diff -r 000000000000 -r 6474c204b198 js/src/jit-test/lib/bytecode-cache.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/lib/bytecode-cache.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,47 @@
+
+function evalWithCache(code, ctx) {
+  ctx = ctx || {};
+  ctx = Object.create(ctx, {
+    fileName: { value: "evalWithCacheCode.js" },
+    lineNumber: { value: 0 }
+  });
+  code = code instanceof Object ? code : cacheEntry(code);
+
+  // We create a new global ...
+  if (!("global" in ctx))
+    ctx.global = newGlobal();
+
+  // ... and by default enable compileAndGo.
+  if (!("compileAndGo" in ctx))
+    ctx.compileAndGo = true;
+
+  // Fetch the verification function from the evaluation context.  This function
+  // is used to assert the state of the script/function after each run of the
+  // evaluate function.
+  var checkAfter = ctx.checkAfter || function(ctx) {};
+
+  // The generation counter is used to represent environment variations which
+  // might cause the program to run differently, and thus to have a different
+  // set of functions executed.
+  ctx.global.generation = 0;
+  var res1 = evaluate(code, Object.create(ctx, {saveBytecode: { value: true } }));
+  checkAfter(ctx);
+
+  ctx.global.generation = 1;
+  var res2 = evaluate(code, Object.create(ctx, {loadBytecode: { value: true }, saveBytecode: { value: true } }));
+  checkAfter(ctx);
+
+  ctx.global.generation = 2;
+  var res3 = evaluate(code, Object.create(ctx, {loadBytecode: { value: true } }));
+  checkAfter(ctx);
+
+  ctx.global.generation = 3;
+  var res0 = evaluate(code, ctx);
+  checkAfter(ctx);
+
+  if (ctx.assertEqResult) {
+    assertEq(res0, res1);
+    assertEq(res0, res2);
+    assertEq(res0, res3);
+  }
+}