[runtime][ic] Constant field tracking support.

test/mjsunit/field-type-tracking.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: --allow-natives-syntax --nostress-opt --track-field-types
 // Flags: --crankshaft --no-always-opt
 
 (function() {
   var o = { text: "Hello World!" };
   function A() {
+    // Assign twice to make the field non-constant.
+    // TODO(ishell): update test once constant field tracking is done.
+    this.a = {text: 'foo'};
     this.a = o;
   }
   function readA(x) {
     return x.a;
   }
   var a = new A();
   assertUnoptimized(readA);
   readA(a); readA(a); readA(a);
   %OptimizeFunctionOnNextCall(readA);
   assertEquals(readA(a), o);
@@ skipping 80 matching lines @@
   x = JSON.parse('{"a":"Short"}');
 })();
 
 (function() {
   var x = {y: {z: 1}};
   x.y.z = 1.1;
 })();
 
 (function() {
   function Foo(x) { this.x = x; }
+  // TODO(ishell): update test once constant field tracking is done.
+  var f0 = new Foo({x: 0});
+  f0.x = {x: 0};  // make Foo.x non-constant here.
   var f1 = new Foo({x: 1});
   var f2 = new Foo({x: 2});
   var f3 = new Foo({x: 3});
   function readX(f) { return f.x.x; }
   assertEquals(readX(f1), 1);
   assertEquals(readX(f2), 2);
   assertUnoptimized(readX);
   %OptimizeFunctionOnNextCall(readX);
   assertEquals(readX(f3), 3);
   assertOptimized(readX);
@@ skipping 16 matching lines @@
 })();
 
 (function() {
   function Narf(x) { this.x = x; }
   var f1 = new Narf(1);
   var f2 = new Narf(2);
   var f3 = new Narf(3);
   function baz(f, y) { f.y = y; }
   baz(f1, {y: 9});
   baz(f2, {y: 9});
+  baz(f2, {y: 9});
   %OptimizeFunctionOnNextCall(baz);
+  baz(f2, {y: 9});
   baz(f3, {a: -1});
   assertUnoptimized(baz);
 })();
 
 (function() {
   function Foo(x) { this.x = x; this.a = x; }
   function Bar(x) { this.x = x; this.b = x; }
   function readA(o) { return o.x.a; }
   var f = new Foo({a:1});
   var b = new Bar({a:2});
   assertEquals(readA(f), 1);
   assertEquals(readA(b), 2);
   assertEquals(readA(f), 1);
   assertEquals(readA(b), 2);
   %OptimizeFunctionOnNextCall(readA);
   assertEquals(readA(f), 1);
   assertEquals(readA(b), 2);
   assertOptimized(readA);
   f.a.y = 0;
   assertUnoptimized(readA);
 })();