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() || !Triple.isX86()) 67 return CCM_Other; 68 69 if (Context.getLangOpts().CPlusPlus && !isExternC(ND) && 70 TI.getCXXABI() == TargetCXXABI::Microsoft) 71 return CCM_Other; 72 73 const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND); 74 if (!FD) 75 return CCM_Other; 76 QualType T = FD->getType(); 77 78 const FunctionType *FT = T->castAs<FunctionType>(); 79 80 CallingConv CC = FT->getCallConv(); 81 switch (CC) { 82 default: 83 return CCM_Other; 84 case CC_X86FastCall: 85 return CCM_Fast; 86 case CC_X86StdCall: 87 return CCM_Std; 88 case CC_X86VectorCall: 89 return CCM_Vector; 90 } 91 } 92 93 bool MangleContext::shouldMangleDeclName(const NamedDecl *D) { 94 const ASTContext &ASTContext = getASTContext(); 95 96 CCMangling CC = getCallingConvMangling(ASTContext, D); 97 if (CC != CCM_Other) 98 return true; 99 100 // If the declaration has an owning module for linkage purposes that needs to 101 // be mangled, we must mangle its name. 102 if (!D->hasExternalFormalLinkage() && D->getOwningModuleForLinkage()) 103 return true; 104 105 // In C, functions with no attributes never need to be mangled. Fastpath them. 106 if (!getASTContext().getLangOpts().CPlusPlus && !D->hasAttrs()) 107 return false; 108 109 // Any decl can be declared with __asm("foo") on it, and this takes precedence 110 // over all other naming in the .o file. 111 if (D->hasAttr<AsmLabelAttr>()) 112 return true; 113 114 return shouldMangleCXXName(D); 115 } 116 117 void MangleContext::mangleName(const NamedDecl *D, raw_ostream &Out) { 118 // Any decl can be declared with __asm("foo") on it, and this takes precedence 119 // over all other naming in the .o file. 120 if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) { 121 // If we have an asm name, then we use it as the mangling. 122 123 // If the label isn't literal, or if this is an alias for an LLVM intrinsic, 124 // do not add a "\01" prefix. 125 if (!ALA->getIsLiteralLabel() || ALA->getLabel().startswith("llvm.")) { 126 Out << ALA->getLabel(); 127 return; 128 } 129 130 // Adding the prefix can cause problems when one file has a "foo" and 131 // another has a "\01foo". That is known to happen on ELF with the 132 // tricks normally used for producing aliases (PR9177). Fortunately the 133 // llvm mangler on ELF is a nop, so we can just avoid adding the \01 134 // marker. 135 char GlobalPrefix = 136 getASTContext().getTargetInfo().getDataLayout().getGlobalPrefix(); 137 if (GlobalPrefix) 138 Out << '\01'; // LLVM IR Marker for __asm("foo") 139 140 Out << ALA->getLabel(); 141 return; 142 } 143 144 const ASTContext &ASTContext = getASTContext(); 145 CCMangling CC = getCallingConvMangling(ASTContext, D); 146 bool MCXX = shouldMangleCXXName(D); 147 const TargetInfo &TI = Context.getTargetInfo(); 148 if (CC == CCM_Other || (MCXX && TI.getCXXABI() == TargetCXXABI::Microsoft)) { 149 if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D)) 150 mangleObjCMethodName(OMD, Out); 151 else 152 mangleCXXName(D, Out); 153 return; 154 } 155 156 Out << '\01'; 157 if (CC == CCM_Std) 158 Out << '_'; 159 else if (CC == CCM_Fast) 160 Out << '@'; 161 else if (CC == CCM_RegCall) 162 Out << "__regcall3__"; 163 164 if (!MCXX) 165 Out << D->getIdentifier()->getName(); 166 else if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D)) 167 mangleObjCMethodName(OMD, Out); 168 else 169 mangleCXXName(D, Out); 170 171 const FunctionDecl *FD = cast<FunctionDecl>(D); 172 const FunctionType *FT = FD->getType()->castAs<FunctionType>(); 173 const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT); 174 if (CC == CCM_Vector) 175 Out << '@'; 176 Out << '@'; 177 if (!Proto) { 178 Out << '0'; 179 return; 180 } 181 assert(!Proto->isVariadic()); 182 unsigned ArgWords = 0; 183 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) 184 if (!MD->isStatic()) 185 ++ArgWords; 186 for (const auto &AT : Proto->param_types()) 187 // Size should be aligned to pointer size. 188 ArgWords += 189 llvm::alignTo(ASTContext.getTypeSize(AT), TI.getPointerWidth(0)) / 190 TI.getPointerWidth(0); 191 Out << ((TI.getPointerWidth(0) / 8) * ArgWords); 192 } 193 194 void MangleContext::mangleGlobalBlock(const BlockDecl *BD, 195 const NamedDecl *ID, 196 raw_ostream &Out) { 197 unsigned discriminator = getBlockId(BD, false); 198 if (ID) { 199 if (shouldMangleDeclName(ID)) 200 mangleName(ID, Out); 201 else { 202 Out << ID->getIdentifier()->getName(); 203 } 204 } 205 if (discriminator == 0) 206 Out << "_block_invoke"; 207 else 208 Out << "_block_invoke_" << discriminator+1; 209 } 210 211 void MangleContext::mangleCtorBlock(const CXXConstructorDecl *CD, 212 CXXCtorType CT, const BlockDecl *BD, 213 raw_ostream &ResStream) { 214 SmallString<64> Buffer; 215 llvm::raw_svector_ostream Out(Buffer); 216 mangleCXXCtor(CD, CT, Out); 217 mangleFunctionBlock(*this, Buffer, BD, ResStream); 218 } 219 220 void MangleContext::mangleDtorBlock(const CXXDestructorDecl *DD, 221 CXXDtorType DT, const BlockDecl *BD, 222 raw_ostream &ResStream) { 223 SmallString<64> Buffer; 224 llvm::raw_svector_ostream Out(Buffer); 225 mangleCXXDtor(DD, DT, Out); 226 mangleFunctionBlock(*this, Buffer, BD, ResStream); 227 } 228 229 void MangleContext::mangleBlock(const DeclContext *DC, const BlockDecl *BD, 230 raw_ostream &Out) { 231 assert(!isa<CXXConstructorDecl>(DC) && !isa<CXXDestructorDecl>(DC)); 232 233 SmallString<64> Buffer; 234 llvm::raw_svector_ostream Stream(Buffer); 235 if (const ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(DC)) { 236 mangleObjCMethodName(Method, Stream); 237 } else { 238 assert((isa<NamedDecl>(DC) || isa<BlockDecl>(DC)) && 239 "expected a NamedDecl or BlockDecl"); 240 if (isa<BlockDecl>(DC)) 241 for (; DC && isa<BlockDecl>(DC); DC = DC->getParent()) 242 (void) getBlockId(cast<BlockDecl>(DC), true); 243 assert((isa<TranslationUnitDecl>(DC) || isa<NamedDecl>(DC)) && 244 "expected a TranslationUnitDecl or a NamedDecl"); 245 if (const auto *CD = dyn_cast<CXXConstructorDecl>(DC)) 246 mangleCtorBlock(CD, /*CT*/ Ctor_Complete, BD, Out); 247 else if (const auto *DD = dyn_cast<CXXDestructorDecl>(DC)) 248 mangleDtorBlock(DD, /*DT*/ Dtor_Complete, BD, Out); 249 else if (auto ND = dyn_cast<NamedDecl>(DC)) { 250 if (!shouldMangleDeclName(ND) && ND->getIdentifier()) 251 Stream << ND->getIdentifier()->getName(); 252 else { 253 // FIXME: We were doing a mangleUnqualifiedName() before, but that's 254 // a private member of a class that will soon itself be private to the 255 // Itanium C++ ABI object. What should we do now? Right now, I'm just 256 // calling the mangleName() method on the MangleContext; is there a 257 // better way? 258 mangleName(ND, Stream); 259 } 260 } 261 } 262 mangleFunctionBlock(*this, Buffer, BD, Out); 263 } 264 265 void MangleContext::mangleObjCMethodNameWithoutSize(const ObjCMethodDecl *MD, 266 raw_ostream &OS) { 267 const ObjCContainerDecl *CD = 268 dyn_cast<ObjCContainerDecl>(MD->getDeclContext()); 269 assert (CD && "Missing container decl in GetNameForMethod"); 270 OS << (MD->isInstanceMethod() ? '-' : '+') << '['; 271 if (const ObjCCategoryImplDecl *CID = dyn_cast<ObjCCategoryImplDecl>(CD)) { 272 OS << CID->getClassInterface()->getName(); 273 OS << '(' << *CID << ')'; 274 } else { 275 OS << CD->getName(); 276 } 277 OS << ' '; 278 MD->getSelector().print(OS); 279 OS << ']'; 280 } 281 282 void MangleContext::mangleObjCMethodName(const ObjCMethodDecl *MD, 283 raw_ostream &Out) { 284 SmallString<64> Name; 285 llvm::raw_svector_ostream OS(Name); 286 287 mangleObjCMethodNameWithoutSize(MD, OS); 288 Out << OS.str().size() << OS.str(); 289 } 290 291 class ASTNameGenerator::Implementation { 292 std::unique_ptr<MangleContext> MC; 293 llvm::DataLayout DL; 294 295 public: 296 explicit Implementation(ASTContext &Ctx) 297 : MC(Ctx.createMangleContext()), DL(Ctx.getTargetInfo().getDataLayout()) { 298 } 299 300 bool writeName(const Decl *D, raw_ostream &OS) { 301 // First apply frontend mangling. 302 SmallString<128> FrontendBuf; 303 llvm::raw_svector_ostream FrontendBufOS(FrontendBuf); 304 if (auto *FD = dyn_cast<FunctionDecl>(D)) { 305 if (FD->isDependentContext()) 306 return true; 307 if (writeFuncOrVarName(FD, FrontendBufOS)) 308 return true; 309 } else if (auto *VD = dyn_cast<VarDecl>(D)) { 310 if (writeFuncOrVarName(VD, FrontendBufOS)) 311 return true; 312 } else if (auto *MD = dyn_cast<ObjCMethodDecl>(D)) { 313 MC->mangleObjCMethodNameWithoutSize(MD, OS); 314 return false; 315 } else if (auto *ID = dyn_cast<ObjCInterfaceDecl>(D)) { 316 writeObjCClassName(ID, FrontendBufOS); 317 } else { 318 return true; 319 } 320 321 // Now apply backend mangling. 322 llvm::Mangler::getNameWithPrefix(OS, FrontendBufOS.str(), DL); 323 return false; 324 } 325 326 std::string getName(const Decl *D) { 327 std::string Name; 328 { 329 llvm::raw_string_ostream OS(Name); 330 writeName(D, OS); 331 } 332 return Name; 333 } 334 335 enum ObjCKind { 336 ObjCClass, 337 ObjCMetaclass, 338 }; 339 340 static StringRef getClassSymbolPrefix(ObjCKind Kind, 341 const ASTContext &Context) { 342 if (Context.getLangOpts().ObjCRuntime.isGNUFamily()) 343 return Kind == ObjCMetaclass ? "_OBJC_METACLASS_" : "_OBJC_CLASS_"; 344 return Kind == ObjCMetaclass ? "OBJC_METACLASS_$_" : "OBJC_CLASS_$_"; 345 } 346 347 std::vector<std::string> getAllManglings(const ObjCContainerDecl *OCD) { 348 StringRef ClassName; 349 if (const auto *OID = dyn_cast<ObjCInterfaceDecl>(OCD)) 350 ClassName = OID->getObjCRuntimeNameAsString(); 351 else if (const auto *OID = dyn_cast<ObjCImplementationDecl>(OCD)) 352 ClassName = OID->getObjCRuntimeNameAsString(); 353 354 if (ClassName.empty()) 355 return {}; 356 357 auto Mangle = [&](ObjCKind Kind, StringRef ClassName) -> std::string { 358 SmallString<40> Mangled; 359 auto Prefix = getClassSymbolPrefix(Kind, OCD->getASTContext()); 360 llvm::Mangler::getNameWithPrefix(Mangled, Prefix + ClassName, DL); 361 return Mangled.str(); 362 }; 363 364 return { 365 Mangle(ObjCClass, ClassName), 366 Mangle(ObjCMetaclass, ClassName), 367 }; 368 } 369 370 std::vector<std::string> getAllManglings(const Decl *D) { 371 if (const auto *OCD = dyn_cast<ObjCContainerDecl>(D)) 372 return getAllManglings(OCD); 373 374 if (!(isa<CXXRecordDecl>(D) || isa<CXXMethodDecl>(D))) 375 return {}; 376 377 const NamedDecl *ND = cast<NamedDecl>(D); 378 379 ASTContext &Ctx = ND->getASTContext(); 380 std::unique_ptr<MangleContext> M(Ctx.createMangleContext()); 381 382 std::vector<std::string> Manglings; 383 384 auto hasDefaultCXXMethodCC = [](ASTContext &C, const CXXMethodDecl *MD) { 385 auto DefaultCC = C.getDefaultCallingConvention(/*IsVariadic=*/false, 386 /*IsCXXMethod=*/true); 387 auto CC = MD->getType()->castAs<FunctionProtoType>()->getCallConv(); 388 return CC == DefaultCC; 389 }; 390 391 if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(ND)) { 392 Manglings.emplace_back(getMangledStructor(CD, Ctor_Base)); 393 394 if (Ctx.getTargetInfo().getCXXABI().isItaniumFamily()) 395 if (!CD->getParent()->isAbstract()) 396 Manglings.emplace_back(getMangledStructor(CD, Ctor_Complete)); 397 398 if (Ctx.getTargetInfo().getCXXABI().isMicrosoft()) 399 if (CD->hasAttr<DLLExportAttr>() && CD->isDefaultConstructor()) 400 if (!(hasDefaultCXXMethodCC(Ctx, CD) && CD->getNumParams() == 0)) 401 Manglings.emplace_back(getMangledStructor(CD, Ctor_DefaultClosure)); 402 } else if (const auto *DD = dyn_cast_or_null<CXXDestructorDecl>(ND)) { 403 Manglings.emplace_back(getMangledStructor(DD, Dtor_Base)); 404 if (Ctx.getTargetInfo().getCXXABI().isItaniumFamily()) { 405 Manglings.emplace_back(getMangledStructor(DD, Dtor_Complete)); 406 if (DD->isVirtual()) 407 Manglings.emplace_back(getMangledStructor(DD, Dtor_Deleting)); 408 } 409 } else if (const auto *MD = dyn_cast_or_null<CXXMethodDecl>(ND)) { 410 Manglings.emplace_back(getName(ND)); 411 if (MD->isVirtual()) 412 if (const auto *TIV = Ctx.getVTableContext()->getThunkInfo(MD)) 413 for (const auto &T : *TIV) 414 Manglings.emplace_back(getMangledThunk(MD, T)); 415 } 416 417 return Manglings; 418 } 419 420 private: 421 bool writeFuncOrVarName(const NamedDecl *D, raw_ostream &OS) { 422 if (MC->shouldMangleDeclName(D)) { 423 if (const auto *CtorD = dyn_cast<CXXConstructorDecl>(D)) 424 MC->mangleCXXCtor(CtorD, Ctor_Complete, OS); 425 else if (const auto *DtorD = dyn_cast<CXXDestructorDecl>(D)) 426 MC->mangleCXXDtor(DtorD, Dtor_Complete, OS); 427 else 428 MC->mangleName(D, OS); 429 return false; 430 } else { 431 IdentifierInfo *II = D->getIdentifier(); 432 if (!II) 433 return true; 434 OS << II->getName(); 435 return false; 436 } 437 } 438 439 void writeObjCClassName(const ObjCInterfaceDecl *D, raw_ostream &OS) { 440 OS << getClassSymbolPrefix(ObjCClass, D->getASTContext()); 441 OS << D->getObjCRuntimeNameAsString(); 442 } 443 444 std::string getMangledStructor(const NamedDecl *ND, unsigned StructorType) { 445 std::string FrontendBuf; 446 llvm::raw_string_ostream FOS(FrontendBuf); 447 448 if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(ND)) 449 MC->mangleCXXCtor(CD, static_cast<CXXCtorType>(StructorType), FOS); 450 else if (const auto *DD = dyn_cast_or_null<CXXDestructorDecl>(ND)) 451 MC->mangleCXXDtor(DD, static_cast<CXXDtorType>(StructorType), FOS); 452 453 std::string BackendBuf; 454 llvm::raw_string_ostream BOS(BackendBuf); 455 456 llvm::Mangler::getNameWithPrefix(BOS, FOS.str(), DL); 457 458 return BOS.str(); 459 } 460 461 std::string getMangledThunk(const CXXMethodDecl *MD, const ThunkInfo &T) { 462 std::string FrontendBuf; 463 llvm::raw_string_ostream FOS(FrontendBuf); 464 465 MC->mangleThunk(MD, T, FOS); 466 467 std::string BackendBuf; 468 llvm::raw_string_ostream BOS(BackendBuf); 469 470 llvm::Mangler::getNameWithPrefix(BOS, FOS.str(), DL); 471 472 return BOS.str(); 473 } 474 }; 475 476 ASTNameGenerator::ASTNameGenerator(ASTContext &Ctx) 477 : Impl(std::make_unique<Implementation>(Ctx)) {} 478 479 ASTNameGenerator::~ASTNameGenerator() {} 480 481 bool ASTNameGenerator::writeName(const Decl *D, raw_ostream &OS) { 482 return Impl->writeName(D, OS); 483 } 484 485 std::string ASTNameGenerator::getName(const Decl *D) { 486 return Impl->getName(D); 487 } 488 489 std::vector<std::string> ASTNameGenerator::getAllManglings(const Decl *D) { 490 return Impl->getAllManglings(D); 491 } 492