[PATCH] Enable ISL's small integer optimization

Michael Kruse llvm-commits at meinersbur.de
Thu Jun 18 07:03:08 PDT 2015

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.


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