Revision: 10683
Author: [email protected]
Date: Mon Feb 13 03:37:39 2012
Log: Optimize call sites that only ever see a single elements
transition
[email protected]
TEST=imaging-gaussian-blur performance improves
Review URL: https://chromiumcodereview.appspot.com/9389001
http://code.google.com/p/v8/source/detail?r=10683
Modified:
/branches/bleeding_edge/src/ic.cc
=======================================
--- /branches/bleeding_edge/src/ic.cc Fri Feb 10 04:36:05 2012
+++ /branches/bleeding_edge/src/ic.cc Mon Feb 13 03:37:39 2012
@@ -1503,8 +1503,32 @@
KeyedAccessGrowMode grow_mode = IsGrowStubKind(stub_kind)
? ALLOW_JSARRAY_GROWTH
: DO_NOT_ALLOW_JSARRAY_GROWTH;
- if ((ic_state == UNINITIALIZED || ic_state == PREMONOMORPHIC) &&
- !IsTransitionStubKind(stub_kind)) {
+
+ bool monomorphic = false;
+ MapHandleList target_receiver_maps;
+ if (ic_state != UNINITIALIZED && ic_state != PREMONOMORPHIC) {
+ GetReceiverMapsForStub(Handle<Code>(target()), &target_receiver_maps);
+ }
+ if (!IsTransitionStubKind(stub_kind)) {
+ if (ic_state == UNINITIALIZED || ic_state == PREMONOMORPHIC) {
+ monomorphic = true;
+ } else {
+ if (ic_state == MONOMORPHIC) {
+ // The first time a receiver is seen that is a transitioned
version of
+ // the previous monomorphic receiver type, assume the new
ElementsKind
+ // is the monomorphic type. This benefits global arrays that only
+ // transition once, and all call sites accessing them are faster
if they
+ // remain monomorphic. If this optimistic assumption is not true,
the IC
+ // will miss again and it will become polymorphic and support both
the
+ // untransitioned and transitioned maps.
+ monomorphic = IsMoreGeneralElementsKindTransition(
+ target_receiver_maps.at(0)->elements_kind(),
+ receiver->GetElementsKind());
+ }
+ }
+ }
+
+ if (monomorphic) {
return ComputeMonomorphicStub(
receiver, stub_kind, strict_mode, generic_stub);
}
@@ -1520,13 +1544,7 @@
// Determine the list of receiver maps that this call site has seen,
// adding the map that was just encountered.
- MapHandleList target_receiver_maps;
Handle<Map> receiver_map(receiver->map());
- if (ic_state == UNINITIALIZED || ic_state == PREMONOMORPHIC) {
- target_receiver_maps.Add(receiver_map);
- } else {
- GetReceiverMapsForStub(Handle<Code>(target()), &target_receiver_maps);
- }
bool map_added =
AddOneReceiverMapIfMissing(&target_receiver_maps, receiver_map);
if (IsTransitionStubKind(stub_kind)) {
--
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