Reviewers: Igor Sheludko,
Message:
PTAL
Description:
Keep function.prototype fast.
BUG=
Please review this at https://codereview.chromium.org/437083004/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+36, -6 lines):
M src/factory.cc
M src/objects.h
M src/objects.cc
M src/objects-inl.h
M test/mjsunit/fast-prototype.js
Index: src/factory.cc
diff --git a/src/factory.cc b/src/factory.cc
index
60dc0b7a8d7a67fe2b507e10e23e89f15e24e881..864672143a800e0e6b5a4672f6697786f35a5341
100644
--- a/src/factory.cc
+++ b/src/factory.cc
@@ -1318,7 +1318,7 @@ Handle<JSObject>
Factory::NewFunctionPrototype(Handle<JSFunction> function) {
// maps between prototypes of different constructors.
Handle<JSFunction> object_function(native_context->object_function());
ASSERT(object_function->has_initial_map());
- new_map = Map::Copy(handle(object_function->initial_map()));
+ new_map =
Map::CopyAsPrototypeMap(handle(object_function->initial_map()));
}
Handle<JSObject> prototype = NewJSObjectFromMap(new_map);
Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index
42b3913e3a2528c6b536e0b27743b747e4db7aa2..32746b0c7a0d9e2100e2a70e47beb80b5d98a992
100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -2115,6 +2115,7 @@ bool JSObject::HasFastProperties() {
bool Map::TooManyFastProperties(StoreFromKeyed store_mode) {
if (unused_property_fields() != 0) return false;
+ if (is_prototype_map()) return false;
int minimum = store_mode == CERTAINLY_NOT_STORE_FROM_KEYED ? 128 : 12;
int limit = Max(minimum, inobject_properties());
int external = NumberOfFields() - inobject_properties();
@@ -4445,6 +4446,15 @@ bool Map::is_extensible() {
}
+void Map::mark_prototype_map() {
+ set_bit_field2(IsPrototypeMapBits::update(bit_field2(), true));
+}
+
+bool Map::is_prototype_map() {
+ return IsPrototypeMapBits::decode(bit_field2());
+}
+
+
void Map::set_is_shared(bool value) {
set_bit_field3(IsShared::update(bit_field3(), value));
}
Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index
4217666afa02b859f0055d4811bb17d41cdb04f2..19a22b433e24e4eca8f43b62c11691fb1051a785
100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -7266,6 +7266,13 @@ Handle<Map> Map::CopyForObserved(Handle<Map> map) {
}
+Handle<Map> Map::CopyAsPrototypeMap(Handle<Map> map) {
+ Handle<Map> result = Copy(map);
+ result->mark_prototype_map();
+ return result;
+}
+
+
Handle<Map> Map::Copy(Handle<Map> map) {
Handle<DescriptorArray> descriptors(map->instance_descriptors());
int number_of_own_descriptors = map->NumberOfOwnDescriptors();
@@ -10003,7 +10010,12 @@ void
JSFunction::SetInstancePrototype(Handle<JSFunction> function,
// First some logic for the map of the prototype to make sure it is in
fast
// mode.
if (value->IsJSObject()) {
- JSObject::OptimizeAsPrototype(Handle<JSObject>::cast(value));
+ Handle<JSObject> js_proto = Handle<JSObject>::cast(value);
+ JSObject::OptimizeAsPrototype(js_proto);
+ if (js_proto->HasFastProperties()) {
+ Handle<Map> new_map =
Map::CopyAsPrototypeMap(handle(js_proto->map()));
+ JSObject::MigrateToMap(js_proto, new_map);
+ }
}
// Now some logic for the maps of the objects that are created by using
this
Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index
701a17a969af6b6d9dd35c59201965c1b7ffcfcb..a0369416bb41ad4ab0c149aed89ce653fe11c48d
100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -6204,6 +6204,8 @@ class Map: public HeapObject {
inline void set_is_extensible(bool value);
inline bool is_extensible();
+ inline void mark_prototype_map();
+ inline bool is_prototype_map();
inline void set_elements_kind(ElementsKind elements_kind) {
ASSERT(elements_kind < kElementsKindCount);
@@ -6537,6 +6539,7 @@ class Map: public HeapObject {
// Returns a copy of the map, with all transitions dropped from the
// instance descriptors.
static Handle<Map> Copy(Handle<Map> map);
+ static Handle<Map> CopyAsPrototypeMap(Handle<Map> map);
static Handle<Map> Create(Handle<JSFunction> constructor,
int extra_inobject_properties);
@@ -6736,7 +6739,7 @@ class Map: public HeapObject {
// Bit positions for bit field 2
static const int kIsExtensible = 0;
static const int kStringWrapperSafeForDefaultValueOf = 1;
- // Currently bit 2 is not used.
+ class IsPrototypeMapBits : public BitField<bool, 2, 1> {};
class ElementsKindBits: public BitField<ElementsKind, 3, 5> {};
// Derived values from bit field 2
Index: test/mjsunit/fast-prototype.js
diff --git a/test/mjsunit/fast-prototype.js b/test/mjsunit/fast-prototype.js
index
cdcc1a9ed68e8995b4642b5702166e781b46e211..55a0faae805341b16804deeef6e53e7a49dfc1cd
100644
--- a/test/mjsunit/fast-prototype.js
+++ b/test/mjsunit/fast-prototype.js
@@ -72,10 +72,15 @@ function test(use_new, add_first, set__proto__,
same_map_as) {
// Still fast
assertTrue(%HasFastProperties(proto));
AddProps(proto);
- // After we add all those properties it went slow mode again :-(
- assertFalse(%HasFastProperties(proto));
+ if (set__proto__) {
+ // After we add all those properties it went slow mode again :-(
+ assertFalse(%HasFastProperties(proto));
+ } else {
+ // .prototype keeps it fast.
+ assertTrue(%HasFastProperties(proto));
+ }
}
- if (same_map_as && !add_first) {
+ if (same_map_as && !add_first && set__proto__) {
assertTrue(%HaveSameMap(same_map_as, proto));
}
return proto;
--
--
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