[Vm-dev] Mantis 0007265: Bug in Matrix2x3Plugin okayIntValue: (was: two small bugs (vm related))

Nicolai Hess nicolaihess at web.de
Tue Sep 15 07:03:47 UTC 2015


Thanks!

2015-09-15 4:24 GMT+02:00 David T. Lewis <lewis at mail.msen.com>:

>
>
> On Sun, Sep 13, 2015 at 07:17:51PM -0400, David T. Lewis wrote:
> >
> > On Sun, Sep 13, 2015 at 10:23:42PM +0200, Nicolai Hess wrote:
> > >
> > > I am about to close some old mantis reports.
> > >
> > > There are two issues related to the vm and easy to solve ( I think).
> > >
> > > http://bugs.squeak.org/view.php?id=7265
> > >
> > > 0007265: Bug in Matrix2x3Plugin okayIntValue:
> > > Method
> > > okayIntValue: value
> > > uses argument to compare with lower bound, m23ResultX for upper bound.
> > >
> > > okayIntValue: value
> > >     ^(value >= -1073741824 asFloat and:[m23ResultX <= 1073741823
> asFloat])
> > >
> > > should be:
> > > okayIntValue: value
> > >     ^(value >= -1073741824 asFloat and:[value <= 1073741823 asFloat])
> > >
> > > I looked at the Matrix2x3Plugin code, and the wrong comparsion
> > > is still there.
> >
> > I am quite sure you are right about this, just from looking at the code.
> > But I do want to check - the method is from ar 1998, so it has been in
> all
> > the VMs for a very long time. How did you find the problem? Is there a
> > test or an example that shows the issue?
> >
> > After fixing the method as you suggest, it will test for integer values
> > with bit values in the range 11000000000000000000000000000000 through
> > 00111111111111111111111111111111, which presumably maps to a range of
> > acceptable values for use in the Matrix2x3Plugin floating point
> operations.
> > So that looks quite reasonable, but I am puzzled that this check has been
> > wrong since 1998, so that is why I ask.
> >
>
> I closed issue 7265. Eliot added your fix to Spur/Cog I did likewise for
> VMM trunk (interpreter VM).
>
> Dave
>
>
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