[turbofan] Initial version of the new LoadElimination.

test/unittests/compiler/load-elimination-unittest.cc

-// Copyright 2014 the V8 project authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.

[Jarin, 2016/07/04 13:18:07]

Actually, this is unit-testable, so we should test.

[Benedikt Meurer, 2016/07/05 11:29:09]

Done.

-
-#include "src/compiler/access-builder.h"
-#include "src/compiler/load-elimination.h"
-#include "src/compiler/simplified-operator.h"
-#include "test/unittests/compiler/graph-unittest.h"
-#include "test/unittests/compiler/node-test-utils.h"
-
-namespace v8 {
-namespace internal {
-namespace compiler {
-
-class LoadEliminationTest : public TypedGraphTest {
- public:
-  LoadEliminationTest() : TypedGraphTest(3), simplified_(zone()) {}
-  ~LoadEliminationTest() override {}
-
- protected:
-  Reduction Reduce(Node* node) {
-    // TODO(titzer): mock the GraphReducer here for better unit testing.
-    GraphReducer graph_reducer(zone(), graph());
-    LoadElimination reducer(&graph_reducer, graph(), simplified());
-    return reducer.Reduce(node);
-  }
-
-  SimplifiedOperatorBuilder* simplified() { return &simplified_; }
-
- private:
-  SimplifiedOperatorBuilder simplified_;
-};
-
-
-TEST_F(LoadEliminationTest, LoadFieldWithStoreField) {
-  Node* object1 = Parameter(Type::Any(), 0);
-  Node* object2 = Parameter(Type::Any(), 1);
-  Node* value = Parameter(Type::Any(), 2);
-  Node* effect = graph()->start();
-  Node* control = graph()->start();
-
-  FieldAccess access1 = AccessBuilder::ForContextSlot(42);
-  Node* store1 = graph()->NewNode(simplified()->StoreField(access1), object1,
-                                  value, effect, control);
-  Reduction r1 = Reduce(graph()->NewNode(simplified()->LoadField(access1),
-                                         object1, store1, control));
-  ASSERT_TRUE(r1.Changed());
-  EXPECT_EQ(value, r1.replacement());
-
-  FieldAccess access2 = AccessBuilder::ForMap();
-  Node* store2 = graph()->NewNode(simplified()->StoreField(access2), object1,
-                                  object2, store1, control);
-  Reduction r2 = Reduce(graph()->NewNode(simplified()->LoadField(access2),
-                                         object1, store2, control));
-  ASSERT_TRUE(r2.Changed());
-  EXPECT_EQ(object2, r2.replacement());
-
-  Node* store3 = graph()->NewNode(
-      simplified()->StoreBuffer(BufferAccess(kExternalInt8Array)), object2,
-      value, Int32Constant(10), object1, store2, control);
-
-  Reduction r3 = Reduce(graph()->NewNode(simplified()->LoadField(access1),
-                                         object2, store3, control));
-  ASSERT_FALSE(r3.Changed());
-
-  Reduction r4 = Reduce(graph()->NewNode(simplified()->LoadField(access1),
-                                         object1, store3, control));
-  ASSERT_TRUE(r4.Changed());
-  EXPECT_EQ(value, r4.replacement());
-}
-
-}  // namespace compiler
-}  // namespace internal
-}  // namespace v8