1 //===- CodegenNameGenerator.cpp - Codegen name generation -----------------===//
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 // Determines the name that the symbol will get for code generation.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/Index/CodegenNameGenerator.h"
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/DeclCXX.h"
17 #include "clang/AST/DeclObjC.h"
18 #include "clang/AST/Mangle.h"
19 #include "clang/AST/VTableBuilder.h"
20 #include "clang/Basic/TargetInfo.h"
21 #include "llvm/IR/DataLayout.h"
22 #include "llvm/IR/Mangler.h"
23 #include "llvm/Support/raw_ostream.h"
24 
25 using namespace clang;
26 using namespace clang::index;
27 
28 struct CodegenNameGenerator::Implementation {
29   std::unique_ptr<MangleContext> MC;
30   llvm::DataLayout DL;
31 
32   Implementation(ASTContext &Ctx)
33     : MC(Ctx.createMangleContext()),
34       DL(Ctx.getTargetInfo().getDataLayout()) {}
35 
36   bool writeName(const Decl *D, raw_ostream &OS) {
37     // First apply frontend mangling.
38     SmallString<128> FrontendBuf;
39     llvm::raw_svector_ostream FrontendBufOS(FrontendBuf);
40     if (auto *FD = dyn_cast<FunctionDecl>(D)) {
41       if (FD->isDependentContext())
42         return true;
43       if (writeFuncOrVarName(FD, FrontendBufOS))
44         return true;
45     } else if (auto *VD = dyn_cast<VarDecl>(D)) {
46       if (writeFuncOrVarName(VD, FrontendBufOS))
47         return true;
48     } else if (auto *MD = dyn_cast<ObjCMethodDecl>(D)) {
49       MC->mangleObjCMethodNameWithoutSize(MD, OS);
50       return false;
51     } else if (auto *ID = dyn_cast<ObjCInterfaceDecl>(D)) {
52       writeObjCClassName(ID, FrontendBufOS);
53     } else {
54       return true;
55     }
56 
57     // Now apply backend mangling.
58     llvm::Mangler::getNameWithPrefix(OS, FrontendBufOS.str(), DL);
59     return false;
60   }
61 
62   std::string getName(const Decl *D) {
63     std::string Name;
64     {
65       llvm::raw_string_ostream OS(Name);
66       writeName(D, OS);
67     }
68     return Name;
69   }
70 
71   enum ObjCKind {
72     ObjCClass,
73     ObjCMetaclass,
74   };
75 
76   std::vector<std::string> getAllManglings(const ObjCContainerDecl *OCD) {
77     StringRef ClassName;
78     if (const auto *OID = dyn_cast<ObjCInterfaceDecl>(OCD))
79       ClassName = OID->getObjCRuntimeNameAsString();
80     else if (const auto *OID = dyn_cast<ObjCImplementationDecl>(OCD))
81       ClassName = OID->getObjCRuntimeNameAsString();
82 
83     if (ClassName.empty())
84       return {};
85 
86     auto Mangle = [&](ObjCKind Kind, StringRef ClassName) -> std::string {
87       SmallString<40> Mangled;
88       auto Prefix = getClassSymbolPrefix(Kind, OCD->getASTContext());
89       llvm::Mangler::getNameWithPrefix(Mangled, Prefix + ClassName, DL);
90       return Mangled.str();
91     };
92 
93     return {
94       Mangle(ObjCClass, ClassName),
95       Mangle(ObjCMetaclass, ClassName),
96     };
97   }
98 
99   std::vector<std::string> getAllManglings(const Decl *D) {
100     if (const auto *OCD = dyn_cast<ObjCContainerDecl>(D))
101       return getAllManglings(OCD);
102 
103     if (!(isa<CXXRecordDecl>(D) || isa<CXXMethodDecl>(D)))
104       return {};
105 
106     const NamedDecl *ND = cast<NamedDecl>(D);
107 
108     ASTContext &Ctx = ND->getASTContext();
109     std::unique_ptr<MangleContext> M(Ctx.createMangleContext());
110 
111     std::vector<std::string> Manglings;
112 
113     auto hasDefaultCXXMethodCC = [](ASTContext &C, const CXXMethodDecl *MD) {
114       auto DefaultCC = C.getDefaultCallingConvention(/*IsVariadic=*/false,
115                                                      /*IsCSSMethod=*/true);
116       auto CC = MD->getType()->getAs<FunctionProtoType>()->getCallConv();
117       return CC == DefaultCC;
118     };
119 
120     if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(ND)) {
121       Manglings.emplace_back(getMangledStructor(CD, Ctor_Base));
122 
123       if (Ctx.getTargetInfo().getCXXABI().isItaniumFamily())
124         if (!CD->getParent()->isAbstract())
125           Manglings.emplace_back(getMangledStructor(CD, Ctor_Complete));
126 
127       if (Ctx.getTargetInfo().getCXXABI().isMicrosoft())
128         if (CD->hasAttr<DLLExportAttr>() && CD->isDefaultConstructor())
129           if (!(hasDefaultCXXMethodCC(Ctx, CD) && CD->getNumParams() == 0))
130             Manglings.emplace_back(getMangledStructor(CD, Ctor_DefaultClosure));
131     } else if (const auto *DD = dyn_cast_or_null<CXXDestructorDecl>(ND)) {
132       Manglings.emplace_back(getMangledStructor(DD, Dtor_Base));
133       if (Ctx.getTargetInfo().getCXXABI().isItaniumFamily()) {
134         Manglings.emplace_back(getMangledStructor(DD, Dtor_Complete));
135         if (DD->isVirtual())
136           Manglings.emplace_back(getMangledStructor(DD, Dtor_Deleting));
137       }
138     } else if (const auto *MD = dyn_cast_or_null<CXXMethodDecl>(ND)) {
139       Manglings.emplace_back(getName(ND));
140       if (MD->isVirtual())
141         if (const auto *TIV = Ctx.getVTableContext()->getThunkInfo(MD))
142           for (const auto &T : *TIV)
143             Manglings.emplace_back(getMangledThunk(MD, T));
144     }
145 
146     return Manglings;
147   }
148 
149 private:
150   bool writeFuncOrVarName(const NamedDecl *D, raw_ostream &OS) {
151     if (MC->shouldMangleDeclName(D)) {
152       if (const auto *CtorD = dyn_cast<CXXConstructorDecl>(D))
153         MC->mangleCXXCtor(CtorD, Ctor_Complete, OS);
154       else if (const auto *DtorD = dyn_cast<CXXDestructorDecl>(D))
155         MC->mangleCXXDtor(DtorD, Dtor_Complete, OS);
156       else
157         MC->mangleName(D, OS);
158       return false;
159     } else {
160       IdentifierInfo *II = D->getIdentifier();
161       if (!II)
162         return true;
163       OS << II->getName();
164       return false;
165     }
166   }
167 
168   void writeObjCClassName(const ObjCInterfaceDecl *D, raw_ostream &OS) {
169     OS << getClassSymbolPrefix(ObjCClass, D->getASTContext());
170     OS << D->getObjCRuntimeNameAsString();
171   }
172 
173   static StringRef getClassSymbolPrefix(ObjCKind Kind, const ASTContext &Context) {
174     if (Context.getLangOpts().ObjCRuntime.isGNUFamily())
175       return Kind == ObjCMetaclass ? "_OBJC_METACLASS_" : "_OBJC_CLASS_";
176     return Kind == ObjCMetaclass ? "OBJC_METACLASS_$_" : "OBJC_CLASS_$_";
177   }
178 
179   std::string getMangledStructor(const NamedDecl *ND, unsigned StructorType) {
180     std::string FrontendBuf;
181     llvm::raw_string_ostream FOS(FrontendBuf);
182 
183     if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(ND))
184       MC->mangleCXXCtor(CD, static_cast<CXXCtorType>(StructorType), FOS);
185     else if (const auto *DD = dyn_cast_or_null<CXXDestructorDecl>(ND))
186       MC->mangleCXXDtor(DD, static_cast<CXXDtorType>(StructorType), FOS);
187 
188     std::string BackendBuf;
189     llvm::raw_string_ostream BOS(BackendBuf);
190 
191     llvm::Mangler::getNameWithPrefix(BOS, FOS.str(), DL);
192 
193     return BOS.str();
194   }
195 
196   std::string getMangledThunk(const CXXMethodDecl *MD, const ThunkInfo &T) {
197     std::string FrontendBuf;
198     llvm::raw_string_ostream FOS(FrontendBuf);
199 
200     MC->mangleThunk(MD, T, FOS);
201 
202     std::string BackendBuf;
203     llvm::raw_string_ostream BOS(BackendBuf);
204 
205     llvm::Mangler::getNameWithPrefix(BOS, FOS.str(), DL);
206 
207     return BOS.str();
208   }
209 };
210 
211 CodegenNameGenerator::CodegenNameGenerator(ASTContext &Ctx)
212   : Impl(new Implementation(Ctx)) {
213 }
214 
215 CodegenNameGenerator::~CodegenNameGenerator() {
216 }
217 
218 bool CodegenNameGenerator::writeName(const Decl *D, raw_ostream &OS) {
219   return Impl->writeName(D, OS);
220 }
221 
222 std::string CodegenNameGenerator::getName(const Decl *D) {
223   return Impl->getName(D);
224 }
225 
226 std::vector<std::string> CodegenNameGenerator::getAllManglings(const Decl *D) {
227   return Impl->getAllManglings(D);
228 }
229