da00c60dae
Close https://github.com/llvm/llvm-project/issues/71034 See https://discourse.llvm.org/t/rfc-c-20-modules-introduce-thin-bmi-and-decls-hash/74755 This patch introduces reduced BMI, which doesn't contain the definitions of functions and variables if its definitions won't contribute to the ABI. Testing is a big part of the patch. We want to make sure the reduced BMI contains the same behavior with the existing and relatively stable fatBMI. This is pretty helpful for further reduction. The user interfaces part it left to following patches to ease the reviewing.
114 lines
4.0 KiB
C++
114 lines
4.0 KiB
C++
//===--- GeneratePCH.cpp - Sema Consumer for PCH Generation -----*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the PCHGenerator, which as a SemaConsumer that generates
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// a PCH file.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/AST/ASTContext.h"
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#include "clang/Frontend/FrontendDiagnostic.h"
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#include "clang/Lex/HeaderSearch.h"
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#include "clang/Lex/Preprocessor.h"
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#include "clang/Sema/SemaConsumer.h"
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#include "clang/Serialization/ASTReader.h"
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#include "clang/Serialization/ASTWriter.h"
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#include "llvm/Bitstream/BitstreamWriter.h"
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using namespace clang;
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PCHGenerator::PCHGenerator(
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const Preprocessor &PP, InMemoryModuleCache &ModuleCache,
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StringRef OutputFile, StringRef isysroot, std::shared_ptr<PCHBuffer> Buffer,
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ArrayRef<std::shared_ptr<ModuleFileExtension>> Extensions,
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bool AllowASTWithErrors, bool IncludeTimestamps,
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bool BuildingImplicitModule, bool ShouldCacheASTInMemory,
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bool GeneratingReducedBMI)
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: PP(PP), OutputFile(OutputFile), isysroot(isysroot.str()),
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SemaPtr(nullptr), Buffer(std::move(Buffer)), Stream(this->Buffer->Data),
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Writer(Stream, this->Buffer->Data, ModuleCache, Extensions,
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IncludeTimestamps, BuildingImplicitModule, GeneratingReducedBMI),
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AllowASTWithErrors(AllowASTWithErrors),
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ShouldCacheASTInMemory(ShouldCacheASTInMemory) {
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this->Buffer->IsComplete = false;
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}
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PCHGenerator::~PCHGenerator() {
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}
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void PCHGenerator::HandleTranslationUnit(ASTContext &Ctx) {
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// Don't create a PCH if there were fatal failures during module loading.
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if (PP.getModuleLoader().HadFatalFailure)
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return;
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bool hasErrors = PP.getDiagnostics().hasErrorOccurred();
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if (hasErrors && !AllowASTWithErrors)
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return;
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Module *Module = nullptr;
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if (PP.getLangOpts().isCompilingModule()) {
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Module = PP.getHeaderSearchInfo().lookupModule(
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PP.getLangOpts().CurrentModule, SourceLocation(),
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/*AllowSearch*/ false);
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if (!Module) {
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assert(hasErrors && "emitting module but current module doesn't exist");
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return;
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}
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}
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// Errors that do not prevent the PCH from being written should not cause the
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// overall compilation to fail either.
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if (AllowASTWithErrors)
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PP.getDiagnostics().getClient()->clear();
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// Emit the PCH file to the Buffer.
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assert(SemaPtr && "No Sema?");
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Buffer->Signature = Writer.WriteAST(*SemaPtr, OutputFile, Module, isysroot,
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ShouldCacheASTInMemory);
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Buffer->IsComplete = true;
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}
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ASTMutationListener *PCHGenerator::GetASTMutationListener() {
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return &Writer;
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}
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ASTDeserializationListener *PCHGenerator::GetASTDeserializationListener() {
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return &Writer;
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}
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ReducedBMIGenerator::ReducedBMIGenerator(const Preprocessor &PP,
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InMemoryModuleCache &ModuleCache,
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StringRef OutputFile,
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std::shared_ptr<PCHBuffer> Buffer,
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bool IncludeTimestamps)
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: PCHGenerator(
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PP, ModuleCache, OutputFile, llvm::StringRef(), Buffer,
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/*Extensions=*/ArrayRef<std::shared_ptr<ModuleFileExtension>>(),
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/*AllowASTWithErrors*/ false, /*IncludeTimestamps=*/IncludeTimestamps,
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/*BuildingImplicitModule=*/false, /*ShouldCacheASTInMemory=*/false,
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/*GeneratingReducedBMI=*/true) {}
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void ReducedBMIGenerator::HandleTranslationUnit(ASTContext &Ctx) {
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PCHGenerator::HandleTranslationUnit(Ctx);
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if (!isComplete())
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return;
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std::error_code EC;
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auto OS = std::make_unique<llvm::raw_fd_ostream>(getOutputFile(), EC);
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if (EC) {
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getDiagnostics().Report(diag::err_fe_unable_to_open_output)
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<< getOutputFile() << EC.message() << "\n";
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return;
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}
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*OS << getBufferPtr()->Data;
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OS->flush();
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}
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