[LLVMdev] ComputeMaskedBits Bug

[David Greene]

On Saturday 19 July 2008 23:53, Nick Lewycky wrote:

> > That said, there are many places that don't respect the Mask.  Closer
> > reading of the comment leads me to believe the Mask is simply a
> > time-saving device, not a correctness-enforcing mechanism.
>
> That's fine, but if you fix it that way, please audit
> InstructionCombiner SimplifyDemandedBits, which I believe has the same bug.

Ok.

> > I've fixed the PHI analysis to do the min in our code and it fixes the
> > testcase I was working on.  Doing a min like this would also allow us
> > to have PHI nodes compute known zero and one bits even when there
> > isn't a recurrence.
>
> Great! Did you commit a patch for this?

Not yet.  :(  I am waiting for some paperwork on this end.  Hopefully we only 
have to go through this pain once and then I can be much more active.  I've
been told it should be approved by the end of the month.

                                                       -Dave