Ryan Macnak
6fe15f6df9
This works around bugs in UndefinedBehaviorSanitizer and Clang. Bug: b/28638298 Change-Id: I6be595f9664516019d28017d24559583a1ae3a21 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/144354 Commit-Queue: Ryan Macnak <rmacnak@google.com> Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
72 lines
2.8 KiB
C++
72 lines
2.8 KiB
C++
// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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#include "vm/compiler/ffi/callback.h"
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#include "vm/symbols.h"
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namespace dart {
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namespace compiler {
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namespace ffi {
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FunctionPtr NativeCallbackFunction(const Function& c_signature,
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const Function& dart_target,
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const Instance& exceptional_return) {
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Thread* const thread = Thread::Current();
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const int32_t callback_id = thread->AllocateFfiCallbackId();
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// Create a new Function named '<target>_FfiCallback' and stick it in the
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// 'dart:ffi' library. Note that these functions will never be invoked by
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// Dart, so they have may have duplicate names.
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Zone* const zone = thread->zone();
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const auto& name = String::Handle(
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zone, Symbols::FromConcat(thread, Symbols::FfiCallback(),
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String::Handle(zone, dart_target.name())));
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const Library& lib = Library::Handle(zone, Library::FfiLibrary());
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const Class& owner_class = Class::Handle(zone, lib.toplevel_class());
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const Function& function =
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Function::Handle(zone, Function::New(name, FunctionLayout::kFfiTrampoline,
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/*is_static=*/true,
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/*is_const=*/false,
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/*is_abstract=*/false,
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/*is_external=*/false,
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/*is_native=*/false, owner_class,
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TokenPosition::kNoSource));
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function.set_is_debuggable(false);
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// Set callback-specific fields which the flow-graph builder needs to generate
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// the body.
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function.SetFfiCSignature(c_signature);
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function.SetFfiCallbackId(callback_id);
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function.SetFfiCallbackTarget(dart_target);
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// We need to load the exceptional return value as a constant in the generated
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// function. Even though the FE ensures that it is a constant, it could still
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// be a literal allocated in new space. We need to copy it into old space in
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// that case.
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//
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// Exceptional return values currently cannot be pointers because we don't
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// have constant pointers.
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//
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// TODO(36730): We'll need to extend this when we support passing/returning
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// structs by value.
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ASSERT(exceptional_return.IsNull() || exceptional_return.IsNumber());
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if (!exceptional_return.IsSmi() && exceptional_return.IsNew()) {
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function.SetFfiCallbackExceptionalReturn(Instance::Handle(
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zone, exceptional_return.CopyShallowToOldSpace(thread)));
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} else {
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function.SetFfiCallbackExceptionalReturn(exceptional_return);
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}
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return function.raw();
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}
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} // namespace ffi
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} // namespace compiler
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} // namespace dart
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