Re: [PATCH] Simple optimization for MASK_STORE.

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

2015-11-10 17:46 GMT+03:00 Richard Biener <richard.guenther@gmail.com>:
> On Tue, Nov 10, 2015 at 1:48 PM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>> 2015-11-10 15:33 GMT+03:00 Richard Biener <richard.guenther@gmail.com>:
>>> On Fri, Nov 6, 2015 at 2:28 PM, Yuri Rumyantsev <ysrumyan@gmail.com> wrote:
>>>> Richard,
>>>>
>>>> I tried it but 256-bit precision integer type is not yet supported.
>>>
>>> What's the symptom?  The compare cannot be expanded?  Just add a pattern then.
>>> After all we have modes up to XImode.
>>
>> I suppose problem may be in:
>>
>> gcc/config/i386/i386-modes.def:#define MAX_BITSIZE_MODE_ANY_INT (128)
>>
>> which doesn't allow to create constants of bigger size.  Changing it
>> to maximum vector size (512) would mean we increase wide_int structure
>> size significantly. New patterns are probably also needed.
>
> Yes, new patterns are needed but wide-int should be fine (we only need to create
> a literal zero AFACS).  The "new pattern" would be equality/inequality
> against zero
> compares only.

Currently 256bit integer creation fails because wide_int for max and
min values cannot be created.
It is fixed by increasing MAX_BITSIZE_MODE_ANY_INT, but it increases
WIDE_INT_MAX_ELTS
and thus increases wide_int structure. If we use 512 for
MAX_BITSIZE_MODE_ANY_INT then
wide_int structure would grow by 48 bytes (16 bytes if use 256 for
MAX_BITSIZE_MODE_ANY_INT).
Is it OK for such narrow usage?

Ilya

>
> Richard.
>
>> Ilya
>>
>>>
>>> Richard.
>>>
>>>> Yuri.
>>>>
>>>>