[jboss-jira] [JBoss JIRA] (JASSIST-152) instrumentation fails when building stackmap for local var of array type : bad array type for AALOAD: null

[Yanic Inghelbrecht (JIRA)]

    [ https://issues.jboss.org/browse/JASSIST-152?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12665335#comment-12665335 ] 

Yanic Inghelbrecht commented on JASSIST-152:
--------------------------------------------

I've traced the failure to class javassist.bytecode.stackmap.TypeData, in particular the nested class ArrayElement.

That class has a method getName :

        public String getName() throws BadBytecode {
            String name = array.getName();
            
            if (name.length() > 1 && name.charAt(0) == '[') {
                char c = name.charAt(1);
                if (c == 'L')
                    return name.substring(2, name.length() - 1).replace('/', '.');                    
                else if (c == '[')
                    return name.substring(1);
            }
    
            throw new BadBytecode("bad array type for AALOAD: "
                                  + name);
        }

In this test case the local variable 'name' is null. 

However, the expectedName is not null. I was able to circumvent the issue by changing the initialisation of that local variable from 
            String name = array.getName();
to
            String name = array.getExpectedName();

I don't really understand the intricacies of the stackmap building code, so that is probably not the right fix for this issue. 

Best regards,
Yanic
                
> instrumentation fails when building stackmap for local var of array type : bad array type for AALOAD: null
> ----------------------------------------------------------------------------------------------------------
>
>                 Key: JASSIST-152
>                 URL: https://issues.jboss.org/browse/JASSIST-152
>             Project: Javassist
>          Issue Type: Bug
>    Affects Versions: 3.15.0-GA
>         Environment: Any
>            Reporter: Yanic Inghelbrecht
>            Assignee: Shigeru Chiba
>         Attachments: demonstration.zip
>
>
> When trying to instrument the attached org.hibernate.cfg.AbstractPropertyHolder (copied from the hibernate 4.0.1 final distribution), instrumentation fails with the following exception :
> java.lang.RuntimeException: fatal error: 
> 	at javassist.bytecode.stackmap.TypeData$TypeName.getTypeData(TypeData.java:177)
> 	at javassist.bytecode.stackmap.MapMaker.fillStackMap(MapMaker.java:410)
> 	at javassist.bytecode.stackmap.MapMaker.toStackMapBody(MapMaker.java:393)
> 	at javassist.bytecode.stackmap.MapMaker.toStackMap(MapMaker.java:323)
> 	at javassist.bytecode.stackmap.MapMaker.make(MapMaker.java:98)
> 	at javassist.bytecode.MethodInfo.rebuildStackMap(MethodInfo.java:417)
> 	at javassist.bytecode.MethodInfo.rebuildStackMapIf6(MethodInfo.java:399)
> 	at javassist.expr.ExprEditor.doit(ExprEditor.java:113)
> 	at javassist.CtBehavior.instrument(CtBehavior.java:672)
> 	at test_abstractpropertyholder.SimpleTranslator.modify(SimpleTranslator.java:25)
> 	at test_abstractpropertyholder.SimpleTranslator.onLoad(SimpleTranslator.java:19)
> 	at test_abstractpropertyholder.JavassistInstrumenter.getInstrumentedClass(JavassistInstrumenter.java:21)
> 	at test_abstractpropertyholder.Main.main(Main.java:32)transforming org.hibernate.cfg.AbstractPropertyHolder
> Caused by: javassist.bytecode.BadBytecode: bad array type for AALOAD: null
> 	at javassist.bytecode.stackmap.TypeData$ArrayElement.getName(TypeData.java:422)
> 	at javassist.bytecode.stackmap.TypeData$TypeName.getExpected(TypeData.java:292)
> 	at javassist.bytecode.stackmap.TypeData$TypeName.getTypeData(TypeData.java:175)
> 	... 12 more

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