[PATCH] Enable ISL's small integer optimization

Tobias Grosser tobias at grosser.es
Mon Jun 22 05:16:56 PDT 2015

On 06/18/2015 04:03 PM, Michael Kruse wrote:
> 2015-06-18 15:32 GMT+02:00 Joerg Sonnenberger <joerg at britannica.bec.de>:
>> On Wed, Jun 17, 2015 at 11:47:27PM +0200, Michael Kruse wrote:
>>> My up-to-date Ubuntu 15.04 has gcc 4.9.2, which still requires
>>> -std=c99 or you get a link error (multiple definitions; debug builds
>>> only because gcc is very aggressive with inlining). gcc 5 changes the
>>> default to C11, but for know the build requirement for LLVM is only
>>> GCC 4.7 (http://llvm.org/docs/GettingStarted.html#host-c-toolchain-both-compiler-and-standard-library).
>> Not true, GCC 5 uses gnu11 as default.
> -std=gnu11 is C11 (+extensions). Saying otherwise seems to imply that
> gcc -std=gnu11 wouldn't compile C11 code anymore. But it seems we have
> only a minor disagreement on definitions.
>> Which is the point, for GCC and
>> Clang, the choice if any should be gnu99.
> Since the compilation of ISL does not need any GNU extensions, I don't
> see the point of using -std=gnu99.
> However, I'd want to wait for Tobias' opinion.

I would probably also go with -std=gnu*. This is what Sven choose for 
isl itself as well. I see no benefit in being more restrictive. Even 
though I do not see immediate problems with strict c99, if choosing 
gnu99 allows us to address Joerg's concerns, even better.


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