xref: /freebsd/contrib/llvm-project/clang/lib/AST/Mangle.cpp (revision b64c5a0ace59af62eff52bfe110a521dc73c937b) 
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   if (Triple.isWasm())
74     if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND))
75       if (FD->isMain() && FD->getNumParams() == 2)
76         return CCM_WasmMainArgcArgv;
77 
78   if (!Triple.isOSWindows() || !Triple.isX86())
79     return CCM_Other;
80 
81   if (Context.getLangOpts().CPlusPlus && !isExternC(ND) &&
82       TI.getCXXABI() == TargetCXXABI::Microsoft)
83     return CCM_Other;
84 
85   const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND);
86   if (!FD)
87     return CCM_Other;
88   QualType T = FD->getType();
89 
90   const FunctionType *FT = T->castAs<FunctionType>();
91 
92   CallingConv CC = FT->getCallConv();
93   switch (CC) {
94   default:
95     return CCM_Other;
96   case CC_X86FastCall:
97     return CCM_Fast;
98   case CC_X86StdCall:
99     return CCM_Std;
100   case CC_X86VectorCall:
101     return CCM_Vector;
102   }
103 }
104 
105 bool MangleContext::shouldMangleDeclName(const NamedDecl *D) {
106   const ASTContext &ASTContext = getASTContext();
107 
108   CCMangling CC = getCallingConvMangling(ASTContext, D);
109   if (CC != CCM_Other)
110     return true;
111 
112   // If the declaration has an owning module for linkage purposes that needs to
113   // be mangled, we must mangle its name.
114   if (!D->hasExternalFormalLinkage() && D->getOwningModuleForLinkage())
115     return true;
116 
117   // C functions with internal linkage have to be mangled with option
118   // -funique-internal-linkage-names.
119   if (!getASTContext().getLangOpts().CPlusPlus &&
120       isUniqueInternalLinkageDecl(D))
121     return true;
122 
123   // In C, functions with no attributes never need to be mangled. Fastpath them.
124   if (!getASTContext().getLangOpts().CPlusPlus && !D->hasAttrs())
125     return false;
126 
127   // Any decl can be declared with __asm("foo") on it, and this takes precedence
128   // over all other naming in the .o file.
129   if (D->hasAttr<AsmLabelAttr>())
130     return true;
131 
132   // Declarations that don't have identifier names always need to be mangled.
133   if (isa<MSGuidDecl>(D))
134     return true;
135 
136   return shouldMangleCXXName(D);
137 }
138 
139 void MangleContext::mangleName(GlobalDecl GD, raw_ostream &Out) {
140   const ASTContext &ASTContext = getASTContext();
141   const NamedDecl *D = cast<NamedDecl>(GD.getDecl());
142 
143   // Any decl can be declared with __asm("foo") on it, and this takes precedence
144   // over all other naming in the .o file.
145   if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) {
146     // If we have an asm name, then we use it as the mangling.
147 
148     // If the label isn't literal, or if this is an alias for an LLVM intrinsic,
149     // do not add a "\01" prefix.
150     if (!ALA->getIsLiteralLabel() || ALA->getLabel().starts_with("llvm.")) {
151       Out << ALA->getLabel();
152       return;
153     }
154 
155     // Adding the prefix can cause problems when one file has a "foo" and
156     // another has a "\01foo". That is known to happen on ELF with the
157     // tricks normally used for producing aliases (PR9177). Fortunately the
158     // llvm mangler on ELF is a nop, so we can just avoid adding the \01
159     // marker.
160     StringRef UserLabelPrefix =
161         getASTContext().getTargetInfo().getUserLabelPrefix();
162 #ifndef NDEBUG
163     char GlobalPrefix =
164         llvm::DataLayout(getASTContext().getTargetInfo().getDataLayoutString())
165             .getGlobalPrefix();
166     assert((UserLabelPrefix.empty() && !GlobalPrefix) ||
167            (UserLabelPrefix.size() == 1 && UserLabelPrefix[0] == GlobalPrefix));
168 #endif
169     if (!UserLabelPrefix.empty())
170       Out << '\01'; // LLVM IR Marker for __asm("foo")
171 
172     Out << ALA->getLabel();
173     return;
174   }
175 
176   if (auto *GD = dyn_cast<MSGuidDecl>(D))
177     return mangleMSGuidDecl(GD, Out);
178 
179   CCMangling CC = getCallingConvMangling(ASTContext, D);
180 
181   if (CC == CCM_WasmMainArgcArgv) {
182     Out << "__main_argc_argv";
183     return;
184   }
185 
186   bool MCXX = shouldMangleCXXName(D);
187   const TargetInfo &TI = Context.getTargetInfo();
188   if (CC == CCM_Other || (MCXX && TI.getCXXABI() == TargetCXXABI::Microsoft)) {
189     if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D))
190       mangleObjCMethodNameAsSourceName(OMD, Out);
191     else
192       mangleCXXName(GD, Out);
193     return;
194   }
195 
196   Out << '\01';
197   if (CC == CCM_Std)
198     Out << '_';
199   else if (CC == CCM_Fast)
200     Out << '@';
201   else if (CC == CCM_RegCall) {
202     if (getASTContext().getLangOpts().RegCall4)
203       Out << "__regcall4__";
204     else
205       Out << "__regcall3__";
206   }
207 
208   if (!MCXX)
209     Out << D->getIdentifier()->getName();
210   else if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D))
211     mangleObjCMethodNameAsSourceName(OMD, Out);
212   else
213     mangleCXXName(GD, Out);
214 
215   const FunctionDecl *FD = cast<FunctionDecl>(D);
216   const FunctionType *FT = FD->getType()->castAs<FunctionType>();
217   const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT);
218   if (CC == CCM_Vector)
219     Out << '@';
220   Out << '@';
221   if (!Proto) {
222     Out << '0';
223     return;
224   }
225   assert(!Proto->isVariadic());
226   unsigned ArgWords = 0;
227   if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD))
228     if (MD->isImplicitObjectMemberFunction())
229       ++ArgWords;
230   uint64_t DefaultPtrWidth = TI.getPointerWidth(LangAS::Default);
231   for (const auto &AT : Proto->param_types()) {
232     // If an argument type is incomplete there is no way to get its size to
233     // correctly encode into the mangling scheme.
234     // Follow GCCs behaviour by simply breaking out of the loop.
235     if (AT->isIncompleteType())
236       break;
237     // Size should be aligned to pointer size.
238     ArgWords += llvm::alignTo(ASTContext.getTypeSize(AT), DefaultPtrWidth) /
239                 DefaultPtrWidth;
240   }
241   Out << ((DefaultPtrWidth / 8) * ArgWords);
242 }
243 
244 void MangleContext::mangleMSGuidDecl(const MSGuidDecl *GD, raw_ostream &Out) {
245   // For now, follow the MSVC naming convention for GUID objects on all
246   // targets.
247   MSGuidDecl::Parts P = GD->getParts();
248   Out << llvm::format("_GUID_%08" PRIx32 "_%04" PRIx32 "_%04" PRIx32 "_",
249                       P.Part1, P.Part2, P.Part3);
250   unsigned I = 0;
251   for (uint8_t C : P.Part4And5) {
252     Out << llvm::format("%02" PRIx8, C);
253     if (++I == 2)
254       Out << "_";
255   }
256 }
257 
258 void MangleContext::mangleGlobalBlock(const BlockDecl *BD,
259                                       const NamedDecl *ID,
260                                       raw_ostream &Out) {
261   unsigned discriminator = getBlockId(BD, false);
262   if (ID) {
263     if (shouldMangleDeclName(ID))
264       mangleName(ID, Out);
265     else {
266       Out << ID->getIdentifier()->getName();
267     }
268   }
269   if (discriminator == 0)
270     Out << "_block_invoke";
271   else
272     Out << "_block_invoke_" << discriminator+1;
273 }
274 
275 void MangleContext::mangleCtorBlock(const CXXConstructorDecl *CD,
276                                     CXXCtorType CT, const BlockDecl *BD,
277                                     raw_ostream &ResStream) {
278   SmallString<64> Buffer;
279   llvm::raw_svector_ostream Out(Buffer);
280   mangleName(GlobalDecl(CD, CT), Out);
281   mangleFunctionBlock(*this, Buffer, BD, ResStream);
282 }
283 
284 void MangleContext::mangleDtorBlock(const CXXDestructorDecl *DD,
285                                     CXXDtorType DT, const BlockDecl *BD,
286                                     raw_ostream &ResStream) {
287   SmallString<64> Buffer;
288   llvm::raw_svector_ostream Out(Buffer);
289   mangleName(GlobalDecl(DD, DT), Out);
290   mangleFunctionBlock(*this, Buffer, BD, ResStream);
291 }
292 
293 void MangleContext::mangleBlock(const DeclContext *DC, const BlockDecl *BD,
294                                 raw_ostream &Out) {
295   assert(!isa<CXXConstructorDecl>(DC) && !isa<CXXDestructorDecl>(DC));
296 
297   SmallString<64> Buffer;
298   llvm::raw_svector_ostream Stream(Buffer);
299   if (const ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(DC)) {
300     mangleObjCMethodNameAsSourceName(Method, Stream);
301   } else {
302     assert((isa<NamedDecl>(DC) || isa<BlockDecl>(DC)) &&
303            "expected a NamedDecl or BlockDecl");
304     for (; isa_and_nonnull<BlockDecl>(DC); DC = DC->getParent())
305       (void)getBlockId(cast<BlockDecl>(DC), true);
306     assert((isa<TranslationUnitDecl>(DC) || isa<NamedDecl>(DC)) &&
307            "expected a TranslationUnitDecl or a NamedDecl");
308     if (const auto *CD = dyn_cast<CXXConstructorDecl>(DC))
309       mangleCtorBlock(CD, /*CT*/ Ctor_Complete, BD, Out);
310     else if (const auto *DD = dyn_cast<CXXDestructorDecl>(DC))
311       mangleDtorBlock(DD, /*DT*/ Dtor_Complete, BD, Out);
312     else if (auto ND = dyn_cast<NamedDecl>(DC)) {
313       if (!shouldMangleDeclName(ND) && ND->getIdentifier())
314         Stream << ND->getIdentifier()->getName();
315       else {
316         // FIXME: We were doing a mangleUnqualifiedName() before, but that's
317         // a private member of a class that will soon itself be private to the
318         // Itanium C++ ABI object. What should we do now? Right now, I'm just
319         // calling the mangleName() method on the MangleContext; is there a
320         // better way?
321         mangleName(ND, Stream);
322       }
323     }
324   }
325   mangleFunctionBlock(*this, Buffer, BD, Out);
326 }
327 
328 void MangleContext::mangleObjCMethodName(const ObjCMethodDecl *MD,
329                                          raw_ostream &OS,
330                                          bool includePrefixByte,
331                                          bool includeCategoryNamespace) {
332   if (getASTContext().getLangOpts().ObjCRuntime.isGNUFamily()) {
333     // This is the mangling we've always used on the GNU runtimes, but it
334     // has obvious collisions in the face of underscores within class
335     // names, category names, and selectors; maybe we should improve it.
336 
337     OS << (MD->isClassMethod() ? "_c_" : "_i_")
338        << MD->getClassInterface()->getName() << '_';
339 
340     if (includeCategoryNamespace) {
341       if (auto category = MD->getCategory())
342         OS << category->getName();
343     }
344     OS << '_';
345 
346     auto selector = MD->getSelector();
347     for (unsigned slotIndex = 0,
348                   numArgs = selector.getNumArgs(),
349                   slotEnd = std::max(numArgs, 1U);
350            slotIndex != slotEnd; ++slotIndex) {
351       if (auto name = selector.getIdentifierInfoForSlot(slotIndex))
352         OS << name->getName();
353 
354       // Replace all the positions that would've been ':' with '_'.
355       // That's after each slot except that a unary selector doesn't
356       // end in ':'.
357       if (numArgs)
358         OS << '_';
359     }
360 
361     return;
362   }
363 
364   // \01+[ContainerName(CategoryName) SelectorName]
365   if (includePrefixByte) {
366     OS << '\01';
367   }
368   OS << (MD->isInstanceMethod() ? '-' : '+') << '[';
369   if (const auto *CID = MD->getCategory()) {
370     OS << CID->getClassInterface()->getName();
371     if (includeCategoryNamespace) {
372       OS << '(' << *CID << ')';
373     }
374   } else if (const auto *CD =
375                  dyn_cast<ObjCContainerDecl>(MD->getDeclContext())) {
376     OS << CD->getName();
377   } else {
378     llvm_unreachable("Unexpected ObjC method decl context");
379   }
380   OS << ' ';
381   MD->getSelector().print(OS);
382   OS << ']';
383 }
384 
385 void MangleContext::mangleObjCMethodNameAsSourceName(const ObjCMethodDecl *MD,
386                                                      raw_ostream &Out) {
387   SmallString<64> Name;
388   llvm::raw_svector_ostream OS(Name);
389 
390   mangleObjCMethodName(MD, OS, /*includePrefixByte=*/false,
391                        /*includeCategoryNamespace=*/true);
392   Out << OS.str().size() << OS.str();
393 }
394 
395 class ASTNameGenerator::Implementation {
396   std::unique_ptr<MangleContext> MC;
397   llvm::DataLayout DL;
398 
399 public:
400   explicit Implementation(ASTContext &Ctx)
401       : MC(Ctx.createMangleContext()),
402         DL(Ctx.getTargetInfo().getDataLayoutString()) {}
403 
404   bool writeName(const Decl *D, raw_ostream &OS) {
405     // First apply frontend mangling.
406     SmallString<128> FrontendBuf;
407     llvm::raw_svector_ostream FrontendBufOS(FrontendBuf);
408     if (auto *FD = dyn_cast<FunctionDecl>(D)) {
409       if (FD->isDependentContext())
410         return true;
411       if (writeFuncOrVarName(FD, FrontendBufOS))
412         return true;
413     } else if (auto *VD = dyn_cast<VarDecl>(D)) {
414       if (writeFuncOrVarName(VD, FrontendBufOS))
415         return true;
416     } else if (auto *MD = dyn_cast<ObjCMethodDecl>(D)) {
417       MC->mangleObjCMethodName(MD, OS, /*includePrefixByte=*/false,
418                                /*includeCategoryNamespace=*/true);
419       return false;
420     } else if (auto *ID = dyn_cast<ObjCInterfaceDecl>(D)) {
421       writeObjCClassName(ID, FrontendBufOS);
422     } else {
423       return true;
424     }
425 
426     // Now apply backend mangling.
427     llvm::Mangler::getNameWithPrefix(OS, FrontendBufOS.str(), DL);
428     return false;
429   }
430 
431   std::string getName(const Decl *D) {
432     std::string Name;
433     {
434       llvm::raw_string_ostream OS(Name);
435       writeName(D, OS);
436     }
437     return Name;
438   }
439 
440   enum ObjCKind {
441     ObjCClass,
442     ObjCMetaclass,
443   };
444 
445   static StringRef getClassSymbolPrefix(ObjCKind Kind,
446                                         const ASTContext &Context) {
447     if (Context.getLangOpts().ObjCRuntime.isGNUFamily())
448       return Kind == ObjCMetaclass ? "_OBJC_METACLASS_" : "_OBJC_CLASS_";
449     return Kind == ObjCMetaclass ? "OBJC_METACLASS_$_" : "OBJC_CLASS_$_";
450   }
451 
452   std::vector<std::string> getAllManglings(const ObjCContainerDecl *OCD) {
453     StringRef ClassName;
454     if (const auto *OID = dyn_cast<ObjCInterfaceDecl>(OCD))
455       ClassName = OID->getObjCRuntimeNameAsString();
456     else if (const auto *OID = dyn_cast<ObjCImplementationDecl>(OCD))
457       ClassName = OID->getObjCRuntimeNameAsString();
458 
459     if (ClassName.empty())
460       return {};
461 
462     auto Mangle = [&](ObjCKind Kind, StringRef ClassName) -> std::string {
463       SmallString<40> Mangled;
464       auto Prefix = getClassSymbolPrefix(Kind, OCD->getASTContext());
465       llvm::Mangler::getNameWithPrefix(Mangled, Prefix + ClassName, DL);
466       return std::string(Mangled);
467     };
468 
469     return {
470         Mangle(ObjCClass, ClassName),
471         Mangle(ObjCMetaclass, ClassName),
472     };
473   }
474 
475   std::vector<std::string> getAllManglings(const Decl *D) {
476     if (const auto *OCD = dyn_cast<ObjCContainerDecl>(D))
477       return getAllManglings(OCD);
478 
479     if (!(isa<CXXRecordDecl>(D) || isa<CXXMethodDecl>(D)))
480       return {};
481 
482     const NamedDecl *ND = cast<NamedDecl>(D);
483 
484     ASTContext &Ctx = ND->getASTContext();
485     std::unique_ptr<MangleContext> M(Ctx.createMangleContext());
486 
487     std::vector<std::string> Manglings;
488 
489     auto hasDefaultCXXMethodCC = [](ASTContext &C, const CXXMethodDecl *MD) {
490       auto DefaultCC = C.getDefaultCallingConvention(/*IsVariadic=*/false,
491                                                      /*IsCXXMethod=*/true);
492       auto CC = MD->getType()->castAs<FunctionProtoType>()->getCallConv();
493       return CC == DefaultCC;
494     };
495 
496     if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(ND)) {
497       Manglings.emplace_back(getMangledStructor(CD, Ctor_Base));
498 
499       if (Ctx.getTargetInfo().getCXXABI().isItaniumFamily())
500         if (!CD->getParent()->isAbstract())
501           Manglings.emplace_back(getMangledStructor(CD, Ctor_Complete));
502 
503       if (Ctx.getTargetInfo().getCXXABI().isMicrosoft())
504         if (CD->hasAttr<DLLExportAttr>() && CD->isDefaultConstructor())
505           if (!(hasDefaultCXXMethodCC(Ctx, CD) && CD->getNumParams() == 0))
506             Manglings.emplace_back(getMangledStructor(CD, Ctor_DefaultClosure));
507     } else if (const auto *DD = dyn_cast_or_null<CXXDestructorDecl>(ND)) {
508       Manglings.emplace_back(getMangledStructor(DD, Dtor_Base));
509       if (Ctx.getTargetInfo().getCXXABI().isItaniumFamily()) {
510         Manglings.emplace_back(getMangledStructor(DD, Dtor_Complete));
511         if (DD->isVirtual())
512           Manglings.emplace_back(getMangledStructor(DD, Dtor_Deleting));
513       }
514     } else if (const auto *MD = dyn_cast_or_null<CXXMethodDecl>(ND)) {
515       Manglings.emplace_back(getName(ND));
516       if (MD->isVirtual()) {
517         if (const auto *TIV = Ctx.getVTableContext()->getThunkInfo(MD)) {
518           for (const auto &T : *TIV) {
519             std::string ThunkName;
520             std::string ContextualizedName =
521                 getMangledThunk(MD, T, /* ElideOverrideInfo */ false);
522             if (Ctx.useAbbreviatedThunkName(MD, ContextualizedName))
523               ThunkName = getMangledThunk(MD, T, /* ElideOverrideInfo */ true);
524             else
525               ThunkName = ContextualizedName;
526             Manglings.emplace_back(ThunkName);
527           }
528         }
529       }
530     }
531 
532     return Manglings;
533   }
534 
535 private:
536   bool writeFuncOrVarName(const NamedDecl *D, raw_ostream &OS) {
537     if (MC->shouldMangleDeclName(D)) {
538       GlobalDecl GD;
539       if (const auto *CtorD = dyn_cast<CXXConstructorDecl>(D))
540         GD = GlobalDecl(CtorD, Ctor_Complete);
541       else if (const auto *DtorD = dyn_cast<CXXDestructorDecl>(D))
542         GD = GlobalDecl(DtorD, Dtor_Complete);
543       else if (D->hasAttr<CUDAGlobalAttr>())
544         GD = GlobalDecl(cast<FunctionDecl>(D));
545       else
546         GD = GlobalDecl(D);
547       MC->mangleName(GD, OS);
548       return false;
549     } else {
550       IdentifierInfo *II = D->getIdentifier();
551       if (!II)
552         return true;
553       OS << II->getName();
554       return false;
555     }
556   }
557 
558   void writeObjCClassName(const ObjCInterfaceDecl *D, raw_ostream &OS) {
559     OS << getClassSymbolPrefix(ObjCClass, D->getASTContext());
560     OS << D->getObjCRuntimeNameAsString();
561   }
562 
563   std::string getMangledStructor(const NamedDecl *ND, unsigned StructorType) {
564     std::string FrontendBuf;
565     llvm::raw_string_ostream FOS(FrontendBuf);
566 
567     GlobalDecl GD;
568     if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(ND))
569       GD = GlobalDecl(CD, static_cast<CXXCtorType>(StructorType));
570     else if (const auto *DD = dyn_cast_or_null<CXXDestructorDecl>(ND))
571       GD = GlobalDecl(DD, static_cast<CXXDtorType>(StructorType));
572     MC->mangleName(GD, FOS);
573 
574     std::string BackendBuf;
575     llvm::raw_string_ostream BOS(BackendBuf);
576 
577     llvm::Mangler::getNameWithPrefix(BOS, FOS.str(), DL);
578 
579     return BOS.str();
580   }
581 
582   std::string getMangledThunk(const CXXMethodDecl *MD, const ThunkInfo &T,
583                               bool ElideOverrideInfo) {
584     std::string FrontendBuf;
585     llvm::raw_string_ostream FOS(FrontendBuf);
586 
587     MC->mangleThunk(MD, T, ElideOverrideInfo, FOS);
588 
589     std::string BackendBuf;
590     llvm::raw_string_ostream BOS(BackendBuf);
591 
592     llvm::Mangler::getNameWithPrefix(BOS, FOS.str(), DL);
593 
594     return BOS.str();
595   }
596 };
597 
598 ASTNameGenerator::ASTNameGenerator(ASTContext &Ctx)
599     : Impl(std::make_unique<Implementation>(Ctx)) {}
600 
601 ASTNameGenerator::~ASTNameGenerator() {}
602 
603 bool ASTNameGenerator::writeName(const Decl *D, raw_ostream &OS) {
604   return Impl->writeName(D, OS);
605 }
606 
607 std::string ASTNameGenerator::getName(const Decl *D) {
608   return Impl->getName(D);
609 }
610 
611 std::vector<std::string> ASTNameGenerator::getAllManglings(const Decl *D) {
612   return Impl->getAllManglings(D);
613 }
614