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Re: STRIP_NOPS and lower-precision/bit-field types
On Thu, Jun 4, 2009 at 10:49 PM, Joseph S. Myers
<joseph@codesourcery.com> wrote:
> On Thu, 4 Jun 2009, Adam Nemet wrote:
>
>> 1. Change STRIP_NOPS not to remove the cast if it's changing the precision
>> (not just when it changes machine modes). ?And then audit code quality where
>> we need to and are allowed to look through these casts.
>
> As I said in <http://gcc.gnu.org/ml/gcc-bugs/2007-03/msg02228.html> and
> <http://gcc.gnu.org/ml/gcc/2008-01/msg00215.html>, I think such references
> to the mode are as a proxy for precision and machine modes are an
> inappropriate level of abstraction for the tree optimizers. ?So I favour
> checking for precision here - but I also favour having a good look at
> anything using STRIP_NOPS etc. and considering whether it should use some
> better defined function for removing redundant conversions instead.
FWIW I agree. STRIP_NOPS should not change the precision - we came
to this conclusion multiple times but never got around to do the change.
Richard.
> --
> Joseph S. Myers
> joseph@codesourcery.com
>