353 lines · cpp
1//===--- ObjectFilePCHContainerWriter.cpp -----------------------------===//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-exception6//7//===----------------------------------------------------------------------===//8 9#include "clang/CodeGen/ObjectFilePCHContainerWriter.h"10#include "CGDebugInfo.h"11#include "CodeGenModule.h"12#include "clang/AST/ASTContext.h"13#include "clang/AST/DeclObjC.h"14#include "clang/AST/Expr.h"15#include "clang/AST/RecursiveASTVisitor.h"16#include "clang/Basic/CodeGenOptions.h"17#include "clang/Basic/Diagnostic.h"18#include "clang/Basic/TargetInfo.h"19#include "clang/CodeGen/BackendUtil.h"20#include "clang/Frontend/CompilerInstance.h"21#include "clang/Lex/HeaderSearch.h"22#include "clang/Lex/Preprocessor.h"23#include "llvm/ADT/StringRef.h"24#include "llvm/IR/Constants.h"25#include "llvm/IR/DataLayout.h"26#include "llvm/IR/LLVMContext.h"27#include "llvm/IR/Module.h"28#include "llvm/MC/TargetRegistry.h"29#include "llvm/Object/COFF.h"30#include "llvm/Support/Path.h"31#include <memory>32#include <utility>33 34using namespace clang;35 36#define DEBUG_TYPE "pchcontainer"37 38namespace {39class PCHContainerGenerator : public ASTConsumer {40 CompilerInstance &CI;41 DiagnosticsEngine &Diags;42 const std::string MainFileName;43 const std::string OutputFileName;44 ASTContext *Ctx;45 ModuleMap &MMap;46 IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS;47 const HeaderSearchOptions &HeaderSearchOpts;48 const PreprocessorOptions &PreprocessorOpts;49 CodeGenOptions CodeGenOpts;50 const TargetOptions TargetOpts;51 LangOptions LangOpts;52 std::unique_ptr<llvm::LLVMContext> VMContext;53 std::unique_ptr<llvm::Module> M;54 std::unique_ptr<CodeGen::CodeGenModule> Builder;55 std::unique_ptr<raw_pwrite_stream> OS;56 std::shared_ptr<PCHBuffer> Buffer;57 58 /// Visit every type and emit debug info for it.59 struct DebugTypeVisitor : public RecursiveASTVisitor<DebugTypeVisitor> {60 clang::CodeGen::CGDebugInfo &DI;61 ASTContext &Ctx;62 DebugTypeVisitor(clang::CodeGen::CGDebugInfo &DI, ASTContext &Ctx)63 : DI(DI), Ctx(Ctx) {}64 65 /// Determine whether this type can be represented in DWARF.66 static bool CanRepresent(const Type *Ty) {67 return !Ty->isDependentType() && !Ty->isUndeducedType();68 }69 70 bool VisitImportDecl(ImportDecl *D) {71 if (!D->getImportedOwningModule())72 DI.EmitImportDecl(*D);73 return true;74 }75 76 bool VisitTypeDecl(TypeDecl *D) {77 // TagDecls may be deferred until after all decls have been merged and we78 // know the complete type. Pure forward declarations will be skipped, but79 // they don't need to be emitted into the module anyway.80 if (auto *TD = dyn_cast<TagDecl>(D))81 if (!TD->isCompleteDefinition())82 return true;83 84 if (D->hasAttr<NoDebugAttr>())85 return true;86 87 QualType QualTy = Ctx.getTypeDeclType(D);88 if (!QualTy.isNull() && CanRepresent(QualTy.getTypePtr()))89 DI.getOrCreateStandaloneType(QualTy, D->getLocation());90 return true;91 }92 93 bool VisitObjCInterfaceDecl(ObjCInterfaceDecl *D) {94 QualType QualTy(D->getTypeForDecl(), 0);95 if (!QualTy.isNull() && CanRepresent(QualTy.getTypePtr()))96 DI.getOrCreateStandaloneType(QualTy, D->getLocation());97 return true;98 }99 100 bool VisitFunctionDecl(FunctionDecl *D) {101 // Skip deduction guides.102 if (isa<CXXDeductionGuideDecl>(D))103 return true;104 105 if (isa<CXXMethodDecl>(D))106 // This is not yet supported. Constructing the `this' argument107 // mandates a CodeGenFunction.108 return true;109 110 SmallVector<QualType, 16> ArgTypes;111 for (auto *i : D->parameters())112 ArgTypes.push_back(i->getType());113 QualType RetTy = D->getReturnType();114 QualType FnTy = Ctx.getFunctionType(RetTy, ArgTypes,115 FunctionProtoType::ExtProtoInfo());116 if (CanRepresent(FnTy.getTypePtr()))117 DI.EmitFunctionDecl(D, D->getLocation(), FnTy);118 return true;119 }120 121 bool VisitObjCMethodDecl(ObjCMethodDecl *D) {122 if (!D->getClassInterface())123 return true;124 125 bool selfIsPseudoStrong, selfIsConsumed;126 SmallVector<QualType, 16> ArgTypes;127 ArgTypes.push_back(D->getSelfType(Ctx, D->getClassInterface(),128 selfIsPseudoStrong, selfIsConsumed));129 ArgTypes.push_back(Ctx.getObjCSelType());130 for (auto *i : D->parameters())131 ArgTypes.push_back(i->getType());132 QualType RetTy = D->getReturnType();133 QualType FnTy = Ctx.getFunctionType(RetTy, ArgTypes,134 FunctionProtoType::ExtProtoInfo());135 if (CanRepresent(FnTy.getTypePtr()))136 DI.EmitFunctionDecl(D, D->getLocation(), FnTy);137 return true;138 }139 };140 141public:142 PCHContainerGenerator(CompilerInstance &CI, const std::string &MainFileName,143 const std::string &OutputFileName,144 std::unique_ptr<raw_pwrite_stream> OS,145 std::shared_ptr<PCHBuffer> Buffer)146 : CI(CI), Diags(CI.getDiagnostics()), MainFileName(MainFileName),147 OutputFileName(OutputFileName), Ctx(nullptr),148 MMap(CI.getPreprocessor().getHeaderSearchInfo().getModuleMap()),149 FS(CI.getVirtualFileSystemPtr()),150 HeaderSearchOpts(CI.getHeaderSearchOpts()),151 PreprocessorOpts(CI.getPreprocessorOpts()),152 TargetOpts(CI.getTargetOpts()), LangOpts(CI.getLangOpts()),153 OS(std::move(OS)), Buffer(std::move(Buffer)) {154 // The debug info output isn't affected by CodeModel and155 // ThreadModel, but the backend expects them to be nonempty.156 CodeGenOpts.CodeModel = "default";157 LangOpts.setThreadModel(LangOptions::ThreadModelKind::Single);158 CodeGenOpts.DebugTypeExtRefs = true;159 // When building a module MainFileName is the name of the modulemap file.160 CodeGenOpts.MainFileName =161 LangOpts.CurrentModule.empty() ? MainFileName : LangOpts.CurrentModule;162 CodeGenOpts.setDebugInfo(llvm::codegenoptions::FullDebugInfo);163 CodeGenOpts.setDebuggerTuning(CI.getCodeGenOpts().getDebuggerTuning());164 CodeGenOpts.DwarfVersion = CI.getCodeGenOpts().DwarfVersion;165 CodeGenOpts.DebugCompilationDir =166 CI.getInvocation().getCodeGenOpts().DebugCompilationDir;167 CodeGenOpts.DebugPrefixMap =168 CI.getInvocation().getCodeGenOpts().DebugPrefixMap;169 CodeGenOpts.DebugStrictDwarf = CI.getCodeGenOpts().DebugStrictDwarf;170 }171 172 ~PCHContainerGenerator() override = default;173 174 void Initialize(ASTContext &Context) override {175 assert(!Ctx && "initialized multiple times");176 177 Ctx = &Context;178 VMContext.reset(new llvm::LLVMContext());179 M.reset(new llvm::Module(MainFileName, *VMContext));180 M->setDataLayout(Ctx->getTargetInfo().getDataLayoutString());181 Builder.reset(new CodeGen::CodeGenModule(182 *Ctx, FS, HeaderSearchOpts, PreprocessorOpts, CodeGenOpts, *M, Diags));183 184 // Prepare CGDebugInfo to emit debug info for a clang module.185 auto *DI = Builder->getModuleDebugInfo();186 StringRef ModuleName = llvm::sys::path::filename(MainFileName);187 DI->setPCHDescriptor(188 {ModuleName, "", OutputFileName, ASTFileSignature::createDISentinel()});189 DI->setModuleMap(MMap);190 }191 192 bool HandleTopLevelDecl(DeclGroupRef D) override {193 if (Diags.hasErrorOccurred())194 return true;195 196 // Collect debug info for all decls in this group.197 for (auto *I : D)198 if (!I->isFromASTFile()) {199 DebugTypeVisitor DTV(*Builder->getModuleDebugInfo(), *Ctx);200 DTV.TraverseDecl(I);201 }202 return true;203 }204 205 void HandleTopLevelDeclInObjCContainer(DeclGroupRef D) override {206 HandleTopLevelDecl(D);207 }208 209 void HandleTagDeclDefinition(TagDecl *D) override {210 if (Diags.hasErrorOccurred())211 return;212 213 if (D->isFromASTFile())214 return;215 216 // Anonymous tag decls are deferred until we are building their declcontext.217 if (D->getName().empty())218 return;219 220 // Defer tag decls until their declcontext is complete.221 auto *DeclCtx = D->getDeclContext();222 while (DeclCtx) {223 if (auto *D = dyn_cast<TagDecl>(DeclCtx))224 if (!D->isCompleteDefinition())225 return;226 DeclCtx = DeclCtx->getParent();227 }228 229 DebugTypeVisitor DTV(*Builder->getModuleDebugInfo(), *Ctx);230 DTV.TraverseDecl(D);231 Builder->UpdateCompletedType(D);232 }233 234 void HandleTagDeclRequiredDefinition(const TagDecl *D) override {235 if (Diags.hasErrorOccurred())236 return;237 238 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))239 Builder->getModuleDebugInfo()->completeRequiredType(RD);240 }241 242 void HandleImplicitImportDecl(ImportDecl *D) override {243 if (!D->getImportedOwningModule())244 Builder->getModuleDebugInfo()->EmitImportDecl(*D);245 }246 247 /// Emit a container holding the serialized AST.248 void HandleTranslationUnit(ASTContext &Ctx) override {249 assert(M && VMContext && Builder);250 // Delete these on function exit.251 std::unique_ptr<llvm::LLVMContext> VMContext = std::move(this->VMContext);252 std::unique_ptr<llvm::Module> M = std::move(this->M);253 std::unique_ptr<CodeGen::CodeGenModule> Builder = std::move(this->Builder);254 255 if (Diags.hasErrorOccurred())256 return;257 258 M->setTargetTriple(Ctx.getTargetInfo().getTriple());259 M->setDataLayout(Ctx.getTargetInfo().getDataLayoutString());260 261 // PCH files don't have a signature field in the control block,262 // but LLVM detects DWO CUs by looking for a non-zero DWO id.263 // We use the lower 64 bits for debug info.264 265 uint64_t Signature =266 Buffer->Signature ? Buffer->Signature.truncatedValue() : ~1ULL;267 268 Builder->getModuleDebugInfo()->setDwoId(Signature);269 270 // Finalize the Builder.271 if (Builder)272 Builder->Release();273 274 // Ensure the target exists.275 std::string Error;276 auto Triple = Ctx.getTargetInfo().getTriple();277 if (!llvm::TargetRegistry::lookupTarget(Triple, Error))278 llvm::report_fatal_error(llvm::Twine(Error));279 280 // Emit the serialized Clang AST into its own section.281 assert(Buffer->IsComplete && "serialization did not complete");282 auto &SerializedAST = Buffer->Data;283 auto Size = SerializedAST.size();284 285 if (Triple.isOSBinFormatWasm()) {286 // Emit __clangast in custom section instead of named data segment287 // to find it while iterating sections.288 // This could be avoided if all data segements (the wasm sense) were289 // represented as their own sections (in the llvm sense).290 // TODO: https://github.com/WebAssembly/tool-conventions/issues/138291 llvm::NamedMDNode *MD =292 M->getOrInsertNamedMetadata("wasm.custom_sections");293 llvm::Metadata *Ops[2] = {294 llvm::MDString::get(*VMContext, "__clangast"),295 llvm::MDString::get(*VMContext,296 StringRef(SerializedAST.data(), Size))};297 auto *NameAndContent = llvm::MDTuple::get(*VMContext, Ops);298 MD->addOperand(NameAndContent);299 } else {300 auto Int8Ty = llvm::Type::getInt8Ty(*VMContext);301 auto *Ty = llvm::ArrayType::get(Int8Ty, Size);302 auto *Data = llvm::ConstantDataArray::getString(303 *VMContext, StringRef(SerializedAST.data(), Size),304 /*AddNull=*/false);305 auto *ASTSym = new llvm::GlobalVariable(306 *M, Ty, /*constant*/ true, llvm::GlobalVariable::InternalLinkage,307 Data, "__clang_ast");308 // The on-disk hashtable needs to be aligned.309 ASTSym->setAlignment(llvm::Align(8));310 311 // Mach-O also needs a segment name.312 if (Triple.isOSBinFormatMachO())313 ASTSym->setSection("__CLANG,__clangast");314 // COFF has an eight character length limit.315 else if (Triple.isOSBinFormatCOFF())316 ASTSym->setSection("clangast");317 else318 ASTSym->setSection("__clangast");319 }320 321 LLVM_DEBUG({322 // Print the IR for the PCH container to the debug output.323 llvm::SmallString<0> Buffer;324 clang::emitBackendOutput(325 CI, CodeGenOpts, Ctx.getTargetInfo().getDataLayoutString(), M.get(),326 BackendAction::Backend_EmitLL, FS,327 std::make_unique<llvm::raw_svector_ostream>(Buffer));328 llvm::dbgs() << Buffer;329 });330 331 // Use the LLVM backend to emit the pch container.332 clang::emitBackendOutput(CI, CodeGenOpts,333 Ctx.getTargetInfo().getDataLayoutString(), M.get(),334 BackendAction::Backend_EmitObj, FS, std::move(OS));335 336 // Free the memory for the temporary buffer.337 llvm::SmallVector<char, 0> Empty;338 SerializedAST = std::move(Empty);339 }340};341 342} // anonymous namespace343 344std::unique_ptr<ASTConsumer>345ObjectFilePCHContainerWriter::CreatePCHContainerGenerator(346 CompilerInstance &CI, const std::string &MainFileName,347 const std::string &OutputFileName,348 std::unique_ptr<llvm::raw_pwrite_stream> OS,349 std::shared_ptr<PCHBuffer> Buffer) const {350 return std::make_unique<PCHContainerGenerator>(351 CI, MainFileName, OutputFileName, std::move(OS), Buffer);352}353