1 //===--- ObjectFilePCHContainerOperations.cpp -----------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "clang/CodeGen/ObjectFilePCHContainerOperations.h"
11 #include "CGDebugInfo.h"
12 #include "CodeGenModule.h"
13 #include "clang/AST/ASTContext.h"
14 #include "clang/AST/DeclObjC.h"
15 #include "clang/AST/Expr.h"
16 #include "clang/AST/RecursiveASTVisitor.h"
17 #include "clang/Basic/Diagnostic.h"
18 #include "clang/Basic/TargetInfo.h"
19 #include "clang/CodeGen/BackendUtil.h"
20 #include "clang/Frontend/CodeGenOptions.h"
21 #include "clang/Serialization/ASTWriter.h"
22 #include "llvm/ADT/StringRef.h"
23 #include "llvm/Bitcode/BitstreamReader.h"
24 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
25 #include "llvm/IR/Constants.h"
26 #include "llvm/IR/DataLayout.h"
27 #include "llvm/IR/LLVMContext.h"
28 #include "llvm/IR/Module.h"
29 #include "llvm/Object/COFF.h"
30 #include "llvm/Object/ObjectFile.h"
31 #include "llvm/Support/TargetRegistry.h"
33 using namespace clang;
35 #define DEBUG_TYPE "pchcontainer"
38 class PCHContainerGenerator : public ASTConsumer {
39 DiagnosticsEngine &Diags;
40 const std::string MainFileName;
42 const HeaderSearchOptions &HeaderSearchOpts;
43 const PreprocessorOptions &PreprocessorOpts;
44 CodeGenOptions CodeGenOpts;
45 const TargetOptions TargetOpts;
46 const LangOptions LangOpts;
47 std::unique_ptr<llvm::LLVMContext> VMContext;
48 std::unique_ptr<llvm::Module> M;
49 std::unique_ptr<CodeGen::CodeGenModule> Builder;
50 raw_pwrite_stream *OS;
51 std::shared_ptr<PCHBuffer> Buffer;
54 PCHContainerGenerator(DiagnosticsEngine &diags,
55 const HeaderSearchOptions &HSO,
56 const PreprocessorOptions &PPO, const TargetOptions &TO,
57 const LangOptions &LO, const std::string &MainFileName,
58 const std::string &OutputFileName,
59 raw_pwrite_stream *OS,
60 std::shared_ptr<PCHBuffer> Buffer)
61 : Diags(diags), HeaderSearchOpts(HSO), PreprocessorOpts(PPO),
62 TargetOpts(TO), LangOpts(LO), OS(OS), Buffer(Buffer) {
63 // The debug info output isn't affected by CodeModel and
64 // ThreadModel, but the backend expects them to be nonempty.
65 CodeGenOpts.CodeModel = "default";
66 CodeGenOpts.ThreadModel = "single";
67 CodeGenOpts.setDebugInfo(CodeGenOptions::FullDebugInfo);
68 CodeGenOpts.SplitDwarfFile = OutputFileName;
71 virtual ~PCHContainerGenerator() {}
73 void Initialize(ASTContext &Context) override {
75 VMContext.reset(new llvm::LLVMContext());
76 M.reset(new llvm::Module(MainFileName, *VMContext));
77 M->setDataLayout(Ctx->getTargetInfo().getTargetDescription());
78 Builder.reset(new CodeGen::CodeGenModule(*Ctx, HeaderSearchOpts,
79 PreprocessorOpts, CodeGenOpts, *M,
80 M->getDataLayout(), Diags));
83 /// Emit a container holding the serialized AST.
84 void HandleTranslationUnit(ASTContext &Ctx) override {
85 assert(M && VMContext && Builder);
86 // Delete these on function exit.
87 std::unique_ptr<llvm::LLVMContext> VMContext = std::move(this->VMContext);
88 std::unique_ptr<llvm::Module> M = std::move(this->M);
89 std::unique_ptr<CodeGen::CodeGenModule> Builder = std::move(this->Builder);
91 if (Diags.hasErrorOccurred())
94 M->setTargetTriple(Ctx.getTargetInfo().getTriple().getTriple());
95 M->setDataLayout(Ctx.getTargetInfo().getTargetDescription());
97 // Finalize the Builder.
101 // Ensure the target exists.
103 auto Triple = Ctx.getTargetInfo().getTriple();
104 if (!llvm::TargetRegistry::lookupTarget(Triple.getTriple(), Error))
105 llvm::report_fatal_error(Error);
107 // Emit the serialized Clang AST into its own section.
108 assert(Buffer->IsComplete && "serialization did not complete");
109 auto &SerializedAST = Buffer->Data;
110 auto Size = SerializedAST.size();
111 auto Int8Ty = llvm::Type::getInt8Ty(*VMContext);
112 auto *Ty = llvm::ArrayType::get(Int8Ty, Size);
113 auto *Data = llvm::ConstantDataArray::getString(
114 *VMContext, StringRef(SerializedAST.data(), Size),
116 auto *ASTSym = new llvm::GlobalVariable(
117 *M, Ty, /*constant*/ true, llvm::GlobalVariable::InternalLinkage, Data,
119 // The on-disk hashtable needs to be aligned.
120 ASTSym->setAlignment(8);
122 // Mach-O also needs a segment name.
123 if (Triple.isOSBinFormatMachO())
124 ASTSym->setSection("__CLANG,__clangast");
125 // COFF has an eight character length limit.
126 else if (Triple.isOSBinFormatCOFF())
127 ASTSym->setSection("clangast");
129 ASTSym->setSection("__clangast");
132 // Print the IR for the PCH container to the debug output.
133 llvm::SmallString<0> Buffer;
134 llvm::raw_svector_ostream OS(Buffer);
135 clang::EmitBackendOutput(Diags, CodeGenOpts, TargetOpts, LangOpts,
136 Ctx.getTargetInfo().getTargetDescription(),
137 M.get(), BackendAction::Backend_EmitLL, &OS);
139 llvm::dbgs() << Buffer;
142 // Use the LLVM backend to emit the pch container.
143 clang::EmitBackendOutput(Diags, CodeGenOpts, TargetOpts, LangOpts,
144 Ctx.getTargetInfo().getTargetDescription(),
145 M.get(), BackendAction::Backend_EmitObj, OS);
147 // Make sure the pch container hits disk.
150 // Free the memory for the temporary buffer.
151 llvm::SmallVector<char, 0> Empty;
152 SerializedAST = std::move(Empty);
158 std::unique_ptr<ASTConsumer>
159 ObjectFilePCHContainerOperations::CreatePCHContainerGenerator(
160 DiagnosticsEngine &Diags, const HeaderSearchOptions &HSO,
161 const PreprocessorOptions &PPO, const TargetOptions &TO,
162 const LangOptions &LO, const std::string &MainFileName,
163 const std::string &OutputFileName, llvm::raw_pwrite_stream *OS,
164 std::shared_ptr<PCHBuffer> Buffer) const {
165 return llvm::make_unique<PCHContainerGenerator>(
166 Diags, HSO, PPO, TO, LO, MainFileName, OutputFileName, OS, Buffer);
169 void ObjectFilePCHContainerOperations::ExtractPCH(
170 llvm::MemoryBufferRef Buffer, llvm::BitstreamReader &StreamFile) const {
171 if (auto OF = llvm::object::ObjectFile::createObjectFile(Buffer)) {
172 auto *Obj = OF.get().get();
173 bool IsCOFF = isa<llvm::object::COFFObjectFile>(Obj);
174 // Find the clang AST section in the container.
175 for (auto &Section : OF->get()->sections()) {
177 Section.getName(Name);
178 if ((!IsCOFF && Name == "__clangast") ||
179 ( IsCOFF && Name == "clangast")) {
181 Section.getContents(Buf);
182 StreamFile.init((const unsigned char *)Buf.begin(),
183 (const unsigned char *)Buf.end());
189 // As a fallback, treat the buffer as a raw AST.
190 StreamFile.init((const unsigned char *)Buffer.getBufferStart(),
191 (const unsigned char *)Buffer.getBufferEnd());