Jan Svoboda 1698beb542
[clang][modules][deps] Optimize in-process timestamping of PCMs (#137363)
In the past, timestamps used for
`-fmodules-validate-once-per-build-session` were found to be a source of
contention in the dependency scanner
([D149802](https://reviews.llvm.org/D149802),
https://github.com/llvm/llvm-project/pull/112452). This PR is yet
another attempt to optimize these. We now make use of the new
`ModuleCache` interface to implement the in-process version in terms of
atomic `std::time_t` variables rather the mtime attribute on
`.timestamp` files.
2025-05-07 14:02:40 -07:00

108 lines
3.8 KiB
C++

//===- ASTCommon.h - Common stuff for ASTReader/ASTWriter -*- 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
//
//===----------------------------------------------------------------------===//
//
// This file defines common functions that both ASTReader and ASTWriter use.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_LIB_SERIALIZATION_ASTCOMMON_H
#define LLVM_CLANG_LIB_SERIALIZATION_ASTCOMMON_H
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclFriend.h"
#include "clang/Basic/LLVM.h"
#include "clang/Serialization/ASTBitCodes.h"
namespace clang {
namespace serialization {
enum class DeclUpdateKind {
CXXAddedImplicitMember,
CXXAddedAnonymousNamespace,
CXXAddedFunctionDefinition,
CXXAddedVarDefinition,
CXXPointOfInstantiation,
CXXInstantiatedClassDefinition,
CXXInstantiatedDefaultArgument,
CXXInstantiatedDefaultMemberInitializer,
CXXResolvedDtorDelete,
CXXResolvedExceptionSpec,
CXXDeducedReturnType,
DeclMarkedUsed,
ManglingNumber,
StaticLocalNumber,
DeclMarkedOpenMPThreadPrivate,
DeclMarkedOpenMPAllocate,
DeclMarkedOpenMPDeclareTarget,
DeclExported,
AddedAttrToRecord
};
TypeIdx TypeIdxFromBuiltin(const BuiltinType *BT);
unsigned ComputeHash(Selector Sel);
/// Retrieve the "definitive" declaration that provides all of the
/// visible entries for the given declaration context, if there is one.
///
/// The "definitive" declaration is the only place where we need to look to
/// find information about the declarations within the given declaration
/// context. For example, C++ and Objective-C classes, C structs/unions, and
/// Objective-C protocols, categories, and extensions are all defined in a
/// single place in the source code, so they have definitive declarations
/// associated with them. C++ namespaces, on the other hand, can have
/// multiple definitions.
const DeclContext *getDefinitiveDeclContext(const DeclContext *DC);
/// Determine whether the given declaration kind is redeclarable.
bool isRedeclarableDeclKind(unsigned Kind);
/// Determine whether the given declaration needs an anonymous
/// declaration number.
bool needsAnonymousDeclarationNumber(const NamedDecl *D);
/// Visit each declaration within \c DC that needs an anonymous
/// declaration number and call \p Visit with the declaration and its number.
template<typename Fn> void numberAnonymousDeclsWithin(const DeclContext *DC,
Fn Visit) {
unsigned Index = 0;
for (Decl *LexicalD : DC->decls()) {
// For a friend decl, we care about the declaration within it, if any.
if (auto *FD = dyn_cast<FriendDecl>(LexicalD))
LexicalD = FD->getFriendDecl();
auto *ND = dyn_cast_or_null<NamedDecl>(LexicalD);
if (!ND || !needsAnonymousDeclarationNumber(ND))
continue;
Visit(ND, Index++);
}
}
/// Determine whether the given declaration will be included in the per-module
/// initializer if it needs to be eagerly handed to the AST consumer. If so, we
/// should not hand it to the consumer when deserializing it, nor include it in
/// the list of eagerly deserialized declarations.
inline bool isPartOfPerModuleInitializer(const Decl *D) {
if (isa<ImportDecl>(D))
return true;
// Template instantiations are notionally in an "instantiation unit" rather
// than in any particular translation unit, so they need not be part of any
// particular (sub)module's per-module initializer.
if (auto *VD = dyn_cast<VarDecl>(D))
return !isTemplateInstantiation(VD->getTemplateSpecializationKind());
return false;
}
} // namespace serialization
} // namespace clang
#endif