A64: Synchronize with r15545.

test/webkit/dfg-cfg-simplify-phantom-get-local-on-same-block-set-local.js

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
 // are met:
 // 1.  Redistributions of source code must retain the above copyright
 //     notice, this list of conditions and the following disclaimer.
 // 2.  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 with the distribution.
 //
 // THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS 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 APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 // DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 // (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 // LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 // ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 description(
-"Tests the behavior of Array.prototype.concat while the array is having a bad time due to one of the elements we are concatenating."
+"Tests that attempts by the DFG simplification to short-circuit a Phantom to a GetLocal on a variable that is SetLocal'd in the same block, and where the predecessor block(s) make no mention of that variable, do not result in crashes."
 );
 
-Object.defineProperty(Array.prototype, 0, { writable: false });
-shouldBe("[42].concat()", "[42]");
+function baz() {
+    // Do something that prevents inlining.
+    return function() { }
+}
 
+function stuff(z) { }
 
+function foo(x, y) {
+    var a = arguments; // Force arguments to be captured, so that x is captured.
+    baz();
+    var z = x;
+    stuff(z); // Force a Flush, and then a Phantom on the GetLocal of x.
+    return 42;
+}
+
+var o = {
+    g: function(x) { }
+};
+
+function thingy(o) {
+    var p = {};
+    var result;
+    // Trick to delay control flow graph simplification until after the flush of x above gets turned into a phantom.
+    if (o.g)
+        p.f = true;
+    if (p.f) {
+        // Basic block that stores to x in foo(), which is a captured variable, with
+        // the predecessor block making no mention of x.
+        result = foo("hello", 2);
+    }
+    return result;
+}
+
+for (var i = 0; i < 200; ++i)
+    shouldBe("thingy(o)", "42");
+