Re-land: Use map transitions when defining accessor properties.

This is basically r11496, with the following changes:

 * Set back pointers in maps (cherry-picked from r11528)

 * Fixed size calculation in CopyInsert, as proposed by mstarzinger/rossberg

 * DefineFastAccessor uses GetCallbackObject instead of GetValue (for __proto__)

 * Put the code under a new flag, which is disabled by default

 * Cut down the corresponding regression test

 * Adapted bootup memory test, we actually only need a bit more memory on 64bit without snapshots, which can easily explained by more live maps lying around. Note that the snapshot variants are back to their previous limits.

Next steps: Investigate any performance degradationswith the flag enabled, and finally remove the flag when things are OK. Furthermore, GetCallbackObject should be merged into GetValue, the distinction is confusing and error-prone.

Review URL: https://chromiumcodereview.appspot.com/10445009

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11651 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/flag-definitions.h

@@ -397,6 +397,8 @@ DEFINE_int(random_seed, 0,
 
 // objects.cc
 DEFINE_bool(use_verbose_printer, true, "allows verbose printing")
+DEFINE_bool(fast_accessor_properties, false,
+            "use map transitions for JavaScript accessors")
 
 // parser.cc
 DEFINE_bool(allow_natives_syntax, false, "allow natives syntax")

src/objects.h

@@ -664,12 +664,13 @@ enum CompareResult {
                          WriteBarrierMode mode = UPDATE_WRITE_BARRIER); \
 
 
+class AccessorPair;
 class DictionaryElementsAccessor;
 class ElementsAccessor;
+class Failure;
 class FixedArrayBase;
 class ObjectVisitor;
 class StringStream;
-class Failure;
 
 struct ValueInfo : public Malloced {
   ValueInfo() : type(FIRST_TYPE), ptr(NULL), str(NULL), number(0) { }
@@ -1608,6 +1609,14 @@ class JSObject: public JSReceiver {
                                               Object* getter,
                                               Object* setter,
                                               PropertyAttributes attributes);
+  // Try to define a single accessor paying attention to map transitions.
+  // Returns a JavaScript null if this was not possible and we have to use the
+  // slow case. Note that we can fail due to allocations, too.
+  MUST_USE_RESULT MaybeObject* DefineFastAccessor(
+      String* name,
+      AccessorComponent component,
+      Object* accessor,
+      PropertyAttributes attributes);
   Object* LookupAccessor(String* name, AccessorComponent component);
 
   MUST_USE_RESULT MaybeObject* DefineAccessor(AccessorInfo* info);
@@ -8100,6 +8109,18 @@ class AccessorPair: public Struct {
 
   MUST_USE_RESULT MaybeObject* CopyWithoutTransitions();
 
+  Object* get(AccessorComponent component) {
+    return component == ACCESSOR_GETTER ? getter() : setter();
+  }
+
+  void set(AccessorComponent component, Object* value) {
+    if (component == ACCESSOR_GETTER) {
+      set_getter(value);
+    } else {
+      set_setter(value);
+    }
+  }
+
   // Note: Returns undefined instead in case of a hole.
   Object* GetComponent(AccessorComponent component);
 

test/cctest/test-mark-compact.cc

@@ -531,18 +531,18 @@ TEST(BootUpMemoryUse) {
   // there we just skip the test.
   if (initial_memory >= 0) {
     InitializeVM();
-    intptr_t booted_memory = MemoryInUse();
+    intptr_t delta = MemoryInUse() - initial_memory;
     if (sizeof(initial_memory) == 8) {
       if (v8::internal::Snapshot::IsEnabled()) {
-        CHECK_LE(booted_memory - initial_memory, 3600 * 1024);  // 3396.
+        CHECK_LE(delta, 3600 * 1024);  // 3396.
       } else {
-        CHECK_LE(booted_memory - initial_memory, 3600 * 1024);  // 3432.
+        CHECK_LE(delta, 4000 * 1024);  // 3948.
       }
     } else {
       if (v8::internal::Snapshot::IsEnabled()) {
-        CHECK_LE(booted_memory - initial_memory, 2800 * 1024);  // 2484.
+        CHECK_LE(delta, 2600 * 1024);  // 2484.
       } else {
-        CHECK_LE(booted_memory - initial_memory, 2950 * 1024);  // 2844
+        CHECK_LE(delta, 2950 * 1024);  // 2844
       }
     }
   }

test/mjsunit/accessor-map-sharing.js

+// Copyright 2012 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --allow-natives-syntax --fast-accessor-properties
+
+// Handy abbreviations.
+var dp = Object.defineProperty;
+var gop = Object.getOwnPropertyDescriptor;
+
+function getter() { return 111; }
+function setter(x) { print(222); }
+function anotherGetter() { return 333; }
+function anotherSetter(x) { print(444); }
+var obj1, obj2;
+
+// Two objects with the same getter.
+obj1 = {};
+dp(obj1, "alpha", { get: getter });
+obj2 = {};
+dp(obj2, "alpha", { get: getter });
+assertTrue(%HaveSameMap(obj1, obj2));
+
+// Two objects with the same getter, oldskool.
+obj1 = {};
+obj1.__defineGetter__("bravo", getter);
+assertEquals(getter, obj1.__lookupGetter__("bravo"));
+obj2 = {};
+obj2.__defineGetter__("bravo", getter);
+assertEquals(getter, obj2.__lookupGetter__("bravo"));
+assertTrue(%HaveSameMap(obj1, obj2));
+
+// Two objects with the same setter.
+obj1 = {};
+dp(obj1, "charlie", { set: setter });
+obj2 = {};
+dp(obj2, "charlie", { set: setter });
+assertTrue(%HaveSameMap(obj1, obj2));
+
+// Two objects with the same setter, oldskool.
+obj1 = {};
+obj1.__defineSetter__("delta", setter);
+assertEquals(setter, obj1.__lookupSetter__("delta"));
+obj2 = {};
+obj2.__defineSetter__("delta", setter);
+assertEquals(setter, obj2.__lookupSetter__("delta"));
+assertTrue(%HaveSameMap(obj1, obj2));
+
+// Two objects with the same getter and setter.
+obj1 = {};
+dp(obj1, "foxtrot", { get: getter, set: setter });
+obj2 = {};
+dp(obj2, "foxtrot", { get: getter, set: setter });
+assertTrue(%HaveSameMap(obj1, obj2));
+
+// Two objects with the same getter and setter, set separately.
+obj1 = {};
+dp(obj1, "golf", { get: getter, configurable: true });
+dp(obj1, "golf", { set: setter, configurable: true });
+obj2 = {};
+dp(obj2, "golf", { get: getter, configurable: true });
+dp(obj2, "golf", { set: setter, configurable: true });
+assertTrue(%HaveSameMap(obj1, obj2));
+
+// Two objects with the same getter and setter, set separately, oldskool.
+obj1 = {};
+obj1.__defineGetter__("hotel", getter);
+obj1.__defineSetter__("hotel", setter);
+obj2 = {};
+obj2.__defineGetter__("hotel", getter);
+obj2.__defineSetter__("hotel", setter);
+assertTrue(%HaveSameMap(obj1, obj2));
+
+// Attribute-only change, shouldn't affect previous descriptor properties.
+obj1 = {};
+dp(obj1, "india", { get: getter, configurable: true, enumerable: true });
+assertEquals(getter, gop(obj1, "india").get);
+assertTrue(gop(obj1, "india").configurable);
+assertTrue(gop(obj1, "india").enumerable);
+dp(obj1, "india", { enumerable: false });
+assertEquals(getter, gop(obj1, "india").get);
+assertTrue(gop(obj1, "india").configurable);
+assertFalse(gop(obj1, "india").enumerable);
+
+// Attribute-only change, shouldn't affect objects with previously shared maps.
+obj1 = {};
+dp(obj1, "juliet", { set: setter, configurable: true, enumerable: false });
+assertEquals(setter, gop(obj1, "juliet").set);
+assertTrue(gop(obj1, "juliet").configurable);
+assertFalse(gop(obj1, "juliet").enumerable);
+obj2 = {};
+dp(obj2, "juliet", { set: setter, configurable: true, enumerable: false });
+assertEquals(setter, gop(obj2, "juliet").set);
+assertTrue(gop(obj2, "juliet").configurable);
+assertFalse(gop(obj2, "juliet").enumerable);
+dp(obj1, "juliet", { set: setter, configurable: false, enumerable: true });
+assertEquals(setter, gop(obj1, "juliet").set);
+assertFalse(gop(obj1, "juliet").configurable);
+assertTrue(gop(obj1, "juliet").enumerable);
+assertEquals(setter, gop(obj2, "juliet").set);
+assertTrue(gop(obj2, "juliet").configurable);
+assertFalse(gop(obj2, "juliet").enumerable);
+
+// Two objects with the different getters.
+obj1 = {};
+dp(obj1, "kilo", { get: getter });
+obj2 = {};
+dp(obj2, "kilo", { get: anotherGetter });
+assertEquals(getter, gop(obj1, "kilo").get);
+assertEquals(anotherGetter, gop(obj2, "kilo").get);
+assertFalse(%HaveSameMap(obj1, obj2));
+
+// Two objects with the same getters and different setters.
+obj1 = {};
+dp(obj1, "lima", { get: getter, set: setter });
+obj2 = {};
+dp(obj2, "lima", { get: getter, set: anotherSetter });
+assertEquals(setter, gop(obj1, "lima").set);
+assertEquals(anotherSetter, gop(obj2, "lima").set);
+assertFalse(%HaveSameMap(obj1, obj2));
+
+// Even 'undefined' is a kind of getter.
+obj1 = {};
+dp(obj1, "mike", { get: undefined });
+assertTrue("mike" in obj1);
+assertEquals(undefined, gop(obj1, "mike").get);
+assertEquals(undefined, obj1.__lookupGetter__("mike"));
+assertEquals(undefined, gop(obj1, "mike").set);
+assertEquals(undefined, obj1.__lookupSetter__("mike"));
+
+// Even 'undefined' is a kind of setter.
+obj1 = {};
+dp(obj1, "november", { set: undefined });
+assertTrue("november" in obj1);
+assertEquals(undefined, gop(obj1, "november").get);
+assertEquals(undefined, obj1.__lookupGetter__("november"));
+assertEquals(undefined, gop(obj1, "november").set);
+assertEquals(undefined, obj1.__lookupSetter__("november"));
+
+// Redefining a data property.
+obj1 = {};
+obj1.oscar = 12345;
+dp(obj1, "oscar", { set: setter });
+assertEquals(setter, gop(obj1, "oscar").set);
+
+// Re-adding the same getter/attributes pair.
+obj1 = {};
+dp(obj1, "papa", { get: getter, configurable: true });
+dp(obj1, "papa", { get: getter, set: setter, configurable: true });
+assertEquals(getter, gop(obj1, "papa").get);
+assertEquals(setter, gop(obj1, "papa").set);
+assertTrue(gop(obj1, "papa").configurable);
+assertFalse(gop(obj1, "papa").enumerable);

test/mjsunit/regress/regress-128146.js

@@ -25,14 +25,9 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+// Define accessor properties, resulting in an AccessorPair with 2 transitions.
 Object.defineProperty({},"foo",{set:function(){},configurable:false});
 Object.defineProperty({},"foo",{get:function(){},configurable:false});
-Object.defineProperty({},"foo",{});
-
-// From WebKit layout tests (fast/js/prototypes.html)
-var wasSet = false;
-var o = { };
-o.__defineGetter__("__proto__", function() { wasSet = true });
-o.__proto__;
-assertFalse(wasSet);
 
+// Define a data property under the same name.
+Object.defineProperty({},"foo",{});