I think recent Christopher suggestions about tail call elimination is worth
to consider, as it would allow to cut invocation cost of script functions
quite nicely in many cases. Plus I am thinking of not creating Object[] array
to pass arguments to callee if it is another interpreted function as it can
directly access the caller stack. But first I decided to make some
preparation work to simplify an implementation of these features later. The
attached patch includes:
1. Moving all code to setup scope from
InterpretedFunction.call/InterpretedFunction.call to Interpreter.interpret so
the call method simply calls Interpreter.interpret. It would make tail call
elimination code much simple. I also hope this simplifies changes Christopher
needs for the continuations support (but I have strong reservation about
possibility to implement it corectly).
2. Moving all declaration of temporary variables used only during processing
of the single ICODE to the case blocks.
3. Interpreter loop termination only in RETURN icodes, not when pc exceeds
icode size, so there is no need to check for this condition on each icode.
(Scripts are handled via the special END_ICODE token).
...
>I did some tinkering and found there are pure java.lang.Object
>instantiations deep inside all the "standard objects" added to the
>ImporterTopLevel with Context.initStandardObject(). This is what is keeping
>it from serializing.
This is due to presence of Scriptable.NOT_FOUND and IdScriptable.NULL_VALUE tags in the data to serialize.
I replaced the type for the tags from Object to UniqueTag which is serializable ad knows how to make restored tags the same objects as Scriptable.NOT_FOUND and IdScriptable.NULL_VALUE.
Similarly Undefined was made serializable and to restore to Undefined.instance upon reading.
While looking into optimizing the modifications I've
made, I noticed that one of the bottlenecks seemed to be calls to the Java
instanceof operator, particularly if the class argument to instanceof isn't
final. Based on this observation I tweaked ScriptRuntime.java to attempt to avoid
some of the many "instanceof Scriptable" calls in it (which I've attached). In
particular I optimized the comparison operators for the case where the arguments
are Number's. This seems to provide some significant performance improvement in
many cases particularly in compiled mode. See below (note the tests were
performed with today's rhinoLatest.zip code patched with the attached
ScriptRuntime.java and didn't include any of my other modifications).
dan
Reflect new JSPD_* defines, make jsd_GetValueProperty degrade gracefully instead of fail outright when we run into a problem fetching the property value.
2. ObjToIntMap.clear and UintMap.clear now do not discard internal buffers, but clears references to external objects to match behavior of Java Vector.clear and Hashtable.clear.
If I have a Java class with a normal method that throws an exception, Rhino
(1.5pre4) will let JavaScript catch the exception. If the Java class has a
getter method, Rhino will NOT let JavaScript catch the exception. Very
disturbing.
Here's a console dump to show you what I'm talking about:
D:\jsSandbox>cat GIJoe.java
public class GIJoe
{
// Getter
public static int getYoJoe()
throws Exception
{
throw new Exception("Please catch me!");
}
// Normal
public static int rebel()
throws Exception
{
throw new Exception("Please catch me too!");
}
}
D:\jsSandbox>javac GIJoe.java
D:\jsSandbox>cat gi.js
var gi = new Packages.GIJoe();
try
{
var i = gi.rebel();
java.lang.System.err.println("rebel(): uncaught");
}
catch(e1)
{
java.lang.System.err.println("rebel(): caught");
}
try
{
var i = gi.yoJoe;
java.lang.System.err.println("yoJoe: uncaught");
}
catch(e2)
{
java.lang.System.err.println("yoJoe: caught");
}
D:\jsSandbox>java -cp .;e:\javas\rhino1_5R4pre\js.jar
org.mozilla.javascript.too
ls.shell.Main
js> load("gi.js");
rebel(): caught
java.lang.Exception: Please catch me!
org.mozilla.javascript.WrappedException: WrappedException of Please catch
me!
at org.mozilla.javascript.JavaMembers.get(JavaMembers.java:105)
at
org.mozilla.javascript.NativeJavaObject.get(NativeJavaObject.java:93)
at
org.mozilla.javascript.ScriptRuntime.getProp(ScriptRuntime.java:691)
at
org.mozilla.javascript.Interpreter.interpret(Interpreter.java:1591)
at
org.mozilla.javascript.InterpretedScript.call(InterpretedScript.java:
63)
at
org.mozilla.javascript.InterpretedScript.exec(InterpretedScript.java:
54)
at org.mozilla.javascript.Context.evaluateReader(Context.java:741)
at
org.mozilla.javascript.tools.shell.Main.evaluateReader(Main.java:347)
at
org.mozilla.javascript.tools.shell.Main.processSource(Main.java:336)
at org.mozilla.javascript.tools.shell.Global.load(Global.java:169)
at java.lang.reflect.Method.invoke(Native Method)
at
org.mozilla.javascript.FunctionObject.callVarargs(FunctionObject.java
:586)
at
org.mozilla.javascript.FunctionObject.call(FunctionObject.java:460)
at
org.mozilla.javascript.ScriptRuntime.call(ScriptRuntime.java:1216)
at
org.mozilla.javascript.Interpreter.interpret(Interpreter.java:1679)
at
org.mozilla.javascript.InterpretedScript.call(InterpretedScript.java:
63)
at
org.mozilla.javascript.InterpretedScript.exec(InterpretedScript.java:
54)
at org.mozilla.javascript.Context.evaluateReader(Context.java:741)
at
org.mozilla.javascript.tools.shell.Main.evaluateReader(Main.java:347)
at
org.mozilla.javascript.tools.shell.Main.processSource(Main.java:284)
at org.mozilla.javascript.tools.shell.Main.exec(Main.java:146)
at org.mozilla.javascript.tools.shell.Main.main(Main.java:74)
js>
Due to a lack of an "uncaught" statement in the output, we see that the
exception from GIJoe::getYoJoe() was indeed thrown, but not caught by the
JavaScript.
Do any nightly builds past 1.5pre4 address this issue?
Todd Trimmer
