Reviewers: mvstanton,
Message:
PTAL
Description:
Avoid repeated rewrites of global store to constant IC due to store of same
value.
Please review this at https://chromiumcodereview.appspot.com/19663007/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/code-stubs-hydrogen.cc
M src/stub-cache.cc
Index: src/code-stubs-hydrogen.cc
diff --git a/src/code-stubs-hydrogen.cc b/src/code-stubs-hydrogen.cc
index
324dfa9f76a4f1965a85d7da1ea36accdb3ab474..21b034100b64cd36ddf37ae3e406f3980967b181
100644
--- a/src/code-stubs-hydrogen.cc
+++ b/src/code-stubs-hydrogen.cc
@@ -850,23 +850,25 @@ HValue*
CodeStubGraphBuilder<StoreGlobalStub>::BuildCodeInitializedStub() {
HParameter* receiver = GetParameter(0);
HParameter* value = GetParameter(2);
- if (stub->is_constant()) {
- // Assume every store to a constant value changes it.
- current_block()->FinishExitWithDeoptimization(HDeoptimize::kUseAll);
- set_current_block(NULL);
- } 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()));
- // 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()) {
+ IfBuilder builder(this);
+ builder.If<HCompareObjectEqAndBranch>(cell_contents, value);
+ builder.Then();
+ builder.ElseDeopt();
+ builder.End();
+ } else {
// 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 @@ HValue*
CodeStubGraphBuilder<StoreGlobalStub>::BuildCodeInitializedStub() {
Add<HStoreNamedField>(cell, access, value);
builder.End();
}
+
return value;
}
Index: src/stub-cache.cc
diff --git a/src/stub-cache.cc b/src/stub-cache.cc
index
436cd46ce162df28ac14c17a1f37d533393f6004..d554d0cb0a5bb9a1490a0e8b7cd07e382382e432
100644
--- a/src/stub-cache.cc
+++ b/src/stub-cache.cc
@@ -563,16 +563,15 @@ Handle<Code>
StubCache::ComputeStoreGlobal(Handle<Name> name,
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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