Re: [vec-cmp, patch 4/6] Support vector mask invariants

[Ilya Enkovich <enkovich.gnu@gmail.com>]

2015-10-14 11:49 GMT+03:00 Richard Biener <richard.guenther@gmail.com>:
> On Tue, Oct 13, 2015 at 4:52 PM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>> I don't understand what you mean. vect_get_vec_def_for_operand has two
>> changes made.
>> 1. For boolean invariants use build_same_sized_truth_vector_type
>> instead of get_vectype_for_scalar_type in case statement produces a
>> boolean vector. This covers cases when we use invariants in
>> comparison, AND, IOR, XOR.
>
> Yes, I understand we need this special-casing to differentiate between
> the vector type
> used for boolean-typed loads/stores and the type for boolean typed constants.
> What happens if we mix them btw, like with
>
>   _Bool b = bools[i];
>   _Bool c = b || d;
>   ...
>
> ?

Here both statements should get vector of char as a vectype and we
never go VECTOR_BOOLEAN_TYPE_P way for them

>
>> 2. COND_EXPR is an exception because it has built-in boolean vector
>> result not reflected in its vecinfo. Thus I added additional operand
>> for vect_get_vec_def_for_operand to directly specify vectype for
>> vector definition in case it is a loop invariant.
>> So what do you propose to do with these changes?
>
> This is the change I don't like and don't see why we need it.  It works today
> and the comparison operands should be of appropriate type already?

Today it works because we always create vector of integer constant.
With boolean vectors it may be either integer vector or boolean vector
depending on context. Consider:

_Bool _1;
int _2;

_2 = _1 != 0 ? 0 : 1

We have two zero constants here requiring different vectypes.

Ilya

>
> Richard.
>
>> Thanks,
>> Ilya