Fix fast array literals to ignore prototype chain.

test/mjsunit/regress/regress-123512.js

+// 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
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+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
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+//       with the distribution.
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+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --allow-natives-syntax
+
+// Test that boilerplate objects for array literals with non-constant
+// elements (which will contain the hole at non-constant positions) will
+// not cause prototype chain lookups when generating optimized code.
+
+function f(x) {
+  return [x][0];
+}
+
+// Test data element on prototype.
+Object.prototype[0] = 23;
+assertSame(1, f(1));
+assertSame(2, f(2));
+%OptimizeFunctionOnNextCall(f);
+assertSame(3, f(3));
+%DeoptimizeFunction(f);
+
+// Test accessor element on prototype.
+Object.prototype.__defineGetter__(0, function() { throw Error(); });
+assertSame(4, f(4));
+assertSame(5, f(5));
+%OptimizeFunctionOnNextCall(f);
+assertSame(6, f(6));
+%DeoptimizeFunction(f);
+
+// Test the same on boilerplate objects for object literals that contain
+// both non-constant properties and non-constant elements.
+
+function g(x, y) {
+  var o = { foo:x, 0:y };
+  return o.foo + o[0];
+}
+
+// Test data property and element on prototype.
+Object.prototype[0] = 23;
+Object.prototype.foo = 42;
+assertSame(3, g(1, 2));
+assertSame(5, g(2, 3));
+%OptimizeFunctionOnNextCall(g);
+assertSame(7, g(3, 4));
+%DeoptimizeFunction(g);
+
+// Test accessor property and element on prototype.
+Object.prototype.__defineGetter__(0, function() { throw Error(); });
+Object.prototype.__defineGetter__('foo', function() { throw Error(); });
+assertSame(3, g(1, 2));
+assertSame(5, g(2, 3));
+%OptimizeFunctionOnNextCall(g);
+assertSame(7, g(3, 4));
+%DeoptimizeFunction(g);