Lab3: if evaluating all statements

[Niklas Logren]

Hi!
I'm having some trouble with jasmin. It seems to not jump when I want it to.
I have an if block that contains invalid code, but I expect the Java interpreter to jump past this block.

See this JVM code:

.class public Foo
.super java/lang/Object

.method public <init>()V
aload_0
invokenonvirtual java/lang/Object/<init>()V
return
.end method

.method public static main([Ljava/lang/String;)V
.limit locals 100
.limit stack 1000
iconst_0
ifeq L1 -- this should always branch?
iload 0 -- this results in runtime error
invokestatic Runtime/printInt(I)V
goto L0
L1:
bipush 42
invokestatic Runtime/printInt(I)V
L0:
return
.end method


When I compile it using Jasmin and run "java Foo", it complains that "Register 0 contains wrong type" because of "iload 0".
But shouldn't "ifeq L1" unconditionally jump? That is, shouldn't the above program work correctly?

Thanks in advance,
Niklas

[Aarne Ranta]

The first argument of main is an array of strings, and not an integer, which make iload 0 invalid.

  Aarne.

[dhausknecht]

the problem is a runtime byte code verification. That's also why good15 complains with 'j' which is not initialised (though it is of the correct type). To disable the verification use the -noverify flag. However, do so only when you're 100% sure what you're doing!

[Niklas Logren]

Oh, so we are allowed to run test case good15.cc with -noverify? Awesome!

Also, thanks Aarne, that's a separate issue we hadn't discovered yet. :-)