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 StringMapEntry<const MCSectionELF*> &Entry = Map.GetOrCreateValue(Section); 57 if (Entry.getValue()) return Entry.getValue(); 58 59 MCSectionELF *Result = MCSectionELF::Create(Entry.getKey(), Type, Flags, Kind, 60 IsExplicit, getContext()); 61 Entry.setValue(Result); 62 return Result; 63 } 64 65 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx, 66 const TargetMachine &TM) { 67 if (UniquingMap != 0) 68 ((ELFUniqueMapTy*)UniquingMap)->clear(); 69 TargetLoweringObjectFile::Initialize(Ctx, TM); 70 71 BSSSection = 72 getELFSection(".bss", MCSectionELF::SHT_NOBITS, 73 MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC, 74 SectionKind::getBSS()); 75 76 TextSection = 77 getELFSection(".text", MCSectionELF::SHT_PROGBITS, 78 MCSectionELF::SHF_EXECINSTR | MCSectionELF::SHF_ALLOC, 79 SectionKind::getText()); 80 81 DataSection = 82 getELFSection(".data", MCSectionELF::SHT_PROGBITS, 83 MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC, 84 SectionKind::getDataRel()); 85 86 ReadOnlySection = 87 getELFSection(".rodata", MCSectionELF::SHT_PROGBITS, 88 MCSectionELF::SHF_ALLOC, 89 SectionKind::getReadOnly()); 90 91 TLSDataSection = 92 getELFSection(".tdata", MCSectionELF::SHT_PROGBITS, 93 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS | 94 MCSectionELF::SHF_WRITE, SectionKind::getThreadData()); 95 96 TLSBSSSection = 97 getELFSection(".tbss", MCSectionELF::SHT_NOBITS, 98 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS | 99 MCSectionELF::SHF_WRITE, SectionKind::getThreadBSS()); 100 101 DataRelSection = 102 getELFSection(".data.rel", MCSectionELF::SHT_PROGBITS, 103 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, 104 SectionKind::getDataRel()); 105 106 DataRelLocalSection = 107 getELFSection(".data.rel.local", MCSectionELF::SHT_PROGBITS, 108 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, 109 SectionKind::getDataRelLocal()); 110 111 DataRelROSection = 112 getELFSection(".data.rel.ro", MCSectionELF::SHT_PROGBITS, 113 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, 114 SectionKind::getReadOnlyWithRel()); 115 116 DataRelROLocalSection = 117 getELFSection(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS, 118 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, 119 SectionKind::getReadOnlyWithRelLocal()); 120 121 MergeableConst4Section = 122 getELFSection(".rodata.cst4", MCSectionELF::SHT_PROGBITS, 123 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE, 124 SectionKind::getMergeableConst4()); 125 126 MergeableConst8Section = 127 getELFSection(".rodata.cst8", MCSectionELF::SHT_PROGBITS, 128 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE, 129 SectionKind::getMergeableConst8()); 130 131 MergeableConst16Section = 132 getELFSection(".rodata.cst16", MCSectionELF::SHT_PROGBITS, 133 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE, 134 SectionKind::getMergeableConst16()); 135 136 StaticCtorSection = 137 getELFSection(".ctors", MCSectionELF::SHT_PROGBITS, 138 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, 139 SectionKind::getDataRel()); 140 141 StaticDtorSection = 142 getELFSection(".dtors", MCSectionELF::SHT_PROGBITS, 143 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, 144 SectionKind::getDataRel()); 145 146 // Exception Handling Sections. 147 148 // FIXME: We're emitting LSDA info into a readonly section on ELF, even though 149 // it contains relocatable pointers. In PIC mode, this is probably a big 150 // runtime hit for C++ apps. Either the contents of the LSDA need to be 151 // adjusted or this should be a data section. 152 LSDASection = 153 getELFSection(".gcc_except_table", MCSectionELF::SHT_PROGBITS, 154 MCSectionELF::SHF_ALLOC, SectionKind::getReadOnly()); 155 EHFrameSection = 156 getELFSection(".eh_frame", MCSectionELF::SHT_PROGBITS, 157 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE, 158 SectionKind::getDataRel()); 159 160 // Debug Info Sections. 161 DwarfAbbrevSection = 162 getELFSection(".debug_abbrev", MCSectionELF::SHT_PROGBITS, 0, 163 SectionKind::getMetadata()); 164 DwarfInfoSection = 165 getELFSection(".debug_info", MCSectionELF::SHT_PROGBITS, 0, 166 SectionKind::getMetadata()); 167 DwarfLineSection = 168 getELFSection(".debug_line", MCSectionELF::SHT_PROGBITS, 0, 169 SectionKind::getMetadata()); 170 DwarfFrameSection = 171 getELFSection(".debug_frame", MCSectionELF::SHT_PROGBITS, 0, 172 SectionKind::getMetadata()); 173 DwarfPubNamesSection = 174 getELFSection(".debug_pubnames", MCSectionELF::SHT_PROGBITS, 0, 175 SectionKind::getMetadata()); 176 DwarfPubTypesSection = 177 getELFSection(".debug_pubtypes", MCSectionELF::SHT_PROGBITS, 0, 178 SectionKind::getMetadata()); 179 DwarfStrSection = 180 getELFSection(".debug_str", MCSectionELF::SHT_PROGBITS, 0, 181 SectionKind::getMetadata()); 182 DwarfLocSection = 183 getELFSection(".debug_loc", MCSectionELF::SHT_PROGBITS, 0, 184 SectionKind::getMetadata()); 185 DwarfARangesSection = 186 getELFSection(".debug_aranges", MCSectionELF::SHT_PROGBITS, 0, 187 SectionKind::getMetadata()); 188 DwarfRangesSection = 189 getELFSection(".debug_ranges", MCSectionELF::SHT_PROGBITS, 0, 190 SectionKind::getMetadata()); 191 DwarfMacroInfoSection = 192 getELFSection(".debug_macinfo", MCSectionELF::SHT_PROGBITS, 0, 193 SectionKind::getMetadata()); 194 } 195 196 197 static SectionKind 198 getELFKindForNamedSection(StringRef Name, SectionKind K) { 199 if (Name.empty() || Name[0] != '.') return K; 200 201 // Some lame default implementation based on some magic section names. 202 if (Name == ".bss" || 203 Name.startswith(".bss.") || 204 Name.startswith(".gnu.linkonce.b.") || 205 Name.startswith(".llvm.linkonce.b.") || 206 Name == ".sbss" || 207 Name.startswith(".sbss.") || 208 Name.startswith(".gnu.linkonce.sb.") || 209 Name.startswith(".llvm.linkonce.sb.")) 210 return SectionKind::getBSS(); 211 212 if (Name == ".tdata" || 213 Name.startswith(".tdata.") || 214 Name.startswith(".gnu.linkonce.td.") || 215 Name.startswith(".llvm.linkonce.td.")) 216 return SectionKind::getThreadData(); 217 218 if (Name == ".tbss" || 219 Name.startswith(".tbss.") || 220 Name.startswith(".gnu.linkonce.tb.") || 221 Name.startswith(".llvm.linkonce.tb.")) 222 return SectionKind::getThreadBSS(); 223 224 return K; 225 } 226 227 228 static unsigned getELFSectionType(StringRef Name, SectionKind K) { 229 230 if (Name == ".init_array") 231 return MCSectionELF::SHT_INIT_ARRAY; 232 233 if (Name == ".fini_array") 234 return MCSectionELF::SHT_FINI_ARRAY; 235 236 if (Name == ".preinit_array") 237 return MCSectionELF::SHT_PREINIT_ARRAY; 238 239 if (K.isBSS() || K.isThreadBSS()) 240 return MCSectionELF::SHT_NOBITS; 241 242 return MCSectionELF::SHT_PROGBITS; 243 } 244 245 246 static unsigned 247 getELFSectionFlags(SectionKind K) { 248 unsigned Flags = 0; 249 250 if (!K.isMetadata()) 251 Flags |= MCSectionELF::SHF_ALLOC; 252 253 if (K.isText()) 254 Flags |= MCSectionELF::SHF_EXECINSTR; 255 256 if (K.isWriteable()) 257 Flags |= MCSectionELF::SHF_WRITE; 258 259 if (K.isThreadLocal()) 260 Flags |= MCSectionELF::SHF_TLS; 261 262 // K.isMergeableConst() is left out to honour PR4650 263 if (K.isMergeableCString() || K.isMergeableConst4() || 264 K.isMergeableConst8() || K.isMergeableConst16()) 265 Flags |= MCSectionELF::SHF_MERGE; 266 267 if (K.isMergeableCString()) 268 Flags |= MCSectionELF::SHF_STRINGS; 269 270 return Flags; 271 } 272 273 274 const MCSection *TargetLoweringObjectFileELF:: 275 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 276 Mangler *Mang, const TargetMachine &TM) const { 277 StringRef SectionName = GV->getSection(); 278 279 // Infer section flags from the section name if we can. 280 Kind = getELFKindForNamedSection(SectionName, Kind); 281 282 return getELFSection(SectionName, 283 getELFSectionType(SectionName, Kind), 284 getELFSectionFlags(Kind), Kind, true); 285 } 286 287 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) { 288 if (Kind.isText()) return ".gnu.linkonce.t."; 289 if (Kind.isReadOnly()) return ".gnu.linkonce.r."; 290 291 if (Kind.isThreadData()) return ".gnu.linkonce.td."; 292 if (Kind.isThreadBSS()) return ".gnu.linkonce.tb."; 293 294 if (Kind.isDataNoRel()) return ".gnu.linkonce.d."; 295 if (Kind.isDataRelLocal()) return ".gnu.linkonce.d.rel.local."; 296 if (Kind.isDataRel()) return ".gnu.linkonce.d.rel."; 297 if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local."; 298 299 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 300 return ".gnu.linkonce.d.rel.ro."; 301 } 302 303 const MCSection *TargetLoweringObjectFileELF:: 304 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 305 Mangler *Mang, const TargetMachine &TM) const { 306 307 // If this global is linkonce/weak and the target handles this by emitting it 308 // into a 'uniqued' section name, create and return the section now. 309 if (GV->isWeakForLinker() && !Kind.isCommon() && !Kind.isBSS()) { 310 const char *Prefix = getSectionPrefixForUniqueGlobal(Kind); 311 SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); 312 MCSymbol *Sym = Mang->getSymbol(GV); 313 Name.append(Sym->getName().begin(), Sym->getName().end()); 314 return getELFSection(Name.str(), getELFSectionType(Name.str(), Kind), 315 getELFSectionFlags(Kind), Kind); 316 } 317 318 if (Kind.isText()) return TextSection; 319 320 if (Kind.isMergeable1ByteCString() || 321 Kind.isMergeable2ByteCString() || 322 Kind.isMergeable4ByteCString()) { 323 324 // We also need alignment here. 325 // FIXME: this is getting the alignment of the character, not the 326 // alignment of the global! 327 unsigned Align = 328 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)); 329 330 const char *SizeSpec = ".rodata.str1."; 331 if (Kind.isMergeable2ByteCString()) 332 SizeSpec = ".rodata.str2."; 333 else if (Kind.isMergeable4ByteCString()) 334 SizeSpec = ".rodata.str4."; 335 else 336 assert(Kind.isMergeable1ByteCString() && "unknown string width"); 337 338 339 std::string Name = SizeSpec + utostr(Align); 340 return getELFSection(Name, MCSectionELF::SHT_PROGBITS, 341 MCSectionELF::SHF_ALLOC | 342 MCSectionELF::SHF_MERGE | 343 MCSectionELF::SHF_STRINGS, 344 Kind); 345 } 346 347 if (Kind.isMergeableConst()) { 348 if (Kind.isMergeableConst4() && MergeableConst4Section) 349 return MergeableConst4Section; 350 if (Kind.isMergeableConst8() && MergeableConst8Section) 351 return MergeableConst8Section; 352 if (Kind.isMergeableConst16() && MergeableConst16Section) 353 return MergeableConst16Section; 354 return ReadOnlySection; // .const 355 } 356 357 if (Kind.isReadOnly()) return ReadOnlySection; 358 359 if (Kind.isThreadData()) return TLSDataSection; 360 if (Kind.isThreadBSS()) return TLSBSSSection; 361 362 // Note: we claim that common symbols are put in BSSSection, but they are 363 // really emitted with the magic .comm directive, which creates a symbol table 364 // entry but not a section. 365 if (Kind.isBSS() || Kind.isCommon()) return BSSSection; 366 367 if (Kind.isDataNoRel()) return DataSection; 368 if (Kind.isDataRelLocal()) return DataRelLocalSection; 369 if (Kind.isDataRel()) return DataRelSection; 370 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 371 372 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 373 return DataRelROSection; 374 } 375 376 /// getSectionForConstant - Given a mergeable constant with the 377 /// specified size and relocation information, return a section that it 378 /// should be placed in. 379 const MCSection *TargetLoweringObjectFileELF:: 380 getSectionForConstant(SectionKind Kind) const { 381 if (Kind.isMergeableConst4() && MergeableConst4Section) 382 return MergeableConst4Section; 383 if (Kind.isMergeableConst8() && MergeableConst8Section) 384 return MergeableConst8Section; 385 if (Kind.isMergeableConst16() && MergeableConst16Section) 386 return MergeableConst16Section; 387 if (Kind.isReadOnly()) 388 return ReadOnlySection; 389 390 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 391 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 392 return DataRelROSection; 393 } 394 395 const MCExpr *TargetLoweringObjectFileELF:: 396 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 397 MachineModuleInfo *MMI, 398 unsigned Encoding, MCStreamer &Streamer) const { 399 400 if (Encoding & dwarf::DW_EH_PE_indirect) { 401 MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>(); 402 403 SmallString<128> Name; 404 Mang->getNameWithPrefix(Name, GV, true); 405 Name += ".DW.stub"; 406 407 // Add information about the stub reference to ELFMMI so that the stub 408 // gets emitted by the asmprinter. 409 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); 410 MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym); 411 if (StubSym.getPointer() == 0) { 412 MCSymbol *Sym = Mang->getSymbol(GV); 413 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 414 } 415 416 return TargetLoweringObjectFile:: 417 getExprForDwarfReference(SSym, Mang, MMI, 418 Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); 419 } 420 421 return TargetLoweringObjectFile:: 422 getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer); 423 } 424 425 //===----------------------------------------------------------------------===// 426 // MachO 427 //===----------------------------------------------------------------------===// 428 429 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx, 430 const TargetMachine &TM) { 431 // _foo.eh symbols are currently always exported so that the linker knows 432 // about them. This is not necessary on 10.6 and later, but it 433 // doesn't hurt anything. 434 // FIXME: I need to get this from Triple. 435 IsFunctionEHSymbolGlobal = true; 436 IsFunctionEHFrameSymbolPrivate = false; 437 SupportsWeakOmittedEHFrame = false; 438 439 TargetLoweringObjectFile::Initialize(Ctx, TM); 440 441 TextSection // .text 442 = getContext().getMachOSection("__TEXT", "__text", 443 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 444 SectionKind::getText()); 445 DataSection // .data 446 = getContext().getMachOSection("__DATA", "__data", 0, 447 SectionKind::getDataRel()); 448 449 CStringSection // .cstring 450 = getContext().getMachOSection("__TEXT", "__cstring", 451 MCSectionMachO::S_CSTRING_LITERALS, 452 SectionKind::getMergeable1ByteCString()); 453 UStringSection 454 = getContext().getMachOSection("__TEXT","__ustring", 0, 455 SectionKind::getMergeable2ByteCString()); 456 FourByteConstantSection // .literal4 457 = getContext().getMachOSection("__TEXT", "__literal4", 458 MCSectionMachO::S_4BYTE_LITERALS, 459 SectionKind::getMergeableConst4()); 460 EightByteConstantSection // .literal8 461 = getContext().getMachOSection("__TEXT", "__literal8", 462 MCSectionMachO::S_8BYTE_LITERALS, 463 SectionKind::getMergeableConst8()); 464 465 // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back 466 // to using it in -static mode. 467 SixteenByteConstantSection = 0; 468 if (TM.getRelocationModel() != Reloc::Static && 469 TM.getTargetData()->getPointerSize() == 32) 470 SixteenByteConstantSection = // .literal16 471 getContext().getMachOSection("__TEXT", "__literal16", 472 MCSectionMachO::S_16BYTE_LITERALS, 473 SectionKind::getMergeableConst16()); 474 475 ReadOnlySection // .const 476 = getContext().getMachOSection("__TEXT", "__const", 0, 477 SectionKind::getReadOnly()); 478 479 TextCoalSection 480 = getContext().getMachOSection("__TEXT", "__textcoal_nt", 481 MCSectionMachO::S_COALESCED | 482 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 483 SectionKind::getText()); 484 ConstTextCoalSection 485 = getContext().getMachOSection("__TEXT", "__const_coal", 486 MCSectionMachO::S_COALESCED, 487 SectionKind::getText()); 488 ConstDataCoalSection 489 = getContext().getMachOSection("__DATA","__const_coal", 490 MCSectionMachO::S_COALESCED, 491 SectionKind::getText()); 492 ConstDataSection // .const_data 493 = getContext().getMachOSection("__DATA", "__const", 0, 494 SectionKind::getReadOnlyWithRel()); 495 DataCoalSection 496 = getContext().getMachOSection("__DATA","__datacoal_nt", 497 MCSectionMachO::S_COALESCED, 498 SectionKind::getDataRel()); 499 DataCommonSection 500 = getContext().getMachOSection("__DATA","__common", 501 MCSectionMachO::S_ZEROFILL, 502 SectionKind::getBSS()); 503 DataBSSSection 504 = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL, 505 SectionKind::getBSS()); 506 507 508 LazySymbolPointerSection 509 = getContext().getMachOSection("__DATA", "__la_symbol_ptr", 510 MCSectionMachO::S_LAZY_SYMBOL_POINTERS, 511 SectionKind::getMetadata()); 512 NonLazySymbolPointerSection 513 = getContext().getMachOSection("__DATA", "__nl_symbol_ptr", 514 MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS, 515 SectionKind::getMetadata()); 516 517 if (TM.getRelocationModel() == Reloc::Static) { 518 StaticCtorSection 519 = getContext().getMachOSection("__TEXT", "__constructor", 0, 520 SectionKind::getDataRel()); 521 StaticDtorSection 522 = getContext().getMachOSection("__TEXT", "__destructor", 0, 523 SectionKind::getDataRel()); 524 } else { 525 StaticCtorSection 526 = getContext().getMachOSection("__DATA", "__mod_init_func", 527 MCSectionMachO::S_MOD_INIT_FUNC_POINTERS, 528 SectionKind::getDataRel()); 529 StaticDtorSection 530 = getContext().getMachOSection("__DATA", "__mod_term_func", 531 MCSectionMachO::S_MOD_TERM_FUNC_POINTERS, 532 SectionKind::getDataRel()); 533 } 534 535 // Exception Handling. 536 LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0, 537 SectionKind::getReadOnlyWithRel()); 538 EHFrameSection = 539 getContext().getMachOSection("__TEXT", "__eh_frame", 540 MCSectionMachO::S_COALESCED | 541 MCSectionMachO::S_ATTR_NO_TOC | 542 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS | 543 MCSectionMachO::S_ATTR_LIVE_SUPPORT, 544 SectionKind::getReadOnly()); 545 546 // Debug Information. 547 DwarfAbbrevSection = 548 getContext().getMachOSection("__DWARF", "__debug_abbrev", 549 MCSectionMachO::S_ATTR_DEBUG, 550 SectionKind::getMetadata()); 551 DwarfInfoSection = 552 getContext().getMachOSection("__DWARF", "__debug_info", 553 MCSectionMachO::S_ATTR_DEBUG, 554 SectionKind::getMetadata()); 555 DwarfLineSection = 556 getContext().getMachOSection("__DWARF", "__debug_line", 557 MCSectionMachO::S_ATTR_DEBUG, 558 SectionKind::getMetadata()); 559 DwarfFrameSection = 560 getContext().getMachOSection("__DWARF", "__debug_frame", 561 MCSectionMachO::S_ATTR_DEBUG, 562 SectionKind::getMetadata()); 563 DwarfPubNamesSection = 564 getContext().getMachOSection("__DWARF", "__debug_pubnames", 565 MCSectionMachO::S_ATTR_DEBUG, 566 SectionKind::getMetadata()); 567 DwarfPubTypesSection = 568 getContext().getMachOSection("__DWARF", "__debug_pubtypes", 569 MCSectionMachO::S_ATTR_DEBUG, 570 SectionKind::getMetadata()); 571 DwarfStrSection = 572 getContext().getMachOSection("__DWARF", "__debug_str", 573 MCSectionMachO::S_ATTR_DEBUG, 574 SectionKind::getMetadata()); 575 DwarfLocSection = 576 getContext().getMachOSection("__DWARF", "__debug_loc", 577 MCSectionMachO::S_ATTR_DEBUG, 578 SectionKind::getMetadata()); 579 DwarfARangesSection = 580 getContext().getMachOSection("__DWARF", "__debug_aranges", 581 MCSectionMachO::S_ATTR_DEBUG, 582 SectionKind::getMetadata()); 583 DwarfRangesSection = 584 getContext().getMachOSection("__DWARF", "__debug_ranges", 585 MCSectionMachO::S_ATTR_DEBUG, 586 SectionKind::getMetadata()); 587 DwarfMacroInfoSection = 588 getContext().getMachOSection("__DWARF", "__debug_macinfo", 589 MCSectionMachO::S_ATTR_DEBUG, 590 SectionKind::getMetadata()); 591 DwarfDebugInlineSection = 592 getContext().getMachOSection("__DWARF", "__debug_inlined", 593 MCSectionMachO::S_ATTR_DEBUG, 594 SectionKind::getMetadata()); 595 } 596 597 const MCSection *TargetLoweringObjectFileMachO:: 598 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 599 Mangler *Mang, const TargetMachine &TM) const { 600 // Parse the section specifier and create it if valid. 601 StringRef Segment, Section; 602 unsigned TAA, StubSize; 603 std::string ErrorCode = 604 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section, 605 TAA, StubSize); 606 if (!ErrorCode.empty()) { 607 // If invalid, report the error with report_fatal_error. 608 report_fatal_error("Global variable '" + GV->getNameStr() + 609 "' has an invalid section specifier '" + GV->getSection()+ 610 "': " + ErrorCode + "."); 611 // Fall back to dropping it into the data section. 612 return DataSection; 613 } 614 615 // Get the section. 616 const MCSectionMachO *S = 617 getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind); 618 619 // Okay, now that we got the section, verify that the TAA & StubSize agree. 620 // If the user declared multiple globals with different section flags, we need 621 // to reject it here. 622 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) { 623 // If invalid, report the error with report_fatal_error. 624 report_fatal_error("Global variable '" + GV->getNameStr() + 625 "' section type or attributes does not match previous" 626 " section specifier"); 627 } 628 629 return S; 630 } 631 632 const MCSection *TargetLoweringObjectFileMachO:: 633 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 634 Mangler *Mang, const TargetMachine &TM) const { 635 assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS"); 636 637 if (Kind.isText()) 638 return GV->isWeakForLinker() ? TextCoalSection : TextSection; 639 640 // If this is weak/linkonce, put this in a coalescable section, either in text 641 // or data depending on if it is writable. 642 if (GV->isWeakForLinker()) { 643 if (Kind.isReadOnly()) 644 return ConstTextCoalSection; 645 return DataCoalSection; 646 } 647 648 // FIXME: Alignment check should be handled by section classifier. 649 if (Kind.isMergeable1ByteCString() && 650 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 651 return CStringSection; 652 653 // Do not put 16-bit arrays in the UString section if they have an 654 // externally visible label, this runs into issues with certain linker 655 // versions. 656 if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() && 657 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 658 return UStringSection; 659 660 if (Kind.isMergeableConst()) { 661 if (Kind.isMergeableConst4()) 662 return FourByteConstantSection; 663 if (Kind.isMergeableConst8()) 664 return EightByteConstantSection; 665 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 666 return SixteenByteConstantSection; 667 } 668 669 // Otherwise, if it is readonly, but not something we can specially optimize, 670 // just drop it in .const. 671 if (Kind.isReadOnly()) 672 return ReadOnlySection; 673 674 // If this is marked const, put it into a const section. But if the dynamic 675 // linker needs to write to it, put it in the data segment. 676 if (Kind.isReadOnlyWithRel()) 677 return ConstDataSection; 678 679 // Put zero initialized globals with strong external linkage in the 680 // DATA, __common section with the .zerofill directive. 681 if (Kind.isBSSExtern()) 682 return DataCommonSection; 683 684 // Put zero initialized globals with local linkage in __DATA,__bss directive 685 // with the .zerofill directive (aka .lcomm). 686 if (Kind.isBSSLocal()) 687 return DataBSSSection; 688 689 // Otherwise, just drop the variable in the normal data section. 690 return DataSection; 691 } 692 693 const MCSection * 694 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { 695 // If this constant requires a relocation, we have to put it in the data 696 // segment, not in the text segment. 697 if (Kind.isDataRel() || Kind.isReadOnlyWithRel()) 698 return ConstDataSection; 699 700 if (Kind.isMergeableConst4()) 701 return FourByteConstantSection; 702 if (Kind.isMergeableConst8()) 703 return EightByteConstantSection; 704 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 705 return SixteenByteConstantSection; 706 return ReadOnlySection; // .const 707 } 708 709 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide 710 /// not to emit the UsedDirective for some symbols in llvm.used. 711 // FIXME: REMOVE this (rdar://7071300) 712 bool TargetLoweringObjectFileMachO:: 713 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { 714 /// On Darwin, internally linked data beginning with "L" or "l" does not have 715 /// the directive emitted (this occurs in ObjC metadata). 716 if (!GV) return false; 717 718 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. 719 if (GV->hasLocalLinkage() && !isa<Function>(GV)) { 720 // FIXME: ObjC metadata is currently emitted as internal symbols that have 721 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and 722 // this horrible hack can go away. 723 MCSymbol *Sym = Mang->getSymbol(GV); 724 if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l') 725 return false; 726 } 727 728 return true; 729 } 730 731 const MCExpr *TargetLoweringObjectFileMachO:: 732 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 733 MachineModuleInfo *MMI, unsigned Encoding, 734 MCStreamer &Streamer) const { 735 // The mach-o version of this method defaults to returning a stub reference. 736 737 if (Encoding & DW_EH_PE_indirect) { 738 MachineModuleInfoMachO &MachOMMI = 739 MMI->getObjFileInfo<MachineModuleInfoMachO>(); 740 741 SmallString<128> Name; 742 Mang->getNameWithPrefix(Name, GV, true); 743 Name += "$non_lazy_ptr"; 744 745 // Add information about the stub reference to MachOMMI so that the stub 746 // gets emitted by the asmprinter. 747 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); 748 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym); 749 if (StubSym.getPointer() == 0) { 750 MCSymbol *Sym = Mang->getSymbol(GV); 751 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 752 } 753 754 return TargetLoweringObjectFile:: 755 getExprForDwarfReference(SSym, Mang, MMI, 756 Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); 757 } 758 759 return TargetLoweringObjectFile:: 760 getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer); 761 } 762 763 unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const { 764 return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4; 765 } 766 767 unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const { 768 return DW_EH_PE_pcrel; 769 } 770 771 unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const { 772 return DW_EH_PE_pcrel; 773 } 774 775 unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const { 776 return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4; 777 } 778 779 //===----------------------------------------------------------------------===// 780 // COFF 781 //===----------------------------------------------------------------------===// 782 783 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy; 784 785 TargetLoweringObjectFileCOFF::~TargetLoweringObjectFileCOFF() { 786 delete (COFFUniqueMapTy*)UniquingMap; 787 } 788 789 790 const MCSection *TargetLoweringObjectFileCOFF:: 791 getCOFFSection(StringRef Name, bool isDirective, SectionKind Kind) const { 792 // Create the map if it doesn't already exist. 793 if (UniquingMap == 0) 794 UniquingMap = new COFFUniqueMapTy(); 795 COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)UniquingMap; 796 797 // Do the lookup, if we have a hit, return it. 798 const MCSectionCOFF *&Entry = Map[Name]; 799 if (Entry) return Entry; 800 801 return Entry = MCSectionCOFF::Create(Name, isDirective, Kind, getContext()); 802 } 803 804 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx, 805 const TargetMachine &TM) { 806 if (UniquingMap != 0) 807 ((COFFUniqueMapTy*)UniquingMap)->clear(); 808 TargetLoweringObjectFile::Initialize(Ctx, TM); 809 TextSection = getCOFFSection("\t.text", true, SectionKind::getText()); 810 DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel()); 811 StaticCtorSection = 812 getCOFFSection(".ctors", false, SectionKind::getDataRel()); 813 StaticDtorSection = 814 getCOFFSection(".dtors", false, SectionKind::getDataRel()); 815 816 // FIXME: We're emitting LSDA info into a readonly section on COFF, even 817 // though it contains relocatable pointers. In PIC mode, this is probably a 818 // big runtime hit for C++ apps. Either the contents of the LSDA need to be 819 // adjusted or this should be a data section. 820 LSDASection = 821 getCOFFSection(".gcc_except_table", false, SectionKind::getReadOnly()); 822 EHFrameSection = 823 getCOFFSection(".eh_frame", false, SectionKind::getDataRel()); 824 825 // Debug info. 826 // FIXME: Don't use 'directive' mode here. 827 DwarfAbbrevSection = 828 getCOFFSection("\t.section\t.debug_abbrev,\"dr\"", 829 true, SectionKind::getMetadata()); 830 DwarfInfoSection = 831 getCOFFSection("\t.section\t.debug_info,\"dr\"", 832 true, SectionKind::getMetadata()); 833 DwarfLineSection = 834 getCOFFSection("\t.section\t.debug_line,\"dr\"", 835 true, SectionKind::getMetadata()); 836 DwarfFrameSection = 837 getCOFFSection("\t.section\t.debug_frame,\"dr\"", 838 true, SectionKind::getMetadata()); 839 DwarfPubNamesSection = 840 getCOFFSection("\t.section\t.debug_pubnames,\"dr\"", 841 true, SectionKind::getMetadata()); 842 DwarfPubTypesSection = 843 getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"", 844 true, SectionKind::getMetadata()); 845 DwarfStrSection = 846 getCOFFSection("\t.section\t.debug_str,\"dr\"", 847 true, SectionKind::getMetadata()); 848 DwarfLocSection = 849 getCOFFSection("\t.section\t.debug_loc,\"dr\"", 850 true, SectionKind::getMetadata()); 851 DwarfARangesSection = 852 getCOFFSection("\t.section\t.debug_aranges,\"dr\"", 853 true, SectionKind::getMetadata()); 854 DwarfRangesSection = 855 getCOFFSection("\t.section\t.debug_ranges,\"dr\"", 856 true, SectionKind::getMetadata()); 857 DwarfMacroInfoSection = 858 getCOFFSection("\t.section\t.debug_macinfo,\"dr\"", 859 true, SectionKind::getMetadata()); 860 } 861 862 const MCSection *TargetLoweringObjectFileCOFF:: 863 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 864 Mangler *Mang, const TargetMachine &TM) const { 865 return getCOFFSection(GV->getSection(), false, Kind); 866 } 867 868 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) { 869 if (Kind.isText()) 870 return ".text$linkonce"; 871 if (Kind.isWriteable()) 872 return ".data$linkonce"; 873 return ".rdata$linkonce"; 874 } 875 876 877 const MCSection *TargetLoweringObjectFileCOFF:: 878 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 879 Mangler *Mang, const TargetMachine &TM) const { 880 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 881 882 // If this global is linkonce/weak and the target handles this by emitting it 883 // into a 'uniqued' section name, create and return the section now. 884 if (GV->isWeakForLinker()) { 885 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind); 886 SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); 887 MCSymbol *Sym = Mang->getSymbol(GV); 888 Name.append(Sym->getName().begin(), Sym->getName().end()); 889 return getCOFFSection(Name.str(), false, Kind); 890 } 891 892 if (Kind.isText()) 893 return getTextSection(); 894 895 return getDataSection(); 896 } 897 898