[turbofan] Redundant load elimination.

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

Index: test/unittests/compiler/load-elimination-unittest.cc
diff --git a/test/unittests/compiler/load-elimination-unittest.cc b/test/unittests/compiler/load-elimination-unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f0cd60ec4d68568e4155ba4d6a8b8465d64eb00c
--- /dev/null
+++ b/test/unittests/compiler/load-elimination-unittest.cc
@@ -0,0 +1,72 @@
+// 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.
+
+#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 GraphTest {
+ public:
+  LoadEliminationTest() : GraphTest(3), simplified_(zone()) {}
+  ~LoadEliminationTest() OVERRIDE {}
+
+ protected:
+  Reduction Reduce(Node* node) {
+    LoadElimination reducer;
+    return reducer.Reduce(node);
+  }
+
+  SimplifiedOperatorBuilder* simplified() { return &simplified_; }
+
+ private:
+  SimplifiedOperatorBuilder simplified_;
+};
+
+
+TEST_F(LoadEliminationTest, LoadFieldWithStoreField) {
+  Node* object1 = Parameter(0);
+  Node* object2 = Parameter(1);
+  Node* value = Parameter(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