[Vm-dev] Integer overflow with BitBlt rule 20 and depth 32

David T. Lewis lewis at mail.msen.com
Fri Oct 30 02:10:42 UTC 2009

On Mon, Oct 26, 2009 at 11:57:16AM -0700, Eliot Miranda wrote:
> On Mon, Oct 26, 2009 at 11:07 AM, Juan Vuletich <juan at jvuletich.org> wrote:
> > Anyway, I'm asking for help on making #copyBitsSimulated work again, like
> > it should do when called from BitBltTest. If nobody can help with that, I
> > guess I'll open a Mantis issue for this problem, in the hope that some day
> > it gets fixed.
> Well with my current VM I see no problems; all 10 tests are green.  What is
> the bug that you see?  How can I reproduce it?

Juan provided six new tests (see Mantis 7047) that document the problems.
I added these six tests to the trunk today, and also updated VMMaker on
SqueakSource with Juan's fixes for bitblt simulation (mainly some memory
access methods that had apparently been overlooked during the original
Squeak 64 bit work).

Juan's patches (VMMaker-BitBlt-AlphaFixes-jmv-M7407.cs on Mantis 7047)
do resolve the problems in the VM, and the changes all look correct to me
(but I have no experience with bitblt, so I'm just commenting on the fixes
for type declarations and arithmetic overflow). 

Has anyone else had a chance to review this? If there are no issues or
concerns, I will add Juan's alpha fixes to VMMaker.


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