1 //===--- CrossTranslationUnit.cpp - -----------------------------*- C++ -*-===//
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 //  This file implements the CrossTranslationUnit interface.
11 //
12 //===----------------------------------------------------------------------===//
13 #include "clang/CrossTU/CrossTranslationUnit.h"
14 #include "clang/AST/ASTImporter.h"
15 #include "clang/AST/Decl.h"
16 #include "clang/Basic/TargetInfo.h"
17 #include "clang/CrossTU/CrossTUDiagnostic.h"
18 #include "clang/Frontend/ASTUnit.h"
19 #include "clang/Frontend/CompilerInstance.h"
20 #include "clang/Frontend/FrontendDiagnostic.h"
21 #include "clang/Frontend/TextDiagnosticPrinter.h"
22 #include "clang/Index/USRGeneration.h"
23 #include "llvm/ADT/Triple.h"
24 #include "llvm/Support/ErrorHandling.h"
25 #include "llvm/Support/ManagedStatic.h"
26 #include "llvm/Support/Path.h"
27 #include "llvm/Support/raw_ostream.h"
28 #include <fstream>
29 #include <sstream>
30 
31 namespace clang {
32 namespace cross_tu {
33 
34 namespace {
35 // FIXME: This class is will be removed after the transition to llvm::Error.
36 class IndexErrorCategory : public std::error_category {
37 public:
38   const char *name() const noexcept override { return "clang.index"; }
39 
40   std::string message(int Condition) const override {
41     switch (static_cast<index_error_code>(Condition)) {
42     case index_error_code::unspecified:
43       return "An unknown error has occurred.";
44     case index_error_code::missing_index_file:
45       return "The index file is missing.";
46     case index_error_code::invalid_index_format:
47       return "Invalid index file format.";
48     case index_error_code::multiple_definitions:
49       return "Multiple definitions in the index file.";
50     case index_error_code::missing_definition:
51       return "Missing definition from the index file.";
52     case index_error_code::failed_import:
53       return "Failed to import the definition.";
54     case index_error_code::failed_to_get_external_ast:
55       return "Failed to load external AST source.";
56     case index_error_code::failed_to_generate_usr:
57       return "Failed to generate USR.";
58     }
59     llvm_unreachable("Unrecognized index_error_code.");
60   }
61 };
62 
63 static llvm::ManagedStatic<IndexErrorCategory> Category;
64 } // end anonymous namespace
65 
66 char IndexError::ID;
67 
68 void IndexError::log(raw_ostream &OS) const {
69   OS << Category->message(static_cast<int>(Code)) << '\n';
70 }
71 
72 std::error_code IndexError::convertToErrorCode() const {
73   return std::error_code(static_cast<int>(Code), *Category);
74 }
75 
76 llvm::Expected<llvm::StringMap<std::string>>
77 parseCrossTUIndex(StringRef IndexPath, StringRef CrossTUDir) {
78   std::ifstream ExternalFnMapFile(IndexPath);
79   if (!ExternalFnMapFile)
80     return llvm::make_error<IndexError>(index_error_code::missing_index_file,
81                                         IndexPath.str());
82 
83   llvm::StringMap<std::string> Result;
84   std::string Line;
85   unsigned LineNo = 1;
86   while (std::getline(ExternalFnMapFile, Line)) {
87     const size_t Pos = Line.find(" ");
88     if (Pos > 0 && Pos != std::string::npos) {
89       StringRef LineRef{Line};
90       StringRef FunctionLookupName = LineRef.substr(0, Pos);
91       if (Result.count(FunctionLookupName))
92         return llvm::make_error<IndexError>(
93             index_error_code::multiple_definitions, IndexPath.str(), LineNo);
94       StringRef FileName = LineRef.substr(Pos + 1);
95       SmallString<256> FilePath = CrossTUDir;
96       llvm::sys::path::append(FilePath, FileName);
97       Result[FunctionLookupName] = FilePath.str().str();
98     } else
99       return llvm::make_error<IndexError>(
100           index_error_code::invalid_index_format, IndexPath.str(), LineNo);
101     LineNo++;
102   }
103   return Result;
104 }
105 
106 std::string
107 createCrossTUIndexString(const llvm::StringMap<std::string> &Index) {
108   std::ostringstream Result;
109   for (const auto &E : Index)
110     Result << E.getKey().str() << " " << E.getValue() << '\n';
111   return Result.str();
112 }
113 
114 CrossTranslationUnitContext::CrossTranslationUnitContext(CompilerInstance &CI)
115     : CI(CI), Context(CI.getASTContext()) {}
116 
117 CrossTranslationUnitContext::~CrossTranslationUnitContext() {}
118 
119 std::string CrossTranslationUnitContext::getLookupName(const NamedDecl *ND) {
120   SmallString<128> DeclUSR;
121   bool Ret = index::generateUSRForDecl(ND, DeclUSR); (void)Ret;
122   assert(!Ret && "Unable to generate USR");
123   return DeclUSR.str();
124 }
125 
126 /// Recursively visits the function decls of a DeclContext, and looks up a
127 /// function based on USRs.
128 const FunctionDecl *
129 CrossTranslationUnitContext::findFunctionInDeclContext(const DeclContext *DC,
130                                                        StringRef LookupFnName) {
131   assert(DC && "Declaration Context must not be null");
132   for (const Decl *D : DC->decls()) {
133     const auto *SubDC = dyn_cast<DeclContext>(D);
134     if (SubDC)
135       if (const auto *FD = findFunctionInDeclContext(SubDC, LookupFnName))
136         return FD;
137 
138     const auto *ND = dyn_cast<FunctionDecl>(D);
139     const FunctionDecl *ResultDecl;
140     if (!ND || !ND->hasBody(ResultDecl))
141       continue;
142     if (getLookupName(ResultDecl) != LookupFnName)
143       continue;
144     return ResultDecl;
145   }
146   return nullptr;
147 }
148 
149 llvm::Expected<const FunctionDecl *>
150 CrossTranslationUnitContext::getCrossTUDefinition(const FunctionDecl *FD,
151                                                   StringRef CrossTUDir,
152                                                   StringRef IndexName) {
153   assert(!FD->hasBody() && "FD has a definition in current translation unit!");
154   const std::string LookupFnName = getLookupName(FD);
155   if (LookupFnName.empty())
156     return llvm::make_error<IndexError>(
157         index_error_code::failed_to_generate_usr);
158   llvm::Expected<ASTUnit *> ASTUnitOrError =
159       loadExternalAST(LookupFnName, CrossTUDir, IndexName);
160   if (!ASTUnitOrError)
161     return ASTUnitOrError.takeError();
162   ASTUnit *Unit = *ASTUnitOrError;
163   if (!Unit)
164     return llvm::make_error<IndexError>(
165         index_error_code::failed_to_get_external_ast);
166   assert(&Unit->getFileManager() ==
167          &Unit->getASTContext().getSourceManager().getFileManager());
168 
169   TranslationUnitDecl *TU = Unit->getASTContext().getTranslationUnitDecl();
170   if (const FunctionDecl *ResultDecl =
171           findFunctionInDeclContext(TU, LookupFnName))
172     return importDefinition(ResultDecl);
173   return llvm::make_error<IndexError>(index_error_code::failed_import);
174 }
175 
176 void CrossTranslationUnitContext::emitCrossTUDiagnostics(const IndexError &IE) {
177   switch (IE.getCode()) {
178   case index_error_code::missing_index_file:
179     Context.getDiagnostics().Report(diag::err_fe_error_opening)
180         << IE.getFileName() << "required by the CrossTU functionality";
181     break;
182   case index_error_code::invalid_index_format:
183     Context.getDiagnostics().Report(diag::err_fnmap_parsing)
184         << IE.getFileName() << IE.getLineNum();
185     break;
186   case index_error_code::multiple_definitions:
187     Context.getDiagnostics().Report(diag::err_multiple_def_index)
188         << IE.getLineNum();
189     break;
190   default:
191     break;
192   }
193 }
194 
195 llvm::Expected<ASTUnit *> CrossTranslationUnitContext::loadExternalAST(
196     StringRef LookupName, StringRef CrossTUDir, StringRef IndexName) {
197   // FIXME: The current implementation only supports loading functions with
198   //        a lookup name from a single translation unit. If multiple
199   //        translation units contains functions with the same lookup name an
200   //        error will be returned.
201   ASTUnit *Unit = nullptr;
202   auto FnUnitCacheEntry = FunctionASTUnitMap.find(LookupName);
203   if (FnUnitCacheEntry == FunctionASTUnitMap.end()) {
204     if (FunctionFileMap.empty()) {
205       SmallString<256> IndexFile = CrossTUDir;
206       if (llvm::sys::path::is_absolute(IndexName))
207         IndexFile = IndexName;
208       else
209         llvm::sys::path::append(IndexFile, IndexName);
210       llvm::Expected<llvm::StringMap<std::string>> IndexOrErr =
211           parseCrossTUIndex(IndexFile, CrossTUDir);
212       if (IndexOrErr)
213         FunctionFileMap = *IndexOrErr;
214       else
215         return IndexOrErr.takeError();
216     }
217 
218     auto It = FunctionFileMap.find(LookupName);
219     if (It == FunctionFileMap.end())
220       return llvm::make_error<IndexError>(index_error_code::missing_definition);
221     StringRef ASTFileName = It->second;
222     auto ASTCacheEntry = FileASTUnitMap.find(ASTFileName);
223     if (ASTCacheEntry == FileASTUnitMap.end()) {
224       IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
225       TextDiagnosticPrinter *DiagClient =
226           new TextDiagnosticPrinter(llvm::errs(), &*DiagOpts);
227       IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
228       IntrusiveRefCntPtr<DiagnosticsEngine> Diags(
229           new DiagnosticsEngine(DiagID, &*DiagOpts, DiagClient));
230 
231       std::unique_ptr<ASTUnit> LoadedUnit(ASTUnit::LoadFromASTFile(
232           ASTFileName, CI.getPCHContainerOperations()->getRawReader(),
233           ASTUnit::LoadEverything, Diags, CI.getFileSystemOpts()));
234       Unit = LoadedUnit.get();
235       FileASTUnitMap[ASTFileName] = std::move(LoadedUnit);
236     } else {
237       Unit = ASTCacheEntry->second.get();
238     }
239     FunctionASTUnitMap[LookupName] = Unit;
240   } else {
241     Unit = FnUnitCacheEntry->second;
242   }
243   return Unit;
244 }
245 
246 llvm::Expected<const FunctionDecl *>
247 CrossTranslationUnitContext::importDefinition(const FunctionDecl *FD) {
248   ASTImporter &Importer = getOrCreateASTImporter(FD->getASTContext());
249   auto *ToDecl =
250       cast<FunctionDecl>(Importer.Import(const_cast<FunctionDecl *>(FD)));
251   assert(ToDecl->hasBody());
252   assert(FD->hasBody() && "Functions already imported should have body.");
253   return ToDecl;
254 }
255 
256 ASTImporter &
257 CrossTranslationUnitContext::getOrCreateASTImporter(ASTContext &From) {
258   auto I = ASTUnitImporterMap.find(From.getTranslationUnitDecl());
259   if (I != ASTUnitImporterMap.end())
260     return *I->second;
261   ASTImporter *NewImporter =
262       new ASTImporter(Context, Context.getSourceManager().getFileManager(),
263                       From, From.getSourceManager().getFileManager(), false);
264   ASTUnitImporterMap[From.getTranslationUnitDecl()].reset(NewImporter);
265   return *NewImporter;
266 }
267 
268 } // namespace cross_tu
269 } // namespace clang
270