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/raw_ostream.h" 29 30 using namespace clang; 31 32 // FIXME: For blocks we currently mimic GCC's mangling scheme, which leaves 33 // much to be desired. Come up with a better mangling scheme. 34 35 static void mangleFunctionBlock(MangleContext &Context, 36 StringRef Outer, 37 const BlockDecl *BD, 38 raw_ostream &Out) { 39 unsigned discriminator = Context.getBlockId(BD, true); 40 if (discriminator == 0) 41 Out << "__" << Outer << "_block_invoke"; 42 else 43 Out << "__" << Outer << "_block_invoke_" << discriminator+1; 44 } 45 46 void MangleContext::anchor() { } 47 48 enum CCMangling { 49 CCM_Other, 50 CCM_Fast, 51 CCM_RegCall, 52 CCM_Vector, 53 CCM_Std 54 }; 55 56 static bool isExternC(const NamedDecl *ND) { 57 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) 58 return FD->isExternC(); 59 return cast<VarDecl>(ND)->isExternC(); 60 } 61 62 static CCMangling getCallingConvMangling(const ASTContext &Context, 63 const NamedDecl *ND) { 64 const TargetInfo &TI = Context.getTargetInfo(); 65 const llvm::Triple &Triple = TI.getTriple(); 66 if (!Triple.isOSWindows() || 67 !(Triple.getArch() == llvm::Triple::x86 || 68 Triple.getArch() == llvm::Triple::x86_64)) 69 return CCM_Other; 70 71 if (Context.getLangOpts().CPlusPlus && !isExternC(ND) && 72 TI.getCXXABI() == TargetCXXABI::Microsoft) 73 return CCM_Other; 74 75 const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND); 76 if (!FD) 77 return CCM_Other; 78 QualType T = FD->getType(); 79 80 const FunctionType *FT = T->castAs<FunctionType>(); 81 82 CallingConv CC = FT->getCallConv(); 83 switch (CC) { 84 default: 85 return CCM_Other; 86 case CC_X86FastCall: 87 return CCM_Fast; 88 case CC_X86StdCall: 89 return CCM_Std; 90 case CC_X86VectorCall: 91 return CCM_Vector; 92 } 93 } 94 95 bool MangleContext::shouldMangleDeclName(const NamedDecl *D) { 96 const ASTContext &ASTContext = getASTContext(); 97 98 CCMangling CC = getCallingConvMangling(ASTContext, D); 99 if (CC != CCM_Other) 100 return true; 101 102 // If the declaration has an owning module for linkage purposes that needs to 103 // be mangled, we must mangle its name. 104 if (!D->hasExternalFormalLinkage() && D->getOwningModuleForLinkage()) 105 return true; 106 107 // In C, functions with no attributes never need to be mangled. Fastpath them. 108 if (!getASTContext().getLangOpts().CPlusPlus && !D->hasAttrs()) 109 return false; 110 111 // Any decl can be declared with __asm("foo") on it, and this takes precedence 112 // over all other naming in the .o file. 113 if (D->hasAttr<AsmLabelAttr>()) 114 return true; 115 116 return shouldMangleCXXName(D); 117 } 118 119 void MangleContext::mangleName(const NamedDecl *D, raw_ostream &Out) { 120 // Any decl can be declared with __asm("foo") on it, and this takes precedence 121 // over all other naming in the .o file. 122 if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) { 123 // If we have an asm name, then we use it as the mangling. 124 125 // If the label isn't literal, or if this is an alias for an LLVM intrinsic, 126 // do not add a "\01" prefix. 127 if (!ALA->getIsLiteralLabel() || ALA->getLabel().startswith("llvm.")) { 128 Out << ALA->getLabel(); 129 return; 130 } 131 132 // Adding the prefix can cause problems when one file has a "foo" and 133 // another has a "\01foo". That is known to happen on ELF with the 134 // tricks normally used for producing aliases (PR9177). Fortunately the 135 // llvm mangler on ELF is a nop, so we can just avoid adding the \01 136 // marker. 137 char GlobalPrefix = 138 getASTContext().getTargetInfo().getDataLayout().getGlobalPrefix(); 139 if (GlobalPrefix) 140 Out << '\01'; // LLVM IR Marker for __asm("foo") 141 142 Out << ALA->getLabel(); 143 return; 144 } 145 146 const ASTContext &ASTContext = getASTContext(); 147 CCMangling CC = getCallingConvMangling(ASTContext, D); 148 bool MCXX = shouldMangleCXXName(D); 149 const TargetInfo &TI = Context.getTargetInfo(); 150 if (CC == CCM_Other || (MCXX && TI.getCXXABI() == TargetCXXABI::Microsoft)) { 151 if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D)) 152 mangleObjCMethodName(OMD, Out); 153 else 154 mangleCXXName(D, Out); 155 return; 156 } 157 158 Out << '\01'; 159 if (CC == CCM_Std) 160 Out << '_'; 161 else if (CC == CCM_Fast) 162 Out << '@'; 163 else if (CC == CCM_RegCall) 164 Out << "__regcall3__"; 165 166 if (!MCXX) 167 Out << D->getIdentifier()->getName(); 168 else if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D)) 169 mangleObjCMethodName(OMD, Out); 170 else 171 mangleCXXName(D, Out); 172 173 const FunctionDecl *FD = cast<FunctionDecl>(D); 174 const FunctionType *FT = FD->getType()->castAs<FunctionType>(); 175 const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT); 176 if (CC == CCM_Vector) 177 Out << '@'; 178 Out << '@'; 179 if (!Proto) { 180 Out << '0'; 181 return; 182 } 183 assert(!Proto->isVariadic()); 184 unsigned ArgWords = 0; 185 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) 186 if (!MD->isStatic()) 187 ++ArgWords; 188 for (const auto &AT : Proto->param_types()) 189 // Size should be aligned to pointer size. 190 ArgWords += 191 llvm::alignTo(ASTContext.getTypeSize(AT), TI.getPointerWidth(0)) / 192 TI.getPointerWidth(0); 193 Out << ((TI.getPointerWidth(0) / 8) * ArgWords); 194 } 195 196 void MangleContext::mangleGlobalBlock(const BlockDecl *BD, 197 const NamedDecl *ID, 198 raw_ostream &Out) { 199 unsigned discriminator = getBlockId(BD, false); 200 if (ID) { 201 if (shouldMangleDeclName(ID)) 202 mangleName(ID, Out); 203 else { 204 Out << ID->getIdentifier()->getName(); 205 } 206 } 207 if (discriminator == 0) 208 Out << "_block_invoke"; 209 else 210 Out << "_block_invoke_" << discriminator+1; 211 } 212 213 void MangleContext::mangleCtorBlock(const CXXConstructorDecl *CD, 214 CXXCtorType CT, const BlockDecl *BD, 215 raw_ostream &ResStream) { 216 SmallString<64> Buffer; 217 llvm::raw_svector_ostream Out(Buffer); 218 mangleCXXCtor(CD, CT, Out); 219 mangleFunctionBlock(*this, Buffer, BD, ResStream); 220 } 221 222 void MangleContext::mangleDtorBlock(const CXXDestructorDecl *DD, 223 CXXDtorType DT, const BlockDecl *BD, 224 raw_ostream &ResStream) { 225 SmallString<64> Buffer; 226 llvm::raw_svector_ostream Out(Buffer); 227 mangleCXXDtor(DD, DT, Out); 228 mangleFunctionBlock(*this, Buffer, BD, ResStream); 229 } 230 231 void MangleContext::mangleBlock(const DeclContext *DC, const BlockDecl *BD, 232 raw_ostream &Out) { 233 assert(!isa<CXXConstructorDecl>(DC) && !isa<CXXDestructorDecl>(DC)); 234 235 SmallString<64> Buffer; 236 llvm::raw_svector_ostream Stream(Buffer); 237 if (const ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(DC)) { 238 mangleObjCMethodName(Method, Stream); 239 } else { 240 assert((isa<NamedDecl>(DC) || isa<BlockDecl>(DC)) && 241 "expected a NamedDecl or BlockDecl"); 242 if (isa<BlockDecl>(DC)) 243 for (; DC && isa<BlockDecl>(DC); DC = DC->getParent()) 244 (void) getBlockId(cast<BlockDecl>(DC), true); 245 assert((isa<TranslationUnitDecl>(DC) || isa<NamedDecl>(DC)) && 246 "expected a TranslationUnitDecl or a NamedDecl"); 247 if (const auto *CD = dyn_cast<CXXConstructorDecl>(DC)) 248 mangleCtorBlock(CD, /*CT*/ Ctor_Complete, BD, Out); 249 else if (const auto *DD = dyn_cast<CXXDestructorDecl>(DC)) 250 mangleDtorBlock(DD, /*DT*/ Dtor_Complete, BD, Out); 251 else if (auto ND = dyn_cast<NamedDecl>(DC)) { 252 if (!shouldMangleDeclName(ND) && ND->getIdentifier()) 253 Stream << ND->getIdentifier()->getName(); 254 else { 255 // FIXME: We were doing a mangleUnqualifiedName() before, but that's 256 // a private member of a class that will soon itself be private to the 257 // Itanium C++ ABI object. What should we do now? Right now, I'm just 258 // calling the mangleName() method on the MangleContext; is there a 259 // better way? 260 mangleName(ND, Stream); 261 } 262 } 263 } 264 mangleFunctionBlock(*this, Buffer, BD, Out); 265 } 266 267 void MangleContext::mangleObjCMethodNameWithoutSize(const ObjCMethodDecl *MD, 268 raw_ostream &OS) { 269 const ObjCContainerDecl *CD = 270 dyn_cast<ObjCContainerDecl>(MD->getDeclContext()); 271 assert (CD && "Missing container decl in GetNameForMethod"); 272 OS << (MD->isInstanceMethod() ? '-' : '+') << '['; 273 if (const ObjCCategoryImplDecl *CID = dyn_cast<ObjCCategoryImplDecl>(CD)) { 274 OS << CID->getClassInterface()->getName(); 275 OS << '(' << *CID << ')'; 276 } else { 277 OS << CD->getName(); 278 } 279 OS << ' '; 280 MD->getSelector().print(OS); 281 OS << ']'; 282 } 283 284 void MangleContext::mangleObjCMethodName(const ObjCMethodDecl *MD, 285 raw_ostream &Out) { 286 SmallString<64> Name; 287 llvm::raw_svector_ostream OS(Name); 288 289 mangleObjCMethodNameWithoutSize(MD, OS); 290 Out << OS.str().size() << OS.str(); 291 } 292 293 class ASTNameGenerator::Implementation { 294 std::unique_ptr<MangleContext> MC; 295 llvm::DataLayout DL; 296 297 public: 298 explicit Implementation(ASTContext &Ctx) 299 : MC(Ctx.createMangleContext()), DL(Ctx.getTargetInfo().getDataLayout()) { 300 } 301 302 bool writeName(const Decl *D, raw_ostream &OS) { 303 // First apply frontend mangling. 304 SmallString<128> FrontendBuf; 305 llvm::raw_svector_ostream FrontendBufOS(FrontendBuf); 306 if (auto *FD = dyn_cast<FunctionDecl>(D)) { 307 if (FD->isDependentContext()) 308 return true; 309 if (writeFuncOrVarName(FD, FrontendBufOS)) 310 return true; 311 } else if (auto *VD = dyn_cast<VarDecl>(D)) { 312 if (writeFuncOrVarName(VD, FrontendBufOS)) 313 return true; 314 } else if (auto *MD = dyn_cast<ObjCMethodDecl>(D)) { 315 MC->mangleObjCMethodNameWithoutSize(MD, OS); 316 return false; 317 } else if (auto *ID = dyn_cast<ObjCInterfaceDecl>(D)) { 318 writeObjCClassName(ID, FrontendBufOS); 319 } else { 320 return true; 321 } 322 323 // Now apply backend mangling. 324 llvm::Mangler::getNameWithPrefix(OS, FrontendBufOS.str(), DL); 325 return false; 326 } 327 328 std::string getName(const Decl *D) { 329 std::string Name; 330 { 331 llvm::raw_string_ostream OS(Name); 332 writeName(D, OS); 333 } 334 return Name; 335 } 336 337 enum ObjCKind { 338 ObjCClass, 339 ObjCMetaclass, 340 }; 341 342 static StringRef getClassSymbolPrefix(ObjCKind Kind, 343 const ASTContext &Context) { 344 if (Context.getLangOpts().ObjCRuntime.isGNUFamily()) 345 return Kind == ObjCMetaclass ? "_OBJC_METACLASS_" : "_OBJC_CLASS_"; 346 return Kind == ObjCMetaclass ? "OBJC_METACLASS_$_" : "OBJC_CLASS_$_"; 347 } 348 349 std::vector<std::string> getAllManglings(const ObjCContainerDecl *OCD) { 350 StringRef ClassName; 351 if (const auto *OID = dyn_cast<ObjCInterfaceDecl>(OCD)) 352 ClassName = OID->getObjCRuntimeNameAsString(); 353 else if (const auto *OID = dyn_cast<ObjCImplementationDecl>(OCD)) 354 ClassName = OID->getObjCRuntimeNameAsString(); 355 356 if (ClassName.empty()) 357 return {}; 358 359 auto Mangle = [&](ObjCKind Kind, StringRef ClassName) -> std::string { 360 SmallString<40> Mangled; 361 auto Prefix = getClassSymbolPrefix(Kind, OCD->getASTContext()); 362 llvm::Mangler::getNameWithPrefix(Mangled, Prefix + ClassName, DL); 363 return Mangled.str(); 364 }; 365 366 return { 367 Mangle(ObjCClass, ClassName), 368 Mangle(ObjCMetaclass, ClassName), 369 }; 370 } 371 372 std::vector<std::string> getAllManglings(const Decl *D) { 373 if (const auto *OCD = dyn_cast<ObjCContainerDecl>(D)) 374 return getAllManglings(OCD); 375 376 if (!(isa<CXXRecordDecl>(D) || isa<CXXMethodDecl>(D))) 377 return {}; 378 379 const NamedDecl *ND = cast<NamedDecl>(D); 380 381 ASTContext &Ctx = ND->getASTContext(); 382 std::unique_ptr<MangleContext> M(Ctx.createMangleContext()); 383 384 std::vector<std::string> Manglings; 385 386 auto hasDefaultCXXMethodCC = [](ASTContext &C, const CXXMethodDecl *MD) { 387 auto DefaultCC = C.getDefaultCallingConvention(/*IsVariadic=*/false, 388 /*IsCXXMethod=*/true); 389 auto CC = MD->getType()->castAs<FunctionProtoType>()->getCallConv(); 390 return CC == DefaultCC; 391 }; 392 393 if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(ND)) { 394 Manglings.emplace_back(getMangledStructor(CD, Ctor_Base)); 395 396 if (Ctx.getTargetInfo().getCXXABI().isItaniumFamily()) 397 if (!CD->getParent()->isAbstract()) 398 Manglings.emplace_back(getMangledStructor(CD, Ctor_Complete)); 399 400 if (Ctx.getTargetInfo().getCXXABI().isMicrosoft()) 401 if (CD->hasAttr<DLLExportAttr>() && CD->isDefaultConstructor()) 402 if (!(hasDefaultCXXMethodCC(Ctx, CD) && CD->getNumParams() == 0)) 403 Manglings.emplace_back(getMangledStructor(CD, Ctor_DefaultClosure)); 404 } else if (const auto *DD = dyn_cast_or_null<CXXDestructorDecl>(ND)) { 405 Manglings.emplace_back(getMangledStructor(DD, Dtor_Base)); 406 if (Ctx.getTargetInfo().getCXXABI().isItaniumFamily()) { 407 Manglings.emplace_back(getMangledStructor(DD, Dtor_Complete)); 408 if (DD->isVirtual()) 409 Manglings.emplace_back(getMangledStructor(DD, Dtor_Deleting)); 410 } 411 } else if (const auto *MD = dyn_cast_or_null<CXXMethodDecl>(ND)) { 412 Manglings.emplace_back(getName(ND)); 413 if (MD->isVirtual()) 414 if (const auto *TIV = Ctx.getVTableContext()->getThunkInfo(MD)) 415 for (const auto &T : *TIV) 416 Manglings.emplace_back(getMangledThunk(MD, T)); 417 } 418 419 return Manglings; 420 } 421 422 private: 423 bool writeFuncOrVarName(const NamedDecl *D, raw_ostream &OS) { 424 if (MC->shouldMangleDeclName(D)) { 425 if (const auto *CtorD = dyn_cast<CXXConstructorDecl>(D)) 426 MC->mangleCXXCtor(CtorD, Ctor_Complete, OS); 427 else if (const auto *DtorD = dyn_cast<CXXDestructorDecl>(D)) 428 MC->mangleCXXDtor(DtorD, Dtor_Complete, OS); 429 else 430 MC->mangleName(D, OS); 431 return false; 432 } else { 433 IdentifierInfo *II = D->getIdentifier(); 434 if (!II) 435 return true; 436 OS << II->getName(); 437 return false; 438 } 439 } 440 441 void writeObjCClassName(const ObjCInterfaceDecl *D, raw_ostream &OS) { 442 OS << getClassSymbolPrefix(ObjCClass, D->getASTContext()); 443 OS << D->getObjCRuntimeNameAsString(); 444 } 445 446 std::string getMangledStructor(const NamedDecl *ND, unsigned StructorType) { 447 std::string FrontendBuf; 448 llvm::raw_string_ostream FOS(FrontendBuf); 449 450 if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(ND)) 451 MC->mangleCXXCtor(CD, static_cast<CXXCtorType>(StructorType), FOS); 452 else if (const auto *DD = dyn_cast_or_null<CXXDestructorDecl>(ND)) 453 MC->mangleCXXDtor(DD, static_cast<CXXDtorType>(StructorType), FOS); 454 455 std::string BackendBuf; 456 llvm::raw_string_ostream BOS(BackendBuf); 457 458 llvm::Mangler::getNameWithPrefix(BOS, FOS.str(), DL); 459 460 return BOS.str(); 461 } 462 463 std::string getMangledThunk(const CXXMethodDecl *MD, const ThunkInfo &T) { 464 std::string FrontendBuf; 465 llvm::raw_string_ostream FOS(FrontendBuf); 466 467 MC->mangleThunk(MD, T, FOS); 468 469 std::string BackendBuf; 470 llvm::raw_string_ostream BOS(BackendBuf); 471 472 llvm::Mangler::getNameWithPrefix(BOS, FOS.str(), DL); 473 474 return BOS.str(); 475 } 476 }; 477 478 ASTNameGenerator::ASTNameGenerator(ASTContext &Ctx) 479 : Impl(std::make_unique<Implementation>(Ctx)) {} 480 481 ASTNameGenerator::~ASTNameGenerator() {} 482 483 bool ASTNameGenerator::writeName(const Decl *D, raw_ostream &OS) { 484 return Impl->writeName(D, OS); 485 } 486 487 std::string ASTNameGenerator::getName(const Decl *D) { 488 return Impl->getName(D); 489 } 490 491 std::vector<std::string> ASTNameGenerator::getAllManglings(const Decl *D) { 492 return Impl->getAllManglings(D); 493 } 494