Revision: 15806
Author: [email protected]
Date: Mon Jul 22 07:15:58 2013
Log: Avoid repeated rewrites of global store to constant IC due to
store of same value.
[email protected]
Review URL: https://chromiumcodereview.appspot.com/19663007
http://code.google.com/p/v8/source/detail?r=15806
Modified:
/branches/bleeding_edge/src/code-stubs-hydrogen.cc
/branches/bleeding_edge/src/stub-cache.cc
=======================================
--- /branches/bleeding_edge/src/code-stubs-hydrogen.cc Fri Jul 19 06:30:49
2013
+++ /branches/bleeding_edge/src/code-stubs-hydrogen.cc Mon Jul 22 07:15:58
2013
@@ -850,23 +850,25 @@
HParameter* receiver = GetParameter(0);
HParameter* value = GetParameter(2);
+ // Check that the map of the global has not changed: use a placeholder
map
+ // that will be replaced later with the global object's map.
+ Handle<Map> placeholder_map = isolate()->factory()->meta_map();
+ AddInstruction(HCheckMaps::New(receiver, placeholder_map, zone()));
+
+ HValue* cell = Add<HConstant>(placeholder_cell,
Representation::Tagged());
+ HObjectAccess access(HObjectAccess::ForCellPayload(isolate()));
+ HValue* cell_contents = Add<HLoadNamedField>(cell, access);
+
if (stub->is_constant()) {
- // Assume every store to a constant value changes it.
- current_block()->FinishExitWithDeoptimization(HDeoptimize::kUseAll);
- set_current_block(NULL);
+ IfBuilder builder(this);
+ builder.If<HCompareObjectEqAndBranch>(cell_contents, value);
+ builder.Then();
+ builder.ElseDeopt();
+ builder.End();
} else {
- HValue* cell = Add<HConstant>(placeholder_cell,
Representation::Tagged());
-
- // Check that the map of the global has not changed: use a placeholder
map
- // that will be replaced later with the global object's map.
- Handle<Map> placeholder_map = isolate()->factory()->meta_map();
- AddInstruction(HCheckMaps::New(receiver, placeholder_map, zone()));
-
// Load the payload of the global parameter cell. A hole indicates
that the
// property has been deleted and that the store must be handled by the
// runtime.
- HObjectAccess access(HObjectAccess::ForCellPayload(isolate()));
- HValue* cell_contents = Add<HLoadNamedField>(cell, access);
IfBuilder builder(this);
HValue* hole_value = Add<HConstant>(hole, Representation::Tagged());
builder.If<HCompareObjectEqAndBranch>(cell_contents, hole_value);
@@ -876,6 +878,7 @@
Add<HStoreNamedField>(cell, access, value);
builder.End();
}
+
return value;
}
=======================================
--- /branches/bleeding_edge/src/stub-cache.cc Wed Jul 17 04:37:20 2013
+++ /branches/bleeding_edge/src/stub-cache.cc Mon Jul 22 07:15:58 2013
@@ -563,16 +563,15 @@
Code::STORE_IC, Code::NORMAL, stub.GetExtraICState());
if (!code.is_null()) return code;
- if (is_constant) return stub.GetCode(isolate_);
-
// Replace the placeholder cell and global object map with the actual
global
// cell and receiver map.
- Handle<Map> cell_map(isolate_->heap()->global_property_cell_map());
Handle<Map> meta_map(isolate_->heap()->meta_map());
Handle<Object> receiver_map(receiver->map(), isolate_);
code = stub.GetCodeCopyFromTemplate(isolate_);
code->ReplaceNthObject(1, *meta_map, *receiver_map);
+ Handle<Map> cell_map(isolate_->heap()->global_property_cell_map());
code->ReplaceNthObject(1, *cell_map, *cell);
+
JSObject::UpdateMapCodeCache(receiver, name, code);
return code;
--
--
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