| //===--- Preamble.h - Reusing expensive parts of the AST ---------*- C++-*-===// |
| // |
| // 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 |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // The vast majority of code in a typical translation unit is in the headers |
| // included at the top of the file. |
| // |
| // The preamble optimization says that we can parse this code once, and reuse |
| // the result multiple times. The preamble is invalidated by changes to the |
| // code in the preamble region, to the compile command, or to files on disk. |
| // |
| // This is the most important optimization in clangd: it allows operations like |
| // code-completion to have sub-second latency. It is supported by the |
| // PrecompiledPreamble functionality in clang, which wraps the techniques used |
| // by PCH files, modules etc into a convenient interface. |
| // |
| //===----------------------------------------------------------------------===// |
| #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_PREAMBLE_H |
| #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_PREAMBLE_H |
| |
| #include "Compiler.h" |
| #include "Diagnostics.h" |
| #include "FS.h" |
| #include "Headers.h" |
| #include "index/CanonicalIncludes.h" |
| #include "clang/Frontend/PrecompiledPreamble.h" |
| #include "clang/Tooling/CompilationDatabase.h" |
| |
| #include <memory> |
| #include <string> |
| #include <vector> |
| |
| namespace clang { |
| namespace clangd { |
| |
| /// The parsed preamble and associated data. |
| /// |
| /// As we must avoid re-parsing the preamble, any information that can only |
| /// be obtained during parsing must be eagerly captured and stored here. |
| struct PreambleData { |
| PreambleData(PrecompiledPreamble Preamble, std::vector<Diag> Diags, |
| IncludeStructure Includes, |
| std::vector<std::string> MainFileMacros, |
| std::unique_ptr<PreambleFileStatusCache> StatCache, |
| CanonicalIncludes CanonIncludes); |
| |
| tooling::CompileCommand CompileCommand; |
| PrecompiledPreamble Preamble; |
| std::vector<Diag> Diags; |
| // Processes like code completions and go-to-definitions will need #include |
| // information, and their compile action skips preamble range. |
| IncludeStructure Includes; |
| // Macros defined in the preamble section of the main file. |
| // Users care about headers vs main-file, not preamble vs non-preamble. |
| // These should be treated as main-file entities e.g. for code completion. |
| std::vector<std::string> MainFileMacros; |
| // Cache of FS operations performed when building the preamble. |
| // When reusing a preamble, this cache can be consumed to save IO. |
| std::unique_ptr<PreambleFileStatusCache> StatCache; |
| CanonicalIncludes CanonIncludes; |
| }; |
| |
| using PreambleParsedCallback = |
| std::function<void(ASTContext &, std::shared_ptr<clang::Preprocessor>, |
| const CanonicalIncludes &)>; |
| |
| /// Build a preamble for the new inputs unless an old one can be reused. |
| /// If \p OldPreamble can be reused, it is returned unchanged. |
| /// If \p OldPreamble is null, always builds the preamble. |
| /// If \p PreambleCallback is set, it will be run on top of the AST while |
| /// building the preamble. Note that if the old preamble was reused, no AST is |
| /// built and, therefore, the callback will not be executed. |
| 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); |
| |
| |
| } // namespace clangd |
| } // namespace clang |
| |
| #endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_PREAMBLE_H |