[LLVMdev] SIV tests in LoopDependence Analysis, Sanjoy's patch

[Hal Finkel]

On Wed, 18 Apr 2012 18:16:47 -0700
Preston Briggs <preston.briggs at gmail.com> wrote:

> Hi Sanjoy,
> 
> Here's a version of Banerjee and Wolfe's Exact SIV test:
> https://sites.google.com/site/parallelizationforllvm/weak-siv-test
> It assumes you've already filtered out the easy cases handled by ZIV,
> strong SIV, etc.
> 
> I'm not confident about my uses of APInt. If you have any comments,
> I'd love to hear them.

Are you worried about properly setting the bit lengths, or about loss
of generality by restricting to constants? I've not thought about this
too deeply, but are there cases where some or all of the relevant
inputs are not constants, but yet we can still determine whether the
expressions involving them satisfy the required inequalities? One of
the nice things about SCEV is its ability, to some extent, to handle
and simplify "algebraic" expressions, and if appropriate, I think we
should use that ability.

Thanks again,
Hal

> 
> Thanks,
> Preston
> 
> 
> On Thu, Apr 12, 2012 at 5:14 AM, Sanjoy Das
> <sanjoy at playingwithpointers.com>wrote:
> 
> > Hi,
> >
> > Here is a preliminary (monolithic) version you can comment on.  This
> > is still buggy, however, and I'll be testing for and fixing bugs
> > over the next few days.  I've used your version of the strong siv
> > test.
> >
> > Thanks!
> > --
> > Sanjoy Das.
> > http://playingwithpointers.com
> >



-- 
Hal Finkel
Postdoctoral Appointee
Leadership Computing Facility
Argonne National Laboratory