Reviewers: Jakob,
Description:
Revert 9111036: Promote double arrays to FAST_ELEMENT that use generic
KeyedLoadIC
It tanked Kraken.
[email protected]
Please review this at https://chromiumcodereview.appspot.com/9368024/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/ic.cc
M src/runtime.cc
Index: src/ic.cc
diff --git a/src/ic.cc b/src/ic.cc
index
715c805ce068284fc9b382905fb1b0bb39e48b8b..b084109a713aa572bb79acdfb7f1155d8a9ba9f8
100644
--- a/src/ic.cc
+++ b/src/ic.cc
@@ -1120,17 +1120,6 @@ MaybeObject* KeyedLoadIC::Load(State state,
} else if (key->IsSmi() && (target() !=
*non_strict_arguments_stub())) {
stub = ComputeStub(receiver, LOAD, kNonStrictMode, stub);
}
- // If the IC is being replaced by the generic stub, loads from
- // FAST_DOUBLE_ELEMENTS arrays will cause unboxing in Crankshafted
- // code. To prevent these expensive allocations, proactively
promote
- // arrays to FAST_ELEMENTS ElementKinds.
- if (*stub == *generic_stub()) {
- if (receiver->HasFastDoubleElements()) {
- MaybeObject* maybe_object =
- receiver->TransitionElementsKind(FAST_ELEMENTS);
- if (maybe_object->IsFailure()) return maybe_object;
- }
- }
}
} else {
TRACE_GENERIC_IC("KeyedLoadIC", "force generic");
Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index
27335c91747a85419a178322120afc0b5c0908af..d80b4a6945218e15ad17039b851db98822959266
100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -4270,24 +4270,14 @@ RUNTIME_FUNCTION(MaybeObject*,
Runtime_KeyedGetProperty) {
// If value is the hole do the general lookup.
}
}
- } else if (args.at<Object>(1)->IsSmi()) {
- // Getting properties from FAST_DOUBLE_ELEMENTS arrays causes
boxing. To
- // proactively avoid excessive boxing, transition
FAST_DOUBLE_ELEMENTS
- // arrays to FAST_ELEMENTS if they are accessed via this function,
which
- // is called by the KeyedLoadIC::GenericStub.
- Handle<JSObject> js_object(args.at<JSObject>(0));
- if (js_object->HasFastDoubleElements()) {
- MaybeObject* maybe_object =
- js_object->TransitionElementsKind(FAST_ELEMENTS);
- if (maybe_object->IsFailure()) return maybe_object;
- }
-
+ } else if (FLAG_smi_only_arrays && args.at<Object>(1)->IsSmi()) {
// JSObject without a string key. If the key is a Smi, check for a
// definite out-of-bounds access to elements, which is a strong
indicator
// that subsequent accesses will also call the runtime. Proactively
// transition elements to FAST_ELEMENTS to avoid excessive boxing of
// doubles for those future calls in the case that the elements would
// become FAST_DOUBLE_ELEMENTS.
+ Handle<JSObject> js_object(args.at<JSObject>(0));
ElementsKind elements_kind = js_object->GetElementsKind();
if (elements_kind == FAST_SMI_ONLY_ELEMENTS ||
elements_kind == FAST_DOUBLE_ELEMENTS) {
--
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