Fix bug that caused invalid code motion for certain loads instructions.

test/mjsunit/compiler/regress-loadfield.js

+// Copyright 2011 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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       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,
+// 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.
+
+// Regression test for GVN on field loads.
+
+function bar() {}
+
+// Make sure there is a transition on adding "bar" inobject property.
+var b = new bar();
+b.bar = "bar";
+
+function test(a) {
+  var b = new Array(10);
+  for (var i = 0; i < 10; i++) {
+    b[i] = new bar();
+  }
+
+  for (var i = 0; i < 10; i++) {
+    b[i].bar = a.foo;
+  }
+}
+
+// Create an object with fast backing store properties.
+var a = {};
+a.p1 = "";
+a.p2 = "";
+a.p3 = "";
+a.p4 = "";
+a.p5 = "";
+a.p6 = "";
+a.p7 = "";
+a.p8 = "";
+a.p9 = "";
+a.p10 = "";
+a.p11 = "";
+a.foo = "foo";
+for (var i = 0; i < 100000; i++) {
+ test(a);
+}
+
+test("");