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Re: patch for merging graphite branch (before tuplification)
- From: Mark Mitchell <mark at codesourcery dot com>
- To: "Joseph S. Myers" <joseph at codesourcery dot com>
- Cc: Sebastian Pop <sebpop at gmail dot com>, Richard Guenther <richard dot guenther 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>, Roberto Bagnara <bagnara at cs dot unipr dot it>
- Date: Sun, 03 Aug 2008 18:36:46 -0700
- Subject: Re: patch for merging graphite branch (before tuplification)
- References: <cb9d34b20807251914jb7fb76q4452be18461d7464@mail.gmail.com> <84fc9c000807260228h12552595x17b2a7556d35913b@mail.gmail.com> <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> <cb9d34b20808031330m6a38c120hbe4a1a971030f17d@mail.gmail.com> <Pine.LNX.4.64.0808032038410.15922@digraph.polyomino.org.uk>
Joseph S. Myers wrote:
GCC 4.4 -fwhatever should generate the same results everywhere. I think
reproducibility of results across hosts, for the same compiler sources, is
a critical matter. This means release branches must require a particular
version, and check the version when the compiler executes if linking
against a Cloog shared library is supported.
I agree with this statement of principle.
There is a logical extreme of this that I think unreasonable; for
example, if we depend on the C library to do something, and it does it
wrong on some host, then we may lose -- and it's not practical to
include the C library as part of the compiler sources. But, people
should know how to get reference versions of core computational
libraries, and I know you're not arguing for the logical extreme.
I'm not sure, however, that we need to try too hard to prevent people
using other versions. We just need to say "the version we used is X; if
you want to try some other version, your mileage may vary." We need to
agree on X (including what version is to be used on branches vs.
mainline) so that if you report a bug in my change and I go to fix it I
don't get confused because you and I are using different versions. A
warning seems appropriate, but an error seems strong.
In the past, I've argued against importing third-party libraries into
our tree, and I still feel that way. I've got no objection to canonical
versions available from the gcc.gnu.org FTP site, but I'd rather not
have them be part of every GCC checkout. I don't feel too strongly
about this, and we compromised on GMP, but that's still my overall
sentiment.
--
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713