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6bf0f26ecd
This is important, for example, for linking correctly to the C++ standard library on Windows, which uses `#pragma comment(lib, ...)` in its headers to specify the correct library to link against.
130 lines
4.5 KiB
C++
130 lines
4.5 KiB
C++
//===--- GenClangDecl.cpp - Swift IRGen for imported Clang declarations ---===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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#include "IRGenModule.h"
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#include "clang/AST/Decl.h"
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#include "clang/AST/DeclGroup.h"
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#include "clang/AST/GlobalDecl.h"
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#include "clang/AST/RecursiveASTVisitor.h"
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#include "clang/CodeGen/ModuleBuilder.h"
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#include "llvm/ADT/SmallPtrSet.h"
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using namespace swift;
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using namespace irgen;
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namespace {
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class ClangDeclRefFinder
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: public clang::RecursiveASTVisitor<ClangDeclRefFinder> {
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std::function<void(const clang::DeclRefExpr *)> callback;
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public:
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template <typename Fn>
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explicit ClangDeclRefFinder(Fn fn) : callback(fn) {}
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bool VisitDeclRefExpr(clang::DeclRefExpr *DRE) {
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callback(DRE);
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return true;
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}
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};
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// If any (re)declaration of `decl` contains executable code, returns that
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// redeclaration; otherwise, returns nullptr.
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// In the case of a function, executable code is contained in the function
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// definition. In the case of a variable, executable code can be contained in
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// the initializer of the variable.
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clang::Decl *getDeclWithExecutableCode(clang::Decl *decl) {
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if (auto fd = dyn_cast<clang::FunctionDecl>(decl)) {
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const clang::FunctionDecl *definition;
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if (fd->hasBody(definition)) {
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return const_cast<clang::FunctionDecl *>(definition);
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}
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} else if (auto vd = dyn_cast<clang::VarDecl>(decl)) {
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clang::VarDecl *initializingDecl = vd->getInitializingDeclaration();
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if (initializingDecl) {
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return initializingDecl;
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}
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}
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return nullptr;
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}
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} // end anonymous namespace
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void IRGenModule::emitClangDecl(const clang::Decl *decl) {
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// Ignore this decl if we've seen it before.
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if (!GlobalClangDecls.insert(decl->getCanonicalDecl()).second)
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return;
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// Fast path for the case where `decl` doesn't contain executable code, so it
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// can't reference any other declarations that we would need to emit.
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if (getDeclWithExecutableCode(const_cast<clang::Decl *>(decl)) == nullptr) {
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ClangCodeGen->HandleTopLevelDecl(
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clang::DeclGroupRef(const_cast<clang::Decl*>(decl)));
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return;
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}
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SmallVector<const clang::Decl *, 8> stack;
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stack.push_back(decl);
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ClangDeclRefFinder refFinder([&](const clang::DeclRefExpr *DRE) {
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const clang::Decl *D = DRE->getDecl();
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// Check that this is a file-level declaration and not inside a function.
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// If it's a member of a file-level decl, like a C++ static member variable,
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// we want to add the entire file-level declaration because Clang doesn't
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// expect to see members directly here.
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for (auto *DC = D->getDeclContext();; DC = DC->getParent()) {
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if (DC->isFunctionOrMethod())
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return;
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if (DC->isFileContext())
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break;
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D = cast<const clang::Decl>(DC);
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}
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if (!GlobalClangDecls.insert(D->getCanonicalDecl()).second)
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return;
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stack.push_back(D);
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});
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while (!stack.empty()) {
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auto *next = const_cast<clang::Decl *>(stack.pop_back_val());
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if (clang::Decl *executableDecl = getDeclWithExecutableCode(next)) {
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refFinder.TraverseDecl(executableDecl);
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next = executableDecl;
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}
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ClangCodeGen->HandleTopLevelDecl(clang::DeclGroupRef(next));
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}
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}
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llvm::Constant *
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IRGenModule::getAddrOfClangGlobalDecl(clang::GlobalDecl global,
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ForDefinition_t forDefinition) {
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// Register the decl with the clang code generator.
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if (auto decl = global.getDecl())
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emitClangDecl(decl);
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return ClangCodeGen->GetAddrOfGlobal(global, (bool) forDefinition);
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}
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void IRGenModule::finalizeClangCodeGen() {
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// Ensure that code is emitted for any `PragmaCommentDecl`s. (These are
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// always guaranteed to be directly below the TranslationUnitDecl.)
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// In Clang, this happens automatically during the Sema phase, but here we
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// need to take care of it manually because our Clang CodeGenerator is not
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// attached to Clang Sema as an ASTConsumer.
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for (const auto *D : ClangASTContext->getTranslationUnitDecl()->decls()) {
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if (const auto *PCD = dyn_cast<clang::PragmaCommentDecl>(D)) {
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emitClangDecl(PCD);
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}
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}
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ClangCodeGen->HandleTranslationUnit(
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*const_cast<clang::ASTContext *>(ClangASTContext));
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}
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