blob: ef58014ee66c4478db78443806e219f813031f97 [file] [log] [blame]
// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/compiler/ffi/callback.h"
#include "vm/class_finalizer.h"
#include "vm/symbols.h"
namespace dart {
namespace compiler {
namespace ffi {
FunctionPtr NativeCallbackFunction(const FunctionType& c_signature,
const Function& dart_target,
const Instance& exceptional_return) {
Thread* const thread = Thread::Current();
const int32_t callback_id = thread->AllocateFfiCallbackId();
// Create a new Function named '<target>_FfiCallback' and stick it in the
// 'dart:ffi' library. Note that these functions will never be invoked by
// Dart, so they may have duplicate names.
Zone* const zone = thread->zone();
const auto& name = String::Handle(
zone, Symbols::FromConcat(thread, Symbols::FfiCallback(),
const Library& lib = Library::Handle(zone, Library::FfiLibrary());
const Class& owner_class = Class::Handle(zone, lib.toplevel_class());
auto& signature = FunctionType::Handle(zone, FunctionType::New());
const Function& function = Function::Handle(
zone, Function::New(signature, name, UntaggedFunction::kFfiTrampoline,
/*is_native=*/false, owner_class,
// Set callback-specific fields which the flow-graph builder needs to generate
// the body.
// We need to load the exceptional return value as a constant in the generated
// function. Even though the FE ensures that it is a constant, it could still
// be a literal allocated in new space. We need to copy it into old space in
// that case.
// Exceptional return values currently cannot be pointers because we don't
// have constant pointers.
ASSERT(exceptional_return.IsNull() || exceptional_return.IsNumber() ||
if (!exceptional_return.IsSmi() && exceptional_return.IsNew()) {
zone, exceptional_return.CopyShallowToOldSpace(thread)));
} else {
// The dart type of the FfiCallback has no arguments or type arguments and
// has a result type of dynamic, as the callback is never invoked via Dart,
// only via native calls that do not use this information. Having no Dart
// arguments ensures the scope builder does not add inappropriate parameter
// variables.
// Finalize (and thus canonicalize) the signature.
signature ^= ClassFinalizer::FinalizeType(signature);
return function.ptr();
} // namespace ffi
} // namespace compiler
} // namespace dart