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//===--- ObjectFilePCHContainerOperations.cpp -----------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "clang/CodeGen/ObjectFilePCHContainerOperations.h"
#include "CGDebugInfo.h"
#include "CodeGenModule.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/Expr.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/Basic/CodeGenOptions.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/CodeGen/BackendUtil.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Lex/HeaderSearch.h"
#include "clang/Lex/Preprocessor.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Bitstream/BitstreamReader.h"
#include "llvm/DebugInfo/DWARF/DWARFContext.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Object/COFF.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/Path.h"
#include <memory>
#include <utility>
using namespace clang;
#define DEBUG_TYPE "pchcontainer"
namespace {
class PCHContainerGenerator : public ASTConsumer {
DiagnosticsEngine &Diags;
const std::string MainFileName;
const std::string OutputFileName;
ASTContext *Ctx;
ModuleMap &MMap;
const HeaderSearchOptions &HeaderSearchOpts;
const PreprocessorOptions &PreprocessorOpts;
CodeGenOptions CodeGenOpts;
const TargetOptions TargetOpts;
LangOptions LangOpts;
std::unique_ptr<llvm::LLVMContext> VMContext;
std::unique_ptr<llvm::Module> M;
std::unique_ptr<CodeGen::CodeGenModule> Builder;
std::unique_ptr<raw_pwrite_stream> OS;
std::shared_ptr<PCHBuffer> Buffer;
/// Visit every type and emit debug info for it.
struct DebugTypeVisitor : public RecursiveASTVisitor<DebugTypeVisitor> {
clang::CodeGen::CGDebugInfo &DI;
ASTContext &Ctx;
DebugTypeVisitor(clang::CodeGen::CGDebugInfo &DI, ASTContext &Ctx)
: DI(DI), Ctx(Ctx) {}
/// Determine whether this type can be represented in DWARF.
static bool CanRepresent(const Type *Ty) {
return !Ty->isDependentType() && !Ty->isUndeducedType();
}
bool VisitImportDecl(ImportDecl *D) {
if (!D->getImportedOwningModule())
DI.EmitImportDecl(*D);
return true;
}
bool VisitTypeDecl(TypeDecl *D) {
// TagDecls may be deferred until after all decls have been merged and we
// know the complete type. Pure forward declarations will be skipped, but
// they don't need to be emitted into the module anyway.
if (auto *TD = dyn_cast<TagDecl>(D))
if (!TD->isCompleteDefinition())
return true;
QualType QualTy = Ctx.getTypeDeclType(D);
if (!QualTy.isNull() && CanRepresent(QualTy.getTypePtr()))
DI.getOrCreateStandaloneType(QualTy, D->getLocation());
return true;
}
bool VisitObjCInterfaceDecl(ObjCInterfaceDecl *D) {
QualType QualTy(D->getTypeForDecl(), 0);
if (!QualTy.isNull() && CanRepresent(QualTy.getTypePtr()))
DI.getOrCreateStandaloneType(QualTy, D->getLocation());
return true;
}
bool VisitFunctionDecl(FunctionDecl *D) {
// Skip deduction guides.
if (isa<CXXDeductionGuideDecl>(D))
return true;
if (isa<CXXMethodDecl>(D))
// This is not yet supported. Constructing the `this' argument
// mandates a CodeGenFunction.
return true;
SmallVector<QualType, 16> ArgTypes;
for (auto i : D->parameters())
ArgTypes.push_back(i->getType());
QualType RetTy = D->getReturnType();
QualType FnTy = Ctx.getFunctionType(RetTy, ArgTypes,
FunctionProtoType::ExtProtoInfo());
if (CanRepresent(FnTy.getTypePtr()))
DI.EmitFunctionDecl(D, D->getLocation(), FnTy);
return true;
}
bool VisitObjCMethodDecl(ObjCMethodDecl *D) {
if (!D->getClassInterface())
return true;
bool selfIsPseudoStrong, selfIsConsumed;
SmallVector<QualType, 16> ArgTypes;
ArgTypes.push_back(D->getSelfType(Ctx, D->getClassInterface(),
selfIsPseudoStrong, selfIsConsumed));
ArgTypes.push_back(Ctx.getObjCSelType());
for (auto i : D->parameters())
ArgTypes.push_back(i->getType());
QualType RetTy = D->getReturnType();
QualType FnTy = Ctx.getFunctionType(RetTy, ArgTypes,
FunctionProtoType::ExtProtoInfo());
if (CanRepresent(FnTy.getTypePtr()))
DI.EmitFunctionDecl(D, D->getLocation(), FnTy);
return true;
}
};
public:
PCHContainerGenerator(CompilerInstance &CI, const std::string &MainFileName,
const std::string &OutputFileName,
std::unique_ptr<raw_pwrite_stream> OS,
std::shared_ptr<PCHBuffer> Buffer)
: Diags(CI.getDiagnostics()), MainFileName(MainFileName),
OutputFileName(OutputFileName), Ctx(nullptr),
MMap(CI.getPreprocessor().getHeaderSearchInfo().getModuleMap()),
HeaderSearchOpts(CI.getHeaderSearchOpts()),
PreprocessorOpts(CI.getPreprocessorOpts()),
TargetOpts(CI.getTargetOpts()), LangOpts(CI.getLangOpts()),
OS(std::move(OS)), Buffer(std::move(Buffer)) {
// The debug info output isn't affected by CodeModel and
// ThreadModel, but the backend expects them to be nonempty.
CodeGenOpts.CodeModel = "default";
LangOpts.setThreadModel(LangOptions::ThreadModelKind::Single);
CodeGenOpts.DebugTypeExtRefs = true;
// When building a module MainFileName is the name of the modulemap file.
CodeGenOpts.MainFileName =
LangOpts.CurrentModule.empty() ? MainFileName : LangOpts.CurrentModule;
CodeGenOpts.setDebugInfo(codegenoptions::FullDebugInfo);
CodeGenOpts.setDebuggerTuning(CI.getCodeGenOpts().getDebuggerTuning());
CodeGenOpts.DebugPrefixMap =
CI.getInvocation().getCodeGenOpts().DebugPrefixMap;
CodeGenOpts.DebugStrictDwarf = CI.getCodeGenOpts().DebugStrictDwarf;
}
~PCHContainerGenerator() override = default;
void Initialize(ASTContext &Context) override {
assert(!Ctx && "initialized multiple times");
Ctx = &Context;
VMContext.reset(new llvm::LLVMContext());
M.reset(new llvm::Module(MainFileName, *VMContext));
M->setDataLayout(Ctx->getTargetInfo().getDataLayoutString());
Builder.reset(new CodeGen::CodeGenModule(
*Ctx, HeaderSearchOpts, PreprocessorOpts, CodeGenOpts, *M, Diags));
// Prepare CGDebugInfo to emit debug info for a clang module.
auto *DI = Builder->getModuleDebugInfo();
StringRef ModuleName = llvm::sys::path::filename(MainFileName);
DI->setPCHDescriptor(
{ModuleName, "", OutputFileName, ASTFileSignature::createDISentinel()});
DI->setModuleMap(MMap);
}
bool HandleTopLevelDecl(DeclGroupRef D) override {
if (Diags.hasErrorOccurred())
return true;
// Collect debug info for all decls in this group.
for (auto *I : D)
if (!I->isFromASTFile()) {
DebugTypeVisitor DTV(*Builder->getModuleDebugInfo(), *Ctx);
DTV.TraverseDecl(I);
}
return true;
}
void HandleTopLevelDeclInObjCContainer(DeclGroupRef D) override {
HandleTopLevelDecl(D);
}
void HandleTagDeclDefinition(TagDecl *D) override {
if (Diags.hasErrorOccurred())
return;
if (D->isFromASTFile())
return;
// Anonymous tag decls are deferred until we are building their declcontext.
if (D->getName().empty())
return;
// Defer tag decls until their declcontext is complete.
auto *DeclCtx = D->getDeclContext();
while (DeclCtx) {
if (auto *D = dyn_cast<TagDecl>(DeclCtx))
if (!D->isCompleteDefinition())
return;
DeclCtx = DeclCtx->getParent();
}
DebugTypeVisitor DTV(*Builder->getModuleDebugInfo(), *Ctx);
DTV.TraverseDecl(D);
Builder->UpdateCompletedType(D);
}
void HandleTagDeclRequiredDefinition(const TagDecl *D) override {
if (Diags.hasErrorOccurred())
return;
if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
Builder->getModuleDebugInfo()->completeRequiredType(RD);
}
void HandleImplicitImportDecl(ImportDecl *D) override {
if (!D->getImportedOwningModule())
Builder->getModuleDebugInfo()->EmitImportDecl(*D);
}
/// Emit a container holding the serialized AST.
void HandleTranslationUnit(ASTContext &Ctx) override {
assert(M && VMContext && Builder);
// Delete these on function exit.
std::unique_ptr<llvm::LLVMContext> VMContext = std::move(this->VMContext);
std::unique_ptr<llvm::Module> M = std::move(this->M);
std::unique_ptr<CodeGen::CodeGenModule> Builder = std::move(this->Builder);
if (Diags.hasErrorOccurred())
return;
M->setTargetTriple(Ctx.getTargetInfo().getTriple().getTriple());
M->setDataLayout(Ctx.getTargetInfo().getDataLayoutString());
// PCH files don't have a signature field in the control block,
// but LLVM detects DWO CUs by looking for a non-zero DWO id.
// We use the lower 64 bits for debug info.
uint64_t Signature =
Buffer->Signature ? Buffer->Signature.truncatedValue() : ~1ULL;
Builder->getModuleDebugInfo()->setDwoId(Signature);
// Finalize the Builder.
if (Builder)
Builder->Release();
// Ensure the target exists.
std::string Error;
auto Triple = Ctx.getTargetInfo().getTriple();
if (!llvm::TargetRegistry::lookupTarget(Triple.getTriple(), Error))
llvm::report_fatal_error(llvm::Twine(Error));
// Emit the serialized Clang AST into its own section.
assert(Buffer->IsComplete && "serialization did not complete");
auto &SerializedAST = Buffer->Data;
auto Size = SerializedAST.size();
if (Triple.isOSBinFormatWasm()) {
// Emit __clangast in custom section instead of named data segment
// to find it while iterating sections.
// This could be avoided if all data segements (the wasm sense) were
// represented as their own sections (in the llvm sense).
// TODO: https://github.com/WebAssembly/tool-conventions/issues/138
llvm::NamedMDNode *MD =
M->getOrInsertNamedMetadata("wasm.custom_sections");
llvm::Metadata *Ops[2] = {
llvm::MDString::get(*VMContext, "__clangast"),
llvm::MDString::get(*VMContext,
StringRef(SerializedAST.data(), Size))};
auto *NameAndContent = llvm::MDTuple::get(*VMContext, Ops);
MD->addOperand(NameAndContent);
} else {
auto Int8Ty = llvm::Type::getInt8Ty(*VMContext);
auto *Ty = llvm::ArrayType::get(Int8Ty, Size);
auto *Data = llvm::ConstantDataArray::getString(
*VMContext, StringRef(SerializedAST.data(), Size),
/*AddNull=*/false);
auto *ASTSym = new llvm::GlobalVariable(
*M, Ty, /*constant*/ true, llvm::GlobalVariable::InternalLinkage,
Data, "__clang_ast");
// The on-disk hashtable needs to be aligned.
ASTSym->setAlignment(llvm::Align(8));
// Mach-O also needs a segment name.
if (Triple.isOSBinFormatMachO())
ASTSym->setSection("__CLANG,__clangast");
// COFF has an eight character length limit.
else if (Triple.isOSBinFormatCOFF())
ASTSym->setSection("clangast");
else
ASTSym->setSection("__clangast");
}
LLVM_DEBUG({
// Print the IR for the PCH container to the debug output.
llvm::SmallString<0> Buffer;
clang::EmitBackendOutput(
Diags, HeaderSearchOpts, CodeGenOpts, TargetOpts, LangOpts,
Ctx.getTargetInfo().getDataLayoutString(), M.get(),
BackendAction::Backend_EmitLL,
std::make_unique<llvm::raw_svector_ostream>(Buffer));
llvm::dbgs() << Buffer;
});
// Use the LLVM backend to emit the pch container.
clang::EmitBackendOutput(Diags, HeaderSearchOpts, CodeGenOpts, TargetOpts,
LangOpts,
Ctx.getTargetInfo().getDataLayoutString(), M.get(),
BackendAction::Backend_EmitObj, std::move(OS));
// Free the memory for the temporary buffer.
llvm::SmallVector<char, 0> Empty;
SerializedAST = std::move(Empty);
}
};
} // anonymous namespace
std::unique_ptr<ASTConsumer>
ObjectFilePCHContainerWriter::CreatePCHContainerGenerator(
CompilerInstance &CI, const std::string &MainFileName,
const std::string &OutputFileName,
std::unique_ptr<llvm::raw_pwrite_stream> OS,
std::shared_ptr<PCHBuffer> Buffer) const {
return std::make_unique<PCHContainerGenerator>(
CI, MainFileName, OutputFileName, std::move(OS), Buffer);
}
StringRef
ObjectFilePCHContainerReader::ExtractPCH(llvm::MemoryBufferRef Buffer) const {
StringRef PCH;
auto OFOrErr = llvm::object::ObjectFile::createObjectFile(Buffer);
if (OFOrErr) {
auto &OF = OFOrErr.get();
bool IsCOFF = isa<llvm::object::COFFObjectFile>(*OF);
// Find the clang AST section in the container.
for (auto &Section : OF->sections()) {
StringRef Name;
if (Expected<StringRef> NameOrErr = Section.getName())
Name = *NameOrErr;
else
consumeError(NameOrErr.takeError());
if ((!IsCOFF && Name == "__clangast") || (IsCOFF && Name == "clangast")) {
if (Expected<StringRef> E = Section.getContents())
return *E;
else {
handleAllErrors(E.takeError(), [&](const llvm::ErrorInfoBase &EIB) {
EIB.log(llvm::errs());
});
return "";
}
}
}
}
handleAllErrors(OFOrErr.takeError(), [&](const llvm::ErrorInfoBase &EIB) {
if (EIB.convertToErrorCode() ==
llvm::object::object_error::invalid_file_type)
// As a fallback, treat the buffer as a raw AST.
PCH = Buffer.getBuffer();
else
EIB.log(llvm::errs());
});
return PCH;
}