1 //===-- llvm/Target/TargetLoweringObjectFile.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/Target/TargetLoweringObjectFile.h" 16 #include "llvm/Constants.h" 17 #include "llvm/DerivedTypes.h" 18 #include "llvm/GlobalVariable.h" 19 #include "llvm/MC/MCContext.h" 20 #include "llvm/MC/MCSectionMachO.h" 21 #include "llvm/Target/TargetAsmInfo.h" 22 #include "llvm/Target/TargetData.h" 23 #include "llvm/Target/TargetMachine.h" 24 #include "llvm/Target/TargetOptions.h" 25 #include "llvm/Support/Mangler.h" 26 #include "llvm/ADT/StringExtras.h" 27 using namespace llvm; 28 29 //===----------------------------------------------------------------------===// 30 // Generic Code 31 //===----------------------------------------------------------------------===// 32 33 TargetLoweringObjectFile::TargetLoweringObjectFile() : Ctx(0) { 34 TextSection = 0; 35 DataSection = 0; 36 BSSSection = 0; 37 ReadOnlySection = 0; 38 StaticCtorSection = 0; 39 StaticDtorSection = 0; 40 LSDASection = 0; 41 EHFrameSection = 0; 42 43 DwarfAbbrevSection = 0; 44 DwarfInfoSection = 0; 45 DwarfLineSection = 0; 46 DwarfFrameSection = 0; 47 DwarfPubNamesSection = 0; 48 DwarfPubTypesSection = 0; 49 DwarfDebugInlineSection = 0; 50 DwarfStrSection = 0; 51 DwarfLocSection = 0; 52 DwarfARangesSection = 0; 53 DwarfRangesSection = 0; 54 DwarfMacroInfoSection = 0; 55 } 56 57 TargetLoweringObjectFile::~TargetLoweringObjectFile() { 58 } 59 60 static bool isSuitableForBSS(const GlobalVariable *GV) { 61 Constant *C = GV->getInitializer(); 62 63 // Must have zero initializer. 64 if (!C->isNullValue()) 65 return false; 66 67 // Leave constant zeros in readonly constant sections, so they can be shared. 68 if (GV->isConstant()) 69 return false; 70 71 // If the global has an explicit section specified, don't put it in BSS. 72 if (!GV->getSection().empty()) 73 return false; 74 75 // If -nozero-initialized-in-bss is specified, don't ever use BSS. 76 if (NoZerosInBSS) 77 return false; 78 79 // Otherwise, put it in BSS! 80 return true; 81 } 82 83 /// IsNullTerminatedString - Return true if the specified constant (which is 84 /// known to have a type that is an array of 1/2/4 byte elements) ends with a 85 /// nul value and contains no other nuls in it. 86 static bool IsNullTerminatedString(const Constant *C) { 87 const ArrayType *ATy = cast<ArrayType>(C->getType()); 88 89 // First check: is we have constant array of i8 terminated with zero 90 if (const ConstantArray *CVA = dyn_cast<ConstantArray>(C)) { 91 if (ATy->getNumElements() == 0) return false; 92 93 ConstantInt *Null = 94 dyn_cast<ConstantInt>(CVA->getOperand(ATy->getNumElements()-1)); 95 if (Null == 0 || Null->getZExtValue() != 0) 96 return false; // Not null terminated. 97 98 // Verify that the null doesn't occur anywhere else in the string. 99 for (unsigned i = 0, e = ATy->getNumElements()-1; i != e; ++i) 100 // Reject constantexpr elements etc. 101 if (!isa<ConstantInt>(CVA->getOperand(i)) || 102 CVA->getOperand(i) == Null) 103 return false; 104 return true; 105 } 106 107 // Another possibility: [1 x i8] zeroinitializer 108 if (isa<ConstantAggregateZero>(C)) 109 return ATy->getNumElements() == 1; 110 111 return false; 112 } 113 114 /// getKindForGlobal - This is a top-level target-independent classifier for 115 /// a global variable. Given an global variable and information from TM, it 116 /// classifies the global in a variety of ways that make various target 117 /// implementations simpler. The target implementation is free to ignore this 118 /// extra info of course. 119 SectionKind TargetLoweringObjectFile::getKindForGlobal(const GlobalValue *GV, 120 const TargetMachine &TM){ 121 assert(!GV->isDeclaration() && !GV->hasAvailableExternallyLinkage() && 122 "Can only be used for global definitions"); 123 124 Reloc::Model ReloModel = TM.getRelocationModel(); 125 126 // Early exit - functions should be always in text sections. 127 const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV); 128 if (GVar == 0) 129 return SectionKind::getText(); 130 131 132 // Handle thread-local data first. 133 if (GVar->isThreadLocal()) { 134 if (isSuitableForBSS(GVar)) 135 return SectionKind::getThreadBSS(); 136 return SectionKind::getThreadData(); 137 } 138 139 // Variable can be easily put to BSS section. 140 if (isSuitableForBSS(GVar)) 141 return SectionKind::getBSS(); 142 143 Constant *C = GVar->getInitializer(); 144 145 // If the global is marked constant, we can put it into a mergable section, 146 // a mergable string section, or general .data if it contains relocations. 147 if (GVar->isConstant()) { 148 // If the initializer for the global contains something that requires a 149 // relocation, then we may have to drop this into a wriable data section 150 // even though it is marked const. 151 switch (C->getRelocationInfo()) { 152 default: llvm_unreachable("unknown relocation info kind"); 153 case Constant::NoRelocation: 154 // If initializer is a null-terminated string, put it in a "cstring" 155 // section of the right width. 156 if (const ArrayType *ATy = dyn_cast<ArrayType>(C->getType())) { 157 if (const IntegerType *ITy = 158 dyn_cast<IntegerType>(ATy->getElementType())) { 159 if ((ITy->getBitWidth() == 8 || ITy->getBitWidth() == 16 || 160 ITy->getBitWidth() == 32) && 161 IsNullTerminatedString(C)) { 162 if (ITy->getBitWidth() == 8) 163 return SectionKind::getMergeable1ByteCString(); 164 if (ITy->getBitWidth() == 16) 165 return SectionKind::getMergeable2ByteCString(); 166 167 assert(ITy->getBitWidth() == 32 && "Unknown width"); 168 return SectionKind::getMergeable4ByteCString(); 169 } 170 } 171 } 172 173 // Otherwise, just drop it into a mergable constant section. If we have 174 // a section for this size, use it, otherwise use the arbitrary sized 175 // mergable section. 176 switch (TM.getTargetData()->getTypeAllocSize(C->getType())) { 177 case 4: return SectionKind::getMergeableConst4(); 178 case 8: return SectionKind::getMergeableConst8(); 179 case 16: return SectionKind::getMergeableConst16(); 180 default: return SectionKind::getMergeableConst(); 181 } 182 183 case Constant::LocalRelocation: 184 // In static relocation model, the linker will resolve all addresses, so 185 // the relocation entries will actually be constants by the time the app 186 // starts up. However, we can't put this into a mergable section, because 187 // the linker doesn't take relocations into consideration when it tries to 188 // merge entries in the section. 189 if (ReloModel == Reloc::Static) 190 return SectionKind::getReadOnly(); 191 192 // Otherwise, the dynamic linker needs to fix it up, put it in the 193 // writable data.rel.local section. 194 return SectionKind::getReadOnlyWithRelLocal(); 195 196 case Constant::GlobalRelocations: 197 // In static relocation model, the linker will resolve all addresses, so 198 // the relocation entries will actually be constants by the time the app 199 // starts up. However, we can't put this into a mergable section, because 200 // the linker doesn't take relocations into consideration when it tries to 201 // merge entries in the section. 202 if (ReloModel == Reloc::Static) 203 return SectionKind::getReadOnly(); 204 205 // Otherwise, the dynamic linker needs to fix it up, put it in the 206 // writable data.rel section. 207 return SectionKind::getReadOnlyWithRel(); 208 } 209 } 210 211 // Okay, this isn't a constant. If the initializer for the global is going 212 // to require a runtime relocation by the dynamic linker, put it into a more 213 // specific section to improve startup time of the app. This coalesces these 214 // globals together onto fewer pages, improving the locality of the dynamic 215 // linker. 216 if (ReloModel == Reloc::Static) 217 return SectionKind::getDataNoRel(); 218 219 switch (C->getRelocationInfo()) { 220 default: llvm_unreachable("unknown relocation info kind"); 221 case Constant::NoRelocation: 222 return SectionKind::getDataNoRel(); 223 case Constant::LocalRelocation: 224 return SectionKind::getDataRelLocal(); 225 case Constant::GlobalRelocations: 226 return SectionKind::getDataRel(); 227 } 228 } 229 230 /// SectionForGlobal - This method computes the appropriate section to emit 231 /// the specified global variable or function definition. This should not 232 /// be passed external (or available externally) globals. 233 const MCSection *TargetLoweringObjectFile:: 234 SectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang, 235 const TargetMachine &TM) const { 236 // Select section name. 237 if (GV->hasSection()) 238 return getExplicitSectionGlobal(GV, Kind, Mang, TM); 239 240 241 // Use default section depending on the 'type' of global 242 return SelectSectionForGlobal(GV, Kind, Mang, TM); 243 } 244 245 246 // Lame default implementation. Calculate the section name for global. 247 const MCSection * 248 TargetLoweringObjectFile::SelectSectionForGlobal(const GlobalValue *GV, 249 SectionKind Kind, 250 Mangler *Mang, 251 const TargetMachine &TM) const{ 252 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 253 254 if (Kind.isText()) 255 return getTextSection(); 256 257 if (Kind.isBSS() && BSSSection != 0) 258 return BSSSection; 259 260 if (Kind.isReadOnly() && ReadOnlySection != 0) 261 return ReadOnlySection; 262 263 return getDataSection(); 264 } 265 266 /// getSectionForConstant - Given a mergable constant with the 267 /// specified size and relocation information, return a section that it 268 /// should be placed in. 269 const MCSection * 270 TargetLoweringObjectFile::getSectionForConstant(SectionKind Kind) const { 271 if (Kind.isReadOnly() && ReadOnlySection != 0) 272 return ReadOnlySection; 273 274 return DataSection; 275 } 276 277 278 279 //===----------------------------------------------------------------------===// 280 // ELF 281 //===----------------------------------------------------------------------===// 282 283 const MCSection *TargetLoweringObjectFileELF:: 284 getELFSection(const char *Name, bool isDirective, SectionKind Kind) const { 285 if (MCSection *S = getContext().GetSection(Name)) 286 return S; 287 return MCSectionELF::Create(Name, isDirective, Kind, getContext()); 288 } 289 290 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx, 291 const TargetMachine &TM) { 292 TargetLoweringObjectFile::Initialize(Ctx, TM); 293 if (!HasCrazyBSS) 294 BSSSection = getELFSection("\t.bss", true, SectionKind::getBSS()); 295 else 296 // PPC/Linux doesn't support the .bss directive, it needs .section .bss. 297 // FIXME: Does .section .bss work everywhere?? 298 // FIXME2: this should just be handle by the section printer. We should get 299 // away from syntactic view of the sections and MCSection should just be a 300 // semantic view. 301 BSSSection = getELFSection("\t.bss", false, SectionKind::getBSS()); 302 303 304 TextSection = getELFSection("\t.text", true, SectionKind::getText()); 305 DataSection = getELFSection("\t.data", true, SectionKind::getDataRel()); 306 ReadOnlySection = 307 getELFSection("\t.rodata", false, SectionKind::getReadOnly()); 308 TLSDataSection = 309 getELFSection("\t.tdata", false, SectionKind::getThreadData()); 310 311 TLSBSSSection = getELFSection("\t.tbss", false, 312 SectionKind::getThreadBSS()); 313 314 DataRelSection = getELFSection("\t.data.rel", false, 315 SectionKind::getDataRel()); 316 DataRelLocalSection = getELFSection("\t.data.rel.local", false, 317 SectionKind::getDataRelLocal()); 318 DataRelROSection = getELFSection("\t.data.rel.ro", false, 319 SectionKind::getReadOnlyWithRel()); 320 DataRelROLocalSection = 321 getELFSection("\t.data.rel.ro.local", false, 322 SectionKind::getReadOnlyWithRelLocal()); 323 324 MergeableConst4Section = getELFSection(".rodata.cst4", false, 325 SectionKind::getMergeableConst4()); 326 MergeableConst8Section = getELFSection(".rodata.cst8", false, 327 SectionKind::getMergeableConst8()); 328 MergeableConst16Section = getELFSection(".rodata.cst16", false, 329 SectionKind::getMergeableConst16()); 330 331 StaticCtorSection = 332 getELFSection(".ctors", false, SectionKind::getDataRel()); 333 StaticDtorSection = 334 getELFSection(".dtors", false, SectionKind::getDataRel()); 335 336 // Exception Handling Sections. 337 338 // FIXME: We're emitting LSDA info into a readonly section on ELF, even though 339 // it contains relocatable pointers. In PIC mode, this is probably a big 340 // runtime hit for C++ apps. Either the contents of the LSDA need to be 341 // adjusted or this should be a data section. 342 LSDASection = 343 getELFSection(".gcc_except_table", false, SectionKind::getReadOnly()); 344 EHFrameSection = 345 getELFSection(".eh_frame", false, SectionKind::getDataRel()); 346 347 // Debug Info Sections. 348 DwarfAbbrevSection = 349 getELFSection(".debug_abbrev", false, SectionKind::getMetadata()); 350 DwarfInfoSection = 351 getELFSection(".debug_info", false, SectionKind::getMetadata()); 352 DwarfLineSection = 353 getELFSection(".debug_line", false, SectionKind::getMetadata()); 354 DwarfFrameSection = 355 getELFSection(".debug_frame", false, SectionKind::getMetadata()); 356 DwarfPubNamesSection = 357 getELFSection(".debug_pubnames", false, SectionKind::getMetadata()); 358 DwarfPubTypesSection = 359 getELFSection(".debug_pubtypes", false, SectionKind::getMetadata()); 360 DwarfStrSection = 361 getELFSection(".debug_str", false, SectionKind::getMetadata()); 362 DwarfLocSection = 363 getELFSection(".debug_loc", false, SectionKind::getMetadata()); 364 DwarfARangesSection = 365 getELFSection(".debug_aranges", false, SectionKind::getMetadata()); 366 DwarfRangesSection = 367 getELFSection(".debug_ranges", false, SectionKind::getMetadata()); 368 DwarfMacroInfoSection = 369 getELFSection(".debug_macinfo", false, SectionKind::getMetadata()); 370 } 371 372 373 static SectionKind 374 getELFKindForNamedSection(const char *Name, SectionKind K) { 375 if (Name[0] != '.') return K; 376 377 // Some lame default implementation based on some magic section names. 378 if (strncmp(Name, ".gnu.linkonce.b.", 16) == 0 || 379 strncmp(Name, ".llvm.linkonce.b.", 17) == 0 || 380 strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 || 381 strncmp(Name, ".llvm.linkonce.sb.", 18) == 0) 382 return SectionKind::getBSS(); 383 384 if (strcmp(Name, ".tdata") == 0 || 385 strncmp(Name, ".tdata.", 7) == 0 || 386 strncmp(Name, ".gnu.linkonce.td.", 17) == 0 || 387 strncmp(Name, ".llvm.linkonce.td.", 18) == 0) 388 return SectionKind::getThreadData(); 389 390 if (strcmp(Name, ".tbss") == 0 || 391 strncmp(Name, ".tbss.", 6) == 0 || 392 strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 || 393 strncmp(Name, ".llvm.linkonce.tb.", 18) == 0) 394 return SectionKind::getThreadBSS(); 395 396 return K; 397 } 398 399 const MCSection *TargetLoweringObjectFileELF:: 400 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 401 Mangler *Mang, const TargetMachine &TM) const { 402 // Infer section flags from the section name if we can. 403 Kind = getELFKindForNamedSection(GV->getSection().c_str(), Kind); 404 405 return getELFSection(GV->getSection().c_str(), false, Kind); 406 } 407 408 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) { 409 if (Kind.isText()) return ".gnu.linkonce.t."; 410 if (Kind.isReadOnly()) return ".gnu.linkonce.r."; 411 412 if (Kind.isThreadData()) return ".gnu.linkonce.td."; 413 if (Kind.isThreadBSS()) return ".gnu.linkonce.tb."; 414 415 if (Kind.isBSS()) return ".gnu.linkonce.b."; 416 if (Kind.isDataNoRel()) return ".gnu.linkonce.d."; 417 if (Kind.isDataRelLocal()) return ".gnu.linkonce.d.rel.local."; 418 if (Kind.isDataRel()) return ".gnu.linkonce.d.rel."; 419 if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local."; 420 421 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 422 return ".gnu.linkonce.d.rel.ro."; 423 } 424 425 const MCSection *TargetLoweringObjectFileELF:: 426 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 427 Mangler *Mang, const TargetMachine &TM) const { 428 429 // If this global is linkonce/weak and the target handles this by emitting it 430 // into a 'uniqued' section name, create and return the section now. 431 if (GV->isWeakForLinker()) { 432 const char *Prefix = getSectionPrefixForUniqueGlobal(Kind); 433 std::string Name = Mang->makeNameProper(GV->getNameStr()); 434 return getELFSection((Prefix+Name).c_str(), false, Kind); 435 } 436 437 if (Kind.isText()) return TextSection; 438 439 if (Kind.isMergeable1ByteCString() || 440 Kind.isMergeable2ByteCString() || 441 Kind.isMergeable4ByteCString()) { 442 443 // We also need alignment here. 444 // FIXME: this is getting the alignment of the character, not the 445 // alignment of the global! 446 unsigned Align = 447 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)); 448 449 const char *SizeSpec = ".rodata.str1."; 450 if (Kind.isMergeable2ByteCString()) 451 SizeSpec = ".rodata.str2."; 452 else if (Kind.isMergeable4ByteCString()) 453 SizeSpec = ".rodata.str4."; 454 else 455 assert(Kind.isMergeable1ByteCString() && "unknown string width"); 456 457 458 std::string Name = SizeSpec + utostr(Align); 459 return getELFSection(Name.c_str(), false, Kind); 460 } 461 462 if (Kind.isMergeableConst()) { 463 if (Kind.isMergeableConst4()) 464 return MergeableConst4Section; 465 if (Kind.isMergeableConst8()) 466 return MergeableConst8Section; 467 if (Kind.isMergeableConst16()) 468 return MergeableConst16Section; 469 return ReadOnlySection; // .const 470 } 471 472 if (Kind.isReadOnly()) return ReadOnlySection; 473 474 if (Kind.isThreadData()) return TLSDataSection; 475 if (Kind.isThreadBSS()) return TLSBSSSection; 476 477 if (Kind.isBSS()) return BSSSection; 478 479 if (Kind.isDataNoRel()) return DataSection; 480 if (Kind.isDataRelLocal()) return DataRelLocalSection; 481 if (Kind.isDataRel()) return DataRelSection; 482 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 483 484 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 485 return DataRelROSection; 486 } 487 488 /// getSectionForConstant - Given a mergeable constant with the 489 /// specified size and relocation information, return a section that it 490 /// should be placed in. 491 const MCSection *TargetLoweringObjectFileELF:: 492 getSectionForConstant(SectionKind Kind) const { 493 if (Kind.isMergeableConst4()) 494 return MergeableConst4Section; 495 if (Kind.isMergeableConst8()) 496 return MergeableConst8Section; 497 if (Kind.isMergeableConst16()) 498 return MergeableConst16Section; 499 if (Kind.isReadOnly()) 500 return ReadOnlySection; 501 502 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 503 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 504 return DataRelROSection; 505 } 506 507 //===----------------------------------------------------------------------===// 508 // MachO 509 //===----------------------------------------------------------------------===// 510 511 512 const MCSection *TargetLoweringObjectFileMachO:: 513 getMachOSection(StringRef Segment, StringRef Section, 514 unsigned TypeAndAttributes, 515 unsigned Reserved2, SectionKind Kind) const { 516 // FIXME: UNIQUE HERE. 517 //if (MCSection *S = getContext().GetSection(Name)) 518 // return S; 519 520 return MCSectionMachO::Create(Segment, Section, TypeAndAttributes, Reserved2, 521 Kind, getContext()); 522 } 523 524 525 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx, 526 const TargetMachine &TM) { 527 TargetLoweringObjectFile::Initialize(Ctx, TM); 528 529 TextSection // .text 530 = getMachOSection("__TEXT", "__text", 531 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 532 SectionKind::getText()); 533 DataSection // .data 534 = getMachOSection("__DATA", "__data", 0, SectionKind::getDataRel()); 535 536 CStringSection // .cstring 537 = getMachOSection("__TEXT", "__cstring", MCSectionMachO::S_CSTRING_LITERALS, 538 SectionKind::getMergeable1ByteCString()); 539 UStringSection 540 = getMachOSection("__TEXT","__ustring", 0, 541 SectionKind::getMergeable2ByteCString()); 542 FourByteConstantSection // .literal4 543 = getMachOSection("__TEXT", "__literal4", MCSectionMachO::S_4BYTE_LITERALS, 544 SectionKind::getMergeableConst4()); 545 EightByteConstantSection // .literal8 546 = getMachOSection("__TEXT", "__literal8", MCSectionMachO::S_8BYTE_LITERALS, 547 SectionKind::getMergeableConst8()); 548 549 // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back 550 // to using it in -static mode. 551 SixteenByteConstantSection = 0; 552 if (TM.getRelocationModel() != Reloc::Static && 553 TM.getTargetData()->getPointerSize() == 32) 554 SixteenByteConstantSection = // .literal16 555 getMachOSection("__TEXT", "__literal16",MCSectionMachO::S_16BYTE_LITERALS, 556 SectionKind::getMergeableConst16()); 557 558 ReadOnlySection // .const 559 = getMachOSection("__TEXT", "__const", 0, SectionKind::getReadOnly()); 560 561 TextCoalSection 562 = getMachOSection("__TEXT", "__textcoal_nt", 563 MCSectionMachO::S_COALESCED | 564 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 565 SectionKind::getText()); 566 ConstTextCoalSection 567 = getMachOSection("__TEXT", "__const_coal", MCSectionMachO::S_COALESCED, 568 SectionKind::getText()); 569 ConstDataCoalSection 570 = getMachOSection("__DATA","__const_coal", MCSectionMachO::S_COALESCED, 571 SectionKind::getText()); 572 ConstDataSection // .const_data 573 = getMachOSection("__DATA", "__const", 0, 574 SectionKind::getReadOnlyWithRel()); 575 DataCoalSection 576 = getMachOSection("__DATA","__datacoal_nt", MCSectionMachO::S_COALESCED, 577 SectionKind::getDataRel()); 578 579 if (TM.getRelocationModel() == Reloc::Static) { 580 StaticCtorSection 581 = getMachOSection("__TEXT", "__constructor", 0,SectionKind::getDataRel()); 582 StaticDtorSection 583 = getMachOSection("__TEXT", "__destructor", 0, SectionKind::getDataRel()); 584 } else { 585 StaticCtorSection 586 = getMachOSection("__DATA", "__mod_init_func", 587 MCSectionMachO::S_MOD_INIT_FUNC_POINTERS, 588 SectionKind::getDataRel()); 589 StaticDtorSection 590 = getMachOSection("__DATA", "__mod_term_func", 591 MCSectionMachO::S_MOD_TERM_FUNC_POINTERS, 592 SectionKind::getDataRel()); 593 } 594 595 // Exception Handling. 596 LSDASection = getMachOSection("__DATA", "__gcc_except_tab", 0, 597 SectionKind::getDataRel()); 598 EHFrameSection = 599 getMachOSection("__TEXT", "__eh_frame", 600 MCSectionMachO::S_COALESCED | 601 MCSectionMachO::S_ATTR_NO_TOC | 602 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS | 603 MCSectionMachO::S_ATTR_LIVE_SUPPORT, 604 SectionKind::getReadOnly()); 605 606 // Debug Information. 607 DwarfAbbrevSection = 608 getMachOSection("__DWARF", "__debug_abbrev", MCSectionMachO::S_ATTR_DEBUG, 609 SectionKind::getMetadata()); 610 DwarfInfoSection = 611 getMachOSection("__DWARF", "__debug_info", MCSectionMachO::S_ATTR_DEBUG, 612 SectionKind::getMetadata()); 613 DwarfLineSection = 614 getMachOSection("__DWARF", "__debug_line", MCSectionMachO::S_ATTR_DEBUG, 615 SectionKind::getMetadata()); 616 DwarfFrameSection = 617 getMachOSection("__DWARF", "__debug_frame", MCSectionMachO::S_ATTR_DEBUG, 618 SectionKind::getMetadata()); 619 DwarfPubNamesSection = 620 getMachOSection("__DWARF", "__debug_pubnames", MCSectionMachO::S_ATTR_DEBUG, 621 SectionKind::getMetadata()); 622 DwarfPubTypesSection = 623 getMachOSection("__DWARF", "__debug_pubtypes", MCSectionMachO::S_ATTR_DEBUG, 624 SectionKind::getMetadata()); 625 DwarfStrSection = 626 getMachOSection("__DWARF", "__debug_str", MCSectionMachO::S_ATTR_DEBUG, 627 SectionKind::getMetadata()); 628 DwarfLocSection = 629 getMachOSection("__DWARF", "__debug_loc", MCSectionMachO::S_ATTR_DEBUG, 630 SectionKind::getMetadata()); 631 DwarfARangesSection = 632 getMachOSection("__DWARF", "__debug_aranges", MCSectionMachO::S_ATTR_DEBUG, 633 SectionKind::getMetadata()); 634 DwarfRangesSection = 635 getMachOSection("__DWARF", "__debug_ranges", MCSectionMachO::S_ATTR_DEBUG, 636 SectionKind::getMetadata()); 637 DwarfMacroInfoSection = 638 getMachOSection("__DWARF", "__debug_macinfo", MCSectionMachO::S_ATTR_DEBUG, 639 SectionKind::getMetadata()); 640 DwarfDebugInlineSection = 641 getMachOSection("__DWARF", "__debug_inlined", MCSectionMachO::S_ATTR_DEBUG, 642 SectionKind::getMetadata()); 643 } 644 645 /// getLazySymbolPointerSection - Return the section corresponding to 646 /// the .lazy_symbol_pointer directive. 647 const MCSection *TargetLoweringObjectFileMachO:: 648 getLazySymbolPointerSection() const { 649 return getMachOSection("__DATA", "__la_symbol_ptr", 650 MCSectionMachO::S_LAZY_SYMBOL_POINTERS, 651 SectionKind::getMetadata()); 652 } 653 654 /// getNonLazySymbolPointerSection - Return the section corresponding to 655 /// the .non_lazy_symbol_pointer directive. 656 const MCSection *TargetLoweringObjectFileMachO:: 657 getNonLazySymbolPointerSection() const { 658 return getMachOSection("__DATA", "__nl_symbol_ptr", 659 MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS, 660 SectionKind::getMetadata()); 661 } 662 663 664 const MCSection *TargetLoweringObjectFileMachO:: 665 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 666 Mangler *Mang, const TargetMachine &TM) const { 667 // Parse the section specifier and create it if valid. 668 StringRef Segment, Section; 669 unsigned TAA, StubSize; 670 std::string ErrorCode = 671 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section, 672 TAA, StubSize); 673 if (ErrorCode.empty()) 674 return getMachOSection(Segment, Section, TAA, StubSize, Kind); 675 676 677 // If invalid, report the error with llvm_report_error. 678 llvm_report_error("Global variable '" + GV->getNameStr() + 679 "' has an invalid section specifier '" + GV->getSection() + 680 "': " + ErrorCode + "."); 681 // Fall back to dropping it into the data section. 682 return DataSection; 683 } 684 685 const MCSection *TargetLoweringObjectFileMachO:: 686 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 687 Mangler *Mang, const TargetMachine &TM) const { 688 assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS"); 689 690 if (Kind.isText()) 691 return GV->isWeakForLinker() ? TextCoalSection : TextSection; 692 693 // If this is weak/linkonce, put this in a coalescable section, either in text 694 // or data depending on if it is writable. 695 if (GV->isWeakForLinker()) { 696 if (Kind.isReadOnly()) 697 return ConstTextCoalSection; 698 return DataCoalSection; 699 } 700 701 // FIXME: Alignment check should be handled by section classifier. 702 if (Kind.isMergeable1ByteCString() || 703 Kind.isMergeable2ByteCString()) { 704 if (TM.getTargetData()->getPreferredAlignment( 705 cast<GlobalVariable>(GV)) < 32) { 706 if (Kind.isMergeable1ByteCString()) 707 return CStringSection; 708 assert(Kind.isMergeable2ByteCString()); 709 return UStringSection; 710 } 711 } 712 713 if (Kind.isMergeableConst()) { 714 if (Kind.isMergeableConst4()) 715 return FourByteConstantSection; 716 if (Kind.isMergeableConst8()) 717 return EightByteConstantSection; 718 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 719 return SixteenByteConstantSection; 720 } 721 722 // Otherwise, if it is readonly, but not something we can specially optimize, 723 // just drop it in .const. 724 if (Kind.isReadOnly()) 725 return ReadOnlySection; 726 727 // If this is marked const, put it into a const section. But if the dynamic 728 // linker needs to write to it, put it in the data segment. 729 if (Kind.isReadOnlyWithRel()) 730 return ConstDataSection; 731 732 // Otherwise, just drop the variable in the normal data section. 733 return DataSection; 734 } 735 736 const MCSection * 737 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { 738 // If this constant requires a relocation, we have to put it in the data 739 // segment, not in the text segment. 740 if (Kind.isDataRel()) 741 return ConstDataSection; 742 743 if (Kind.isMergeableConst4()) 744 return FourByteConstantSection; 745 if (Kind.isMergeableConst8()) 746 return EightByteConstantSection; 747 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 748 return SixteenByteConstantSection; 749 return ReadOnlySection; // .const 750 } 751 752 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide 753 /// not to emit the UsedDirective for some symbols in llvm.used. 754 // FIXME: REMOVE this (rdar://7071300) 755 bool TargetLoweringObjectFileMachO:: 756 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { 757 /// On Darwin, internally linked data beginning with "L" or "l" does not have 758 /// the directive emitted (this occurs in ObjC metadata). 759 if (!GV) return false; 760 761 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. 762 if (GV->hasLocalLinkage() && !isa<Function>(GV)) { 763 // FIXME: ObjC metadata is currently emitted as internal symbols that have 764 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and 765 // this horrible hack can go away. 766 const std::string &Name = Mang->getMangledName(GV); 767 if (Name[0] == 'L' || Name[0] == 'l') 768 return false; 769 } 770 771 return true; 772 } 773 774 775 //===----------------------------------------------------------------------===// 776 // COFF 777 //===----------------------------------------------------------------------===// 778 779 780 const MCSection *TargetLoweringObjectFileCOFF:: 781 getCOFFSection(const char *Name, bool isDirective, SectionKind Kind) const { 782 if (MCSection *S = getContext().GetSection(Name)) 783 return S; 784 return MCSectionCOFF::Create(Name, isDirective, Kind, getContext()); 785 } 786 787 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx, 788 const TargetMachine &TM) { 789 TargetLoweringObjectFile::Initialize(Ctx, TM); 790 TextSection = getCOFFSection("\t.text", true, SectionKind::getText()); 791 DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel()); 792 StaticCtorSection = 793 getCOFFSection(".ctors", false, SectionKind::getDataRel()); 794 StaticDtorSection = 795 getCOFFSection(".dtors", false, SectionKind::getDataRel()); 796 797 798 // Debug info. 799 // FIXME: Don't use 'directive' mode here. 800 DwarfAbbrevSection = 801 getCOFFSection("\t.section\t.debug_abbrev,\"dr\"", 802 true, SectionKind::getMetadata()); 803 DwarfInfoSection = 804 getCOFFSection("\t.section\t.debug_info,\"dr\"", 805 true, SectionKind::getMetadata()); 806 DwarfLineSection = 807 getCOFFSection("\t.section\t.debug_line,\"dr\"", 808 true, SectionKind::getMetadata()); 809 DwarfFrameSection = 810 getCOFFSection("\t.section\t.debug_frame,\"dr\"", 811 true, SectionKind::getMetadata()); 812 DwarfPubNamesSection = 813 getCOFFSection("\t.section\t.debug_pubnames,\"dr\"", 814 true, SectionKind::getMetadata()); 815 DwarfPubTypesSection = 816 getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"", 817 true, SectionKind::getMetadata()); 818 DwarfStrSection = 819 getCOFFSection("\t.section\t.debug_str,\"dr\"", 820 true, SectionKind::getMetadata()); 821 DwarfLocSection = 822 getCOFFSection("\t.section\t.debug_loc,\"dr\"", 823 true, SectionKind::getMetadata()); 824 DwarfARangesSection = 825 getCOFFSection("\t.section\t.debug_aranges,\"dr\"", 826 true, SectionKind::getMetadata()); 827 DwarfRangesSection = 828 getCOFFSection("\t.section\t.debug_ranges,\"dr\"", 829 true, SectionKind::getMetadata()); 830 DwarfMacroInfoSection = 831 getCOFFSection("\t.section\t.debug_macinfo,\"dr\"", 832 true, SectionKind::getMetadata()); 833 } 834 835 const MCSection *TargetLoweringObjectFileCOFF:: 836 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 837 Mangler *Mang, const TargetMachine &TM) const { 838 return getCOFFSection(GV->getSection().c_str(), false, Kind); 839 } 840 841 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) { 842 if (Kind.isText()) 843 return ".text$linkonce"; 844 if (Kind.isWriteable()) 845 return ".data$linkonce"; 846 return ".rdata$linkonce"; 847 } 848 849 850 const MCSection *TargetLoweringObjectFileCOFF:: 851 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 852 Mangler *Mang, const TargetMachine &TM) const { 853 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 854 855 // If this global is linkonce/weak and the target handles this by emitting it 856 // into a 'uniqued' section name, create and return the section now. 857 if (GV->isWeakForLinker()) { 858 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind); 859 std::string Name = Mang->makeNameProper(GV->getNameStr()); 860 return getCOFFSection((Prefix+Name).c_str(), false, Kind); 861 } 862 863 if (Kind.isText()) 864 return getTextSection(); 865 866 return getDataSection(); 867 } 868 869