[Boolean Vector, patch 1/5] Introduce boolean vector to be used as a vector comparison type

[Richard Biener]

On Mon, Nov 2, 2015 at 8:41 PM, Jeff Law <law@redhat.com> wrote:
> On 10/29/2015 07:08 AM, Ilya Enkovich wrote:
>>
>> On 28 Oct 22:37, Ilya Enkovich wrote:
>>>
>>> Seems the problem occurs in this check in expand_vector_operations_1:
>>>
>>>    /* A scalar operation pretending to be a vector one.  */
>>>    if (VECTOR_BOOLEAN_TYPE_P (type)
>>>        && !VECTOR_MODE_P (TYPE_MODE (type))
>>>        && TYPE_MODE (type) != BLKmode)
>>>      return;
>>>
>>> This is to filter out scalar operations on boolean vectors.
>>> The problem here is that TYPE_MODE (type) doesn't return
>>> V4SImode assigned to the type but calls vector_type_mode
>>> instead which tries to find an integer mode for it and returns
>>> TImode. This causes function exit and we don't expand vector
>>> comparison.
>>>
>>> Suppose simple option to fix it is to change default get_mask_mode
>>> hook to return BLKmode in case chosen integer vector mode is not
>>> vector_mode_supported_p.
>>>
>>> Thanks,
>>> Ilya
>>>
>>
>> Here is a patch which fixes the problem on ARM (and on i386 with -mno-sse
>> also).  I checked it fixes the problem on ARM and also bootstrapped and
>> checked it on x86_64-unknown-linux-gnu.  Is it OK?
>>
>> Thanks,
>> Ilya
>> --
>> gcc/
>>
>> 2015-10-29  Ilya Enkovich  <enkovich.gnu@gmail.com>
>>
>>         * targhooks.c (default_get_mask_mode): Use BLKmode in
>>         case target doesn't support required vector mode.
>>         * stor-layout.c (layout_type): Check for BLKmode.
>
> VOIDmode would probably be a better choice than BLKmode to signal when the
> target doesn't support the required vector mode.

Though we're using BLKmode vectors in all other cases to signal that.

Richard.

>
> Jeff
>