Re: [PATCH, rs6000] (PR84302) Fix _mm_slli_epi{32,64} for shift values 16 through 31 and negative

[Segher Boessenkool <segher at kernel dot crashing dot org>]

Hi!

On Thu, Apr 12, 2018 at 07:07:21PM -0500, Paul Clarke wrote:
> The powerpc versions of _mm_slli_epi32 and __mm_slli_epi64 in emmintrin.h
> do not properly handle shift values between 16 and 31, inclusive.
> These were setting up the shift with vec_splat_s32, which only accepts
> *5 bit signed* shift values, or a range of -16 to 15.  Values above 15
> produced an error:
> 
>   error: argument 1 must be a 5-bit signed literal
> 
> Fix is to effectively reduce the range for which vec_splat_s32 is used
> to < 32 and use vec_splats otherwise.
> 
> Also, __mm_slli_epi{16,32,64}, when given a negative shift value,
> should always return a vector of {0}.

Yup.

> 2018-04-12  Paul A. Clarke  <pc@us.ibm.com>
> 
> gcc/config

There is no changelog there; the changelog is in gcc/.  I'll fix it up.

> --- gcc/config/rs6000/emmintrin.h	(revision 259016)
> +++ gcc/config/rs6000/emmintrin.h	(working copy)
> @@ -1488,7 +1488,7 @@ _mm_slli_epi16 (__m128i __A, int __B)
>    __v8hu lshift;
>    __v8hi result = { 0, 0, 0, 0, 0, 0, 0, 0 };
>  
> -  if (__B < 16)
> +  if (__B > 0 && __B < 16)
>      {
>        if (__builtin_constant_p(__B))
>  	  lshift = (__v8hu) vec_splat_s16(__B);
> @@ -1507,12 +1507,12 @@ _mm_slli_epi32 (__m128i __A, int __B)
>    __v4su lshift;
>    __v4si result = { 0, 0, 0, 0 };
>  
> -  if (__B < 32)
> +  if (__B > 0 && __B < 32)

These should >= 0 (I'll fix it).

Thanks for the patch!  I'll commit it; please get your commit access in
order if you plan any further patches.

Cheers,


Segher