[RFB] IRA and regclass both ignore '!' attribute

[Paolo Bonzini]

Andrew_Pinski@PlayStation.Sony.Com wrote:
> Vladimir Makarov <vmakarov@redhat.com> wrote on 10/31/2008 07:54:06 AM:
>> The problem you mentioned (selecting GPR instead of FPR) could be solved 
> 
>> by putting one or more ? in the alternative to get the same effect you 
>> are trying to achieve with this patch.  Imho, the patch you are 
>> proposing probably decrease some gcc functionality. Probably ! was 
>> supposed to be used only for reload.
> 
> 
> The documentation says this about '!':
> Disparage severely the alternative that the `!' appears in. This 
> alternative can still be used if it fits without reloading, but if 
> reloading is needed, some other alternative will be used.

But that's almost what the compiler does.

Until reload, i.e. in regclass, the alternative can still be used, but
if reloading is needed, some other alternative will be used.

In other words the only important thing to say is: "During reload,
disparage severely the alternative that the `!' appears in".

Now, I'm not expert enough to understand why this makes sense, but
indeed I saw lots of ?! constraints and that's probably why.

Paolo