Re: [PATCH v1] x86: Remove SSE3 instruction for broadcast in memset.S (SSE2 Only)

["H.J. Lu" <hjl.tools@gmail.com>]

On Mon, Feb 7, 2022 at 4:54 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Sun, Feb 6, 2022 at 10:39 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> >
> > commit b62ace2740a106222e124cc86956448fa07abf4d
> > Author: Noah Goldstein <goldstein.w.n@gmail.com>
> > Date:   Sun Feb 6 00:54:18 2022 -0600
> >
> >     x86: Improve vec generation in memset-vec-unaligned-erms.S
> >
> > Revert usage of 'pshufb' in broadcast logic as it is an SSE3

pshufb is an SSSE3, not SSE3, instruction.

> > instruction and memset.S is restricted to only SSE2 instructions.
> > ---
> >  sysdeps/x86_64/memset.S | 19 ++++++++++---------
> >  1 file changed, 10 insertions(+), 9 deletions(-)
> >
> > diff --git a/sysdeps/x86_64/memset.S b/sysdeps/x86_64/memset.S
> > index ccf036be53..148553cf3d 100644
> > --- a/sysdeps/x86_64/memset.S
> > +++ b/sysdeps/x86_64/memset.S
> > @@ -28,22 +28,23 @@
> >  #define VMOVU     movups
> >  #define VMOVA     movaps
> >
> > -# define MEMSET_SET_VEC0_AND_SET_RETURN(d, r) \
> > +#define MEMSET_SET_VEC0_AND_SET_RETURN(d, r) \
> >    movd d, %xmm0; \
> > -  pxor %xmm1, %xmm1; \
> > -  pshufb %xmm1, %xmm0; \
> > -  movq r, %rax
> > +  movq r, %rax; \
> > +  punpcklbw %xmm0, %xmm0; \
> > +  punpcklwd %xmm0, %xmm0; \
> > +  pshufd $0, %xmm0, %xmm0
> >
> > -# define WMEMSET_SET_VEC0_AND_SET_RETURN(d, r) \
> > +#define WMEMSET_SET_VEC0_AND_SET_RETURN(d, r) \
> >    movd d, %xmm0; \
> >    pshufd $0, %xmm0, %xmm0; \
> >    movq r, %rax
> >
> > -# define MEMSET_VDUP_TO_VEC0_HIGH()
> > -# define MEMSET_VDUP_TO_VEC0_LOW()
> > +#define MEMSET_VDUP_TO_VEC0_HIGH()
> > +#define MEMSET_VDUP_TO_VEC0_LOW()
>
> What are these changes for?
>
> > -# define WMEMSET_VDUP_TO_VEC0_HIGH()
> > -# define WMEMSET_VDUP_TO_VEC0_LOW()
> > +#define WMEMSET_VDUP_TO_VEC0_HIGH()
> > +#define WMEMSET_VDUP_TO_VEC0_LOW()
>
> What are these changes for?
>
> >  #define SECTION(p)             p
> >
> > --
> > 2.25.1
> >
>
>
> --
> H.J.



-- 
H.J.