Improve performance of keyed loads/stores which have a HeapNumber index.

src/ic.cc

 // Copyright 2012 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 1035 matching lines @@
   KeyedLoadStubCompiler compiler(isolate());
   Handle<Code> code = compiler.CompileLoadPolymorphic(
       receiver_maps, &handler_ics);
   isolate()->counters()->keyed_load_polymorphic_stubs()->Increment();
   PROFILE(isolate(),
           CodeCreateEvent(Logger::KEYED_LOAD_MEGAMORPHIC_IC_TAG, *code, 0));
   return code;
 }
 
 
+static Handle<Object> TryConvertKey(Handle<Object> key, Isolate* isolate) {
+  // This helper implements a few common fast cases for converting
+  // non-smi keys of keyed loads/stores to a smi or a string.
+  if (key->IsHeapNumber()) {
+    double value = Handle<HeapNumber>::cast(key)->value();
+    if (isnan(value)) {
+      key = isolate->factory()->nan_symbol();
+    } else {
+      int int_value = FastD2I(value);
+      if (value == int_value && Smi::IsValid(int_value)) {
+        key = Handle<Smi>(Smi::FromInt(int_value));
+      }
+    }
+  } else if (key->IsUndefined()) {
+    key = isolate->factory()->undefined_symbol();
+  }
+  return key;
+}
+
+
 MaybeObject* KeyedLoadIC::Load(State state,
                                Handle<Object> object,
                                Handle<Object> key,
                                bool force_generic_stub) {
-  // Check for values that can be converted into a symbol.
-  // TODO(1295): Remove this code.
-  if (key->IsHeapNumber() &&
-      isnan(Handle<HeapNumber>::cast(key)->value())) {
-    key = isolate()->factory()->nan_symbol();
-  } else if (key->IsUndefined()) {
-    key = isolate()->factory()->undefined_symbol();
-  }
+  // Check for values that can be converted into a symbol directly or
+  // is representable as a smi.
+  key = TryConvertKey(key, isolate());
 
   if (key->IsSymbol()) {
     Handle<String> name = Handle<String>::cast(key);
 
     // If the object is undefined or null it's illegal to try to get any
     // of its properties; throw a TypeError in that case.
     if (object->IsUndefined() || object->IsNull()) {
       return TypeError("non_object_property_load", object, name);
     }
 
@@ skipping 676 matching lines @@
   }
 }
 
 
 MaybeObject* KeyedStoreIC::Store(State state,
                                  StrictModeFlag strict_mode,
                                  Handle<Object> object,
                                  Handle<Object> key,
                                  Handle<Object> value,
                                  bool force_generic) {
+  // Check for values that can be converted into a symbol directly or
+  // is representable as a smi.
+  key = TryConvertKey(key, isolate());
+
   if (key->IsSymbol()) {
     Handle<String> name = Handle<String>::cast(key);
 
     // Handle proxies.
     if (object->IsJSProxy()) {
       return JSProxy::cast(*object)->SetProperty(
           *name, *value, NONE, strict_mode);
     }
 
     // If the object is undefined or null it's illegal to try to set any
@@ skipping 789 matching lines @@
 #undef ADDR
 };
 
 
 Address IC::AddressFromUtilityId(IC::UtilityId id) {
   return IC_utilities[id];
 }
 
 
 } }  // namespace v8::internal