Re: [PATCH] Allow all 1s of integer as standard SSE constants

[Uros Bizjak]

On Mon, Apr 25, 2016 at 9:45 PM, Richard Sandiford
<rdsandif...@googlemail.com> wrote:

>>> Can you please investigate, what is wrong with all_ones_operand so it
>>> doesn't accept all (-1) operands?
>>
>> Does following work:
>>
>> ;; Return true if operand is a (vector) constant with all bits set.
>> (define_predicate "all_ones_operand"
>>   (match_code "const_int,const_wide_int,const_vector")
>> {
>>   if (op == constm1_rtx)
>>     return true;
>>
>>   if (CONST_INT_P (op))
>>     return INTVAL (op) == HOST_WIDE_INT_M1;
>>
>>   if (mode == VOIDmode)
>>     mode = GET_MODE (op);
>>   return op == CONSTM1_RTX (mode);
>> })
>
> const_wide_int isn't necessary here.  An all-1s integer will always
> use CONST_INT, regardless of the mode size.
>
> I think this reduces to:
>
> (define_predicate "all_ones_operand"
>   (match_code "const_int,const_vector")
> {
>   if (CONST_INT_P (op))
>     return INTVAL (op) == HOST_WIDE_INT_M1;
>   return op == CONSTM1_RTX (GET_MODE (op));
> }
>
> (which is still more complex than it should be -- roll on CONST_INTs
> with modes. :-))

This is now implemented in a different way, but nevertheless some
const_wide_int codes were removed from other predicates in a follow-up
patch.

Uros.