mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 22:02:23 +01:00
Chandler Carruth
7901fb3857
Fundamentally, this uses forward declarations of Clang types to reduce the overall compile time cost of Clang headers across the codebase. Tracing and profiling showed ~2s of every check TU's ~8-12s compile time going just to parsing Clang frontend and AST headers pulled in via a few sem_ir and check headers that only use the Clang types by pointer or reference: - sem_ir/cpp_file.h (reached via sem_ir/file.h by ~150 TUs) included clang/Frontend/CompilerInstance.h, clang/CodeGen/ModuleBuilder.h, clang/AST/Mangle.h, and llvm/IR/Module.h. CppFile's accessors move out of line to a new cpp_file.cpp and the header now forward-declares the Clang types. - check/cpp/context.h (reached via check/context.h by ~100 TUs) included clang/Frontend/FrontendAction.h and clang/Parse/Parser.h, pulling in clang's Sema.h and ASTUnit.h. - sem_ir/clang_decl.h included clang/AST/Decl.h; the three small functions that need complete Clang types move out of line. - sem_ir/cpp_overload_set.h included clang/Sema/Overload.h solely for the three-field OverloadCandidateSet::OperatorRewriteInfo, which is now mirrored as CppOverloadSet::OperatorRewriteInfo, and clang/AST/Decl.h solely for a pointer. - sem_ir/name_scope.h's clang/AST/DeclBase.h include was vestigial. TUs (and more narrowly included headers) that genuinely use the Clang definitions now include the Clang headers directly. Representative compile times (fastbuild, aarch64), combined with the preceding instantiation-cost changes, relative to trunk: - check/eval.cpp: 11.85s -> 6.94s (-41%) - check/handle_operator.cpp: 7.71s -> 3.30s (-57%) - language_server.cpp: 6.68s -> 3.16s (-53%) - lower/handle.cpp: 6.75s -> 3.66s (-46%) - sem_ir/file.cpp: 8.60s -> 6.11s (-29%) - driver.cpp: 6.68s -> 4.78s (-28%) Measured full-rebuild impact (316 first-party TUs, fastbuild): -689.5s CPU, -29.9% relative to trunk. Assisted-by: Claude
72 lines
2.4 KiB
C++
72 lines
2.4 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#ifndef CARBON_TOOLCHAIN_SEM_IR_CPP_OVERLOAD_SET_H_
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#define CARBON_TOOLCHAIN_SEM_IR_CPP_OVERLOAD_SET_H_
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#include "clang/AST/UnresolvedSet.h"
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#include "clang/Basic/OperatorKinds.h"
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#include "clang/Basic/SourceLocation.h"
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#include "common/ostream.h"
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#include "toolchain/base/value_store.h"
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#include "toolchain/sem_ir/ids.h"
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namespace clang {
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class CXXRecordDecl;
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} // namespace clang
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namespace Carbon::SemIR {
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// An overloaded C++ function.
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struct CppOverloadSet : public Printable<CppOverloadSet> {
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// Information about operator rewrites to consider when adding operator
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// functions to a candidate set.
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//
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// This mirrors `clang::OverloadCandidateSet::OperatorRewriteInfo` so that
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// this header doesn't need `clang/Sema/Overload.h`; the use sites construct
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// the Clang type from these fields.
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struct OperatorRewriteInfo {
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// The original operator as written in the source.
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clang::OverloadedOperatorKind original_operator = clang::OO_None;
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// The source location of the operator.
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clang::SourceLocation op_loc;
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// Whether we should include rewritten candidates in the overload set.
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bool allow_rewritten_candidates = false;
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};
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// The function's name.
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NameId name_id;
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// The parent scope.
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NameScopeId parent_scope_id;
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// The naming class in the name lookup that found this overload set.
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clang::CXXRecordDecl* naming_class;
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// List of all named decls found at name lookup.
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// TODO: Find a good small size for the UnresolvedSet<size> or rework how we
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// store the candidates.
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clang::UnresolvedSet<4> candidate_functions;
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/// Information about operator rewrites to consider when adding operator
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/// functions to a candidate set.
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OperatorRewriteInfo operator_rewrite_info;
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auto Print(llvm::raw_ostream& out) const -> void {
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out << "name: " << name_id << ", parent_scope: " << parent_scope_id;
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}
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};
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using CppOverloadSetStore =
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ValueStore<CppOverloadSetId, CppOverloadSet, Tag<CheckIRId>>;
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} // namespace Carbon::SemIR
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namespace Carbon {
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extern template class ValueStore<SemIR::CppOverloadSetId, SemIR::CppOverloadSet,
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Tag<SemIR::CheckIRId>>;
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} // namespace Carbon
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#endif // CARBON_TOOLCHAIN_SEM_IR_CPP_OVERLOAD_SET_H_
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