computation_cost too blind to hard regs

[Geert Bosch]

On Jan 19, 2005, at 22:48, Richard Henderson wrote:
> On Wed, Jan 19, 2005 at 09:19:58PM -0500, DJ Delorie wrote:
>> -  int regno = 0;
>> +  int regno = FIRST_PSEUDO_REGISTER;
>
> To be totally safe, you need LAST_VIRTUAL_REGISTER+1.

Also, this definitely needs a comment.

   -Geert