[jboss-jira] [JBoss JIRA] Closed: (JASSIST-72) Instrumenting write access using CodeConverter.replaceArrayAccess(...) causes VerifyError (Unable to pop operand off an empty stack) - buggy aastore

Thu Apr 15 10:55:27 EDT 2010

     [ https://jira.jboss.org/jira/browse/JASSIST-72?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Shigeru Chiba closed JASSIST-72.
--------------------------------


> Instrumenting write access using CodeConverter.replaceArrayAccess(...) causes VerifyError (Unable to pop operand off an empty stack) - buggy aastore
> ----------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: JASSIST-72
>                 URL: https://jira.jboss.org/jira/browse/JASSIST-72
>             Project: Javassist
>          Issue Type: Bug
>         Environment: javassist 3.9.0.GA
>            Reporter: Martin Burger
>            Assignee: Shigeru Chiba
>         Attachments: array_issue.tgz
>
>
> I use Javassist to instrument class files in order to catch some runtime information. Basically, I insert probes to get information about method calls, field accesses, and so on. This includes access to arrays. Unfortunately, when I instrument array accesses using CodeConverter.replaceArrayAccess(...) the Java verifier throws an exception while loading the changed method: Unable to pop operand off an empty stack.
> Instrumenting array accesses is one instrumentation of many. If I disable instrumentation of array accesses, the instrumented program will run and I will get runtime information about method calls etc. As soon as I enable the instrumentation of arrays, the byte code created by javassist causes the java.lang.VerifyError mentioned above.
> The buggy byte code instruction seems to be:
>    7016:	anewarray	#51; //class java/lang/Object
>    7019:	dup
>    7020:	iconst_0
>    7021:	iload_1
>    7022:	bipush	56
>    7024:	if_icmpne	7036
>    7027:	ldc_w	#5369; //String 8
>    7030:	nop
>    7031:	nop
>    7032:	nop
>    7033:	goto	7042
>    7036:	ldc_w	#5371; //String 9
>    7039:	nop
>    7040:	nop
>    7041:	nop
>    7042:	invokestatic	#5373;
>    7045:	nop
>    7046:	aastore <-- causes VerifyError
> At least when executing aastore the stack is empty already.
> The original source code:
> if (base == 8 && c >= '8') {
>     Object[] errArgs = { c == '8' ? "8" : "9" };
>     reportCurrentLineWarning(
>         "msg.bad.octal.literal", errArgs);
>     base = 10;
> }

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