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/ADT/SmallString.h" 17 #include "llvm/ADT/StringExtras.h" 18 #include "llvm/ADT/Triple.h" 19 #include "llvm/CodeGen/MachineModuleInfoImpls.h" 20 #include "llvm/IR/Constants.h" 21 #include "llvm/IR/DataLayout.h" 22 #include "llvm/IR/DerivedTypes.h" 23 #include "llvm/IR/Function.h" 24 #include "llvm/IR/GlobalVariable.h" 25 #include "llvm/IR/Module.h" 26 #include "llvm/MC/MCContext.h" 27 #include "llvm/MC/MCExpr.h" 28 #include "llvm/MC/MCSectionCOFF.h" 29 #include "llvm/MC/MCSectionELF.h" 30 #include "llvm/MC/MCSectionMachO.h" 31 #include "llvm/MC/MCStreamer.h" 32 #include "llvm/MC/MCSymbol.h" 33 #include "llvm/Support/Dwarf.h" 34 #include "llvm/Support/ELF.h" 35 #include "llvm/Support/ErrorHandling.h" 36 #include "llvm/Support/raw_ostream.h" 37 #include "llvm/Target/Mangler.h" 38 #include "llvm/Target/TargetMachine.h" 39 using namespace llvm; 40 using namespace dwarf; 41 42 //===----------------------------------------------------------------------===// 43 // ELF 44 //===----------------------------------------------------------------------===// 45 46 MCSymbol * 47 TargetLoweringObjectFileELF::getCFIPersonalitySymbol(const GlobalValue *GV, 48 Mangler *Mang, 49 MachineModuleInfo *MMI) const { 50 unsigned Encoding = getPersonalityEncoding(); 51 switch (Encoding & 0x70) { 52 default: 53 report_fatal_error("We do not support this DWARF encoding yet!"); 54 case dwarf::DW_EH_PE_absptr: 55 return getSymbol(*Mang, GV); 56 case dwarf::DW_EH_PE_pcrel: { 57 return getContext().GetOrCreateSymbol(StringRef("DW.ref.") + 58 getSymbol(*Mang, GV)->getName()); 59 } 60 } 61 } 62 63 void TargetLoweringObjectFileELF::emitPersonalityValue(MCStreamer &Streamer, 64 const TargetMachine &TM, 65 const MCSymbol *Sym) const { 66 SmallString<64> NameData("DW.ref."); 67 NameData += Sym->getName(); 68 MCSymbol *Label = getContext().GetOrCreateSymbol(NameData); 69 Streamer.EmitSymbolAttribute(Label, MCSA_Hidden); 70 Streamer.EmitSymbolAttribute(Label, MCSA_Weak); 71 StringRef Prefix = ".data."; 72 NameData.insert(NameData.begin(), Prefix.begin(), Prefix.end()); 73 unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP; 74 const MCSection *Sec = getContext().getELFSection(NameData, 75 ELF::SHT_PROGBITS, 76 Flags, 77 SectionKind::getDataRel(), 78 0, Label->getName()); 79 unsigned Size = TM.getDataLayout()->getPointerSize(); 80 Streamer.SwitchSection(Sec); 81 Streamer.EmitValueToAlignment(TM.getDataLayout()->getPointerABIAlignment()); 82 Streamer.EmitSymbolAttribute(Label, MCSA_ELF_TypeObject); 83 const MCExpr *E = MCConstantExpr::Create(Size, getContext()); 84 Streamer.EmitELFSize(Label, E); 85 Streamer.EmitLabel(Label); 86 87 Streamer.EmitSymbolValue(Sym, Size); 88 } 89 90 const MCExpr *TargetLoweringObjectFileELF:: 91 getTTypeGlobalReference(const GlobalValue *GV, Mangler *Mang, 92 MachineModuleInfo *MMI, unsigned Encoding, 93 MCStreamer &Streamer) const { 94 95 if (Encoding & dwarf::DW_EH_PE_indirect) { 96 MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>(); 97 98 MCSymbol *SSym = getSymbolWithGlobalValueBase(*Mang, GV, ".DW.stub"); 99 100 // Add information about the stub reference to ELFMMI so that the stub 101 // gets emitted by the asmprinter. 102 MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym); 103 if (StubSym.getPointer() == 0) { 104 MCSymbol *Sym = getSymbol(*Mang, GV); 105 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 106 } 107 108 return TargetLoweringObjectFile:: 109 getTTypeReference(MCSymbolRefExpr::Create(SSym, getContext()), 110 Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); 111 } 112 113 return TargetLoweringObjectFile:: 114 getTTypeGlobalReference(GV, Mang, MMI, Encoding, Streamer); 115 } 116 117 static SectionKind 118 getELFKindForNamedSection(StringRef Name, SectionKind K) { 119 // N.B.: The defaults used in here are no the same ones used in MC. 120 // We follow gcc, MC follows gas. For example, given ".section .eh_frame", 121 // both gas and MC will produce a section with no flags. Given 122 // section(".eh_frame") gcc will produce: 123 // 124 // .section .eh_frame,"a",@progbits 125 if (Name.empty() || Name[0] != '.') return K; 126 127 // Some lame default implementation based on some magic section names. 128 if (Name == ".bss" || 129 Name.startswith(".bss.") || 130 Name.startswith(".gnu.linkonce.b.") || 131 Name.startswith(".llvm.linkonce.b.") || 132 Name == ".sbss" || 133 Name.startswith(".sbss.") || 134 Name.startswith(".gnu.linkonce.sb.") || 135 Name.startswith(".llvm.linkonce.sb.")) 136 return SectionKind::getBSS(); 137 138 if (Name == ".tdata" || 139 Name.startswith(".tdata.") || 140 Name.startswith(".gnu.linkonce.td.") || 141 Name.startswith(".llvm.linkonce.td.")) 142 return SectionKind::getThreadData(); 143 144 if (Name == ".tbss" || 145 Name.startswith(".tbss.") || 146 Name.startswith(".gnu.linkonce.tb.") || 147 Name.startswith(".llvm.linkonce.tb.")) 148 return SectionKind::getThreadBSS(); 149 150 return K; 151 } 152 153 154 static unsigned getELFSectionType(StringRef Name, SectionKind K) { 155 156 if (Name == ".init_array") 157 return ELF::SHT_INIT_ARRAY; 158 159 if (Name == ".fini_array") 160 return ELF::SHT_FINI_ARRAY; 161 162 if (Name == ".preinit_array") 163 return ELF::SHT_PREINIT_ARRAY; 164 165 if (K.isBSS() || K.isThreadBSS()) 166 return ELF::SHT_NOBITS; 167 168 return ELF::SHT_PROGBITS; 169 } 170 171 172 static unsigned 173 getELFSectionFlags(SectionKind K) { 174 unsigned Flags = 0; 175 176 if (!K.isMetadata()) 177 Flags |= ELF::SHF_ALLOC; 178 179 if (K.isText()) 180 Flags |= ELF::SHF_EXECINSTR; 181 182 if (K.isWriteable()) 183 Flags |= ELF::SHF_WRITE; 184 185 if (K.isThreadLocal()) 186 Flags |= ELF::SHF_TLS; 187 188 // K.isMergeableConst() is left out to honour PR4650 189 if (K.isMergeableCString() || K.isMergeableConst4() || 190 K.isMergeableConst8() || K.isMergeableConst16()) 191 Flags |= ELF::SHF_MERGE; 192 193 if (K.isMergeableCString()) 194 Flags |= ELF::SHF_STRINGS; 195 196 return Flags; 197 } 198 199 200 const MCSection *TargetLoweringObjectFileELF:: 201 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 202 Mangler *Mang, const TargetMachine &TM) const { 203 StringRef SectionName = GV->getSection(); 204 205 // Infer section flags from the section name if we can. 206 Kind = getELFKindForNamedSection(SectionName, Kind); 207 208 return getContext().getELFSection(SectionName, 209 getELFSectionType(SectionName, Kind), 210 getELFSectionFlags(Kind), Kind); 211 } 212 213 /// getSectionPrefixForGlobal - Return the section prefix name used by options 214 /// FunctionsSections and DataSections. 215 static const char *getSectionPrefixForGlobal(SectionKind Kind) { 216 if (Kind.isText()) return ".text."; 217 if (Kind.isReadOnly()) return ".rodata."; 218 if (Kind.isBSS()) return ".bss."; 219 220 if (Kind.isThreadData()) return ".tdata."; 221 if (Kind.isThreadBSS()) return ".tbss."; 222 223 if (Kind.isDataNoRel()) return ".data."; 224 if (Kind.isDataRelLocal()) return ".data.rel.local."; 225 if (Kind.isDataRel()) return ".data.rel."; 226 if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local."; 227 228 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 229 return ".data.rel.ro."; 230 } 231 232 233 const MCSection *TargetLoweringObjectFileELF:: 234 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 235 Mangler *Mang, const TargetMachine &TM) const { 236 // If we have -ffunction-section or -fdata-section then we should emit the 237 // global value to a uniqued section specifically for it. 238 bool EmitUniquedSection; 239 if (Kind.isText()) 240 EmitUniquedSection = TM.getFunctionSections(); 241 else 242 EmitUniquedSection = TM.getDataSections(); 243 244 // If this global is linkonce/weak and the target handles this by emitting it 245 // into a 'uniqued' section name, create and return the section now. 246 if ((GV->isWeakForLinker() || EmitUniquedSection) && 247 !Kind.isCommon()) { 248 const char *Prefix; 249 Prefix = getSectionPrefixForGlobal(Kind); 250 251 SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); 252 MCSymbol *Sym = getSymbol(*Mang, GV); 253 Name.append(Sym->getName().begin(), Sym->getName().end()); 254 StringRef Group = ""; 255 unsigned Flags = getELFSectionFlags(Kind); 256 if (GV->isWeakForLinker()) { 257 Group = Sym->getName(); 258 Flags |= ELF::SHF_GROUP; 259 } 260 261 return getContext().getELFSection(Name.str(), 262 getELFSectionType(Name.str(), Kind), 263 Flags, Kind, 0, Group); 264 } 265 266 if (Kind.isText()) return TextSection; 267 268 if (Kind.isMergeable1ByteCString() || 269 Kind.isMergeable2ByteCString() || 270 Kind.isMergeable4ByteCString()) { 271 272 // We also need alignment here. 273 // FIXME: this is getting the alignment of the character, not the 274 // alignment of the global! 275 unsigned Align = 276 TM.getDataLayout()->getPreferredAlignment(cast<GlobalVariable>(GV)); 277 278 const char *SizeSpec = ".rodata.str1."; 279 if (Kind.isMergeable2ByteCString()) 280 SizeSpec = ".rodata.str2."; 281 else if (Kind.isMergeable4ByteCString()) 282 SizeSpec = ".rodata.str4."; 283 else 284 assert(Kind.isMergeable1ByteCString() && "unknown string width"); 285 286 287 std::string Name = SizeSpec + utostr(Align); 288 return getContext().getELFSection(Name, ELF::SHT_PROGBITS, 289 ELF::SHF_ALLOC | 290 ELF::SHF_MERGE | 291 ELF::SHF_STRINGS, 292 Kind); 293 } 294 295 if (Kind.isMergeableConst()) { 296 if (Kind.isMergeableConst4() && MergeableConst4Section) 297 return MergeableConst4Section; 298 if (Kind.isMergeableConst8() && MergeableConst8Section) 299 return MergeableConst8Section; 300 if (Kind.isMergeableConst16() && MergeableConst16Section) 301 return MergeableConst16Section; 302 return ReadOnlySection; // .const 303 } 304 305 if (Kind.isReadOnly()) return ReadOnlySection; 306 307 if (Kind.isThreadData()) return TLSDataSection; 308 if (Kind.isThreadBSS()) return TLSBSSSection; 309 310 // Note: we claim that common symbols are put in BSSSection, but they are 311 // really emitted with the magic .comm directive, which creates a symbol table 312 // entry but not a section. 313 if (Kind.isBSS() || Kind.isCommon()) return BSSSection; 314 315 if (Kind.isDataNoRel()) return DataSection; 316 if (Kind.isDataRelLocal()) return DataRelLocalSection; 317 if (Kind.isDataRel()) return DataRelSection; 318 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 319 320 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 321 return DataRelROSection; 322 } 323 324 /// getSectionForConstant - Given a mergeable constant with the 325 /// specified size and relocation information, return a section that it 326 /// should be placed in. 327 const MCSection *TargetLoweringObjectFileELF:: 328 getSectionForConstant(SectionKind Kind) const { 329 if (Kind.isMergeableConst4() && MergeableConst4Section) 330 return MergeableConst4Section; 331 if (Kind.isMergeableConst8() && MergeableConst8Section) 332 return MergeableConst8Section; 333 if (Kind.isMergeableConst16() && MergeableConst16Section) 334 return MergeableConst16Section; 335 if (Kind.isReadOnly()) 336 return ReadOnlySection; 337 338 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 339 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 340 return DataRelROSection; 341 } 342 343 const MCSection * 344 TargetLoweringObjectFileELF::getStaticCtorSection(unsigned Priority) const { 345 // The default scheme is .ctor / .dtor, so we have to invert the priority 346 // numbering. 347 if (Priority == 65535) 348 return StaticCtorSection; 349 350 if (UseInitArray) { 351 std::string Name = std::string(".init_array.") + utostr(Priority); 352 return getContext().getELFSection(Name, ELF::SHT_INIT_ARRAY, 353 ELF::SHF_ALLOC | ELF::SHF_WRITE, 354 SectionKind::getDataRel()); 355 } else { 356 std::string Name = std::string(".ctors.") + utostr(65535 - Priority); 357 return getContext().getELFSection(Name, ELF::SHT_PROGBITS, 358 ELF::SHF_ALLOC |ELF::SHF_WRITE, 359 SectionKind::getDataRel()); 360 } 361 } 362 363 const MCSection * 364 TargetLoweringObjectFileELF::getStaticDtorSection(unsigned Priority) const { 365 // The default scheme is .ctor / .dtor, so we have to invert the priority 366 // numbering. 367 if (Priority == 65535) 368 return StaticDtorSection; 369 370 if (UseInitArray) { 371 std::string Name = std::string(".fini_array.") + utostr(Priority); 372 return getContext().getELFSection(Name, ELF::SHT_FINI_ARRAY, 373 ELF::SHF_ALLOC | ELF::SHF_WRITE, 374 SectionKind::getDataRel()); 375 } else { 376 std::string Name = std::string(".dtors.") + utostr(65535 - Priority); 377 return getContext().getELFSection(Name, ELF::SHT_PROGBITS, 378 ELF::SHF_ALLOC |ELF::SHF_WRITE, 379 SectionKind::getDataRel()); 380 } 381 } 382 383 void 384 TargetLoweringObjectFileELF::InitializeELF(bool UseInitArray_) { 385 UseInitArray = UseInitArray_; 386 if (!UseInitArray) 387 return; 388 389 StaticCtorSection = 390 getContext().getELFSection(".init_array", ELF::SHT_INIT_ARRAY, 391 ELF::SHF_WRITE | 392 ELF::SHF_ALLOC, 393 SectionKind::getDataRel()); 394 StaticDtorSection = 395 getContext().getELFSection(".fini_array", ELF::SHT_FINI_ARRAY, 396 ELF::SHF_WRITE | 397 ELF::SHF_ALLOC, 398 SectionKind::getDataRel()); 399 } 400 401 //===----------------------------------------------------------------------===// 402 // MachO 403 //===----------------------------------------------------------------------===// 404 405 /// emitModuleFlags - Perform code emission for module flags. 406 void TargetLoweringObjectFileMachO:: 407 emitModuleFlags(MCStreamer &Streamer, 408 ArrayRef<Module::ModuleFlagEntry> ModuleFlags, 409 Mangler *Mang, const TargetMachine &TM) const { 410 unsigned VersionVal = 0; 411 unsigned ImageInfoFlags = 0; 412 MDNode *LinkerOptions = 0; 413 StringRef SectionVal; 414 415 for (ArrayRef<Module::ModuleFlagEntry>::iterator 416 i = ModuleFlags.begin(), e = ModuleFlags.end(); i != e; ++i) { 417 const Module::ModuleFlagEntry &MFE = *i; 418 419 // Ignore flags with 'Require' behavior. 420 if (MFE.Behavior == Module::Require) 421 continue; 422 423 StringRef Key = MFE.Key->getString(); 424 Value *Val = MFE.Val; 425 426 if (Key == "Objective-C Image Info Version") { 427 VersionVal = cast<ConstantInt>(Val)->getZExtValue(); 428 } else if (Key == "Objective-C Garbage Collection" || 429 Key == "Objective-C GC Only" || 430 Key == "Objective-C Is Simulated") { 431 ImageInfoFlags |= cast<ConstantInt>(Val)->getZExtValue(); 432 } else if (Key == "Objective-C Image Info Section") { 433 SectionVal = cast<MDString>(Val)->getString(); 434 } else if (Key == "Linker Options") { 435 LinkerOptions = cast<MDNode>(Val); 436 } 437 } 438 439 // Emit the linker options if present. 440 if (LinkerOptions) { 441 for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) { 442 MDNode *MDOptions = cast<MDNode>(LinkerOptions->getOperand(i)); 443 SmallVector<std::string, 4> StrOptions; 444 445 // Convert to strings. 446 for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) { 447 MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii)); 448 StrOptions.push_back(MDOption->getString()); 449 } 450 451 Streamer.EmitLinkerOptions(StrOptions); 452 } 453 } 454 455 // The section is mandatory. If we don't have it, then we don't have GC info. 456 if (SectionVal.empty()) return; 457 458 StringRef Segment, Section; 459 unsigned TAA = 0, StubSize = 0; 460 bool TAAParsed; 461 std::string ErrorCode = 462 MCSectionMachO::ParseSectionSpecifier(SectionVal, Segment, Section, 463 TAA, TAAParsed, StubSize); 464 if (!ErrorCode.empty()) 465 // If invalid, report the error with report_fatal_error. 466 report_fatal_error("Invalid section specifier '" + Section + "': " + 467 ErrorCode + "."); 468 469 // Get the section. 470 const MCSectionMachO *S = 471 getContext().getMachOSection(Segment, Section, TAA, StubSize, 472 SectionKind::getDataNoRel()); 473 Streamer.SwitchSection(S); 474 Streamer.EmitLabel(getContext(). 475 GetOrCreateSymbol(StringRef("L_OBJC_IMAGE_INFO"))); 476 Streamer.EmitIntValue(VersionVal, 4); 477 Streamer.EmitIntValue(ImageInfoFlags, 4); 478 Streamer.AddBlankLine(); 479 } 480 481 const MCSection *TargetLoweringObjectFileMachO:: 482 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 483 Mangler *Mang, const TargetMachine &TM) const { 484 // Parse the section specifier and create it if valid. 485 StringRef Segment, Section; 486 unsigned TAA = 0, StubSize = 0; 487 bool TAAParsed; 488 std::string ErrorCode = 489 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section, 490 TAA, TAAParsed, StubSize); 491 if (!ErrorCode.empty()) { 492 // If invalid, report the error with report_fatal_error. 493 report_fatal_error("Global variable '" + GV->getName() + 494 "' has an invalid section specifier '" + 495 GV->getSection() + "': " + ErrorCode + "."); 496 } 497 498 // Get the section. 499 const MCSectionMachO *S = 500 getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind); 501 502 // If TAA wasn't set by ParseSectionSpecifier() above, 503 // use the value returned by getMachOSection() as a default. 504 if (!TAAParsed) 505 TAA = S->getTypeAndAttributes(); 506 507 // Okay, now that we got the section, verify that the TAA & StubSize agree. 508 // If the user declared multiple globals with different section flags, we need 509 // to reject it here. 510 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) { 511 // If invalid, report the error with report_fatal_error. 512 report_fatal_error("Global variable '" + GV->getName() + 513 "' section type or attributes does not match previous" 514 " section specifier"); 515 } 516 517 return S; 518 } 519 520 const MCSection *TargetLoweringObjectFileMachO:: 521 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 522 Mangler *Mang, const TargetMachine &TM) const { 523 524 // Handle thread local data. 525 if (Kind.isThreadBSS()) return TLSBSSSection; 526 if (Kind.isThreadData()) return TLSDataSection; 527 528 if (Kind.isText()) 529 return GV->isWeakForLinker() ? TextCoalSection : TextSection; 530 531 // If this is weak/linkonce, put this in a coalescable section, either in text 532 // or data depending on if it is writable. 533 if (GV->isWeakForLinker()) { 534 if (Kind.isReadOnly()) 535 return ConstTextCoalSection; 536 return DataCoalSection; 537 } 538 539 // FIXME: Alignment check should be handled by section classifier. 540 if (Kind.isMergeable1ByteCString() && 541 TM.getDataLayout()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 542 return CStringSection; 543 544 // Do not put 16-bit arrays in the UString section if they have an 545 // externally visible label, this runs into issues with certain linker 546 // versions. 547 if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() && 548 TM.getDataLayout()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 549 return UStringSection; 550 551 if (Kind.isMergeableConst()) { 552 if (Kind.isMergeableConst4()) 553 return FourByteConstantSection; 554 if (Kind.isMergeableConst8()) 555 return EightByteConstantSection; 556 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 557 return SixteenByteConstantSection; 558 } 559 560 // Otherwise, if it is readonly, but not something we can specially optimize, 561 // just drop it in .const. 562 if (Kind.isReadOnly()) 563 return ReadOnlySection; 564 565 // If this is marked const, put it into a const section. But if the dynamic 566 // linker needs to write to it, put it in the data segment. 567 if (Kind.isReadOnlyWithRel()) 568 return ConstDataSection; 569 570 // Put zero initialized globals with strong external linkage in the 571 // DATA, __common section with the .zerofill directive. 572 if (Kind.isBSSExtern()) 573 return DataCommonSection; 574 575 // Put zero initialized globals with local linkage in __DATA,__bss directive 576 // with the .zerofill directive (aka .lcomm). 577 if (Kind.isBSSLocal()) 578 return DataBSSSection; 579 580 // Otherwise, just drop the variable in the normal data section. 581 return DataSection; 582 } 583 584 const MCSection * 585 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { 586 // If this constant requires a relocation, we have to put it in the data 587 // segment, not in the text segment. 588 if (Kind.isDataRel() || Kind.isReadOnlyWithRel()) 589 return ConstDataSection; 590 591 if (Kind.isMergeableConst4()) 592 return FourByteConstantSection; 593 if (Kind.isMergeableConst8()) 594 return EightByteConstantSection; 595 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 596 return SixteenByteConstantSection; 597 return ReadOnlySection; // .const 598 } 599 600 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide 601 /// not to emit the UsedDirective for some symbols in llvm.used. 602 // FIXME: REMOVE this (rdar://7071300) 603 bool TargetLoweringObjectFileMachO:: 604 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { 605 /// On Darwin, internally linked data beginning with "L" or "l" does not have 606 /// the directive emitted (this occurs in ObjC metadata). 607 if (!GV) return false; 608 609 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. 610 if (GV->hasLocalLinkage() && !isa<Function>(GV)) { 611 // FIXME: ObjC metadata is currently emitted as internal symbols that have 612 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and 613 // this horrible hack can go away. 614 MCSymbol *Sym = getSymbol(*Mang, GV); 615 if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l') 616 return false; 617 } 618 619 return true; 620 } 621 622 const MCExpr *TargetLoweringObjectFileMachO:: 623 getTTypeGlobalReference(const GlobalValue *GV, Mangler *Mang, 624 MachineModuleInfo *MMI, unsigned Encoding, 625 MCStreamer &Streamer) const { 626 // The mach-o version of this method defaults to returning a stub reference. 627 628 if (Encoding & DW_EH_PE_indirect) { 629 MachineModuleInfoMachO &MachOMMI = 630 MMI->getObjFileInfo<MachineModuleInfoMachO>(); 631 632 MCSymbol *SSym = getSymbolWithGlobalValueBase(*Mang, GV, "$non_lazy_ptr"); 633 634 // Add information about the stub reference to MachOMMI so that the stub 635 // gets emitted by the asmprinter. 636 MachineModuleInfoImpl::StubValueTy &StubSym = 637 GV->hasHiddenVisibility() ? MachOMMI.getHiddenGVStubEntry(SSym) : 638 MachOMMI.getGVStubEntry(SSym); 639 if (StubSym.getPointer() == 0) { 640 MCSymbol *Sym = getSymbol(*Mang, GV); 641 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 642 } 643 644 return TargetLoweringObjectFile:: 645 getTTypeReference(MCSymbolRefExpr::Create(SSym, getContext()), 646 Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); 647 } 648 649 return TargetLoweringObjectFile:: 650 getTTypeGlobalReference(GV, Mang, MMI, Encoding, Streamer); 651 } 652 653 MCSymbol *TargetLoweringObjectFileMachO:: 654 getCFIPersonalitySymbol(const GlobalValue *GV, Mangler *Mang, 655 MachineModuleInfo *MMI) const { 656 // The mach-o version of this method defaults to returning a stub reference. 657 MachineModuleInfoMachO &MachOMMI = 658 MMI->getObjFileInfo<MachineModuleInfoMachO>(); 659 660 MCSymbol *SSym = getSymbolWithGlobalValueBase(*Mang, GV, "$non_lazy_ptr"); 661 662 // Add information about the stub reference to MachOMMI so that the stub 663 // gets emitted by the asmprinter. 664 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym); 665 if (StubSym.getPointer() == 0) { 666 MCSymbol *Sym = getSymbol(*Mang, GV); 667 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 668 } 669 670 return SSym; 671 } 672 673 //===----------------------------------------------------------------------===// 674 // COFF 675 //===----------------------------------------------------------------------===// 676 677 static unsigned 678 getCOFFSectionFlags(SectionKind K) { 679 unsigned Flags = 0; 680 681 if (K.isMetadata()) 682 Flags |= 683 COFF::IMAGE_SCN_MEM_DISCARDABLE; 684 else if (K.isText()) 685 Flags |= 686 COFF::IMAGE_SCN_MEM_EXECUTE | 687 COFF::IMAGE_SCN_MEM_READ | 688 COFF::IMAGE_SCN_CNT_CODE; 689 else if (K.isBSS ()) 690 Flags |= 691 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA | 692 COFF::IMAGE_SCN_MEM_READ | 693 COFF::IMAGE_SCN_MEM_WRITE; 694 else if (K.isThreadLocal()) 695 Flags |= 696 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 697 COFF::IMAGE_SCN_MEM_READ | 698 COFF::IMAGE_SCN_MEM_WRITE; 699 else if (K.isReadOnly()) 700 Flags |= 701 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 702 COFF::IMAGE_SCN_MEM_READ; 703 else if (K.isWriteable()) 704 Flags |= 705 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 706 COFF::IMAGE_SCN_MEM_READ | 707 COFF::IMAGE_SCN_MEM_WRITE; 708 709 return Flags; 710 } 711 712 const MCSection *TargetLoweringObjectFileCOFF:: 713 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 714 Mangler *Mang, const TargetMachine &TM) const { 715 int Selection = 0; 716 unsigned Characteristics = getCOFFSectionFlags(Kind); 717 StringRef Name = GV->getSection(); 718 StringRef COMDATSymName = ""; 719 if (GV->isWeakForLinker()) { 720 Selection = COFF::IMAGE_COMDAT_SELECT_ANY; 721 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT; 722 MCSymbol *Sym = getSymbol(*Mang, GV); 723 COMDATSymName = Sym->getName(); 724 } 725 return getContext().getCOFFSection(Name, 726 Characteristics, 727 Kind, 728 COMDATSymName, 729 Selection); 730 } 731 732 static const char *getCOFFSectionNameForUniqueGlobal(SectionKind Kind) { 733 if (Kind.isText()) 734 return ".text"; 735 if (Kind.isBSS ()) 736 return ".bss"; 737 if (Kind.isThreadLocal()) 738 return ".tls$"; 739 if (Kind.isWriteable()) 740 return ".data"; 741 return ".rdata"; 742 } 743 744 745 const MCSection *TargetLoweringObjectFileCOFF:: 746 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 747 Mangler *Mang, const TargetMachine &TM) const { 748 749 // If this global is linkonce/weak and the target handles this by emitting it 750 // into a 'uniqued' section name, create and return the section now. 751 if (GV->isWeakForLinker()) { 752 const char *Name = getCOFFSectionNameForUniqueGlobal(Kind); 753 unsigned Characteristics = getCOFFSectionFlags(Kind); 754 755 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT; 756 MCSymbol *Sym = getSymbol(*Mang, GV); 757 return getContext().getCOFFSection(Name, Characteristics, 758 Kind, Sym->getName(), 759 COFF::IMAGE_COMDAT_SELECT_ANY); 760 } 761 762 if (Kind.isText()) 763 return TextSection; 764 765 if (Kind.isThreadLocal()) 766 return TLSDataSection; 767 768 if (Kind.isReadOnly()) 769 return ReadOnlySection; 770 771 if (Kind.isBSS()) 772 return BSSSection; 773 774 return DataSection; 775 } 776 777 void TargetLoweringObjectFileCOFF:: 778 emitModuleFlags(MCStreamer &Streamer, 779 ArrayRef<Module::ModuleFlagEntry> ModuleFlags, 780 Mangler *Mang, const TargetMachine &TM) const { 781 MDNode *LinkerOptions = 0; 782 783 // Look for the "Linker Options" flag, since it's the only one we support. 784 for (ArrayRef<Module::ModuleFlagEntry>::iterator 785 i = ModuleFlags.begin(), e = ModuleFlags.end(); i != e; ++i) { 786 const Module::ModuleFlagEntry &MFE = *i; 787 StringRef Key = MFE.Key->getString(); 788 Value *Val = MFE.Val; 789 if (Key == "Linker Options") { 790 LinkerOptions = cast<MDNode>(Val); 791 break; 792 } 793 } 794 if (!LinkerOptions) 795 return; 796 797 // Emit the linker options to the linker .drectve section. According to the 798 // spec, this section is a space-separated string containing flags for linker. 799 const MCSection *Sec = getDrectveSection(); 800 Streamer.SwitchSection(Sec); 801 for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) { 802 MDNode *MDOptions = cast<MDNode>(LinkerOptions->getOperand(i)); 803 for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) { 804 MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii)); 805 StringRef Op = MDOption->getString(); 806 // Lead with a space for consistency with our dllexport implementation. 807 std::string Escaped(" "); 808 if (Op.find(" ") != StringRef::npos) { 809 // The PE-COFF spec says args with spaces must be quoted. It doesn't say 810 // how to escape quotes, but it probably uses this algorithm: 811 // http://msdn.microsoft.com/en-us/library/17w5ykft(v=vs.85).aspx 812 // FIXME: Reuse escaping code from Support/Windows/Program.inc 813 Escaped.push_back('\"'); 814 Escaped.append(Op); 815 Escaped.push_back('\"'); 816 } else { 817 Escaped.append(Op); 818 } 819 Streamer.EmitBytes(Escaped); 820 } 821 } 822 } 823