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 MCSymbol *&StubSym = ELFMMI.getGVStubEntry(Sym); 408 if (StubSym == 0) { 409 Name.clear(); 410 Mang->getNameWithPrefix(Name, GV, false); 411 if (GV->hasPrivateLinkage()) 412 StubSym = getContext().GetOrCreateTemporarySymbol(Name.str()); 413 else 414 StubSym = getContext().GetOrCreateSymbol(Name.str()); 415 } 416 417 return TargetLoweringObjectFile:: 418 getSymbolForDwarfReference(Sym, MMI, 419 Encoding & ~dwarf::DW_EH_PE_indirect); 420 } 421 422 return TargetLoweringObjectFile:: 423 getSymbolForDwarfGlobalReference(GV, Mang, MMI, Encoding); 424 } 425 426 //===----------------------------------------------------------------------===// 427 // MachO 428 //===----------------------------------------------------------------------===// 429 430 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy; 431 432 TargetLoweringObjectFileMachO::~TargetLoweringObjectFileMachO() { 433 // If we have the MachO uniquing map, free it. 434 delete (MachOUniqueMapTy*)UniquingMap; 435 } 436 437 438 const MCSectionMachO *TargetLoweringObjectFileMachO:: 439 getMachOSection(StringRef Segment, StringRef Section, 440 unsigned TypeAndAttributes, 441 unsigned Reserved2, SectionKind Kind) const { 442 // We unique sections by their segment/section pair. The returned section 443 // may not have the same flags as the requested section, if so this should be 444 // diagnosed by the client as an error. 445 446 // Create the map if it doesn't already exist. 447 if (UniquingMap == 0) 448 UniquingMap = new MachOUniqueMapTy(); 449 MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)UniquingMap; 450 451 // Form the name to look up. 452 SmallString<64> Name; 453 Name += Segment; 454 Name.push_back(','); 455 Name += Section; 456 457 // Do the lookup, if we have a hit, return it. 458 const MCSectionMachO *&Entry = Map[Name.str()]; 459 if (Entry) return Entry; 460 461 // Otherwise, return a new section. 462 return Entry = MCSectionMachO::Create(Segment, Section, TypeAndAttributes, 463 Reserved2, Kind, getContext()); 464 } 465 466 467 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx, 468 const TargetMachine &TM) { 469 if (UniquingMap != 0) 470 ((MachOUniqueMapTy*)UniquingMap)->clear(); 471 TargetLoweringObjectFile::Initialize(Ctx, TM); 472 473 TextSection // .text 474 = getMachOSection("__TEXT", "__text", 475 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 476 SectionKind::getText()); 477 DataSection // .data 478 = getMachOSection("__DATA", "__data", 0, SectionKind::getDataRel()); 479 480 CStringSection // .cstring 481 = getMachOSection("__TEXT", "__cstring", MCSectionMachO::S_CSTRING_LITERALS, 482 SectionKind::getMergeable1ByteCString()); 483 UStringSection 484 = getMachOSection("__TEXT","__ustring", 0, 485 SectionKind::getMergeable2ByteCString()); 486 FourByteConstantSection // .literal4 487 = getMachOSection("__TEXT", "__literal4", MCSectionMachO::S_4BYTE_LITERALS, 488 SectionKind::getMergeableConst4()); 489 EightByteConstantSection // .literal8 490 = getMachOSection("__TEXT", "__literal8", MCSectionMachO::S_8BYTE_LITERALS, 491 SectionKind::getMergeableConst8()); 492 493 // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back 494 // to using it in -static mode. 495 SixteenByteConstantSection = 0; 496 if (TM.getRelocationModel() != Reloc::Static && 497 TM.getTargetData()->getPointerSize() == 32) 498 SixteenByteConstantSection = // .literal16 499 getMachOSection("__TEXT", "__literal16",MCSectionMachO::S_16BYTE_LITERALS, 500 SectionKind::getMergeableConst16()); 501 502 ReadOnlySection // .const 503 = getMachOSection("__TEXT", "__const", 0, SectionKind::getReadOnly()); 504 505 TextCoalSection 506 = getMachOSection("__TEXT", "__textcoal_nt", 507 MCSectionMachO::S_COALESCED | 508 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 509 SectionKind::getText()); 510 ConstTextCoalSection 511 = getMachOSection("__TEXT", "__const_coal", MCSectionMachO::S_COALESCED, 512 SectionKind::getText()); 513 ConstDataCoalSection 514 = getMachOSection("__DATA","__const_coal", MCSectionMachO::S_COALESCED, 515 SectionKind::getText()); 516 ConstDataSection // .const_data 517 = getMachOSection("__DATA", "__const", 0, 518 SectionKind::getReadOnlyWithRel()); 519 DataCoalSection 520 = getMachOSection("__DATA","__datacoal_nt", MCSectionMachO::S_COALESCED, 521 SectionKind::getDataRel()); 522 DataCommonSection 523 = getMachOSection("__DATA","__common", MCSectionMachO::S_ZEROFILL, 524 SectionKind::getBSS()); 525 DataBSSSection 526 = getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL, 527 SectionKind::getBSS()); 528 529 530 LazySymbolPointerSection 531 = getMachOSection("__DATA", "__la_symbol_ptr", 532 MCSectionMachO::S_LAZY_SYMBOL_POINTERS, 533 SectionKind::getMetadata()); 534 NonLazySymbolPointerSection 535 = getMachOSection("__DATA", "__nl_symbol_ptr", 536 MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS, 537 SectionKind::getMetadata()); 538 539 if (TM.getRelocationModel() == Reloc::Static) { 540 StaticCtorSection 541 = getMachOSection("__TEXT", "__constructor", 0,SectionKind::getDataRel()); 542 StaticDtorSection 543 = getMachOSection("__TEXT", "__destructor", 0, SectionKind::getDataRel()); 544 } else { 545 StaticCtorSection 546 = getMachOSection("__DATA", "__mod_init_func", 547 MCSectionMachO::S_MOD_INIT_FUNC_POINTERS, 548 SectionKind::getDataRel()); 549 StaticDtorSection 550 = getMachOSection("__DATA", "__mod_term_func", 551 MCSectionMachO::S_MOD_TERM_FUNC_POINTERS, 552 SectionKind::getDataRel()); 553 } 554 555 // Exception Handling. 556 LSDASection = getMachOSection("__DATA", "__gcc_except_tab", 0, 557 SectionKind::getDataRel()); 558 EHFrameSection = 559 getMachOSection("__TEXT", "__eh_frame", 560 MCSectionMachO::S_COALESCED | 561 MCSectionMachO::S_ATTR_NO_TOC | 562 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS | 563 MCSectionMachO::S_ATTR_LIVE_SUPPORT, 564 SectionKind::getReadOnly()); 565 566 // Debug Information. 567 DwarfAbbrevSection = 568 getMachOSection("__DWARF", "__debug_abbrev", MCSectionMachO::S_ATTR_DEBUG, 569 SectionKind::getMetadata()); 570 DwarfInfoSection = 571 getMachOSection("__DWARF", "__debug_info", MCSectionMachO::S_ATTR_DEBUG, 572 SectionKind::getMetadata()); 573 DwarfLineSection = 574 getMachOSection("__DWARF", "__debug_line", MCSectionMachO::S_ATTR_DEBUG, 575 SectionKind::getMetadata()); 576 DwarfFrameSection = 577 getMachOSection("__DWARF", "__debug_frame", MCSectionMachO::S_ATTR_DEBUG, 578 SectionKind::getMetadata()); 579 DwarfPubNamesSection = 580 getMachOSection("__DWARF", "__debug_pubnames", MCSectionMachO::S_ATTR_DEBUG, 581 SectionKind::getMetadata()); 582 DwarfPubTypesSection = 583 getMachOSection("__DWARF", "__debug_pubtypes", MCSectionMachO::S_ATTR_DEBUG, 584 SectionKind::getMetadata()); 585 DwarfStrSection = 586 getMachOSection("__DWARF", "__debug_str", MCSectionMachO::S_ATTR_DEBUG, 587 SectionKind::getMetadata()); 588 DwarfLocSection = 589 getMachOSection("__DWARF", "__debug_loc", MCSectionMachO::S_ATTR_DEBUG, 590 SectionKind::getMetadata()); 591 DwarfARangesSection = 592 getMachOSection("__DWARF", "__debug_aranges", MCSectionMachO::S_ATTR_DEBUG, 593 SectionKind::getMetadata()); 594 DwarfRangesSection = 595 getMachOSection("__DWARF", "__debug_ranges", MCSectionMachO::S_ATTR_DEBUG, 596 SectionKind::getMetadata()); 597 DwarfMacroInfoSection = 598 getMachOSection("__DWARF", "__debug_macinfo", MCSectionMachO::S_ATTR_DEBUG, 599 SectionKind::getMetadata()); 600 DwarfDebugInlineSection = 601 getMachOSection("__DWARF", "__debug_inlined", MCSectionMachO::S_ATTR_DEBUG, 602 SectionKind::getMetadata()); 603 } 604 605 const MCSection *TargetLoweringObjectFileMachO:: 606 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 607 Mangler *Mang, const TargetMachine &TM) const { 608 // Parse the section specifier and create it if valid. 609 StringRef Segment, Section; 610 unsigned TAA, StubSize; 611 std::string ErrorCode = 612 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section, 613 TAA, StubSize); 614 if (!ErrorCode.empty()) { 615 // If invalid, report the error with llvm_report_error. 616 llvm_report_error("Global variable '" + GV->getNameStr() + 617 "' has an invalid section specifier '" + GV->getSection()+ 618 "': " + ErrorCode + "."); 619 // Fall back to dropping it into the data section. 620 return DataSection; 621 } 622 623 // Get the section. 624 const MCSectionMachO *S = 625 getMachOSection(Segment, Section, TAA, StubSize, Kind); 626 627 // Okay, now that we got the section, verify that the TAA & StubSize agree. 628 // If the user declared multiple globals with different section flags, we need 629 // to reject it here. 630 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) { 631 // If invalid, report the error with llvm_report_error. 632 llvm_report_error("Global variable '" + GV->getNameStr() + 633 "' section type or attributes does not match previous" 634 " section specifier"); 635 } 636 637 return S; 638 } 639 640 const MCSection *TargetLoweringObjectFileMachO:: 641 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 642 Mangler *Mang, const TargetMachine &TM) const { 643 assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS"); 644 645 if (Kind.isText()) 646 return GV->isWeakForLinker() ? TextCoalSection : TextSection; 647 648 // If this is weak/linkonce, put this in a coalescable section, either in text 649 // or data depending on if it is writable. 650 if (GV->isWeakForLinker()) { 651 if (Kind.isReadOnly()) 652 return ConstTextCoalSection; 653 return DataCoalSection; 654 } 655 656 // FIXME: Alignment check should be handled by section classifier. 657 if (Kind.isMergeable1ByteCString() && 658 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 659 return CStringSection; 660 661 // Do not put 16-bit arrays in the UString section if they have an 662 // externally visible label, this runs into issues with certain linker 663 // versions. 664 if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() && 665 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 666 return UStringSection; 667 668 if (Kind.isMergeableConst()) { 669 if (Kind.isMergeableConst4()) 670 return FourByteConstantSection; 671 if (Kind.isMergeableConst8()) 672 return EightByteConstantSection; 673 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 674 return SixteenByteConstantSection; 675 } 676 677 // Otherwise, if it is readonly, but not something we can specially optimize, 678 // just drop it in .const. 679 if (Kind.isReadOnly()) 680 return ReadOnlySection; 681 682 // If this is marked const, put it into a const section. But if the dynamic 683 // linker needs to write to it, put it in the data segment. 684 if (Kind.isReadOnlyWithRel()) 685 return ConstDataSection; 686 687 // Put zero initialized globals with strong external linkage in the 688 // DATA, __common section with the .zerofill directive. 689 if (Kind.isBSSExtern()) 690 return DataCommonSection; 691 692 // Put zero initialized globals with local linkage in __DATA,__bss directive 693 // with the .zerofill directive (aka .lcomm). 694 if (Kind.isBSSLocal()) 695 return DataBSSSection; 696 697 // Otherwise, just drop the variable in the normal data section. 698 return DataSection; 699 } 700 701 const MCSection * 702 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { 703 // If this constant requires a relocation, we have to put it in the data 704 // segment, not in the text segment. 705 if (Kind.isDataRel() || Kind.isReadOnlyWithRel()) 706 return ConstDataSection; 707 708 if (Kind.isMergeableConst4()) 709 return FourByteConstantSection; 710 if (Kind.isMergeableConst8()) 711 return EightByteConstantSection; 712 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 713 return SixteenByteConstantSection; 714 return ReadOnlySection; // .const 715 } 716 717 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide 718 /// not to emit the UsedDirective for some symbols in llvm.used. 719 // FIXME: REMOVE this (rdar://7071300) 720 bool TargetLoweringObjectFileMachO:: 721 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { 722 /// On Darwin, internally linked data beginning with "L" or "l" does not have 723 /// the directive emitted (this occurs in ObjC metadata). 724 if (!GV) return false; 725 726 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. 727 if (GV->hasLocalLinkage() && !isa<Function>(GV)) { 728 // FIXME: ObjC metadata is currently emitted as internal symbols that have 729 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and 730 // this horrible hack can go away. 731 SmallString<64> Name; 732 Mang->getNameWithPrefix(Name, GV, false); 733 if (Name[0] == 'L' || Name[0] == 'l') 734 return false; 735 } 736 737 return true; 738 } 739 740 const MCExpr *TargetLoweringObjectFileMachO:: 741 getSymbolForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 742 MachineModuleInfo *MMI, unsigned Encoding) const { 743 // The mach-o version of this method defaults to returning a stub reference. 744 745 if (Encoding & DW_EH_PE_indirect) { 746 MachineModuleInfoMachO &MachOMMI = 747 MMI->getObjFileInfo<MachineModuleInfoMachO>(); 748 749 SmallString<128> Name; 750 Mang->getNameWithPrefix(Name, GV, true); 751 Name += "$non_lazy_ptr"; 752 753 // Add information about the stub reference to MachOMMI so that the stub 754 // gets emitted by the asmprinter. 755 MCSymbol *Sym = getContext().GetOrCreateTemporarySymbol(Name.str()); 756 MCSymbol *&StubSym = MachOMMI.getGVStubEntry(Sym); 757 if (StubSym == 0) { 758 Name.clear(); 759 Mang->getNameWithPrefix(Name, GV, false); 760 if (GV->hasPrivateLinkage()) 761 StubSym = getContext().GetOrCreateTemporarySymbol(Name.str()); 762 else 763 StubSym = getContext().GetOrCreateSymbol(Name.str()); 764 } 765 766 return TargetLoweringObjectFile:: 767 getSymbolForDwarfReference(Sym, MMI, 768 Encoding & ~dwarf::DW_EH_PE_indirect); 769 } 770 771 return TargetLoweringObjectFile:: 772 getSymbolForDwarfGlobalReference(GV, Mang, MMI, Encoding); 773 } 774 775 unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const { 776 return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4; 777 } 778 779 unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const { 780 return DW_EH_PE_pcrel; 781 } 782 783 unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const { 784 return DW_EH_PE_pcrel; 785 } 786 787 unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const { 788 return DW_EH_PE_absptr; 789 } 790 791 //===----------------------------------------------------------------------===// 792 // COFF 793 //===----------------------------------------------------------------------===// 794 795 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy; 796 797 TargetLoweringObjectFileCOFF::~TargetLoweringObjectFileCOFF() { 798 delete (COFFUniqueMapTy*)UniquingMap; 799 } 800 801 802 const MCSection *TargetLoweringObjectFileCOFF:: 803 getCOFFSection(StringRef Name, bool isDirective, SectionKind Kind) const { 804 // Create the map if it doesn't already exist. 805 if (UniquingMap == 0) 806 UniquingMap = new MachOUniqueMapTy(); 807 COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)UniquingMap; 808 809 // Do the lookup, if we have a hit, return it. 810 const MCSectionCOFF *&Entry = Map[Name]; 811 if (Entry) return Entry; 812 813 return Entry = MCSectionCOFF::Create(Name, isDirective, Kind, getContext()); 814 } 815 816 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx, 817 const TargetMachine &TM) { 818 if (UniquingMap != 0) 819 ((COFFUniqueMapTy*)UniquingMap)->clear(); 820 TargetLoweringObjectFile::Initialize(Ctx, TM); 821 TextSection = getCOFFSection("\t.text", true, SectionKind::getText()); 822 DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel()); 823 StaticCtorSection = 824 getCOFFSection(".ctors", false, SectionKind::getDataRel()); 825 StaticDtorSection = 826 getCOFFSection(".dtors", false, SectionKind::getDataRel()); 827 828 // FIXME: We're emitting LSDA info into a readonly section on COFF, even 829 // though it contains relocatable pointers. In PIC mode, this is probably a 830 // big runtime hit for C++ apps. Either the contents of the LSDA need to be 831 // adjusted or this should be a data section. 832 LSDASection = 833 getCOFFSection(".gcc_except_table", false, SectionKind::getReadOnly()); 834 EHFrameSection = 835 getCOFFSection(".eh_frame", false, SectionKind::getDataRel()); 836 837 // Debug info. 838 // FIXME: Don't use 'directive' mode here. 839 DwarfAbbrevSection = 840 getCOFFSection("\t.section\t.debug_abbrev,\"dr\"", 841 true, SectionKind::getMetadata()); 842 DwarfInfoSection = 843 getCOFFSection("\t.section\t.debug_info,\"dr\"", 844 true, SectionKind::getMetadata()); 845 DwarfLineSection = 846 getCOFFSection("\t.section\t.debug_line,\"dr\"", 847 true, SectionKind::getMetadata()); 848 DwarfFrameSection = 849 getCOFFSection("\t.section\t.debug_frame,\"dr\"", 850 true, SectionKind::getMetadata()); 851 DwarfPubNamesSection = 852 getCOFFSection("\t.section\t.debug_pubnames,\"dr\"", 853 true, SectionKind::getMetadata()); 854 DwarfPubTypesSection = 855 getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"", 856 true, SectionKind::getMetadata()); 857 DwarfStrSection = 858 getCOFFSection("\t.section\t.debug_str,\"dr\"", 859 true, SectionKind::getMetadata()); 860 DwarfLocSection = 861 getCOFFSection("\t.section\t.debug_loc,\"dr\"", 862 true, SectionKind::getMetadata()); 863 DwarfARangesSection = 864 getCOFFSection("\t.section\t.debug_aranges,\"dr\"", 865 true, SectionKind::getMetadata()); 866 DwarfRangesSection = 867 getCOFFSection("\t.section\t.debug_ranges,\"dr\"", 868 true, SectionKind::getMetadata()); 869 DwarfMacroInfoSection = 870 getCOFFSection("\t.section\t.debug_macinfo,\"dr\"", 871 true, SectionKind::getMetadata()); 872 } 873 874 const MCSection *TargetLoweringObjectFileCOFF:: 875 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 876 Mangler *Mang, const TargetMachine &TM) const { 877 return getCOFFSection(GV->getSection(), false, Kind); 878 } 879 880 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) { 881 if (Kind.isText()) 882 return ".text$linkonce"; 883 if (Kind.isWriteable()) 884 return ".data$linkonce"; 885 return ".rdata$linkonce"; 886 } 887 888 889 const MCSection *TargetLoweringObjectFileCOFF:: 890 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 891 Mangler *Mang, const TargetMachine &TM) const { 892 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 893 894 // If this global is linkonce/weak and the target handles this by emitting it 895 // into a 'uniqued' section name, create and return the section now. 896 if (GV->isWeakForLinker()) { 897 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind); 898 SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); 899 Mang->getNameWithPrefix(Name, GV, false); 900 return getCOFFSection(Name.str(), false, Kind); 901 } 902 903 if (Kind.isText()) 904 return getTextSection(); 905 906 return getDataSection(); 907 } 908 909