Re: [PATCH, rs6000] 2/2 Add x86 SSE2 <emmintrin,h> intrinsics to GCC PPC64LE target

[Steven Munroe <munroesj@linux.vnet.ibm.com>]

On Wed, 2017-10-25 at 18:37 -0500, Segher Boessenkool wrote:
> Hi!
> 
> On Tue, Oct 17, 2017 at 01:27:16PM -0500, Steven Munroe wrote:
> > This it part 2/2 for contributing PPC64LE support for X86 SSE2
> > instrisics. This patch includes testsuite/gcc.target tests for the
> > intrinsics included by emmintrin.h. 
> 
> > --- gcc/testsuite/gcc.target/powerpc/sse2-mmx.c	(revision 0)
> > +++ gcc/testsuite/gcc.target/powerpc/sse2-mmx.c	(revision 0)
> > @@ -0,0 +1,83 @@
> > +/* { dg-do run } */
> > +/* { dg-options "-O3 -mdirect-move" } */
> > +/* { dg-require-effective-target lp64 } */
> > +/* { dg-require-effective-target p8vector_hw } */
> > +/* { dg-skip-if "do not override -mcpu" { powerpc*-*-* } { "-mcpu=*" } { "-mcpu=power8" } } */
> 
> Why this dg-skip-if?  Also, why -mdirect-move?
> 
this is weird test because it the effectively MMX style operations but
added to IA under the SSE2 Technology.

Normally mmintrin.h compare operations require a transfer to/from vector
with direct move for efficient execution on power.

The one exception to that is _mm_cmpeq_pi8 which can be implemented
directly in GPRs using cmpb.

The cmpb instruction is from power6 but I do not want to use
-mcpu=power6 here. -mdirect-move is a compromise.

I suspect that the dg-skip-if is an artifact of the early struggles to
make this stuff work across various --withcpu= settings.

I think the key is dg-require-effective-target p8vector_hw which should
allow dropping both the -mdirect-move and the whole dg-skip-if clause.

Will need to try this change and retest.

> 
> Okay for trunk with that taken care of.  Sorry it took a while.
> 
> Have you tested this on big endian btw?
> 
Yes.

I have tested on P8 BE using --withcpu=[power6 | power7 | power8 ]

> 
> Segher
>