Reduce field type tracking to a single stable map per field.

test/cctest/test-migrations.cc

 // Copyright 2015 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 <stdlib.h>
 #include <utility>
 
 #include "src/v8.h"
 
 #include "src/code-stubs.h"
@@ skipping 676 matching lines @@
                                Representation::Tagged(), any_type);
 }
 
 
 TEST(GeneralizeRepresentationHeapObjectToHeapObject) {
   CcTest::InitializeVM();
   v8::HandleScope scope(CcTest::isolate());
   Isolate* isolate = CcTest::i_isolate();
   Handle<HeapType> any_type = HeapType::Any(isolate);
 
-  const int kMaxClassesPerFieldType = 5;
+  const int kMaxClassesPerFieldType = 1;
   Handle<HeapType> current_type =
       HeapType::Class(Map::Create(isolate, 0), isolate);
 
   for (int i = 0; i < kMaxClassesPerFieldType; i++) {
     Handle<HeapType> new_type =
         HeapType::Class(Map::Create(isolate, 0), isolate);
 
     Handle<HeapType> expected_type =
         (i < kMaxClassesPerFieldType - 1)
             ? HeapType::Union(current_type, new_type, isolate)
@@ skipping 355 matching lines @@
       value_type, Representation::Tagged(), any_type);
 }
 
 
 TEST(ReconfigureDataFieldAttribute_GeneralizeRepresentationHeapObjToHeapObj) {
   CcTest::InitializeVM();
   v8::HandleScope scope(CcTest::isolate());
   Isolate* isolate = CcTest::i_isolate();
   Handle<HeapType> any_type = HeapType::Any(isolate);
 
-  const int kMaxClassesPerFieldType = 5;
+  const int kMaxClassesPerFieldType = 1;
   Handle<HeapType> current_type =
       HeapType::Class(Map::Create(isolate, 0), isolate);
 
   for (int i = 0; i < kMaxClassesPerFieldType; i++) {
     Handle<HeapType> new_type =
         HeapType::Class(Map::Create(isolate, 0), isolate);
 
     Handle<HeapType> expected_type =
         (i < kMaxClassesPerFieldType - 1)
             ? HeapType::Union(current_type, new_type, isolate)
@@ skipping 939 matching lines @@
   Handle<AccessorPair> pair = CreateAccessorPair(true, true);
   TransitionToAccessorConstantOperator transition_op(pair);
 
   SameMapChecker checker;
   TestTransitionTo(transition_op, transition_op, checker);
 }
 
 
 // TODO(ishell): add this test once IS_ACCESSOR_FIELD_SUPPORTED is supported.
 // TEST(TransitionAccessorConstantToAnotherAccessorConstant)