Re: [Bug-jel] java.lang.VerifyError

[Mark Taylor]

Konstanin,

many thanks for this quick fix - yes it's now working perfectly.

Mark

On Tue, 17 Nov 2020, Konstantin L. Metlov wrote:

> Dear Mark,
> 
> Thank you very much for finding and reporting this bug !
> 
> It happened because evaluation of logical expressions does not actually
> put the (intermediate) boolean values on Java stack but instead compiles
> into an intertwined (if there are logical operators and brackets) braid of
> conditional jumps. To have the boolean value on stack the compiler has to
> land all the dangling labels to "true" and "false" branches of the logical
> expression and actually load the constants 0 or 1 to stack. This last step
> was missing when wrapping (boxing) the boolean values into the
> java.lang.Boolean type.
> 
> It compiled (verified, but not worked properly) for doubles, because in
> Java the double comparisons are actually done via intermediate integers
> (created via dcmpg/dcmpl instructions). These intermediate values
> (incorrectly) served as final boolean values on stack.
> 
> This bug is now fixed. The actual fix consists of 4 modified characters:
> 
> -      cf.code(0x00FEL+((29+resID-20)<<8));
> +      cf.code(0x00FEFAL+((29+resID-20)<<16));
> 
> in src/java/gnu/jel/OPunary.java . I have also added the corresponding
> tests to JEL testsuite. You can find the updated jel.jar (and jel_g.jar)
> in the pre-release version 2.1.2-pre1 version of JEL I've posted on my
> homepage:
> 
> http://www.donfti.ru/~metlov/jel-2_1_2-pre1.zip
> 
> $ md5sum jel-2_1_2-pre1.zip
> 44aa87b8f8bd0bdc8c9040b2e55cb6b8  jel-2_1_2-pre1.zip
> $ sha256sum jel-2_1_2-pre1.zip
> 8d606890fb3241adc989fdec3271b17e6621872bc29631c6623d21df88a88e18
> jel-2_1_2-pre1.zip
> 
> Please try this version and tell me if it fixes the bug for you.
> 
> I've also uploaded the source changes to savannah:
> 
> http://svn.savannah.gnu.org/viewvc/jel/trunk/
> 
> With the best regards,
>                            Konstantin.
> 
> > Dear Konstantin,
> >
> > I think I have encountered a (weird) JEL bug.
> >
> > If I compile and run the following program against (e.g.) JEL 2.1.1:
> >
> >     import gnu.jel.Evaluator;
> >     import gnu.jel.Library;
> >
> >     public class Jelly3 {
> >
> >         public static void main(String[] args) throws Throwable {
> >             Library lib = new Library(new Class[] {Jelly3.ALib.class},
> >                                       null, null, null, null);
> >
> >             // These calls work OK:
> >             Evaluator.compile("dx==1", lib, null);
> >             Evaluator.compile("dx==1", lib, Boolean.class);
> >             Evaluator.compile("ix==1", lib, null);
> >
> >             // But this one causes a java.lang.VerifyError:
> >             Evaluator.compile("ix==1", lib, Boolean.class);
> >         }
> >
> >         public static class ALib {
> >             public static double dx() {
> >                 return 1.0;
> >             }
> >             public static int ix() {
> >                 return 1;
> >             }
> >         }
> >     }
> >
> > I see this error:
> >
> >     Exception in thread "main" java.lang.VerifyError: (class: dump,
> > method: evaluate signature: ([Ljava/lang/Object;)Ljava/lang/Object;)
> > Expecting to find unitialized object on stack
> >             at java.lang.Class.getDeclaredConstructors0(Native Method)
> >             at
> > java.lang.Class.privateGetDeclaredConstructors(Class.java:2671)
> >             at java.lang.Class.getConstructor0(Class.java:3075)
> >             at java.lang.Class.newInstance(Class.java:412)
> >             at gnu.jel.Evaluator.compile(Evaluator.java:158)
> >             at Jelly3.main(Jelly3.java:16)
> >
> > Any ideas?
> >
> > Many thanks,
> >
> > Mark
> >
> > --
> > Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
> > m.b.taylor@bris.ac.uk +44-117-9288776  http://www.star.bris.ac.uk/~mbt/
> >
> > _______________________________________________
> > Bug-jel mailing list
> > Bug-jel@gnu.org
> > https://lists.gnu.org/mailman/listinfo/bug-jel
> >
> 
> 
> 
> 
> 
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--
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor@bris.ac.uk +44-117-9288776  http://www.star.bris.ac.uk/~mbt/