blob: 9e81ee5cafa4962ffd2734b2adff94ae14b50a0e [file] [log] [blame]
// Copyright (c) 2019, 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 "include/dart_api.h"
#include "platform/globals.h"
#include "vm/compiler/backend/slot.h"
#include "vm/compiler/compiler_state.h"
#include "vm/object.h"
#include "vm/parser.h"
#include "vm/symbols.h"
#include "vm/unit_test.h"
namespace dart {
// This is a regression test for b/121271056: there might be a race between
// background compiler and mutator where mutator changes guarded state of
// the field after Slot was created from it. A situation is possible where we
// have a clone of a field with its guarded state set to unknown, however
// Slot::Get for this field returns a Slot created from the previous clone of
// the same field with a known guarded state. In this case we must add *old*
// clone from which the Slot was created to guarded fields and not the new
// clone, because new clone has no guarded state to begin with and thus
// ParsedFunction::AddToGuardedFields(...) would simply ignore it.
// Such slots with inconsistent guarded state that are not in the current
// list of guarded fields arise due to unsuccessful inlining attempts.
// If we built and discard the graph, then guarded fields associated with
// that graph are also discarded. However the slot itself stays behind in
// the global cache.
// Adding old clone would lead to correct rejection of the compilation
// attempt because Slot type information is different from the current guarded
// state of the field.
TEST_CASE(SlotFromGuardedField) {
if (!FLAG_use_field_guards) {
TransitionNativeToVM transition(thread);
Zone* zone = thread->zone();
// Setup: create dummy class, function and a field.
const Class& dummy_class = Class::Handle(Class::New(
Library::Handle(), String::Handle(Symbols::New(thread, "DummyClass")),
Script::Handle(), TokenPosition::kNoSource));
const Function& dummy_function = Function::ZoneHandle(
Function::New(String::Handle(Symbols::New(thread, "foo")),
RawFunction::kRegularFunction, false, false, false, false,
false, dummy_class, TokenPosition::kMinSource));
const Field& field = Field::Handle(
Field::New(String::Handle(Symbols::New(thread, "field")),
/*is_static=*/false, /*is_final=*/false, /*is_const=*/false,
/*is_reflectable=*/true, dummy_class, Object::dynamic_type(),
TokenPosition::kMinSource, TokenPosition::kMinSource));
// Set non-trivial guarded state on the field.
// Enter compiler state.
CompilerState compiler_state(thread);
const Field& field_clone_1 = Field::ZoneHandle(field.CloneFromOriginal());
const Field& field_clone_2 = Field::ZoneHandle(field.CloneFromOriginal());
// Check that Slot::Get() returns correctly canonicalized and configured
// slot that matches properties of the field.
ParsedFunction* parsed_function =
new (zone) ParsedFunction(thread, dummy_function);
const Slot& slot1 = Slot::Get(field_clone_1, parsed_function);
const Slot& slot2 = Slot::Get(field_clone_2, parsed_function);
EXPECT_EQ(&slot1, &slot2);
EXPECT_EQ(kSmiCid, slot1.nullable_cid());
// Check that the field was added (once) to the list of guarded fields.
EXPECT_EQ(1, parsed_function->guarded_fields()->length());
// Change the guarded state of the field to "unknown" - emulating concurrent
// modification of the guarded state in mutator) and create a new clone of
// the field.
const Field& field_clone_3 = Field::ZoneHandle(field.CloneFromOriginal());
// Slot::Get must return the same slot and add the field from which it
// was created to the guarded fields list.
ParsedFunction* parsed_function2 =
new (zone) ParsedFunction(thread, dummy_function);
const Slot& slot3 = Slot::Get(field_clone_3, parsed_function2);
EXPECT_EQ(&slot1, &slot3);
EXPECT_EQ(1, parsed_function2->guarded_fields()->length());
} // namespace dart