[es6] Optimize TypedArray.subarray()

src/typedarray.js

 // Copyright 2013 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.
 
 (function(global, utils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
@@ skipping 19 matching lines @@
 FUNCTION(8, Float64Array, 8)
 FUNCTION(9, Uint8ClampedArray, 1)
 endmacro
 
 macro DECLARE_GLOBALS(INDEX, NAME, SIZE)
 var GlobalNAME = global.NAME;
 endmacro
 
 TYPED_ARRAYS(DECLARE_GLOBALS)
 
-var MathMax;
-var MathMin;
 var ToNumber;
 
 utils.Import(function(from) {
-  MathMax = from.MathMax;
-  MathMin = from.MathMin;
   ToNumber = from.ToNumber;
 });
 
 var InternalArray = utils.InternalArray;
 
 // --------------- Typed Arrays ---------------------
 
 macro TYPED_ARRAY_CONSTRUCTOR(ARRAY_ID, NAME, ELEMENT_SIZE)
 function NAMEConstructByArrayBuffer(obj, buffer, byteOffset, length) {
   if (!IS_UNDEFINED(byteOffset)) {
@@ skipping 146 matching lines @@
   }
   return %_TypedArrayGetLength(this);
 }
 
 function NAMESubArray(begin, end) {
   if (!(%_ClassOf(this) === 'NAME')) {
     throw MakeTypeError(kIncompatibleMethodReceiver, "NAME.subarray", this);
   }
   var beginInt = TO_INTEGER(begin);
   if (!IS_UNDEFINED(end)) {
-    end = TO_INTEGER(end);
+    var endInt = TO_INTEGER(end);
+    var srcLength = %_TypedArrayGetLength(this);
+  } else {
+    var srcLength = %_TypedArrayGetLength(this);
+    var endInt = srcLength;
   }
 
-  var srcLength = %_TypedArrayGetLength(this);
   if (beginInt < 0) {
-    beginInt = MathMax(0, srcLength + beginInt);
+    beginInt = MAX_SIMPLE(0, srcLength + beginInt);
   } else {
-    beginInt = MathMin(srcLength, beginInt);
+    beginInt = MIN_SIMPLE(beginInt, srcLength);
   }
 
-  var endInt = IS_UNDEFINED(end) ? srcLength : end;
   if (endInt < 0) {
-    endInt = MathMax(0, srcLength + endInt);
+    endInt = MAX_SIMPLE(0, srcLength + endInt);
   } else {
-    endInt = MathMin(endInt, srcLength);
+    endInt = MIN_SIMPLE(endInt, srcLength);
   }
+
   if (endInt < beginInt) {
     endInt = beginInt;
   }
+
   var newLength = endInt - beginInt;
   var beginByteOffset =
       %_ArrayBufferViewGetByteOffset(this) + beginInt * ELEMENT_SIZE;
   return new GlobalNAME(%TypedArrayGetBuffer(this),
                         beginByteOffset, newLength);
 }
 endmacro
 
 TYPED_ARRAYS(TYPED_ARRAY_CONSTRUCTOR)
 
@@ skipping 263 matching lines @@
   "setUint32", DataViewSetUint32JS,
 
   "getFloat32", DataViewGetFloat32JS,
   "setFloat32", DataViewSetFloat32JS,
 
   "getFloat64", DataViewGetFloat64JS,
   "setFloat64", DataViewSetFloat64JS
 ]);
 
 })