Re: More type narrowing in match.pd

[Richard Biener <richard.guenther@gmail.com>]

On Thu, Apr 30, 2015 at 12:53 PM, Marc Glisse <marc.glisse@inria.fr> wrote:
> On Thu, 30 Apr 2015, Richard Biener wrote:
>
>> I have in my local dev tree (so completely untested...)
>>
>> @@ -1040,31 +1052,22 @@ (define_operator_list CBRT BUILT_IN_CBRT
>>    operation and convert the result to the desired type.  */
>> (for op (plus minus)
>>   (simplify
>> -    (convert (op (convert@2 @0) (convert@3 @1)))
>> +    (convert (op:c@4 (convert@2 @0) (convert?@3 @1)))
>
>
> I believe the :c here requires extra code further down, so we don't turn a-b
> into b-a.

Indeed.  I've added :c only for minus as 5 - x can't be canonicalized to
move the constant to 2nd position which is always possible for plus.

Might be cleaner to add a separate pattern for that case.

Richard.

>
>>     (if (INTEGRAL_TYPE_P (type)
>> -        /* We check for type compatibility between @0 and @1 below,
>> -           so there's no need to check that @1/@3 are integral types.  */
>>         && INTEGRAL_TYPE_P (TREE_TYPE (@0))
>> -        && INTEGRAL_TYPE_P (TREE_TYPE (@2))
>> +        && INTEGRAL_TYPE_P (TREE_TYPE (@4))
>>         /* The precision of the type of each operand must match the
>>            precision of the mode of each operand, similarly for the
>>            result.  */
>>         && (TYPE_PRECISION (TREE_TYPE (@0))
>>             == GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (@0))))
>> -        && (TYPE_PRECISION (TREE_TYPE (@1))
>> -            == GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (@1))))
>> -        && TYPE_PRECISION (type) == GET_MODE_PRECISION (TYPE_MODE (type))
>>         /* The inner conversion must be a widening conversion.  */
>>         && TYPE_PRECISION (TREE_TYPE (@2)) > TYPE_PRECISION (TREE_TYPE
>> (@0))
>> -        && ((GENERIC
>> -             && (TYPE_MAIN_VARIANT (TREE_TYPE (@0))
>> -                 == TYPE_MAIN_VARIANT (TREE_TYPE (@1)))
>> -             && (TYPE_MAIN_VARIANT (TREE_TYPE (@0))
>> -                 == TYPE_MAIN_VARIANT (type)))
>> -            || (GIMPLE
>> -                && types_compatible_p (TREE_TYPE (@0), TREE_TYPE (@1))
>> -                && types_compatible_p (TREE_TYPE (@0), type))))
>> +        /* The final precision should match that of operand @0.  */
>> +        && TYPE_PRECISION (type) == TYPE_PRECISION (TREE_TYPE (@0))
>> +        /* Make sure the wide operation is dead after the transform.  */
>> +        && (TREE_CODE (@4) != SSA_NAME || has_single_use (@4)))
>>       (if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (@0)))
>> -       (convert (op @0 @1)))
>> +       (convert (op @0 (convert @1))))
>>       (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
>>        (convert (op (convert:utype @0) (convert:utype @1)))))))
>
>
> --
> Marc Glisse