Re: [PATCH V5, rs6000] Support vrotr<mode>3 for int vector types

["Kewen.Lin" <linkw at linux dot ibm dot com>]

Hi Segher,

on 2019/8/4 上午4:52, Segher Boessenkool wrote:
> Hi!
> 
> I somehow lost track of this email, sorry.
> 
> On Fri, Aug 02, 2019 at 04:59:44PM +0800, Kewen.Lin wrote:
>> As to the predicate name and usage, I checked the current vector shifts, 
>> they don't need to check const_vector specially (like right to left 
>> conversion), excepting for the one "vec_shr_<mode>", but it checks for
>> scalar const int.
> 
> I don't understand why we want to expand rotate-by-vector-of-immediates
> if we have no insns for that?  If you just use vint_operand, what happens
> then?
> 

You are right, if we just use vint_operand, the functionality should be the
same, the only small difference is the adjusted constant rotation number 
isn't masked, but it would be fine for functionality.

One example for ULL >r 8, with const vector handling, it gets
  xxspltib 33,56

Without the handling, it gets 
  xxsplitb 33,248

But I agree that it's trivial and unified it as below attached patch.

>> +/* { dg-options "-O3" } */
>> +/* { dg-require-effective-target powerpc_altivec_ok } */
> 
> If you use altivec_ok, you need to use -maltivec in the options, too.
> This test should probably work with -O2 as well; use that, if possible.
> 

Sorry, the test case depends on vectorization which isn't enabled at -O2
by default.

>> +/* { dg-require-effective-target powerpc_p8vector_ok } */
> 
> I don't think we need this anymore?  Not sure.
> 

I thought -mdejagnu-cpu=power8 can only ensure power8 cpu setting takes
preference, but can't guarantee the current driver supports power8
complication.  As your comments, I guess since gcc configuration don't
have without-cpu= etc., the power8 support should be always guaranteed?


Thanks,
Kewen

-----------------

gcc/ChangeLog

2019-08-05  Kewen Lin  <linkw@gcc.gnu.org>

	* config/rs6000/vector.md (vrotr<mode>3): New define_expand.

gcc/testsuite/ChangeLog

2019-08-05  Kewen Lin  <linkw@gcc.gnu.org>

	* gcc.target/powerpc/vec_rotate-1.c: New test.
	* gcc.target/powerpc/vec_rotate-2.c: New test.
	* gcc.target/powerpc/vec_rotate-3.c: New test.
	* gcc.target/powerpc/vec_rotate-4.c: New test.

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