From: Archie Cobbs (archie@whistle.com)
Date: Tue Nov 17 1998 - 23:18:06 EST
Godmar Back writes:
> Alright, here's another issue. I'm sure all of you have noticed that
> Kaffe is a lot more eager as far as the loading of classes is concerned.
> The reason is that we call getClass on all classes in the constant pool
> if a class is brought to the CSTATE_OK state, even if some classes are
> never referenced. This means, for instance, that hotjava now fails
> with a NoClassDefFoundError because of some javax/security/...X509 class. (*)
>
> Here's the code:
>
> --------------------------------------------------------------------------
> /*
> * Initialise the constants.
> * First we make sure all the constant strings are converted to java strings.
> */
> static
> bool
> resolveConstants(Hjava_lang_Class* class, errorInfo *einfo)
> {
> int idx;
> constants* pool;
> bool success = true;
>
> lockMutex(class->centry);
>
> /* Scan constant pool and convert any constant strings into true
> * java strings.
> */
> pool = CLASS_CONSTANTS (class);
> for (idx = 0; idx < pool->size; idx++) {
> switch (pool->tags[idx]) {
> case CONSTANT_String:
> pool->data[idx] = (ConstSlot)Utf8Const2JavaString(WORD2U
> TF(pool->data[idx]));
> pool->tags[idx] = CONSTANT_ResolvedString;
> break;
>
> ? case CONSTANT_Class:
> ? if (getClass(idx, class, einfo) == 0) {
> ? success = false;
> ? goto done;
> ? }
> ? break;
> ?
Well, seeing as the ? code doesn't set any variables, and assuming
that the class will be loaded later when necessary (how could it
not be?) then it looks like it's OK to simply remove it.
> ps: as an aside, in Edouard's testcase, where you have
>
> class Third extends DontExists
> {
> static {
> new DontExists();
> }
> }
>
> (and there's no DontExists.class), what should Class.forName("Third")
> throw? Sun throws "NoClassDefFoundError: DontExists."
>
> This is what we throw if and only if we resolve eagerly in resolveConstants.
> Otherwise, we throw ExceptionInInitializerError because the lack of
> DontExists isn't noticed before the static initializer is invoked.
> I believe this is correct (i.e., Sun is wrong).
Godmar-
If you believe this is a real Sun bug, would you like me to
file it on the JDK developers page? I'd need all the vital
statistics: JDK version, etc.
> Let's play this game some more.
> What if the missing class sits in a path of code that's not taken?
>
> class Third extends DontExists
> {
> static {
> if ("X".equals("Y")) {
> new DontExists();
> }
> }
> }
>
> In this case, Sun's correct in not complaining about anything.
> Kaffe's interpreter, when not loading eagerly, will also do
> just fine. Kaffe's jitter, unfortunately, will want to see the
> class when jitting the NEW instruction.
>
> The way to fix this is by emitting a soft_noclassdeffounderror
> if the class is not found as opposed to throwing a error when jitting ---
> just like soft_nosuchmethoderror is used. I guess we should put this
> on the todo list.
Yes, the interp and JIT code should be functionally equivalent, I think..
-Archie
___________________________________________________________________________
Archie Cobbs * Whistle Communications, Inc. * http://www.whistle.com
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