[runtime] Add fast-paths for common conversion methods

src/objects.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <memory>
 #include <sstream>
@@ skipping 185 matching lines @@
 // static
 MaybeHandle<Name> Object::ConvertToName(Isolate* isolate,
                                         Handle<Object> input) {
   ASSIGN_RETURN_ON_EXCEPTION(
       isolate, input, Object::ToPrimitive(input, ToPrimitiveHint::kString),
       Name);
   if (input->IsName()) return Handle<Name>::cast(input);
   return ToString(isolate, input);
 }
 
+// ES6 7.1.14
+// static
+MaybeHandle<Object> Object::ConvertToPropertyKey(Isolate* isolate,
+                                                 Handle<Object> value) {
+  // 1. Let key be ToPrimitive(argument, hint String).
+  MaybeHandle<Object> maybe_key =
+      Object::ToPrimitive(value, ToPrimitiveHint::kString);
+  // 2. ReturnIfAbrupt(key).
+  Handle<Object> key;
+  if (!maybe_key.ToHandle(&key)) return key;
+  // 3. If Type(key) is Symbol, then return key.
+  if (key->IsSymbol()) return key;
+  // 4. Return ToString(key).
+  // Extending spec'ed behavior, we'd be happy to return an element index.
+  if (key->IsSmi()) return key;
+  if (key->IsHeapNumber()) {
+    uint32_t uint_value;
+    if (value->ToArrayLength(&uint_value) &&
+        uint_value <= static_cast<uint32_t>(Smi::kMaxValue)) {
+      return handle(Smi::FromInt(static_cast<int>(uint_value)), isolate);
+    }
+  }
+  return Object::ToString(isolate, key);
+}
+
 // static
 MaybeHandle<String> Object::ConvertToString(Isolate* isolate,
                                             Handle<Object> input) {
   while (true) {
     if (input->IsOddball()) {
       return handle(Handle<Oddball>::cast(input)->to_string(), isolate);
     }
     if (input->IsNumber()) {
       return isolate->factory()->NumberToString(input);
     }
@@ skipping 160 matching lines @@
 
   IncrementalStringBuilder builder(isolate);
   builder.AppendCString("[object ");
   builder.AppendString(tag);
   builder.AppendCString("]");
 
   return builder.Finish().ToHandleChecked();
 }
 
 // static
-MaybeHandle<Object> Object::ToLength(Isolate* isolate, Handle<Object> input) {
+MaybeHandle<Object> Object::ConvertToLength(Isolate* isolate,
+                                            Handle<Object> input) {
   ASSIGN_RETURN_ON_EXCEPTION(isolate, input, ToNumber(input), Object);
+  if (input->IsSmi()) {
+    int value = std::max(Smi::cast(*input)->value(), 0);
+    return handle(Smi::FromInt(value), isolate);
+  }
   double len = DoubleToInteger(input->Number());
   if (len <= 0.0) {
-    len = 0.0;
+    return handle(Smi::kZero, isolate);
   } else if (len >= kMaxSafeInteger) {
     len = kMaxSafeInteger;
   }
   return isolate->factory()->NewNumber(len);
 }
 
 // static
-MaybeHandle<Object> Object::ToIndex(Isolate* isolate, Handle<Object> input,
-                                    MessageTemplate::Template error_index) {
-  if (input->IsUndefined(isolate)) return isolate->factory()->NewNumber(0.0);
+MaybeHandle<Object> Object::ConvertToIndex(
+    Isolate* isolate, Handle<Object> input,
+    MessageTemplate::Template error_index) {
+  if (input->IsUndefined(isolate)) return handle(Smi::kZero, isolate);
   ASSIGN_RETURN_ON_EXCEPTION(isolate, input, ToNumber(input), Object);
+  if (input->IsSmi() && Smi::cast(*input)->value() >= 0) return input;
   double len = DoubleToInteger(input->Number()) + 0.0;
   auto js_len = isolate->factory()->NewNumber(len);
   if (len < 0.0 || len > kMaxSafeInteger) {
     THROW_NEW_ERROR(isolate, NewRangeError(error_index, js_len), Object);
   }
   return js_len;
 }
 
 bool Object::BooleanValue() {
   if (IsSmi()) return Smi::cast(this)->value() != 0;
@@ skipping 6074 matching lines @@
 
 
 Maybe<bool> JSReceiver::DeletePropertyOrElement(Handle<JSReceiver> object,
                                                 Handle<Name> name,
                                                 LanguageMode language_mode) {
   LookupIterator it = LookupIterator::PropertyOrElement(
       name->GetIsolate(), object, name, object, LookupIterator::OWN);
   return DeleteProperty(&it, language_mode);
 }
 
-
-// ES6 7.1.14
-// static
-MaybeHandle<Object> Object::ToPropertyKey(Isolate* isolate,
-                                          Handle<Object> value) {
-  // 1. Let key be ToPrimitive(argument, hint String).
-  MaybeHandle<Object> maybe_key =
-      Object::ToPrimitive(value, ToPrimitiveHint::kString);
-  // 2. ReturnIfAbrupt(key).
-  Handle<Object> key;
-  if (!maybe_key.ToHandle(&key)) return key;
-  // 3. If Type(key) is Symbol, then return key.
-  if (key->IsSymbol()) return key;
-  // 4. Return ToString(key).
-  // Extending spec'ed behavior, we'd be happy to return an element index.
-  if (key->IsSmi()) return key;
-  if (key->IsHeapNumber()) {
-    uint32_t uint_value;
-    if (value->ToArrayLength(&uint_value) &&
-        uint_value <= static_cast<uint32_t>(Smi::kMaxValue)) {
-      return handle(Smi::FromInt(static_cast<int>(uint_value)), isolate);
-    }
-  }
-  return Object::ToString(isolate, key);
-}
-
-
 // ES6 19.1.2.4
 // static
 Object* JSReceiver::DefineProperty(Isolate* isolate, Handle<Object> object,
                                    Handle<Object> key,
                                    Handle<Object> attributes) {
   // 1. If Type(O) is not Object, throw a TypeError exception.
   if (!object->IsJSReceiver()) {
     Handle<String> fun_name =
         isolate->factory()->InternalizeUtf8String("Object.defineProperty");
     THROW_NEW_ERROR_RETURN_FAILURE(
@@ skipping 13907 matching lines @@
       // depend on this.
       return DICTIONARY_ELEMENTS;
     }
     DCHECK_LE(kind, LAST_ELEMENTS_KIND);
     return kind;
   }
 }
 
 }  // namespace internal
 }  // namespace v8