Harmony: implement Math.clz32

test/mjsunit/harmony/math-clz32.js

+// Copyright 2014 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.
+
+// Flags: --harmony-maths
+
+[NaN, Infinity, -Infinity, 0, -0, "abc", "Infinity", "-Infinity", {}].forEach(
+  function(x) {
+    assertEquals(32, Math.clz32(x));
+  }
+);
+
+function testclz(x) {
+  for (var i = 0; i < 33; i++) {
+    if (x & 0x80000000) return i;
+    x <<= 1;
+  }
+  return 32;
+}
+
+var max = Math.pow(2, 40);
+for (var x = 0; x < max; x = x * 1.01 + 1) {
+  assertEquals(testclz(x), Math.clz32(x));
+  assertEquals(testclz(-x), Math.clz32(-x));
+  assertEquals(testclz(x), Math.clz32({ valueOf: function() { return x; } }));
+  assertEquals(testclz(-x),
+               Math.clz32({ toString: function() { return -x; } }));
+}