VerifyError when compiling jetty

Wed Jan 29 17:46:00 GMT 2003

Bjarni Thorisson writes:
 > Hello, and thanks for the quick reply.
 > 
 > Below is a simple class you can compile into bytecode with gcj and try to
 > run it. Then this error should occurr:
 > 
 > <--------------------clip----------------------------->
 > Exception in thread "main" java.lang.VerifyError: (class: Smu$Foo, method:
 > run signature: ()V) Illegal use of nonvirtual function call
 > at Smu.start(Smu.java:28)
 > at Smu.main(Smu.java:13)
 > <-------------------/clip----------------------------->
I can confirm this.
We generate the same code for Smu.start. 
Looking at Smu$Foo:
Method name:"run" public Signature: 17=()void Method name:"run" public Signature: 9=()void						 
Attribute "Code", length:115, max_stack:2, max_locals:4, code_length:55	 Attribute "Code", length:116, max_stack:2, max_locals:3, code_length:56			 
 0: goto 20								 0: aload_0										 
 3: ldc2_w #1=<Long 1000>						 1: getfield #12=<Field Smu$Foo.this0ドル Smu>						 
 6: invokestatic #3=<Method java.lang.Thread.sleep (long)void>		 4: invokevirtual #18=<Method Smu.isStarted ()boolean>					 
 9: aload_0								 7: ifeq 31										 
 10: getfield #4=<Field Smu$Foo.this0ドル Smu>				 10: sipush 1000									 
 13: invokestatic #5=<Method Smu.access000ドル (Smu)void>			 13: i2l										 
 16: goto 20								 14: invokestatic #22=<Method java.lang.Thread.sleep (long)void>			 
 19: astore_1								 17: aload_0										 
 20: aload_0								 18: getfield #12=<Field Smu$Foo.this0ドル Smu>						 
 21: getfield #4=<Field Smu$Foo.this0ドル Smu>				 21: invokespecial #25=<Method Smu.doFoo ()void>					 
 24: invokevirtual #7=<Method Smu.isStarted ()boolean>			 24: goto 28										 
 27: ifne 3								 27: astore_1										 
 30: jsr 42								 28: goto 0										 
 33: goto 54								 31: jsr 43										 
 36: astore_2								 34: goto 55										 
 37: jsr 42								 37: astore_2										 
 40: aload_2								 38: jsr 43										 
 41: athrow								 41: aload_2										 
 42: astore_3								 42: athrow										 
 43: aload_0								 43: astore_1										 
 44: getfield #4=<Field Smu$Foo.this0ドル Smu>				 44: aload_0										 
 47: aconst_null							 45: getfield #12=<Field Smu$Foo.this0ドル Smu>						 
 48: invokestatic #8=<Method Smu.access102ドル (Smu,Smu$Foo)Smu$Foo>	 48: aconst_null									 
 51: pop								 49: invokestatic #29=<Method Smu.access1ドル (Smu,Smu$Foo)Smu$Foo>			 
 52: ret 3								 52: pop										 
 54: return								 53: ret 1										 
 55: return

IBMJava2-131/bin/javac is on the left, we are on the right. javac
calls Smu.access100ドル with invokestatic, whereas we call Smu.doFoo with
invokespecial. Let's look at Smu.access000ドル:
Method name:"access000ドル" static Signature: 32=(Smu)void
Attribute "Code", length:29, max_stack:1, max_locals:1, code_length:5
 0: aload_0
 1: invokespecial #2=<Method Smu.doFoo ()void>
 4: return
Attribute "LineNumberTable", length:6, count: 1
 line: 1 at pc: 0
Attribute "Synthetic", length:0
So, Smu.access000ドル is a thunk that javac generates in order to enable
inner classes to access methods in the enclosing class. AFAICS we
aren't doing that in this case.
This is illegal code on our part, because we're not allowed to use
invokepsecial on a private method. We should generate an access
method for Smu.doFoo and use it.
Andrew.