Re: [PATCH] Avoid 1x vectors in tree-vect-generic (PR rtl-optimization/69896)

[Richard Biener <rguenther@suse.de>]

On February 27, 2016 2:07:43 AM GMT+01:00, Bill Schmidt <wschmidt@linux.vnet.ibm.com> wrote:
>Also tested with powerpc64le-unknown-linux-gnu native bootstrap with no
>regressions, where it fixes this bug as well as the (reopened) PR69613.
>
>Bill
>
>On Sat, 2016-02-27 at 00:04 +0100, Jakub Jelinek wrote:
>> Hi!
>> 
>> On ppc64, the widest (and only) supported vector mode for __int128
>> element type is V1TImode, and there is a V1TImode or opcode
>> and a couple of others, but IMNSHO it is highly undesirable to lower
>> BLKmode (say 2xTI, 4xTI etc.) generic vectors to V1TI instead of
>> TI, there are no advantages in doing that and apparently lots of
>various
>> bugs (the PR contains a WIP partial patch to fix some of them, but
>that is
>> just a tip of an iceberg, apparently lots of the folding etc. code
>> is returning sometimes a 1x vector type when it should be returning
>the
>> element type or vice versa, if CTOR contains 1x VECTOR_CSTs, there
>are
>> issues too etc.
>> 
>> So while I think it is desirable to fix all those V1?? handling
>issues
>> eventually, IMHO it is right to also just use element type instead
>> of 1x vectors during the generic vector lowering.
>> 
>> Bootstrapped/regtested on x86_64-linux and i686-linux and tested on
>the
>> testcase using powerpc64le-linux cross, ok for trunk?

OK.

Richard.

>> 2016-02-26  Jakub Jelinek  <jakub@redhat.com>
>> 
>> 	PR rtl-optimization/69896
>> 	* tree-vect-generic.c (get_compute_type): Avoid single element
>> 	vector types.
>> 
>> --- gcc/tree-vect-generic.c.jj	2016-01-04 14:55:52.000000000 +0100
>> +++ gcc/tree-vect-generic.c	2016-02-26 21:11:36.694482256 +0100
>> @@ -1405,6 +1405,7 @@ get_compute_type (enum tree_code code, o
>>        if (vector_compute_type != NULL_TREE
>>  	  && (TYPE_VECTOR_SUBPARTS (vector_compute_type)
>>  	      < TYPE_VECTOR_SUBPARTS (compute_type))
>> +	  && TYPE_VECTOR_SUBPARTS (vector_compute_type) > 1
>>  	  && (optab_handler (op, TYPE_MODE (vector_compute_type))
>>  	      != CODE_FOR_nothing))
>>  	compute_type = vector_compute_type;
>> 
>> 	Jakub
>>