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| //===--- Preamble.cpp - Reusing expensive parts of the AST ----------------===//
//
// 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 "Preamble.h"
#include "Logger.h"
#include "Trace.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Lex/PPCallbacks.h"
#include "clang/Lex/PreprocessorOptions.h"
namespace clang {
namespace clangd {
namespace {
bool compileCommandsAreEqual(const tooling::CompileCommand &LHS,
const tooling::CompileCommand &RHS) {
// We don't check for Output, it should not matter to clangd.
return LHS.Directory == RHS.Directory && LHS.Filename == RHS.Filename &&
llvm::makeArrayRef(LHS.CommandLine).equals(RHS.CommandLine);
}
class CppFilePreambleCallbacks : public PreambleCallbacks {
public:
CppFilePreambleCallbacks(PathRef File, PreambleParsedCallback ParsedCallback)
: File(File), ParsedCallback(ParsedCallback) {}
IncludeStructure takeIncludes() { return std::move(Includes); }
MainFileMacros takeMacros() { return std::move(Macros); }
CanonicalIncludes takeCanonicalIncludes() { return std::move(CanonIncludes); }
void AfterExecute(CompilerInstance &CI) override {
if (!ParsedCallback)
return;
trace::Span Tracer("Running PreambleCallback");
ParsedCallback(CI.getASTContext(), CI.getPreprocessorPtr(), CanonIncludes);
}
void BeforeExecute(CompilerInstance &CI) override {
CanonIncludes.addSystemHeadersMapping(CI.getLangOpts());
LangOpts = &CI.getLangOpts();
SourceMgr = &CI.getSourceManager();
}
std::unique_ptr<PPCallbacks> createPPCallbacks() override {
assert(SourceMgr && LangOpts &&
"SourceMgr and LangOpts must be set at this point");
return std::make_unique<PPChainedCallbacks>(
collectIncludeStructureCallback(*SourceMgr, &Includes),
std::make_unique<CollectMainFileMacros>(*SourceMgr, *LangOpts, Macros));
}
CommentHandler *getCommentHandler() override {
IWYUHandler = collectIWYUHeaderMaps(&CanonIncludes);
return IWYUHandler.get();
}
private:
PathRef File;
PreambleParsedCallback ParsedCallback;
IncludeStructure Includes;
CanonicalIncludes CanonIncludes;
MainFileMacros Macros;
std::unique_ptr<CommentHandler> IWYUHandler = nullptr;
const clang::LangOptions *LangOpts = nullptr;
const SourceManager *SourceMgr = nullptr;
};
} // namespace
PreambleData::PreambleData(PrecompiledPreamble Preamble,
std::vector<Diag> Diags, IncludeStructure Includes,
MainFileMacros Macros,
std::unique_ptr<PreambleFileStatusCache> StatCache,
CanonicalIncludes CanonIncludes)
: Preamble(std::move(Preamble)), Diags(std::move(Diags)),
Includes(std::move(Includes)), Macros(std::move(Macros)),
StatCache(std::move(StatCache)), CanonIncludes(std::move(CanonIncludes)) {
}
std::shared_ptr<const PreambleData>
buildPreamble(PathRef FileName, CompilerInvocation &CI,
std::shared_ptr<const PreambleData> OldPreamble,
const tooling::CompileCommand &OldCompileCommand,
const ParseInputs &Inputs, bool StoreInMemory,
PreambleParsedCallback PreambleCallback) {
// Note that we don't need to copy the input contents, preamble can live
// without those.
auto ContentsBuffer =
llvm::MemoryBuffer::getMemBuffer(Inputs.Contents, FileName);
auto Bounds =
ComputePreambleBounds(*CI.getLangOpts(), ContentsBuffer.get(), 0);
if (OldPreamble &&
compileCommandsAreEqual(Inputs.CompileCommand, OldCompileCommand) &&
OldPreamble->Preamble.CanReuse(CI, ContentsBuffer.get(), Bounds,
Inputs.FS.get())) {
vlog("Reusing preamble for file {0}", llvm::Twine(FileName));
return OldPreamble;
}
vlog("Preamble for file {0} cannot be reused. Attempting to rebuild it.",
FileName);
trace::Span Tracer("BuildPreamble");
SPAN_ATTACH(Tracer, "File", FileName);
StoreDiags PreambleDiagnostics;
llvm::IntrusiveRefCntPtr<DiagnosticsEngine> PreambleDiagsEngine =
CompilerInstance::createDiagnostics(&CI.getDiagnosticOpts(),
&PreambleDiagnostics, false);
// Skip function bodies when building the preamble to speed up building
// the preamble and make it smaller.
assert(!CI.getFrontendOpts().SkipFunctionBodies);
CI.getFrontendOpts().SkipFunctionBodies = true;
// We don't want to write comment locations into PCH. They are racy and slow
// to read back. We rely on dynamic index for the comments instead.
CI.getPreprocessorOpts().WriteCommentListToPCH = false;
CppFilePreambleCallbacks SerializedDeclsCollector(FileName, PreambleCallback);
if (Inputs.FS->setCurrentWorkingDirectory(Inputs.CompileCommand.Directory)) {
log("Couldn't set working directory when building the preamble.");
// We proceed anyway, our lit-tests rely on results for non-existing working
// dirs.
}
llvm::SmallString<32> AbsFileName(FileName);
Inputs.FS->makeAbsolute(AbsFileName);
auto StatCache = std::make_unique<PreambleFileStatusCache>(AbsFileName);
auto BuiltPreamble = PrecompiledPreamble::Build(
CI, ContentsBuffer.get(), Bounds, *PreambleDiagsEngine,
StatCache->getProducingFS(Inputs.FS),
std::make_shared<PCHContainerOperations>(), StoreInMemory,
SerializedDeclsCollector);
// When building the AST for the main file, we do want the function
// bodies.
CI.getFrontendOpts().SkipFunctionBodies = false;
if (BuiltPreamble) {
vlog("Built preamble of size {0} for file {1}", BuiltPreamble->getSize(),
FileName);
std::vector<Diag> Diags = PreambleDiagnostics.take();
return std::make_shared<PreambleData>(
std::move(*BuiltPreamble), std::move(Diags),
SerializedDeclsCollector.takeIncludes(),
SerializedDeclsCollector.takeMacros(), std::move(StatCache),
SerializedDeclsCollector.takeCanonicalIncludes());
} else {
elog("Could not build a preamble for file {0}", FileName);
return nullptr;
}
}
} // namespace clangd
} // namespace clang
|