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/MCSection.h" 21 #include "llvm/Target/TargetMachine.h" 22 #include "llvm/Target/TargetData.h" 23 #include "llvm/Target/TargetOptions.h" 24 #include "llvm/Support/Mangler.h" 25 #include "llvm/ADT/StringExtras.h" 26 using namespace llvm; 27 28 //===----------------------------------------------------------------------===// 29 // Generic Code 30 //===----------------------------------------------------------------------===// 31 32 TargetLoweringObjectFile::TargetLoweringObjectFile() : Ctx(0) { 33 TextSection = 0; 34 DataSection = 0; 35 BSSSection = 0; 36 ReadOnlySection = 0; 37 StaticCtorSection = 0; 38 StaticDtorSection = 0; 39 LSDASection = 0; 40 EHFrameSection = 0; 41 42 DwarfAbbrevSection = 0; 43 DwarfInfoSection = 0; 44 DwarfLineSection = 0; 45 DwarfFrameSection = 0; 46 DwarfPubNamesSection = 0; 47 DwarfPubTypesSection = 0; 48 DwarfDebugInlineSection = 0; 49 DwarfStrSection = 0; 50 DwarfLocSection = 0; 51 DwarfARangesSection = 0; 52 DwarfRangesSection = 0; 53 DwarfMacroInfoSection = 0; 54 } 55 56 TargetLoweringObjectFile::~TargetLoweringObjectFile() { 57 } 58 59 static bool isSuitableForBSS(const GlobalVariable *GV) { 60 Constant *C = GV->getInitializer(); 61 62 // Must have zero initializer. 63 if (!C->isNullValue()) 64 return false; 65 66 // Leave constant zeros in readonly constant sections, so they can be shared. 67 if (GV->isConstant()) 68 return false; 69 70 // If the global has an explicit section specified, don't put it in BSS. 71 if (!GV->getSection().empty()) 72 return false; 73 74 // If -nozero-initialized-in-bss is specified, don't ever use BSS. 75 if (NoZerosInBSS) 76 return false; 77 78 // Otherwise, put it in BSS! 79 return true; 80 } 81 82 /// IsNullTerminatedString - Return true if the specified constant (which is 83 /// known to have a type that is an array of 1/2/4 byte elements) ends with a 84 /// nul value and contains no other nuls in it. 85 static bool IsNullTerminatedString(const Constant *C) { 86 const ArrayType *ATy = cast<ArrayType>(C->getType()); 87 88 // First check: is we have constant array of i8 terminated with zero 89 if (const ConstantArray *CVA = dyn_cast<ConstantArray>(C)) { 90 if (ATy->getNumElements() == 0) return false; 91 92 ConstantInt *Null = 93 dyn_cast<ConstantInt>(CVA->getOperand(ATy->getNumElements()-1)); 94 if (Null == 0 || Null->getZExtValue() != 0) 95 return false; // Not null terminated. 96 97 // Verify that the null doesn't occur anywhere else in the string. 98 for (unsigned i = 0, e = ATy->getNumElements()-1; i != e; ++i) 99 // Reject constantexpr elements etc. 100 if (!isa<ConstantInt>(CVA->getOperand(i)) || 101 CVA->getOperand(i) == Null) 102 return false; 103 return true; 104 } 105 106 // Another possibility: [1 x i8] zeroinitializer 107 if (isa<ConstantAggregateZero>(C)) 108 return ATy->getNumElements() == 1; 109 110 return false; 111 } 112 113 /// getKindForGlobal - This is a top-level target-independent classifier for 114 /// a global variable. Given an global variable and information from TM, it 115 /// classifies the global in a variety of ways that make various target 116 /// implementations simpler. The target implementation is free to ignore this 117 /// extra info of course. 118 SectionKind TargetLoweringObjectFile::getKindForGlobal(const GlobalValue *GV, 119 const TargetMachine &TM){ 120 assert(!GV->isDeclaration() && !GV->hasAvailableExternallyLinkage() && 121 "Can only be used for global definitions"); 122 123 Reloc::Model ReloModel = TM.getRelocationModel(); 124 125 // Early exit - functions should be always in text sections. 126 const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV); 127 if (GVar == 0) 128 return SectionKind::getText(); 129 130 131 // Handle thread-local data first. 132 if (GVar->isThreadLocal()) { 133 if (isSuitableForBSS(GVar)) 134 return SectionKind::getThreadBSS(); 135 return SectionKind::getThreadData(); 136 } 137 138 // Variable can be easily put to BSS section. 139 if (isSuitableForBSS(GVar)) 140 return SectionKind::getBSS(); 141 142 Constant *C = GVar->getInitializer(); 143 144 // If the global is marked constant, we can put it into a mergable section, 145 // a mergable string section, or general .data if it contains relocations. 146 if (GVar->isConstant()) { 147 // If the initializer for the global contains something that requires a 148 // relocation, then we may have to drop this into a wriable data section 149 // even though it is marked const. 150 switch (C->getRelocationInfo()) { 151 default: llvm_unreachable("unknown relocation info kind"); 152 case Constant::NoRelocation: 153 // If initializer is a null-terminated string, put it in a "cstring" 154 // section of the right width. 155 if (const ArrayType *ATy = dyn_cast<ArrayType>(C->getType())) { 156 if (const IntegerType *ITy = 157 dyn_cast<IntegerType>(ATy->getElementType())) { 158 if ((ITy->getBitWidth() == 8 || ITy->getBitWidth() == 16 || 159 ITy->getBitWidth() == 32) && 160 IsNullTerminatedString(C)) { 161 if (ITy->getBitWidth() == 8) 162 return SectionKind::getMergeable1ByteCString(); 163 if (ITy->getBitWidth() == 16) 164 return SectionKind::getMergeable2ByteCString(); 165 166 assert(ITy->getBitWidth() == 32 && "Unknown width"); 167 return SectionKind::getMergeable4ByteCString(); 168 } 169 } 170 } 171 172 // Otherwise, just drop it into a mergable constant section. If we have 173 // a section for this size, use it, otherwise use the arbitrary sized 174 // mergable section. 175 switch (TM.getTargetData()->getTypeAllocSize(C->getType())) { 176 case 4: return SectionKind::getMergeableConst4(); 177 case 8: return SectionKind::getMergeableConst8(); 178 case 16: return SectionKind::getMergeableConst16(); 179 default: return SectionKind::getMergeableConst(); 180 } 181 182 case Constant::LocalRelocation: 183 // In static relocation model, the linker will resolve all addresses, so 184 // the relocation entries will actually be constants by the time the app 185 // starts up. However, we can't put this into a mergable section, because 186 // the linker doesn't take relocations into consideration when it tries to 187 // merge entries in the section. 188 if (ReloModel == Reloc::Static) 189 return SectionKind::getReadOnly(); 190 191 // Otherwise, the dynamic linker needs to fix it up, put it in the 192 // writable data.rel.local section. 193 return SectionKind::getReadOnlyWithRelLocal(); 194 195 case Constant::GlobalRelocations: 196 // In static relocation model, the linker will resolve all addresses, so 197 // the relocation entries will actually be constants by the time the app 198 // starts up. However, we can't put this into a mergable section, because 199 // the linker doesn't take relocations into consideration when it tries to 200 // merge entries in the section. 201 if (ReloModel == Reloc::Static) 202 return SectionKind::getReadOnly(); 203 204 // Otherwise, the dynamic linker needs to fix it up, put it in the 205 // writable data.rel section. 206 return SectionKind::getReadOnlyWithRel(); 207 } 208 } 209 210 // Okay, this isn't a constant. If the initializer for the global is going 211 // to require a runtime relocation by the dynamic linker, put it into a more 212 // specific section to improve startup time of the app. This coalesces these 213 // globals together onto fewer pages, improving the locality of the dynamic 214 // linker. 215 if (ReloModel == Reloc::Static) 216 return SectionKind::getDataNoRel(); 217 218 switch (C->getRelocationInfo()) { 219 default: llvm_unreachable("unknown relocation info kind"); 220 case Constant::NoRelocation: 221 return SectionKind::getDataNoRel(); 222 case Constant::LocalRelocation: 223 return SectionKind::getDataRelLocal(); 224 case Constant::GlobalRelocations: 225 return SectionKind::getDataRel(); 226 } 227 } 228 229 /// SectionForGlobal - This method computes the appropriate section to emit 230 /// the specified global variable or function definition. This should not 231 /// be passed external (or available externally) globals. 232 const MCSection *TargetLoweringObjectFile:: 233 SectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang, 234 const TargetMachine &TM) const { 235 // Select section name. 236 if (GV->hasSection()) 237 return getExplicitSectionGlobal(GV, Kind, Mang, TM); 238 239 240 // Use default section depending on the 'type' of global 241 return SelectSectionForGlobal(GV, Kind, Mang, TM); 242 } 243 244 245 // Lame default implementation. Calculate the section name for global. 246 const MCSection * 247 TargetLoweringObjectFile::SelectSectionForGlobal(const GlobalValue *GV, 248 SectionKind Kind, 249 Mangler *Mang, 250 const TargetMachine &TM) const{ 251 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 252 253 if (Kind.isText()) 254 return getTextSection(); 255 256 if (Kind.isBSS() && BSSSection != 0) 257 return BSSSection; 258 259 if (Kind.isReadOnly() && ReadOnlySection != 0) 260 return ReadOnlySection; 261 262 return getDataSection(); 263 } 264 265 /// getSectionForConstant - Given a mergable constant with the 266 /// specified size and relocation information, return a section that it 267 /// should be placed in. 268 const MCSection * 269 TargetLoweringObjectFile::getSectionForConstant(SectionKind Kind) const { 270 if (Kind.isReadOnly() && ReadOnlySection != 0) 271 return ReadOnlySection; 272 273 return DataSection; 274 } 275 276 277 278 //===----------------------------------------------------------------------===// 279 // ELF 280 //===----------------------------------------------------------------------===// 281 282 const MCSection *TargetLoweringObjectFileELF:: 283 getOrCreateSection(const char *Name, bool isDirective, SectionKind Kind) const { 284 if (MCSection *S = getContext().GetSection(Name)) 285 return S; 286 return MCSection::Create(Name, isDirective, Kind, getContext()); 287 } 288 289 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx, 290 const TargetMachine &TM) { 291 TargetLoweringObjectFile::Initialize(Ctx, TM); 292 if (!HasCrazyBSS) 293 BSSSection = getOrCreateSection("\t.bss", true, SectionKind::getBSS()); 294 else 295 // PPC/Linux doesn't support the .bss directive, it needs .section .bss. 296 // FIXME: Does .section .bss work everywhere?? 297 // FIXME2: this should just be handle by the section printer. We should get 298 // away from syntactic view of the sections and MCSection should just be a 299 // semantic view. 300 BSSSection = getOrCreateSection("\t.bss", false, SectionKind::getBSS()); 301 302 303 TextSection = getOrCreateSection("\t.text", true, SectionKind::getText()); 304 DataSection = getOrCreateSection("\t.data", true, SectionKind::getDataRel()); 305 ReadOnlySection = 306 getOrCreateSection("\t.rodata", false, SectionKind::getReadOnly()); 307 TLSDataSection = 308 getOrCreateSection("\t.tdata", false, SectionKind::getThreadData()); 309 310 TLSBSSSection = getOrCreateSection("\t.tbss", false, 311 SectionKind::getThreadBSS()); 312 313 DataRelSection = getOrCreateSection("\t.data.rel", false, 314 SectionKind::getDataRel()); 315 DataRelLocalSection = getOrCreateSection("\t.data.rel.local", false, 316 SectionKind::getDataRelLocal()); 317 DataRelROSection = getOrCreateSection("\t.data.rel.ro", false, 318 SectionKind::getReadOnlyWithRel()); 319 DataRelROLocalSection = 320 getOrCreateSection("\t.data.rel.ro.local", false, 321 SectionKind::getReadOnlyWithRelLocal()); 322 323 MergeableConst4Section = getOrCreateSection(".rodata.cst4", false, 324 SectionKind::getMergeableConst4()); 325 MergeableConst8Section = getOrCreateSection(".rodata.cst8", false, 326 SectionKind::getMergeableConst8()); 327 MergeableConst16Section = getOrCreateSection(".rodata.cst16", false, 328 SectionKind::getMergeableConst16()); 329 330 StaticCtorSection = 331 getOrCreateSection(".ctors", false, SectionKind::getDataRel()); 332 StaticDtorSection = 333 getOrCreateSection(".dtors", false, SectionKind::getDataRel()); 334 335 // Exception Handling Sections. 336 337 // FIXME: We're emitting LSDA info into a readonly section on ELF, even though 338 // it contains relocatable pointers. In PIC mode, this is probably a big 339 // runtime hit for C++ apps. Either the contents of the LSDA need to be 340 // adjusted or this should be a data section. 341 LSDASection = 342 getOrCreateSection(".gcc_except_table", false, SectionKind::getReadOnly()); 343 EHFrameSection = 344 getOrCreateSection(".eh_frame", false, SectionKind::getDataRel()); 345 346 // Debug Info Sections. 347 DwarfAbbrevSection = 348 getOrCreateSection(".debug_abbrev", false, SectionKind::getMetadata()); 349 DwarfInfoSection = 350 getOrCreateSection(".debug_info", false, SectionKind::getMetadata()); 351 DwarfLineSection = 352 getOrCreateSection(".debug_line", false, SectionKind::getMetadata()); 353 DwarfFrameSection = 354 getOrCreateSection(".debug_frame", false, SectionKind::getMetadata()); 355 DwarfPubNamesSection = 356 getOrCreateSection(".debug_pubnames", false, SectionKind::getMetadata()); 357 DwarfPubTypesSection = 358 getOrCreateSection(".debug_pubtypes", false, SectionKind::getMetadata()); 359 DwarfStrSection = 360 getOrCreateSection(".debug_str", false, SectionKind::getMetadata()); 361 DwarfLocSection = 362 getOrCreateSection(".debug_loc", false, SectionKind::getMetadata()); 363 DwarfARangesSection = 364 getOrCreateSection(".debug_aranges", false, SectionKind::getMetadata()); 365 DwarfRangesSection = 366 getOrCreateSection(".debug_ranges", false, SectionKind::getMetadata()); 367 DwarfMacroInfoSection = 368 getOrCreateSection(".debug_macinfo", false, SectionKind::getMetadata()); 369 } 370 371 372 static SectionKind 373 getELFKindForNamedSection(const char *Name, SectionKind K) { 374 if (Name[0] != '.') return K; 375 376 // Some lame default implementation based on some magic section names. 377 if (strncmp(Name, ".gnu.linkonce.b.", 16) == 0 || 378 strncmp(Name, ".llvm.linkonce.b.", 17) == 0 || 379 strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 || 380 strncmp(Name, ".llvm.linkonce.sb.", 18) == 0) 381 return SectionKind::getBSS(); 382 383 if (strcmp(Name, ".tdata") == 0 || 384 strncmp(Name, ".tdata.", 7) == 0 || 385 strncmp(Name, ".gnu.linkonce.td.", 17) == 0 || 386 strncmp(Name, ".llvm.linkonce.td.", 18) == 0) 387 return SectionKind::getThreadData(); 388 389 if (strcmp(Name, ".tbss") == 0 || 390 strncmp(Name, ".tbss.", 6) == 0 || 391 strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 || 392 strncmp(Name, ".llvm.linkonce.tb.", 18) == 0) 393 return SectionKind::getThreadBSS(); 394 395 return K; 396 } 397 398 const MCSection *TargetLoweringObjectFileELF:: 399 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 400 Mangler *Mang, const TargetMachine &TM) const { 401 // Infer section flags from the section name if we can. 402 Kind = getELFKindForNamedSection(GV->getSection().c_str(), Kind); 403 404 return getOrCreateSection(GV->getSection().c_str(), false, Kind); 405 } 406 407 408 409 void TargetLoweringObjectFileELF:: 410 getSectionFlagsAsString(SectionKind Kind, SmallVectorImpl<char> &Str) const { 411 Str.push_back(','); 412 Str.push_back('"'); 413 414 if (!Kind.isMetadata()) 415 Str.push_back('a'); 416 if (Kind.isText()) 417 Str.push_back('x'); 418 if (Kind.isWriteable()) 419 Str.push_back('w'); 420 if (Kind.isMergeable1ByteCString() || 421 Kind.isMergeable2ByteCString() || 422 Kind.isMergeable4ByteCString() || 423 Kind.isMergeableConst4() || 424 Kind.isMergeableConst8() || 425 Kind.isMergeableConst16()) 426 Str.push_back('M'); 427 if (Kind.isMergeable1ByteCString() || 428 Kind.isMergeable2ByteCString() || 429 Kind.isMergeable4ByteCString()) 430 Str.push_back('S'); 431 if (Kind.isThreadLocal()) 432 Str.push_back('T'); 433 434 Str.push_back('"'); 435 Str.push_back(','); 436 437 // If comment string is '@', e.g. as on ARM - use '%' instead 438 if (AtIsCommentChar) 439 Str.push_back('%'); 440 else 441 Str.push_back('@'); 442 443 const char *KindStr; 444 if (Kind.isBSS() || Kind.isThreadBSS()) 445 KindStr = "nobits"; 446 else 447 KindStr = "progbits"; 448 449 Str.append(KindStr, KindStr+strlen(KindStr)); 450 451 if (Kind.isMergeable1ByteCString()) { 452 Str.push_back(','); 453 Str.push_back('1'); 454 } else if (Kind.isMergeable2ByteCString()) { 455 Str.push_back(','); 456 Str.push_back('2'); 457 } else if (Kind.isMergeable4ByteCString()) { 458 Str.push_back(','); 459 Str.push_back('4'); 460 } else if (Kind.isMergeableConst4()) { 461 Str.push_back(','); 462 Str.push_back('4'); 463 } else if (Kind.isMergeableConst8()) { 464 Str.push_back(','); 465 Str.push_back('8'); 466 } else if (Kind.isMergeableConst16()) { 467 Str.push_back(','); 468 Str.push_back('1'); 469 Str.push_back('6'); 470 } 471 } 472 473 474 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) { 475 if (Kind.isText()) return ".gnu.linkonce.t."; 476 if (Kind.isReadOnly()) return ".gnu.linkonce.r."; 477 478 if (Kind.isThreadData()) return ".gnu.linkonce.td."; 479 if (Kind.isThreadBSS()) return ".gnu.linkonce.tb."; 480 481 if (Kind.isBSS()) return ".gnu.linkonce.b."; 482 if (Kind.isDataNoRel()) return ".gnu.linkonce.d."; 483 if (Kind.isDataRelLocal()) return ".gnu.linkonce.d.rel.local."; 484 if (Kind.isDataRel()) return ".gnu.linkonce.d.rel."; 485 if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local."; 486 487 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 488 return ".gnu.linkonce.d.rel.ro."; 489 } 490 491 const MCSection *TargetLoweringObjectFileELF:: 492 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 493 Mangler *Mang, const TargetMachine &TM) const { 494 495 // If this global is linkonce/weak and the target handles this by emitting it 496 // into a 'uniqued' section name, create and return the section now. 497 if (GV->isWeakForLinker()) { 498 const char *Prefix = getSectionPrefixForUniqueGlobal(Kind); 499 std::string Name = Mang->makeNameProper(GV->getNameStr()); 500 return getOrCreateSection((Prefix+Name).c_str(), false, Kind); 501 } 502 503 if (Kind.isText()) return TextSection; 504 505 if (Kind.isMergeable1ByteCString() || 506 Kind.isMergeable2ByteCString() || 507 Kind.isMergeable4ByteCString()) { 508 509 // We also need alignment here. 510 // FIXME: this is getting the alignment of the character, not the 511 // alignment of the global! 512 unsigned Align = 513 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)); 514 515 const char *SizeSpec = ".rodata.str1."; 516 if (Kind.isMergeable2ByteCString()) 517 SizeSpec = ".rodata.str2."; 518 else if (Kind.isMergeable4ByteCString()) 519 SizeSpec = ".rodata.str4."; 520 else 521 assert(Kind.isMergeable1ByteCString() && "unknown string width"); 522 523 524 std::string Name = SizeSpec + utostr(Align); 525 return getOrCreateSection(Name.c_str(), false, Kind); 526 } 527 528 if (Kind.isMergeableConst()) { 529 if (Kind.isMergeableConst4()) 530 return MergeableConst4Section; 531 if (Kind.isMergeableConst8()) 532 return MergeableConst8Section; 533 if (Kind.isMergeableConst16()) 534 return MergeableConst16Section; 535 return ReadOnlySection; // .const 536 } 537 538 if (Kind.isReadOnly()) return ReadOnlySection; 539 540 if (Kind.isThreadData()) return TLSDataSection; 541 if (Kind.isThreadBSS()) return TLSBSSSection; 542 543 if (Kind.isBSS()) return BSSSection; 544 545 if (Kind.isDataNoRel()) return DataSection; 546 if (Kind.isDataRelLocal()) return DataRelLocalSection; 547 if (Kind.isDataRel()) return DataRelSection; 548 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 549 550 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 551 return DataRelROSection; 552 } 553 554 /// getSectionForConstant - Given a mergeable constant with the 555 /// specified size and relocation information, return a section that it 556 /// should be placed in. 557 const MCSection *TargetLoweringObjectFileELF:: 558 getSectionForConstant(SectionKind Kind) const { 559 if (Kind.isMergeableConst4()) 560 return MergeableConst4Section; 561 if (Kind.isMergeableConst8()) 562 return MergeableConst8Section; 563 if (Kind.isMergeableConst16()) 564 return MergeableConst16Section; 565 if (Kind.isReadOnly()) 566 return ReadOnlySection; 567 568 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 569 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 570 return DataRelROSection; 571 } 572 573 //===----------------------------------------------------------------------===// 574 // MachO 575 //===----------------------------------------------------------------------===// 576 577 const MCSection *TargetLoweringObjectFileMachO:: 578 getOrCreateSection(const char *Name, bool isDirective, SectionKind Kind) const { 579 if (MCSection *S = getContext().GetSection(Name)) 580 return S; 581 return MCSection::Create(Name, isDirective, Kind, getContext()); 582 } 583 584 const MCSection *TargetLoweringObjectFileMachO:: 585 getMachOSection(const char *Name, bool isDirective, SectionKind K) { 586 // FOR NOW, Just forward. 587 return getOrCreateSection(Name, isDirective, K); 588 } 589 590 591 592 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx, 593 const TargetMachine &TM) { 594 TargetLoweringObjectFile::Initialize(Ctx, TM); 595 TextSection = getOrCreateSection("\t.text", true, 596 SectionKind::getText()); 597 DataSection = getOrCreateSection("\t.data", true, 598 SectionKind::getDataRel()); 599 600 CStringSection = getOrCreateSection("\t.cstring", true, 601 SectionKind::getMergeable1ByteCString()); 602 UStringSection = getOrCreateSection("__TEXT,__ustring", false, 603 SectionKind::getMergeable2ByteCString()); 604 FourByteConstantSection = getOrCreateSection("\t.literal4\n", true, 605 SectionKind::getMergeableConst4()); 606 EightByteConstantSection = getOrCreateSection("\t.literal8\n", true, 607 SectionKind::getMergeableConst8()); 608 609 // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back 610 // to using it in -static mode. 611 if (TM.getRelocationModel() != Reloc::Static && 612 TM.getTargetData()->getPointerSize() == 32) 613 SixteenByteConstantSection = 614 getOrCreateSection("\t.literal16\n", true, 615 SectionKind::getMergeableConst16()); 616 else 617 SixteenByteConstantSection = 0; 618 619 ReadOnlySection = getOrCreateSection("\t.const", true, 620 SectionKind::getReadOnly()); 621 622 TextCoalSection = 623 getOrCreateSection("\t__TEXT,__textcoal_nt,coalesced,pure_instructions", 624 false, SectionKind::getText()); 625 ConstTextCoalSection = getOrCreateSection("\t__TEXT,__const_coal,coalesced", 626 false, 627 SectionKind::getText()); 628 ConstDataCoalSection = getOrCreateSection("\t__DATA,__const_coal,coalesced", 629 false, 630 SectionKind::getText()); 631 ConstDataSection = getOrCreateSection("\t.const_data", true, 632 SectionKind::getReadOnlyWithRel()); 633 DataCoalSection = getOrCreateSection("\t__DATA,__datacoal_nt,coalesced", 634 false, 635 SectionKind::getDataRel()); 636 637 if (TM.getRelocationModel() == Reloc::Static) { 638 StaticCtorSection = 639 getOrCreateSection(".constructor", true, SectionKind::getDataRel()); 640 StaticDtorSection = 641 getOrCreateSection(".destructor", true, SectionKind::getDataRel()); 642 } else { 643 StaticCtorSection = 644 getOrCreateSection(".mod_init_func", true, SectionKind::getDataRel()); 645 StaticDtorSection = 646 getOrCreateSection(".mod_term_func", true, SectionKind::getDataRel()); 647 } 648 649 // Exception Handling. 650 LSDASection = getOrCreateSection("__DATA,__gcc_except_tab", false, 651 SectionKind::getDataRel()); 652 EHFrameSection = 653 getOrCreateSection("__TEXT,__eh_frame,coalesced,no_toc+strip_static_syms" 654 "+live_support", false, SectionKind::getReadOnly()); 655 656 // Debug Information. 657 // FIXME: Don't use 'directive' syntax: need flags for debug/regular?? 658 // FIXME: Need __DWARF segment. 659 DwarfAbbrevSection = 660 getOrCreateSection(".section __DWARF,__debug_abbrev,regular,debug", true, 661 SectionKind::getMetadata()); 662 DwarfInfoSection = 663 getOrCreateSection(".section __DWARF,__debug_info,regular,debug", true, 664 SectionKind::getMetadata()); 665 DwarfLineSection = 666 getOrCreateSection(".section __DWARF,__debug_line,regular,debug", true, 667 SectionKind::getMetadata()); 668 DwarfFrameSection = 669 getOrCreateSection(".section __DWARF,__debug_frame,regular,debug", true, 670 SectionKind::getMetadata()); 671 DwarfPubNamesSection = 672 getOrCreateSection(".section __DWARF,__debug_pubnames,regular,debug", true, 673 SectionKind::getMetadata()); 674 DwarfPubTypesSection = 675 getOrCreateSection(".section __DWARF,__debug_pubtypes,regular,debug", true, 676 SectionKind::getMetadata()); 677 DwarfStrSection = 678 getOrCreateSection(".section __DWARF,__debug_str,regular,debug", true, 679 SectionKind::getMetadata()); 680 DwarfLocSection = 681 getOrCreateSection(".section __DWARF,__debug_loc,regular,debug", true, 682 SectionKind::getMetadata()); 683 DwarfARangesSection = 684 getOrCreateSection(".section __DWARF,__debug_aranges,regular,debug", true, 685 SectionKind::getMetadata()); 686 DwarfRangesSection = 687 getOrCreateSection(".section __DWARF,__debug_ranges,regular,debug", true, 688 SectionKind::getMetadata()); 689 DwarfMacroInfoSection = 690 getOrCreateSection(".section __DWARF,__debug_macinfo,regular,debug", true, 691 SectionKind::getMetadata()); 692 DwarfDebugInlineSection = 693 getOrCreateSection(".section __DWARF,__debug_inlined,regular,debug", true, 694 SectionKind::getMetadata()); 695 } 696 697 const MCSection *TargetLoweringObjectFileMachO:: 698 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 699 Mangler *Mang, const TargetMachine &TM) const { 700 return getOrCreateSection(GV->getSection().c_str(), false, Kind); 701 } 702 703 const MCSection *TargetLoweringObjectFileMachO:: 704 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 705 Mangler *Mang, const TargetMachine &TM) const { 706 assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS"); 707 708 if (Kind.isText()) 709 return GV->isWeakForLinker() ? TextCoalSection : TextSection; 710 711 // If this is weak/linkonce, put this in a coalescable section, either in text 712 // or data depending on if it is writable. 713 if (GV->isWeakForLinker()) { 714 if (Kind.isReadOnly()) 715 return ConstTextCoalSection; 716 return DataCoalSection; 717 } 718 719 // FIXME: Alignment check should be handled by section classifier. 720 if (Kind.isMergeable1ByteCString() || 721 Kind.isMergeable2ByteCString()) { 722 if (TM.getTargetData()->getPreferredAlignment( 723 cast<GlobalVariable>(GV)) < 32) { 724 if (Kind.isMergeable1ByteCString()) 725 return CStringSection; 726 assert(Kind.isMergeable2ByteCString()); 727 return UStringSection; 728 } 729 } 730 731 if (Kind.isMergeableConst()) { 732 if (Kind.isMergeableConst4()) 733 return FourByteConstantSection; 734 if (Kind.isMergeableConst8()) 735 return EightByteConstantSection; 736 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 737 return SixteenByteConstantSection; 738 } 739 740 // Otherwise, if it is readonly, but not something we can specially optimize, 741 // just drop it in .const. 742 if (Kind.isReadOnly()) 743 return ReadOnlySection; 744 745 // If this is marked const, put it into a const section. But if the dynamic 746 // linker needs to write to it, put it in the data segment. 747 if (Kind.isReadOnlyWithRel()) 748 return ConstDataSection; 749 750 // Otherwise, just drop the variable in the normal data section. 751 return DataSection; 752 } 753 754 const MCSection * 755 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { 756 // If this constant requires a relocation, we have to put it in the data 757 // segment, not in the text segment. 758 if (Kind.isDataRel()) 759 return ConstDataSection; 760 761 if (Kind.isMergeableConst4()) 762 return FourByteConstantSection; 763 if (Kind.isMergeableConst8()) 764 return EightByteConstantSection; 765 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 766 return SixteenByteConstantSection; 767 return ReadOnlySection; // .const 768 } 769 770 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide 771 /// not to emit the UsedDirective for some symbols in llvm.used. 772 // FIXME: REMOVE this (rdar://7071300) 773 bool TargetLoweringObjectFileMachO:: 774 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { 775 /// On Darwin, internally linked data beginning with "L" or "l" does not have 776 /// the directive emitted (this occurs in ObjC metadata). 777 if (!GV) return false; 778 779 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. 780 if (GV->hasLocalLinkage() && !isa<Function>(GV)) { 781 // FIXME: ObjC metadata is currently emitted as internal symbols that have 782 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and 783 // this horrible hack can go away. 784 const std::string &Name = Mang->getMangledName(GV); 785 if (Name[0] == 'L' || Name[0] == 'l') 786 return false; 787 } 788 789 return true; 790 } 791 792 793 //===----------------------------------------------------------------------===// 794 // COFF 795 //===----------------------------------------------------------------------===// 796 797 const MCSection *TargetLoweringObjectFileCOFF:: 798 getOrCreateSection(const char *Name, bool isDirective, SectionKind Kind) const { 799 if (MCSection *S = getContext().GetSection(Name)) 800 return S; 801 return MCSection::Create(Name, isDirective, Kind, getContext()); 802 } 803 804 const MCSection *TargetLoweringObjectFileCOFF:: 805 getCOFFSection(const char *Name, bool isDirective, SectionKind K) { 806 return getOrCreateSection(Name, isDirective, K); 807 } 808 809 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx, 810 const TargetMachine &TM) { 811 TargetLoweringObjectFile::Initialize(Ctx, TM); 812 TextSection = getOrCreateSection("\t.text", true, 813 SectionKind::getText()); 814 DataSection = getOrCreateSection("\t.data", true, 815 SectionKind::getDataRel()); 816 StaticCtorSection = 817 getOrCreateSection(".ctors", false, SectionKind::getDataRel()); 818 StaticDtorSection = 819 getOrCreateSection(".dtors", false, SectionKind::getDataRel()); 820 821 822 // Debug info. 823 // FIXME: Don't use 'directive' mode here. 824 DwarfAbbrevSection = 825 getOrCreateSection("\t.section\t.debug_abbrev,\"dr\"", 826 true, SectionKind::getMetadata()); 827 DwarfInfoSection = 828 getOrCreateSection("\t.section\t.debug_info,\"dr\"", 829 true, SectionKind::getMetadata()); 830 DwarfLineSection = 831 getOrCreateSection("\t.section\t.debug_line,\"dr\"", 832 true, SectionKind::getMetadata()); 833 DwarfFrameSection = 834 getOrCreateSection("\t.section\t.debug_frame,\"dr\"", 835 true, SectionKind::getMetadata()); 836 DwarfPubNamesSection = 837 getOrCreateSection("\t.section\t.debug_pubnames,\"dr\"", 838 true, SectionKind::getMetadata()); 839 DwarfPubTypesSection = 840 getOrCreateSection("\t.section\t.debug_pubtypes,\"dr\"", 841 true, SectionKind::getMetadata()); 842 DwarfStrSection = 843 getOrCreateSection("\t.section\t.debug_str,\"dr\"", 844 true, SectionKind::getMetadata()); 845 DwarfLocSection = 846 getOrCreateSection("\t.section\t.debug_loc,\"dr\"", 847 true, SectionKind::getMetadata()); 848 DwarfARangesSection = 849 getOrCreateSection("\t.section\t.debug_aranges,\"dr\"", 850 true, SectionKind::getMetadata()); 851 DwarfRangesSection = 852 getOrCreateSection("\t.section\t.debug_ranges,\"dr\"", 853 true, SectionKind::getMetadata()); 854 DwarfMacroInfoSection = 855 getOrCreateSection("\t.section\t.debug_macinfo,\"dr\"", 856 true, SectionKind::getMetadata()); 857 } 858 859 const MCSection *TargetLoweringObjectFileCOFF:: 860 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 861 Mangler *Mang, const TargetMachine &TM) const { 862 return getOrCreateSection(GV->getSection().c_str(), false, Kind); 863 } 864 865 866 void TargetLoweringObjectFileCOFF:: 867 getSectionFlagsAsString(SectionKind Kind, SmallVectorImpl<char> &Str) const { 868 // FIXME: Inefficient. 869 std::string Res = ",\""; 870 if (Kind.isText()) 871 Res += 'x'; 872 if (Kind.isWriteable()) 873 Res += 'w'; 874 Res += "\""; 875 876 Str.append(Res.begin(), Res.end()); 877 } 878 879 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) { 880 if (Kind.isText()) 881 return ".text$linkonce"; 882 if (Kind.isWriteable()) 883 return ".data$linkonce"; 884 return ".rdata$linkonce"; 885 } 886 887 888 const MCSection *TargetLoweringObjectFileCOFF:: 889 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 890 Mangler *Mang, const TargetMachine &TM) const { 891 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 892 893 // If this global is linkonce/weak and the target handles this by emitting it 894 // into a 'uniqued' section name, create and return the section now. 895 if (GV->isWeakForLinker()) { 896 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind); 897 std::string Name = Mang->makeNameProper(GV->getNameStr()); 898 return getOrCreateSection((Prefix+Name).c_str(), false, Kind); 899 } 900 901 if (Kind.isText()) 902 return getTextSection(); 903 904 return getDataSection(); 905 } 906 907