RFR:JDK-8190391:nashorn: "!!" of nonzero even integer var becomes false when returned

[Attila Szegedi]

+1. Nice catch. Feels like an implementation detail, but the JVM
specification is indeed unclear on the behavior in case there's a bytecode
method doing this:

public static func(I)Z
    0     iload 0
    1     ireturn


I went spelunking in the JVM spec, and the closest I could find is in
section 2.3.4 says "The Java Virtual Machine encodes boolean array
components using 1 to represent true and 0 to represent false. Where Java
programming language boolean values are mapped by compilers to values of
Java Virtual Machine type int, the compilers must use the same encoding."
So I guess we better stick to that.

Attila.


On Mon, Nov 13, 2017 at 7:21 AM, Priya Lakshmi Muthuswamy <
priya.lakshmi.muthuswamy at oracle.com> wrote:

> Hi,
>
> Please review JDK-8190391 : nashorn: "!!" of nonzero even integer var
> becomes false when returned
>
> JBS : https://bugs.openjdk.java.net/browse/JDK-8190391
> webrev : http://cr.openjdk.java.net/~pmuthuswamy/8190391/webrev.00/
>
> Thanks,
> Priya
>