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 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; } -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: https://jira.jboss.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira