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Re: Trouble building Graphite
- From: Roberto Bagnara <bagnara at cs dot unipr dot it>
- To: Ian Lance Taylor <iant at google dot com>
- Cc: gcc at gcc dot gnu dot org, "The Parma Polyhedra Library developers' list" <ppl-devel at cs dot unipr dot it>
- Date: Tue, 12 May 2009 18:38:49 +0200
- Subject: Re: Trouble building Graphite
- References: <firstname.lastname@example.org>
Ian Lance Taylor wrote:
I'm having some trouble building the Graphite support.
Using ftp://gcc.gnu.org/pub/gcc/infrastructure/ppl-0.10.2.tar.gz :
* Unlike gcc, does not support a --with-gmp option.
+ Does support a --with-libgmpxx-prefix option.
What is the trouble with this? I mean, is it a matter of syntax
(you prefer the option to be called --with-gmp) or semantics
(the --with-libgmpxx-prefix does not do the right thing)?
* If GMP was not built with C++ support, fails at build time.
Yes, the C++ interface of GMP is required. On the other hand,
also the core of PPL is written in C++. In whhich sense requiring
the C++ interface of GMP is a trouble?
* If GMP was not built with exception support, complains at configure
time, and recommends using CPPFLAGS=-fexceptions when building GMP.
Well, "complain" is not the right word. The PPL configuration script
simply warns about the fact that the bounded memory capabilities of
the PPL are not available. Which is not a problem for GCC, since these
capabilities are not used by CLooG. The message was designed not
to alarm people unnecessarily. It says: "This is OK, if you do not
plan to use the bounded memory capabilities offered by the PPL."
Do you think a different wording could help?
+ CPPFLAGS is for preprocessor flags, and -fexceptions is not a
preprocessor flag. However, I admit that setting CFLAGS does not
work correctly, as GMP seems to have special requirements for it.
In facto, our use of CPPFLAGS is motivated by the fact that using CFLAGS
for that purpose was not working, once upon a time. See:
Perhaps it works now: we will check again and, in case it works,
we will amend the configuration script, documentation and web site.
+ I think they mean -funwind-tables anyhow.
We do that because:
Similar to -fexceptions, except that it will just generate any
needed static data, but will not affect the generated code in any
other way. You will normally not enable this option; instead, a
language processor that needs this handling would enable it on your
Please let us know if we are mistaken on this point.
Generally speaking, we are 100% willing to improve the PPL as much as possible:
any suggestion is welcome in this respect. Please mail to email@example.com
All the best,
Prof. Roberto Bagnara
Computer Science Group
Department of Mathematics, University of Parma, Italy