Avoid redundant smi check for Math.abs

test/mjsunit/math-abs.js

 // Copyright 2010 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 91 matching lines @@
 function foo(x) {
   return Math.abs(x);
 }
 // Get some smi type feedback.
 for(var i = 0; i < 1000; i++) {
   foo(-i);
 }
 assertEquals(42, foo(-42));
 %OptimizeFunctionOnNextCall(foo)
 assertEquals(42, foo(-42));
+
+// Regression test for SMI input of Math.abs on X64, see:
+// https://codereview.chromium.org/21180004/
+var a = [-1, -2];
+function foo2() {
+  return Math.abs(a[0]);
+}
+assertEquals(1, foo2());
+assertEquals(1, foo2());
+%OptimizeFunctionOnNextCall(foo2);
+assertEquals(1, foo2());