1 //===--- Mangle.cpp - Mangle C++ Names --------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // Implements generic name mangling support for blocks and Objective-C. 10 // 11 //===----------------------------------------------------------------------===// 12 #include "clang/AST/Attr.h" 13 #include "clang/AST/ASTContext.h" 14 #include "clang/AST/Decl.h" 15 #include "clang/AST/DeclCXX.h" 16 #include "clang/AST/DeclObjC.h" 17 #include "clang/AST/DeclTemplate.h" 18 #include "clang/AST/ExprCXX.h" 19 #include "clang/AST/Mangle.h" 20 #include "clang/AST/VTableBuilder.h" 21 #include "clang/Basic/ABI.h" 22 #include "clang/Basic/SourceManager.h" 23 #include "clang/Basic/TargetInfo.h" 24 #include "llvm/ADT/StringExtras.h" 25 #include "llvm/IR/DataLayout.h" 26 #include "llvm/IR/Mangler.h" 27 #include "llvm/Support/ErrorHandling.h" 28 #include "llvm/Support/Format.h" 29 #include "llvm/Support/raw_ostream.h" 30 31 using namespace clang; 32 33 // FIXME: For blocks we currently mimic GCC's mangling scheme, which leaves 34 // much to be desired. Come up with a better mangling scheme. 35 36 static void mangleFunctionBlock(MangleContext &Context, 37 StringRef Outer, 38 const BlockDecl *BD, 39 raw_ostream &Out) { 40 unsigned discriminator = Context.getBlockId(BD, true); 41 if (discriminator == 0) 42 Out << "__" << Outer << "_block_invoke"; 43 else 44 Out << "__" << Outer << "_block_invoke_" << discriminator+1; 45 } 46 47 void MangleContext::anchor() { } 48 49 enum CCMangling { 50 CCM_Other, 51 CCM_Fast, 52 CCM_RegCall, 53 CCM_Vector, 54 CCM_Std, 55 CCM_WasmMainArgcArgv 56 }; 57 58 static bool isExternC(const NamedDecl *ND) { 59 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) 60 return FD->isExternC(); 61 if (const VarDecl *VD = dyn_cast<VarDecl>(ND)) 62 return VD->isExternC(); 63 return false; 64 } 65 66 static CCMangling getCallingConvMangling(const ASTContext &Context, 67 const NamedDecl *ND) { 68 const TargetInfo &TI = Context.getTargetInfo(); 69 const llvm::Triple &Triple = TI.getTriple(); 70 71 // On wasm, the argc/argv form of "main" is renamed so that the startup code 72 // can call it with the correct function signature. 73 // On Emscripten, users may be exporting "main" and expecting to call it 74 // themselves, so we can't mangle it. 75 if (Triple.isWasm() && !Triple.isOSEmscripten()) 76 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) 77 if (FD->isMain() && FD->hasPrototype() && FD->param_size() == 2) 78 return CCM_WasmMainArgcArgv; 79 80 if (!Triple.isOSWindows() || !Triple.isX86()) 81 return CCM_Other; 82 83 if (Context.getLangOpts().CPlusPlus && !isExternC(ND) && 84 TI.getCXXABI() == TargetCXXABI::Microsoft) 85 return CCM_Other; 86 87 const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND); 88 if (!FD) 89 return CCM_Other; 90 QualType T = FD->getType(); 91 92 const FunctionType *FT = T->castAs<FunctionType>(); 93 94 CallingConv CC = FT->getCallConv(); 95 switch (CC) { 96 default: 97 return CCM_Other; 98 case CC_X86FastCall: 99 return CCM_Fast; 100 case CC_X86StdCall: 101 return CCM_Std; 102 case CC_X86VectorCall: 103 return CCM_Vector; 104 } 105 } 106 107 bool MangleContext::shouldMangleDeclName(const NamedDecl *D) { 108 const ASTContext &ASTContext = getASTContext(); 109 110 CCMangling CC = getCallingConvMangling(ASTContext, D); 111 if (CC != CCM_Other) 112 return true; 113 114 // If the declaration has an owning module for linkage purposes that needs to 115 // be mangled, we must mangle its name. 116 if (!D->hasExternalFormalLinkage() && D->getOwningModuleForLinkage()) 117 return true; 118 119 // In C, functions with no attributes never need to be mangled. Fastpath them. 120 if (!getASTContext().getLangOpts().CPlusPlus && !D->hasAttrs()) 121 return false; 122 123 // Any decl can be declared with __asm("foo") on it, and this takes precedence 124 // over all other naming in the .o file. 125 if (D->hasAttr<AsmLabelAttr>()) 126 return true; 127 128 // Declarations that don't have identifier names always need to be mangled. 129 if (isa<MSGuidDecl>(D)) 130 return true; 131 132 return shouldMangleCXXName(D); 133 } 134 135 void MangleContext::mangleName(GlobalDecl GD, raw_ostream &Out) { 136 const NamedDecl *D = cast<NamedDecl>(GD.getDecl()); 137 // Any decl can be declared with __asm("foo") on it, and this takes precedence 138 // over all other naming in the .o file. 139 if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) { 140 // If we have an asm name, then we use it as the mangling. 141 142 // If the label isn't literal, or if this is an alias for an LLVM intrinsic, 143 // do not add a "\01" prefix. 144 if (!ALA->getIsLiteralLabel() || ALA->getLabel().startswith("llvm.")) { 145 Out << ALA->getLabel(); 146 return; 147 } 148 149 // Adding the prefix can cause problems when one file has a "foo" and 150 // another has a "\01foo". That is known to happen on ELF with the 151 // tricks normally used for producing aliases (PR9177). Fortunately the 152 // llvm mangler on ELF is a nop, so we can just avoid adding the \01 153 // marker. 154 char GlobalPrefix = 155 getASTContext().getTargetInfo().getDataLayout().getGlobalPrefix(); 156 if (GlobalPrefix) 157 Out << '\01'; // LLVM IR Marker for __asm("foo") 158 159 Out << ALA->getLabel(); 160 return; 161 } 162 163 if (auto *GD = dyn_cast<MSGuidDecl>(D)) 164 return mangleMSGuidDecl(GD, Out); 165 166 const ASTContext &ASTContext = getASTContext(); 167 CCMangling CC = getCallingConvMangling(ASTContext, D); 168 169 if (CC == CCM_WasmMainArgcArgv) { 170 Out << "__main_argc_argv"; 171 return; 172 } 173 174 bool MCXX = shouldMangleCXXName(D); 175 const TargetInfo &TI = Context.getTargetInfo(); 176 if (CC == CCM_Other || (MCXX && TI.getCXXABI() == TargetCXXABI::Microsoft)) { 177 if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D)) 178 mangleObjCMethodNameAsSourceName(OMD, Out); 179 else 180 mangleCXXName(GD, Out); 181 return; 182 } 183 184 Out << '\01'; 185 if (CC == CCM_Std) 186 Out << '_'; 187 else if (CC == CCM_Fast) 188 Out << '@'; 189 else if (CC == CCM_RegCall) 190 Out << "__regcall3__"; 191 192 if (!MCXX) 193 Out << D->getIdentifier()->getName(); 194 else if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D)) 195 mangleObjCMethodNameAsSourceName(OMD, Out); 196 else 197 mangleCXXName(GD, Out); 198 199 const FunctionDecl *FD = cast<FunctionDecl>(D); 200 const FunctionType *FT = FD->getType()->castAs<FunctionType>(); 201 const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT); 202 if (CC == CCM_Vector) 203 Out << '@'; 204 Out << '@'; 205 if (!Proto) { 206 Out << '0'; 207 return; 208 } 209 assert(!Proto->isVariadic()); 210 unsigned ArgWords = 0; 211 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) 212 if (!MD->isStatic()) 213 ++ArgWords; 214 for (const auto &AT : Proto->param_types()) 215 // Size should be aligned to pointer size. 216 ArgWords += 217 llvm::alignTo(ASTContext.getTypeSize(AT), TI.getPointerWidth(0)) / 218 TI.getPointerWidth(0); 219 Out << ((TI.getPointerWidth(0) / 8) * ArgWords); 220 } 221 222 void MangleContext::mangleMSGuidDecl(const MSGuidDecl *GD, raw_ostream &Out) { 223 // For now, follow the MSVC naming convention for GUID objects on all 224 // targets. 225 MSGuidDecl::Parts P = GD->getParts(); 226 Out << llvm::format("_GUID_%08" PRIx32 "_%04" PRIx32 "_%04" PRIx32 "_", 227 P.Part1, P.Part2, P.Part3); 228 unsigned I = 0; 229 for (uint8_t C : P.Part4And5) { 230 Out << llvm::format("%02" PRIx8, C); 231 if (++I == 2) 232 Out << "_"; 233 } 234 } 235 236 void MangleContext::mangleGlobalBlock(const BlockDecl *BD, 237 const NamedDecl *ID, 238 raw_ostream &Out) { 239 unsigned discriminator = getBlockId(BD, false); 240 if (ID) { 241 if (shouldMangleDeclName(ID)) 242 mangleName(ID, Out); 243 else { 244 Out << ID->getIdentifier()->getName(); 245 } 246 } 247 if (discriminator == 0) 248 Out << "_block_invoke"; 249 else 250 Out << "_block_invoke_" << discriminator+1; 251 } 252 253 void MangleContext::mangleCtorBlock(const CXXConstructorDecl *CD, 254 CXXCtorType CT, const BlockDecl *BD, 255 raw_ostream &ResStream) { 256 SmallString<64> Buffer; 257 llvm::raw_svector_ostream Out(Buffer); 258 mangleName(GlobalDecl(CD, CT), Out); 259 mangleFunctionBlock(*this, Buffer, BD, ResStream); 260 } 261 262 void MangleContext::mangleDtorBlock(const CXXDestructorDecl *DD, 263 CXXDtorType DT, const BlockDecl *BD, 264 raw_ostream &ResStream) { 265 SmallString<64> Buffer; 266 llvm::raw_svector_ostream Out(Buffer); 267 mangleName(GlobalDecl(DD, DT), Out); 268 mangleFunctionBlock(*this, Buffer, BD, ResStream); 269 } 270 271 void MangleContext::mangleBlock(const DeclContext *DC, const BlockDecl *BD, 272 raw_ostream &Out) { 273 assert(!isa<CXXConstructorDecl>(DC) && !isa<CXXDestructorDecl>(DC)); 274 275 SmallString<64> Buffer; 276 llvm::raw_svector_ostream Stream(Buffer); 277 if (const ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(DC)) { 278 mangleObjCMethodNameAsSourceName(Method, Stream); 279 } else { 280 assert((isa<NamedDecl>(DC) || isa<BlockDecl>(DC)) && 281 "expected a NamedDecl or BlockDecl"); 282 if (isa<BlockDecl>(DC)) 283 for (; DC && isa<BlockDecl>(DC); DC = DC->getParent()) 284 (void) getBlockId(cast<BlockDecl>(DC), true); 285 assert((isa<TranslationUnitDecl>(DC) || isa<NamedDecl>(DC)) && 286 "expected a TranslationUnitDecl or a NamedDecl"); 287 if (const auto *CD = dyn_cast<CXXConstructorDecl>(DC)) 288 mangleCtorBlock(CD, /*CT*/ Ctor_Complete, BD, Out); 289 else if (const auto *DD = dyn_cast<CXXDestructorDecl>(DC)) 290 mangleDtorBlock(DD, /*DT*/ Dtor_Complete, BD, Out); 291 else if (auto ND = dyn_cast<NamedDecl>(DC)) { 292 if (!shouldMangleDeclName(ND) && ND->getIdentifier()) 293 Stream << ND->getIdentifier()->getName(); 294 else { 295 // FIXME: We were doing a mangleUnqualifiedName() before, but that's 296 // a private member of a class that will soon itself be private to the 297 // Itanium C++ ABI object. What should we do now? Right now, I'm just 298 // calling the mangleName() method on the MangleContext; is there a 299 // better way? 300 mangleName(ND, Stream); 301 } 302 } 303 } 304 mangleFunctionBlock(*this, Buffer, BD, Out); 305 } 306 307 void MangleContext::mangleObjCMethodName(const ObjCMethodDecl *MD, 308 raw_ostream &OS, 309 bool includePrefixByte, 310 bool includeCategoryNamespace) { 311 if (getASTContext().getLangOpts().ObjCRuntime.isGNUFamily()) { 312 // This is the mangling we've always used on the GNU runtimes, but it 313 // has obvious collisions in the face of underscores within class 314 // names, category names, and selectors; maybe we should improve it. 315 316 OS << (MD->isClassMethod() ? "_c_" : "_i_") 317 << MD->getClassInterface()->getName() << '_'; 318 319 if (includeCategoryNamespace) { 320 if (auto category = MD->getCategory()) 321 OS << category->getName(); 322 } 323 OS << '_'; 324 325 auto selector = MD->getSelector(); 326 for (unsigned slotIndex = 0, 327 numArgs = selector.getNumArgs(), 328 slotEnd = std::max(numArgs, 1U); 329 slotIndex != slotEnd; ++slotIndex) { 330 if (auto name = selector.getIdentifierInfoForSlot(slotIndex)) 331 OS << name->getName(); 332 333 // Replace all the positions that would've been ':' with '_'. 334 // That's after each slot except that a unary selector doesn't 335 // end in ':'. 336 if (numArgs) 337 OS << '_'; 338 } 339 340 return; 341 } 342 343 // \01+[ContainerName(CategoryName) SelectorName] 344 if (includePrefixByte) { 345 OS << '\01'; 346 } 347 OS << (MD->isInstanceMethod() ? '-' : '+') << '['; 348 if (const auto *CID = MD->getCategory()) { 349 OS << CID->getClassInterface()->getName(); 350 if (includeCategoryNamespace) { 351 OS << '(' << *CID << ')'; 352 } 353 } else if (const auto *CD = 354 dyn_cast<ObjCContainerDecl>(MD->getDeclContext())) { 355 OS << CD->getName(); 356 } else { 357 llvm_unreachable("Unexpected ObjC method decl context"); 358 } 359 OS << ' '; 360 MD->getSelector().print(OS); 361 OS << ']'; 362 } 363 364 void MangleContext::mangleObjCMethodNameAsSourceName(const ObjCMethodDecl *MD, 365 raw_ostream &Out) { 366 SmallString<64> Name; 367 llvm::raw_svector_ostream OS(Name); 368 369 mangleObjCMethodName(MD, OS, /*includePrefixByte=*/false, 370 /*includeCategoryNamespace=*/true); 371 Out << OS.str().size() << OS.str(); 372 } 373 374 class ASTNameGenerator::Implementation { 375 std::unique_ptr<MangleContext> MC; 376 llvm::DataLayout DL; 377 378 public: 379 explicit Implementation(ASTContext &Ctx) 380 : MC(Ctx.createMangleContext()), DL(Ctx.getTargetInfo().getDataLayout()) { 381 } 382 383 bool writeName(const Decl *D, raw_ostream &OS) { 384 // First apply frontend mangling. 385 SmallString<128> FrontendBuf; 386 llvm::raw_svector_ostream FrontendBufOS(FrontendBuf); 387 if (auto *FD = dyn_cast<FunctionDecl>(D)) { 388 if (FD->isDependentContext()) 389 return true; 390 if (writeFuncOrVarName(FD, FrontendBufOS)) 391 return true; 392 } else if (auto *VD = dyn_cast<VarDecl>(D)) { 393 if (writeFuncOrVarName(VD, FrontendBufOS)) 394 return true; 395 } else if (auto *MD = dyn_cast<ObjCMethodDecl>(D)) { 396 MC->mangleObjCMethodName(MD, OS, /*includePrefixByte=*/false, 397 /*includeCategoryNamespace=*/true); 398 return false; 399 } else if (auto *ID = dyn_cast<ObjCInterfaceDecl>(D)) { 400 writeObjCClassName(ID, FrontendBufOS); 401 } else { 402 return true; 403 } 404 405 // Now apply backend mangling. 406 llvm::Mangler::getNameWithPrefix(OS, FrontendBufOS.str(), DL); 407 return false; 408 } 409 410 std::string getName(const Decl *D) { 411 std::string Name; 412 { 413 llvm::raw_string_ostream OS(Name); 414 writeName(D, OS); 415 } 416 return Name; 417 } 418 419 enum ObjCKind { 420 ObjCClass, 421 ObjCMetaclass, 422 }; 423 424 static StringRef getClassSymbolPrefix(ObjCKind Kind, 425 const ASTContext &Context) { 426 if (Context.getLangOpts().ObjCRuntime.isGNUFamily()) 427 return Kind == ObjCMetaclass ? "_OBJC_METACLASS_" : "_OBJC_CLASS_"; 428 return Kind == ObjCMetaclass ? "OBJC_METACLASS_$_" : "OBJC_CLASS_$_"; 429 } 430 431 std::vector<std::string> getAllManglings(const ObjCContainerDecl *OCD) { 432 StringRef ClassName; 433 if (const auto *OID = dyn_cast<ObjCInterfaceDecl>(OCD)) 434 ClassName = OID->getObjCRuntimeNameAsString(); 435 else if (const auto *OID = dyn_cast<ObjCImplementationDecl>(OCD)) 436 ClassName = OID->getObjCRuntimeNameAsString(); 437 438 if (ClassName.empty()) 439 return {}; 440 441 auto Mangle = [&](ObjCKind Kind, StringRef ClassName) -> std::string { 442 SmallString<40> Mangled; 443 auto Prefix = getClassSymbolPrefix(Kind, OCD->getASTContext()); 444 llvm::Mangler::getNameWithPrefix(Mangled, Prefix + ClassName, DL); 445 return std::string(Mangled.str()); 446 }; 447 448 return { 449 Mangle(ObjCClass, ClassName), 450 Mangle(ObjCMetaclass, ClassName), 451 }; 452 } 453 454 std::vector<std::string> getAllManglings(const Decl *D) { 455 if (const auto *OCD = dyn_cast<ObjCContainerDecl>(D)) 456 return getAllManglings(OCD); 457 458 if (!(isa<CXXRecordDecl>(D) || isa<CXXMethodDecl>(D))) 459 return {}; 460 461 const NamedDecl *ND = cast<NamedDecl>(D); 462 463 ASTContext &Ctx = ND->getASTContext(); 464 std::unique_ptr<MangleContext> M(Ctx.createMangleContext()); 465 466 std::vector<std::string> Manglings; 467 468 auto hasDefaultCXXMethodCC = [](ASTContext &C, const CXXMethodDecl *MD) { 469 auto DefaultCC = C.getDefaultCallingConvention(/*IsVariadic=*/false, 470 /*IsCXXMethod=*/true); 471 auto CC = MD->getType()->castAs<FunctionProtoType>()->getCallConv(); 472 return CC == DefaultCC; 473 }; 474 475 if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(ND)) { 476 Manglings.emplace_back(getMangledStructor(CD, Ctor_Base)); 477 478 if (Ctx.getTargetInfo().getCXXABI().isItaniumFamily()) 479 if (!CD->getParent()->isAbstract()) 480 Manglings.emplace_back(getMangledStructor(CD, Ctor_Complete)); 481 482 if (Ctx.getTargetInfo().getCXXABI().isMicrosoft()) 483 if (CD->hasAttr<DLLExportAttr>() && CD->isDefaultConstructor()) 484 if (!(hasDefaultCXXMethodCC(Ctx, CD) && CD->getNumParams() == 0)) 485 Manglings.emplace_back(getMangledStructor(CD, Ctor_DefaultClosure)); 486 } else if (const auto *DD = dyn_cast_or_null<CXXDestructorDecl>(ND)) { 487 Manglings.emplace_back(getMangledStructor(DD, Dtor_Base)); 488 if (Ctx.getTargetInfo().getCXXABI().isItaniumFamily()) { 489 Manglings.emplace_back(getMangledStructor(DD, Dtor_Complete)); 490 if (DD->isVirtual()) 491 Manglings.emplace_back(getMangledStructor(DD, Dtor_Deleting)); 492 } 493 } else if (const auto *MD = dyn_cast_or_null<CXXMethodDecl>(ND)) { 494 Manglings.emplace_back(getName(ND)); 495 if (MD->isVirtual()) 496 if (const auto *TIV = Ctx.getVTableContext()->getThunkInfo(MD)) 497 for (const auto &T : *TIV) 498 Manglings.emplace_back(getMangledThunk(MD, T)); 499 } 500 501 return Manglings; 502 } 503 504 private: 505 bool writeFuncOrVarName(const NamedDecl *D, raw_ostream &OS) { 506 if (MC->shouldMangleDeclName(D)) { 507 GlobalDecl GD; 508 if (const auto *CtorD = dyn_cast<CXXConstructorDecl>(D)) 509 GD = GlobalDecl(CtorD, Ctor_Complete); 510 else if (const auto *DtorD = dyn_cast<CXXDestructorDecl>(D)) 511 GD = GlobalDecl(DtorD, Dtor_Complete); 512 else if (D->hasAttr<CUDAGlobalAttr>()) 513 GD = GlobalDecl(cast<FunctionDecl>(D)); 514 else 515 GD = GlobalDecl(D); 516 MC->mangleName(GD, OS); 517 return false; 518 } else { 519 IdentifierInfo *II = D->getIdentifier(); 520 if (!II) 521 return true; 522 OS << II->getName(); 523 return false; 524 } 525 } 526 527 void writeObjCClassName(const ObjCInterfaceDecl *D, raw_ostream &OS) { 528 OS << getClassSymbolPrefix(ObjCClass, D->getASTContext()); 529 OS << D->getObjCRuntimeNameAsString(); 530 } 531 532 std::string getMangledStructor(const NamedDecl *ND, unsigned StructorType) { 533 std::string FrontendBuf; 534 llvm::raw_string_ostream FOS(FrontendBuf); 535 536 GlobalDecl GD; 537 if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(ND)) 538 GD = GlobalDecl(CD, static_cast<CXXCtorType>(StructorType)); 539 else if (const auto *DD = dyn_cast_or_null<CXXDestructorDecl>(ND)) 540 GD = GlobalDecl(DD, static_cast<CXXDtorType>(StructorType)); 541 MC->mangleName(GD, FOS); 542 543 std::string BackendBuf; 544 llvm::raw_string_ostream BOS(BackendBuf); 545 546 llvm::Mangler::getNameWithPrefix(BOS, FOS.str(), DL); 547 548 return BOS.str(); 549 } 550 551 std::string getMangledThunk(const CXXMethodDecl *MD, const ThunkInfo &T) { 552 std::string FrontendBuf; 553 llvm::raw_string_ostream FOS(FrontendBuf); 554 555 MC->mangleThunk(MD, T, FOS); 556 557 std::string BackendBuf; 558 llvm::raw_string_ostream BOS(BackendBuf); 559 560 llvm::Mangler::getNameWithPrefix(BOS, FOS.str(), DL); 561 562 return BOS.str(); 563 } 564 }; 565 566 ASTNameGenerator::ASTNameGenerator(ASTContext &Ctx) 567 : Impl(std::make_unique<Implementation>(Ctx)) {} 568 569 ASTNameGenerator::~ASTNameGenerator() {} 570 571 bool ASTNameGenerator::writeName(const Decl *D, raw_ostream &OS) { 572 return Impl->writeName(D, OS); 573 } 574 575 std::string ASTNameGenerator::getName(const Decl *D) { 576 return Impl->getName(D); 577 } 578 579 std::vector<std::string> ASTNameGenerator::getAllManglings(const Decl *D) { 580 return Impl->getAllManglings(D); 581 } 582