT", "__cstring", MCSectionMachO::S_CSTRING_LITERALS, 496 SectionKind::getMergeable1ByteCString()); 497 UStringSection 498 = getMachOSection("__TEXT","__ustring", 0, 499 SectionKind::getMergeable2ByteCString()); 500 FourByteConstantSection // .literal4 501 = getMachOSection("__TEXT", "__literal4", MCSectionMachO::S_4BYTE_LITERALS, 502 SectionKind::getMergeableConst4()); 503 EightByteConstantSection // .literal8 504 = getMachOSection("__TEXT", "__literal8", MCSectionMachO::S_8BYTE_LITERALS, 505 SectionKind::getMergeableConst8()); 506 507 // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back 508 // to using it in -static mode. 509 SixteenByteConstantSection = 0; 510 if (TM.getRelocationModel() != Reloc::Static && 511 TM.getTargetData()->getPointerSize() == 32) 512 SixteenByteConstantSection = // .literal16 513 getMachOSection("__TEXT", "__literal16",MCSectionMachO::S_16BYTE_LITERALS, 514 SectionKind::getMergeableConst16()); 515 516 ReadOnlySection // .const 517 = getMachOSection("__TEXT", "__const", 0, SectionKind::getReadOnly()); 518 519 TextCoalSection 520 = getMachOSection("__TEXT", "__textcoal_nt", 521 MCSectionMachO::S_COALESCED | 522 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 523 SectionKind::getText()); 524 ConstTextCoalSection 525 = getMachOSection("__TEXT", "__const_coal", MCSectionMachO::S_COALESCED, 526 SectionKind::getText()); 527 ConstDataCoalSection 528 = getMachOSection("__DATA","__const_coal", MCSectionMachO::S_COALESCED, 529 SectionKind::getText()); 530 ConstDataSection // .const_data 531 = getMachOSection("__DATA", "__const", 0, 532 SectionKind::getReadOnlyWithRel()); 533 DataCoalSection 534 = getMachOSection("__DATA","__datacoal_nt", MCSectionMachO::S_COALESCED, 535 SectionKind::getDataRel()); 536 DataCommonSection 537 = getMachOSection("__DATA","__common", MCSectionMachO::S_ZEROFILL, 538 SectionKind::getBSS()); 539 DataBSSSection 540 = getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL, 541 SectionKind::getBSS()); 542 543 544 LazySymbolPointerSection 545 = getMachOSection("__DATA", "__la_symbol_ptr", 546 MCSectionMachO::S_LAZY_SYMBOL_POINTERS, 547 SectionKind::getMetadata()); 548 NonLazySymbolPointerSection 549 = 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 = getMachOSection("__TEXT", "__constructor", 0,SectionKind::getDataRel()); 556 StaticDtorSection 557 = getMachOSection("__TEXT", "__destructor", 0, SectionKind::getDataRel()); 558 } else { 559 StaticCtorSection 560 = getMachOSection("__DATA", "__mod_init_func", 561 MCSectionMachO::S_MOD_INIT_FUNC_POINTERS, 562 SectionKind::getDataRel()); 563 StaticDtorSection 564 = getMachOSection("__DATA", "__mod_term_func", 565 MCSectionMachO::S_MOD_TERM_FUNC_POINTERS, 566 SectionKind::getDataRel()); 567 } 568 569 // Exception Handling. 570 LSDASection = getMachOSection("__DATA", "__gcc_except_tab", 0, 571 SectionKind::getDataRel()); 572 EHFrameSection = 573 getMachOSection("__TEXT", "__eh_frame", 574 MCSectionMachO::S_COALESCED | 575 MCSectionMachO::S_ATTR_NO_TOC | 576 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS | 577 MCSectionMachO::S_ATTR_LIVE_SUPPORT, 578 SectionKind::getReadOnly()); 579 580 // Debug Information. 581 DwarfAbbrevSection = 582 getMachOSection("__DWARF", "__debug_abbrev", MCSectionMachO::S_ATTR_DEBUG, 583 SectionKind::getMetadata()); 584 DwarfInfoSection = 585 getMachOSection("__DWARF", "__debug_info", MCSectionMachO::S_ATTR_DEBUG, 586 SectionKind::getMetadata()); 587 DwarfLineSection = 588 getMachOSection("__DWARF", "__debug_line", MCSectionMachO::S_ATTR_DEBUG, 589 SectionKind::getMetadata()); 590 DwarfFrameSection = 591 getMachOSection("__DWARF", "__debug_frame", MCSectionMachO::S_ATTR_DEBUG, 592 SectionKind::getMetadata()); 593 DwarfPubNamesSection = 594 getMachOSection("__DWARF", "__debug_pubnames", MCSectionMachO::S_ATTR_DEBUG, 595 SectionKind::getMetadata()); 596 DwarfPubTypesSection = 597 getMachOSection("__DWARF", "__debug_pubtypes", MCSectionMachO::S_ATTR_DEBUG, 598 SectionKind::getMetadata()); 599 DwarfStrSection = 600 getMachOSection("__DWARF", "__debug_str", MCSectionMachO::S_ATTR_DEBUG, 601 SectionKind::getMetadata()); 602 DwarfLocSection = 603 getMachOSection("__DWARF", "__debug_loc", MCSectionMachO::S_ATTR_DEBUG, 604 SectionKind::getMetadata()); 605 DwarfARangesSection = 606 getMachOSection("__DWARF", "__debug_aranges", MCSectionMachO::S_ATTR_DEBUG, 607 SectionKind::getMetadata()); 608 DwarfRangesSection = 609 getMachOSection("__DWARF", "__debug_ranges", MCSectionMachO::S_ATTR_DEBUG, 610 SectionKind::getMetadata()); 611 DwarfMacroInfoSection = 612 getMachOSection("__DWARF", "__debug_macinfo", MCSectionMachO::S_ATTR_DEBUG, 613 SectionKind::getMetadata()); 614 DwarfDebugInlineSection = 615 getMachOSection("__DWARF", "__debug_inlined", MCSectionMachO::S_ATTR_DEBUG, 616 SectionKind::getMetadata()); 617 } 618 619 const MCSection *TargetLoweringObjectFileMachO:: 620 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 621 Mangler *Mang, const TargetMachine &TM) const { 622 // Parse the section specifier and create it if valid. 623 StringRef Segment, Section; 624 unsigned TAA, StubSize; 625 std::string ErrorCode = 626 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section, 627 TAA, StubSize); 628 if (!ErrorCode.empty()) { 629 // If invalid, report the error with llvm_report_error. 630 llvm_report_error("Global variable '" + GV->getNameStr() + 631 "' has an invalid section specifier '" + GV->getSection()+ 632 "': " + ErrorCode + "."); 633 // Fall back to dropping it into the data section. 634 return DataSection; 635 } 636 637 // Get the section. 638 const MCSectionMachO *S = 639 getMachOSection(Segment, Section, TAA, StubSize, Kind); 640 641 // Okay, now that we got the section, verify that the TAA & StubSize agree. 642 // If the user declared multiple globals with different section flags, we need 643 // to reject it here. 644 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) { 645 // If invalid, report the error with llvm_report_error. 646 llvm_report_error("Global variable '" + GV->getNameStr() + 647 "' section type or attributes does not match previous" 648 " section specifier"); 649 } 650 651 return S; 652 } 653 654 const MCSection *TargetLoweringObjectFileMachO:: 655 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 656 Mangler *Mang, const TargetMachine &TM) const { 657 assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS"); 658 659 if (Kind.isText()) 660 return GV->isWeakForLinker() ? TextCoalSection : TextSection; 661 662 // If this is weak/linkonce, put this in a coalescable section, either in text 663 // or data depending on if it is writable. 664 if (GV->isWeakForLinker()) { 665 if (Kind.isReadOnly()) 666 return ConstTextCoalSection; 667 return DataCoalSection; 668 } 669 670 // FIXME: Alignment check should be handled by section classifier. 671 if (Kind.isMergeable1ByteCString() && 672 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 673 return CStringSection; 674 675 // Do not put 16-bit arrays in the UString section if they have an 676 // externally visible label, this runs into issues with certain linker 677 // versions. 678 if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() && 679 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 680 return UStringSection; 681 682 if (Kind.isMergeableConst()) { 683 if (Kind.isMergeableConst4()) 684 return FourByteConstantSection; 685 if (Kind.isMergeableConst8()) 686 return EightByteConstantSection; 687 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 688 return SixteenByteConstantSection; 689 } 690 691 // Otherwise, if it is readonly, but not something we can specially optimize, 692 // just drop it in .const. 693 if (Kind.isReadOnly()) 694 return ReadOnlySection; 695 696 // If this is marked const, put it into a const section. But if the dynamic 697 // linker needs to write to it, put it in the data segment. 698 if (Kind.isReadOnlyWithRel()) 699 return ConstDataSection; 700 701 // Put zero initialized globals with strong external linkage in the 702 // DATA, __common section with the .zerofill directive. 703 if (Kind.isBSSExtern()) 704 return DataCommonSection; 705 706 // Put zero initialized globals with local linkage in __DATA,__bss directive 707 // with the .zerofill directive (aka .lcomm). 708 if (Kind.isBSSLocal()) 709 return DataBSSSection; 710 711 // Otherwise, just drop the variable in the normal data section. 712 return DataSection; 713 } 714 715 const MCSection * 716 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { 717 // If this constant requires a relocation, we have to put it in the data 718 // segment, not in the text segment. 719 if (Kind.isDataRel() || Kind.isReadOnlyWithRel()) 720 return ConstDataSection; 721 722 if (Kind.isMergeableConst4()) 723 return FourByteConstantSection; 724 if (Kind.isMergeableConst8()) 725 return EightByteConstantSection; 726 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 727 return SixteenByteConstantSection; 728 return ReadOnlySection; // .const 729 } 730 731 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide 732 /// not to emit the UsedDirective for some symbols in llvm.used. 733 // FIXME: REMOVE this (rdar://7071300) 734 bool TargetLoweringObjectFileMachO:: 735 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { 736 /// On Darwin, internally linked data beginning with "L" or "l" does not have 737 /// the directive emitted (this occurs in ObjC metadata). 738 if (!GV) return false; 739 740 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. 741 if (GV->hasLocalLinkage() && !isa<Function>(GV)) { 742 // FIXME: ObjC metadata is currently emitted as internal symbols that have 743 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and 744 // this horrible hack can go away. 745 SmallString<64> Name; 746 Mang->getNameWithPrefix(Name, GV, false); 747 if (Name[0] == 'L' || Name[0] == 'l') 748 return false; 749 } 750 751 return true; 752 } 753 754 const MCExpr *TargetLoweringObjectFileMachO:: 755 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 756 MachineModuleInfo *MMI, unsigned Encoding, 757 MCStreamer &Streamer) const { 758 // The mach-o version of this method defaults to returning a stub reference. 759 760 if (Encoding & DW_EH_PE_indirect) { 761 MachineModuleInfoMachO &MachOMMI = 762 MMI->getObjFileInfo<MachineModuleInfoMachO>(); 763 764 SmallString<128> Name; 765 Mang->getNameWithPrefix(Name, GV, true); 766 Name += "$non_lazy_ptr"; 767 768 // Add information about the stub reference to MachOMMI so that the stub 769 // gets emitted by the asmprinter. 770 MCSymbol *Sym = getContext().GetOrCreateTemporarySymbol(Name.str()); 771 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(Sym); 772 if (StubSym.getPointer() == 0) { 773 Name.clear(); 774 Mang->getNameWithPrefix(Name, GV, false); 775 776 if (GV->hasPrivateLinkage()) 777 StubSym = MachineModuleInfoImpl:: 778 StubValueTy(getContext().GetOrCreateTemporarySymbol(Name.str()), 779 false); 780 else 781 StubSym = MachineModuleInfoImpl:: 782 StubValueTy(getContext().GetOrCreateSymbol(Name.str()), 783 !GV->hasInternalLinkage()); 784 } 785 786 return TargetLoweringObjectFile:: 787 getExprForDwarfReference(Sym, Mang, MMI, 788 Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); 789 } 790 791 return TargetLoweringObjectFile:: 792 getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer); 793 } 794 795 unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const { 796 return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4; 797 } 798 799 unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const { 800 return DW_EH_PE_pcrel; 801 } 802 803 unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const { 804 return DW_EH_PE_pcrel; 805 } 806 807 unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const { 808 return DW_EH_PE_absptr; 809 } 810 811 //===----------------------------------------------------------------------===// 812 // COFF 813 //===----------------------------------------------------------------------===// 814 815 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy; 816 817 TargetLoweringObjectFileCOFF::~TargetLoweringObjectFileCOFF() { 818 delete (COFFUniqueMapTy*)UniquingMap; 819 } 820 821 822 const MCSection *TargetLoweringObjectFileCOFF:: 823 getCOFFSection(StringRef Name, bool isDirective, SectionKind Kind) const { 824 // Create the map if it doesn't already exist. 825 if (UniquingMap == 0) 826 UniquingMap = new MachOUniqueMapTy(); 827 COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)UniquingMap; 828 829 // Do the lookup, if we have a hit, return it. 830 const MCSectionCOFF *&Entry = Map[Name]; 831 if (Entry) return Entry; 832 833 return Entry = MCSectionCOFF::Create(Name, isDirective, Kind, getContext()); 834 } 835 836 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx, 837 const TargetMachine &TM) { 838 if (UniquingMap != 0) 839 ((COFFUniqueMapTy*)UniquingMap)->clear(); 840 TargetLoweringObjectFile::Initialize(Ctx, TM); 841 TextSection = getCOFFSection("\t.text", true, SectionKind::getText()); 842 DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel()); 843 StaticCtorSection = 844 getCOFFSection(".ctors", false, SectionKind::getDataRel()); 845 StaticDtorSection = 846 getCOFFSection(".dtors", false, SectionKind::getDataRel()); 847 848 // FIXME: We're emitting LSDA info into a readonly section on COFF, even 849 // though it contains relocatable pointers. In PIC mode, this is probably a 850 // big runtime hit for C++ apps. Either the contents of the LSDA need to be 851 // adjusted or this should be a data section. 852 LSDASection = 853 getCOFFSection(".gcc_except_table", false, SectionKind::getReadOnly()); 854 EHFrameSection = 855 getCOFFSection(".eh_frame", false, SectionKind::getDataRel()); 856 857 // Debug info. 858 // FIXME: Don't use 'directive' mode here. 859 DwarfAbbrevSection = 860 getCOFFSection("\t.section\t.debug_abbrev,\"dr\"", 861 true, SectionKind::getMetadata()); 862 DwarfInfoSection = 863 getCOFFSection("\t.section\t.debug_info,\"dr\"", 864 true, SectionKind::getMetadata()); 865 DwarfLineSection = 866 getCOFFSection("\t.section\t.debug_line,\"dr\"", 867 true, SectionKind::getMetadata()); 868 DwarfFrameSection = 869 getCOFFSection("\t.section\t.debug_frame,\"dr\"", 870 true, SectionKind::getMetadata()); 871 DwarfPubNamesSection = 872 getCOFFSection("\t.section\t.debug_pubnames,\"dr\"", 873 true, SectionKind::getMetadata()); 874 DwarfPubTypesSection = 875 getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"", 876 true, SectionKind::getMetadata()); 877 DwarfStrSection = 878 getCOFFSection("\t.section\t.debug_str,\"dr\"", 879 true, SectionKind::getMetadata()); 880 DwarfLocSection = 881 getCOFFSection("\t.section\t.debug_loc,\"dr\"", 882 true, SectionKind::getMetadata()); 883 DwarfARangesSection = 884 getCOFFSection("\t.section\t.debug_aranges,\"dr\"", 885 true, SectionKind::getMetadata()); 886 DwarfRangesSection = 887 getCOFFSection("\t.section\t.debug_ranges,\"dr\"", 888 true, SectionKind::getMetadata()); 889 DwarfMacroInfoSection = 890 getCOFFSection("\t.section\t.debug_macinfo,\"dr\"", 891 true, SectionKind::getMetadata()); 892 } 893 894 const MCSection *TargetLoweringObjectFileCOFF:: 895 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 896 Mangler *Mang, const TargetMachine &TM) const { 897 return getCOFFSection(GV->getSection(), false, Kind); 898 } 899 900 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) { 901 if (Kind.isText()) 902 return ".text$linkonce"; 903 if (Kind.isWriteable()) 904 return ".data$linkonce"; 905 return ".rdata$linkonce"; 906 } 907 908 909 const MCSection *TargetLoweringObjectFileCOFF:: 910 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 911 Mangler *Mang, const TargetMachine &TM) const { 912 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 913 914 // If this global is linkonce/weak and the target handles this by emitting it 915 // into a 'uniqued' section name, create and return the section now. 916 if (GV->isWeakForLinker()) { 917 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind); 918 SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); 919 Mang->getNameWithPrefix(Name, GV, false); 920 return getCOFFSection(Name.str(), false, Kind); 921 } 922 923 if (Kind.isText()) 924 return getTextSection(); 925 926 return getDataSection(); 927 } 928 929