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Re: patch for merging graphite branch (before tuplification)
- From: Jack Howarth <howarth at bromo dot msbb dot uc dot edu>
- To: Mark Mitchell <mark at codesourcery dot com>
- Cc: Paolo Bonzini <bonzini at gnu dot org>, Roberto Bagnara <bagnara at cs dot unipr dot it>, "Joseph S. Myers" <joseph at codesourcery dot com>, Richard Guenther <richard dot guenther at gmail dot com>, Sebastian Pop <sebpop at gmail dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>, Jakub Jelinek <jakub at redhat dot com>, David Edelsohn <edelsohn at gmail dot com>, "Harle, Christophe" <christophe dot harle at amd dot com>, Tobias Grosser <grosser at fim dot uni-passau dot de>, Konrad Trifunovic <konrad dot trifunovic at gmail dot com>, Albert Cohen <Albert dot Cohen at inria dot fr>
- Date: Fri, 8 Aug 2008 13:25:32 -0400
- Subject: Re: patch for merging graphite branch (before tuplification)
- References: <cb9d34b20808021726w3dcb5015o9b256ef393dba02c@mail.gmail.com> <Pine.LNX.4.64.0808031809020.15922@digraph.polyomino.org.uk> <84fc9c000808031220t14f60e5bie1760eaaa413aeb5@mail.gmail.com> <Pine.LNX.4.64.0808031925260.15922@digraph.polyomino.org.uk> <84fc9c000808031320m153160b0l60db9d80b1f58742@mail.gmail.com> <Pine.LNX.4.64.0808032051010.15922@digraph.polyomino.org.uk> <489C60E3.6010105@cs.unipr.it> <489C67D0.8080004@codesourcery.com> <489C6BD7.3010405@gnu.org> <489C6CD1.3000109@codesourcery.com>
Mark,
I thought Roberto covered that when he said...
So the most that can be guaranteed is a minimal form (i.e., with
the minimum number of individually-normalized constraints),
but there is no guarantee to obtain, for the same polyhedron,
the same set of constraints. However, if you stick to a particular
PPL release, you can count on obtaining the same set of constraints
on all architectures.
That sentence was a little confusing, but I took it to mean that
the solutions were implementation dependent and as long as you
stuck with a specific implemenentation (ie version of ppl), you
wouldn't get THE correct answer but at least a consistent one.
Jack
On Fri, Aug 08, 2008 at 08:57:05AM -0700, Mark Mitchell wrote:
> Paolo Bonzini wrote:
>>
>>> Sebastian, will the behavior of Graphite be deterministic, in that
>>> for a given compiler and a given input program, we can be assured of
>>> the same output? (I would assume so, but I would like to check.)
>>
>> Roberto said that the parts of PPL that are used in Graphite *do not*
>> require floating point. In fact, off list he even told me that some
>> parts of PPL were written specially because other available packages
>> used floating point.
>
> OK, great! I'd 99.9% sure it's not an issue, but I'd still like a
> direct answer from Sebastian on the determinism issue.
>
> Thanks,
>
> --
> Mark Mitchell
> CodeSourcery
> mark@codesourcery.com
> (650) 331-3385 x713