This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: Ada front-end depends on signed overflow
- From: Paul Schlie <schlie at comcast dot net>
- To: Georg Bauhaus <bauhaus at futureapps dot de>
- Cc: GCC List <gcc at gcc dot gnu dot org>
- Date: Thu, 09 Jun 2005 05:43:50 -0400
- Subject: Re: Ada front-end depends on signed overflow
> From: Georg Bauhaus <bauhaus@futureapps.de>
>> Paul Schlie wrote:
>> - How is it necessary or desirable to define that the result is undefined
>> vs. being target defined?
>
> What does C say about how a target performs an instruction?
> And why shouldn't GCC take advantage of this?
- In essence I believe the difference is consistency. Where although a
target implementation defined behavior seems no more clear, it implies
that the semantics of an operation in question should directly result
from it's target implementation, and any corresponding compile-time
constant propagation optimizations should be consistent with their
otherwise run-time computed counterparts, as otherwise they will be
needlessly and arguably erroneously inconsistent; which an undefined
behavior would seem to allow, without providing any tangible benefit.