Free one bit in Map by removing unused retaining counter.

test/cctest/test-inobject-slack-tracking.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 <sstream>
 #include <utility>
 
 #include "src/api.h"
 #include "src/objects.h"
@@ skipping 137 matching lines @@
   CHECK(!func->has_initial_map());
 
   v8::Local<v8::Script> new_A_script = v8_compile("new A();");
 
   Handle<JSObject> obj = Run<JSObject>(new_A_script);
 
   CHECK(func->has_initial_map());
   Handle<Map> initial_map(func->initial_map());
 
   // One instance created.
-  CHECK_EQ(Map::kSlackTrackingCounterStart - 1, initial_map->counter());
+  CHECK_EQ(Map::kSlackTrackingCounterStart - 1,
+           initial_map->construction_counter());
   CHECK(initial_map->IsInobjectSlackTrackingInProgress());
 
   // There must be at least some slack.
   CHECK_LT(5, obj->map()->GetInObjectProperties());
   CHECK_EQ(Smi::FromInt(42), GetFieldValue(*obj, 0));
   CHECK_EQ(4.2, GetDoubleFieldValue(*obj, 1));
   CHECK_EQ(*obj, GetFieldValue(*obj, 2));
   CHECK(IsObjectShrinkable(*obj));
 
   // Create several objects to complete the tracking.
@@ skipping 40 matching lines @@
   CHECK(!func->has_initial_map());
 
   Handle<JSObject> obj1 = CompileRun<JSObject>("new A(1);");
   Handle<JSObject> obj3 = CompileRun<JSObject>("new A(3);");
   Handle<JSObject> obj5 = CompileRun<JSObject>("new A(5);");
 
   CHECK(func->has_initial_map());
   Handle<Map> initial_map(func->initial_map());
 
   // Three instances created.
-  CHECK_EQ(Map::kSlackTrackingCounterStart - 3, initial_map->counter());
+  CHECK_EQ(Map::kSlackTrackingCounterStart - 3,
+           initial_map->construction_counter());
   CHECK(initial_map->IsInobjectSlackTrackingInProgress());
 
   // There must be at least some slack.
   CHECK_LT(5, obj3->map()->GetInObjectProperties());
   CHECK_EQ(Smi::FromInt(42), GetFieldValue(*obj3, 0));
   CHECK_EQ(4.2, GetDoubleFieldValue(*obj3, 1));
   CHECK_EQ(*obj3, GetFieldValue(*obj3, 2));
   CHECK(IsObjectShrinkable(*obj1));
   CHECK(IsObjectShrinkable(*obj3));
   CHECK(IsObjectShrinkable(*obj5));
@@ skipping 64 matching lines @@
   CHECK(!func->has_initial_map());
 
   v8::Local<v8::Script> new_A_script = v8_compile("CreateGenerator();");
 
   Handle<JSObject> obj = Run<JSObject>(new_A_script);
 
   CHECK(func->has_initial_map());
   Handle<Map> initial_map(func->initial_map());
 
   // One instance created.
-  CHECK_EQ(Map::kSlackTrackingCounterStart - 1, initial_map->counter());
+  CHECK_EQ(Map::kSlackTrackingCounterStart - 1,
+           initial_map->construction_counter());
   CHECK(initial_map->IsInobjectSlackTrackingInProgress());
 
   // There must be at least some slack.
   CHECK_LT(5, obj->map()->GetInObjectProperties());
   CHECK_EQ(Smi::FromInt(42), GetFieldValue(*obj, 0));
   CHECK_EQ(4.2, GetDoubleFieldValue(*obj, 1));
   CHECK_EQ(*obj, GetFieldValue(*obj, 2));
   CHECK(IsObjectShrinkable(*obj));
 
   // Create several objects to complete the tracking.
@@ skipping 58 matching lines @@
 
   Handle<JSObject> obj = Run<JSObject>(new_B_script);
 
   CHECK(a_func->has_initial_map());
   Handle<Map> a_initial_map(a_func->initial_map());
 
   CHECK(b_func->has_initial_map());
   Handle<Map> b_initial_map(b_func->initial_map());
 
   // Zero instances of A created.
-  CHECK_EQ(Map::kSlackTrackingCounterStart, a_initial_map->counter());
+  CHECK_EQ(Map::kSlackTrackingCounterStart,
+           a_initial_map->construction_counter());
   CHECK(a_initial_map->IsInobjectSlackTrackingInProgress());
 
   // One instance of B created.
-  CHECK_EQ(Map::kSlackTrackingCounterStart - 1, b_initial_map->counter());
+  CHECK_EQ(Map::kSlackTrackingCounterStart - 1,
+           b_initial_map->construction_counter());
   CHECK(b_initial_map->IsInobjectSlackTrackingInProgress());
 
   // There must be at least some slack.
   CHECK_LT(10, obj->map()->GetInObjectProperties());
   CHECK_EQ(Smi::FromInt(42), GetFieldValue(*obj, 0));
   CHECK_EQ(4.2, GetDoubleFieldValue(*obj, 1));
   CHECK_EQ(*obj, GetFieldValue(*obj, 2));
   CHECK_EQ(Smi::FromInt(142), GetFieldValue(*obj, 3));
   CHECK_EQ(14.2, GetDoubleFieldValue(*obj, 4));
   CHECK_EQ(*obj, GetFieldValue(*obj, 5));
   CHECK(IsObjectShrinkable(*obj));
 
   // Create several subclass instances to complete the tracking.
   for (int i = 1; i < Map::kGenerousAllocationCount; i++) {
     CHECK(b_initial_map->IsInobjectSlackTrackingInProgress());
     Handle<JSObject> tmp = Run<JSObject>(new_B_script);
     CHECK_EQ(b_initial_map->IsInobjectSlackTrackingInProgress(),
              IsObjectShrinkable(*tmp));
   }
   CHECK(!b_initial_map->IsInobjectSlackTrackingInProgress());
   CHECK(!IsObjectShrinkable(*obj));
 
   // Zero instances of A created.
-  CHECK_EQ(Map::kSlackTrackingCounterStart, a_initial_map->counter());
+  CHECK_EQ(Map::kSlackTrackingCounterStart,
+           a_initial_map->construction_counter());
   CHECK(a_initial_map->IsInobjectSlackTrackingInProgress());
 
   // No slack left.
   CHECK_EQ(6, obj->map()->GetInObjectProperties());
 }
 
 
 TEST(SubclassBasicNoBaseClassInstancesNoInlineNew) {
   FLAG_inline_new = false;
   TestSubclassBasicNoBaseClassInstances();
@@ skipping 44 matching lines @@
   Handle<JSObject> a_obj = Run<JSObject>(new_A_script);
   Handle<JSObject> b_obj = Run<JSObject>(new_B_script);
 
   CHECK(a_func->has_initial_map());
   Handle<Map> a_initial_map(a_func->initial_map());
 
   CHECK(b_func->has_initial_map());
   Handle<Map> b_initial_map(b_func->initial_map());
 
   // One instance of a base class created.
-  CHECK_EQ(Map::kSlackTrackingCounterStart - 1, a_initial_map->counter());
+  CHECK_EQ(Map::kSlackTrackingCounterStart - 1,
+           a_initial_map->construction_counter());
   CHECK(a_initial_map->IsInobjectSlackTrackingInProgress());
 
   // One instance of a subclass created.
-  CHECK_EQ(Map::kSlackTrackingCounterStart - 1, b_initial_map->counter());
+  CHECK_EQ(Map::kSlackTrackingCounterStart - 1,
+           b_initial_map->construction_counter());
   CHECK(b_initial_map->IsInobjectSlackTrackingInProgress());
 
   // Create several base class instances to complete the tracking.
   for (int i = 1; i < Map::kGenerousAllocationCount; i++) {
     CHECK(a_initial_map->IsInobjectSlackTrackingInProgress());
     Handle<JSObject> tmp = Run<JSObject>(new_A_script);
     CHECK_EQ(a_initial_map->IsInobjectSlackTrackingInProgress(),
              IsObjectShrinkable(*tmp));
   }
   CHECK(!a_initial_map->IsInobjectSlackTrackingInProgress());
@@ skipping 96 matching lines @@
 
     Handle<JSObject> obj = Run<JSObject>(new_script);
 
     CHECK(func->has_initial_map());
     Handle<Map> initial_map(func->initial_map());
 
     // There must be at least some slack.
     CHECK_LT(fields_count, obj->map()->GetInObjectProperties());
 
     // One instance was created.
-    CHECK_EQ(Map::kSlackTrackingCounterStart - 1, initial_map->counter());
+    CHECK_EQ(Map::kSlackTrackingCounterStart - 1,
+             initial_map->construction_counter());
     CHECK(initial_map->IsInobjectSlackTrackingInProgress());
 
     // Create several instances to complete the tracking.
     for (int i = 1; i < Map::kGenerousAllocationCount; i++) {
       CHECK(initial_map->IsInobjectSlackTrackingInProgress());
       Handle<JSObject> tmp = Run<JSObject>(new_script);
       CHECK_EQ(initial_map->IsInobjectSlackTrackingInProgress(),
                IsObjectShrinkable(*tmp));
     }
     CHECK(!initial_map->IsInobjectSlackTrackingInProgress());
@@ skipping 76 matching lines @@
     Handle<JSObject> obj = Run<JSObject>(new_script);
 
     CHECK(func->has_initial_map());
     Handle<Map> initial_map(func->initial_map());
 
     // There must be no slack left.
     CHECK_EQ(JSObject::kMaxInstanceSize, obj->map()->instance_size());
     CHECK_EQ(kMaxInobjectProperties, obj->map()->GetInObjectProperties());
 
     // One instance was created.
-    CHECK_EQ(Map::kSlackTrackingCounterStart - 1, initial_map->counter());
+    CHECK_EQ(Map::kSlackTrackingCounterStart - 1,
+             initial_map->construction_counter());
     CHECK(initial_map->IsInobjectSlackTrackingInProgress());
 
     // Create several instances to complete the tracking.
     for (int i = 1; i < Map::kGenerousAllocationCount; i++) {
       CHECK(initial_map->IsInobjectSlackTrackingInProgress());
       Handle<JSObject> tmp = Run<JSObject>(new_script);
       CHECK(!IsObjectShrinkable(*tmp));
     }
     CHECK(!initial_map->IsInobjectSlackTrackingInProgress());
     CHECK(!IsObjectShrinkable(*obj));
@@ skipping 37 matching lines @@
     Handle<JSObject> obj = Run<JSObject>(new_script);
 
     CHECK(func->has_initial_map());
     Handle<Map> initial_map(func->initial_map());
 
     // Object should go dictionary mode.
     CHECK_EQ(JSObject::kHeaderSize, obj->map()->instance_size());
     CHECK(obj->map()->is_dictionary_map());
 
     // One instance was created.
-    CHECK_EQ(Map::kSlackTrackingCounterStart - 1, initial_map->counter());
+    CHECK_EQ(Map::kSlackTrackingCounterStart - 1,
+             initial_map->construction_counter());
     CHECK(initial_map->IsInobjectSlackTrackingInProgress());
 
     // Create several instances to complete the tracking.
     for (int i = 1; i < Map::kGenerousAllocationCount; i++) {
       CHECK(initial_map->IsInobjectSlackTrackingInProgress());
       Handle<JSObject> tmp = Run<JSObject>(new_script);
       CHECK(!IsObjectShrinkable(*tmp));
     }
     CHECK(!initial_map->IsInobjectSlackTrackingInProgress());
     CHECK(!IsObjectShrinkable(*obj));
@@ skipping 42 matching lines @@
   }
 
   Run<JSObject>(new_script);
 
   CHECK(func->has_initial_map());
   Handle<Map> initial_map(func->initial_map());
 
   CHECK_EQ(instance_type, initial_map->instance_type());
 
   // One instance of a subclass created.
-  CHECK_EQ(Map::kSlackTrackingCounterStart - 1, initial_map->counter());
+  CHECK_EQ(Map::kSlackTrackingCounterStart - 1,
+           initial_map->construction_counter());
   CHECK(initial_map->IsInobjectSlackTrackingInProgress());
 
   // Create two instances in order to ensure that |obj|.o is a data field
   // in case of Function subclassing.
   Handle<JSObject> obj = Run<JSObject>(new_script);
 
   // Two instances of a subclass created.
-  CHECK_EQ(Map::kSlackTrackingCounterStart - 2, initial_map->counter());
+  CHECK_EQ(Map::kSlackTrackingCounterStart - 2,
+           initial_map->construction_counter());
   CHECK(initial_map->IsInobjectSlackTrackingInProgress());
 
   // There must be at least some slack.
   CHECK_LT(builtin_properties_count + 5, obj->map()->GetInObjectProperties());
   CHECK_EQ(Smi::FromInt(42), GetFieldValue(*obj, builtin_properties_count + 0));
   CHECK_EQ(4.2, GetDoubleFieldValue(*obj, builtin_properties_count + 1));
   CHECK_EQ(*obj, GetFieldValue(*obj, builtin_properties_count + 2));
   CHECK(IsObjectShrinkable(*obj));
 
   // Create several subclass instances to complete the tracking.
@@ skipping 255 matching lines @@
   TestSubclassBuiltin("A1", JS_PROMISE_TYPE, "Promise",
                       "function(resolve, reject) { resolve('ok'); }",
                       first_field);
 }
 
 
 TEST(SubclassPromiseBuiltinNoInlineNew) {
   FLAG_inline_new = false;
   TestSubclassPromiseBuiltin();
 }