Properly filter types using the initial map from HAllocate.

src/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4972 matching lines @@
                                              BailoutId assignment_id,
                                              Property* prop,
                                              HValue* object,
                                              HValue* value) {
   Literal* key = prop->key()->AsLiteral();
   Handle<String> name = Handle<String>::cast(key->value());
   ASSERT(!name.is_null());
 
   HInstruction* instr = NULL;
   SmallMapList* types = expr->GetReceiverTypes();
+
   bool monomorphic = expr->IsMonomorphic();
+  if (types != NULL && object->HasMonomorphicJSObjectType()) {
+    types->FilterForPossibleTransitions(
+        object->GetMonomorphicJSObjectMap()->FindRootMap(), zone());
+    monomorphic = types->length() == 1;
+  }
+
   Handle<Map> map;
   if (monomorphic) {
     map = types->first();
     monomorphic = CanInlinePropertyAccess(*map);
   }
+
   if (monomorphic) {
     Handle<JSFunction> setter;
     Handle<JSObject> holder;
     if (LookupSetter(map, name, &setter, &holder)) {
       AddCheckConstantFunction(holder, object, map);
       if (FLAG_inline_accessors &&
           TryInlineSetter(setter, id, assignment_id, value)) {
         return;
       }
       Drop(2);
@@ skipping 676 matching lines @@
     HValue* obj,
     HValue* key,
     HValue* val,
     Expression* expr,
     BailoutId ast_id,
     int position,
     bool is_store,
     bool* has_side_effects) {
   ASSERT(!expr->IsPropertyName());
   HInstruction* instr = NULL;
-  if (expr->IsMonomorphic()) {
+  bool monomorphic = expr->IsMonomorphic();
+  SmallMapList* types = expr->GetReceiverTypes();
+
+  if (types != NULL && obj->HasMonomorphicJSObjectType()) {

[Michael Starzinger, 2013/09/05 20:07:23]

suggestion: Does it make sense to factor this out into a static helper method
that computes the receiver types for us? I was thinking along the lines of a
method with either of the following signatures (I prefer the first one)...

// Return true if receiver is monomorphic.
static bool ComputeReceiverTypes(Expression* expr,
                                 Object* receiver,
                                 SmallMapList** types);

static SmallMapList* ComputeReceiverTypes(Expression* expr,
                                          Object* receiver,
                                          bool* monomorphic);

[Toon Verwaest, 2013/09/06 09:23:12]

Done.

+    types->FilterForPossibleTransitions(
+        obj->GetMonomorphicJSObjectMap()->FindRootMap(), zone());
+    monomorphic = types->length() == 1;
+  }
+
+  if (monomorphic) {
     Handle<Map> map = expr->GetMonomorphicReceiverType();
     if (map->has_slow_elements_kind()) {
       instr = is_store ? BuildStoreKeyedGeneric(obj, key, val)
                        : BuildLoadKeyedGeneric(obj, key);
       AddInstruction(instr);
     } else {
       BuildCheckHeapObject(obj);
       instr = BuildMonomorphicElementAccess(
           obj, key, val, NULL, map, is_store, expr->GetStoreMode());
     }
@@ skipping 148 matching lines @@
   } else if (expr->IsFunctionPrototype()) {
     HValue* function = Pop();
     BuildCheckHeapObject(function);
     instr = new(zone()) HLoadFunctionPrototype(function);
 
   } else if (expr->key()->IsPropertyName()) {
     Handle<String> name = expr->key()->AsLiteral()->AsPropertyName();
     SmallMapList* types = expr->GetReceiverTypes();
     HValue* object = Top();
 
+    bool monomorphic = expr->IsMonomorphic();
+    if (types != NULL && object->HasMonomorphicJSObjectType()) {
+      types->FilterForPossibleTransitions(
+          object->GetMonomorphicJSObjectMap()->FindRootMap(), zone());
+      monomorphic = types->length() == 1;
+    }
+
     Handle<Map> map;
-    bool monomorphic = false;
-    if (expr->IsMonomorphic()) {
+    if (monomorphic) {
       map = types->first();
       monomorphic = CanInlinePropertyAccess(*map);
-    } else if (object->HasMonomorphicJSObjectType()) {
-      map = object->GetMonomorphicJSObjectMap();
-      monomorphic = CanInlinePropertyAccess(*map);
     }
+
     if (monomorphic) {
       Handle<JSFunction> getter;
       Handle<JSObject> holder;
       if (LookupGetter(map, name, &getter, &holder)) {
         AddCheckConstantFunction(holder, Top(), map);
         if (FLAG_inline_accessors &&
             TryInlineGetter(getter, ast_id, expr->LoadId())) {
           return;
         }
         Add<HPushArgument>(Pop());
@@ skipping 1077 matching lines @@
 
     // Named function call.
     if (TryCallApply(expr)) return;
 
     CHECK_ALIVE(VisitForValue(prop->obj()));
     CHECK_ALIVE(VisitExpressions(expr->arguments()));
 
     Handle<String> name = prop->key()->AsLiteral()->AsPropertyName();
     SmallMapList* types = expr->GetReceiverTypes();
 
+

[Michael Starzinger, 2013/09/05 20:07:23]

nit: Drop one of the two empty newlines.

+    HValue* receiver =
+        environment()->ExpressionStackAt(expr->arguments()->length());
+
     bool monomorphic = expr->IsMonomorphic();
+    if (types != NULL && receiver->HasMonomorphicJSObjectType()) {
+      types->FilterForPossibleTransitions(
+          receiver->GetMonomorphicJSObjectMap()->FindRootMap(), zone());
+      monomorphic = types->length() == 1 &&
+          expr->ComputeTarget(types->at(0), name);
+    }
+
     Handle<Map> receiver_map;
     if (monomorphic) {
       receiver_map = (types == NULL || types->is_empty())

[Michael Starzinger, 2013/09/05 20:07:23]

I know it's not part of this change, but can "types" really be NULL or empty of
expr->IsMonomorphic() reports true? The lines 7003 until 7008 look needlessly
verbose.

           ? Handle<Map>::null()
           : types->first();
     }
 
-    HValue* receiver =
-        environment()->ExpressionStackAt(expr->arguments()->length());
     if (monomorphic) {
       if (TryInlineBuiltinMethodCall(expr,
                                      receiver,
                                      receiver_map,
                                      expr->check_type())) {
         if (FLAG_trace_inlining) {
           PrintF("Inlining builtin ");
           expr->target()->ShortPrint();
           PrintF("\n");
         }
@@ skipping 2732 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal