On Fri, Sep 01, 2017 at 02:22:17PM +0100, Tamar Christina wrote:
> Hi All,
>
> This patch adds the instructions for Dot Product to AArch64 along
> with the intrinsics and vectorizer pattern.
>
> Armv8.2-a dot product supports 8-bit element values both
> signed and unsigned.
>
> Dot product is available from Arm8.2-a and onwards.
>
> Regtested and bootstrapped on aarch64-none-elf and no issues.
>
> Ok for trunk?
>
> gcc/
> 2017-09-01 Tamar Christina <tamar.christ...@arm.com>
>
> * config/aarch64/aarch64-builtins.c
> (aarch64_types_quadopu_lane_qualifiers): New.
> (TYPES_QUADOPU_LANE): New.
> * config/aarch64/aarch64-simd.md (aarch64_<sur>dot<dot_mode>): New.
> (<sur>dot_prod<dot_mode>, aarch64_<sur>dot_lane<dot_mode>): New.
> (aarch64_<sur>dot_laneq<dot_mode>): New.
> * config/aarch64/aarch64-simd-builtins.def (sdot, udot): New.
> (sdot_lane, udot_lane, sdot_laneq, udot_laneq): New.
> * config/aarch64/iterators.md (UNSPEC_SDOT, UNSPEC_UDOT): New.
> (DOT_MODE, dot_mode, Vdottype, DOTPROD): New.
> (sur): Add SDOT and UDOT.
>
> --
> diff --git a/gcc/config/aarch64/aarch64-simd.md
> b/gcc/config/aarch64/aarch64-simd.md
> index
> f3e084f8778d70c82823b92fa80ff96021ad26db..21d46c84ab317c2d62afdf8c48117886aaf483b0
> 100644
> --- a/gcc/config/aarch64/aarch64-simd.md
> +++ b/gcc/config/aarch64/aarch64-simd.md
> @@ -386,6 +386,87 @@
> }
> )
>
> +;; These instructions map to the __builtins for the Dot Product operations.
> +(define_insn "aarch64_<sur>dot<dot_mode>"
> + [(set (match_operand:VS 0 "register_operand" "=w")
> + (unspec:VS [(match_operand:VS 1 "register_operand" "0")
> + (match_operand:<DOT_MODE> 2 "register_operand" "w")
> + (match_operand:<DOT_MODE> 3 "register_operand" "w")]
> + DOTPROD))]
> + "TARGET_DOTPROD"
> + "<sur>dot\\t%0.<Vtype>, %2.<Vdottype>, %3.<Vdottype>"
> + [(set_attr "type" "neon_dot")]
Would there be a small benefit in modelling this as:
[(set (match_operand:VS 0 "register_operand" "=w")
(add:VS ((match_operand:VS 1 "register_operand" "0")
(unsepc:VS [(match_operand:<DOT_MODE> 2 "register_operand" "w")
(match_operand:<DOT_MODE> 3 "register_operand" "w")]
DOTPROD)))]
> +)
> +
> +;; These expands map to the Dot Product optab the vectorizer checks for.
> +;; The auto-vectorizer expects a dot product builtin that also does an
> +;; accumulation into the provided register.
> +;; Given the following pattern
> +;;
> +;; for (i=0; i<len; i++) {
> +;; c = a[i] * b[i];
> +;; r += c;
> +;; }
> +;; return result;
> +;;
> +;; This can be auto-vectorized to
> +;; r = a[0]*b[0] + a[1]*b[1] + a[2]*b[2] + a[3]*b[3];
> +;;
> +;; given enough iterations. However the vectorizer can keep unrolling the
> loop
> +;; r += a[4]*b[4] + a[5]*b[5] + a[6]*b[6] + a[7]*b[7];
> +;; r += a[8]*b[8] + a[9]*b[9] + a[10]*b[10] + a[11]*b[11];
> +;; ...
> +;;
> +;; and so the vectorizer provides r, in which the result has to be
> accumulated.
> +(define_expand "<sur>dot_prod<dot_mode>"
> + [(set (match_operand:VS 0 "register_operand")
> + (unspec:VS [(match_operand:<DOT_MODE> 1 "register_operand")
> + (match_operand:<DOT_MODE> 2 "register_operand")
> + (match_operand:VS 3 "register_operand")]
> + DOTPROD))]
This is just an expand that always ends in a DONE, so doesn't need the
full description here, just:
[(match_operand:VS 0 "register_operand)
(match_operand:<DOT_MODE> 1 "register_operand")
(match_operand:<DOT_MODE> 2 "register_operand")
(match_operand:VS 3 "register_operand")]
> diff --git a/gcc/config/aarch64/iterators.md b/gcc/config/aarch64/iterators.md
> index
> cceb57525c7aa44933419bd317b1f03a7b76f4c4..533c12cca916669195e9b094527ee0de31542b12
> 100644
> --- a/gcc/config/aarch64/iterators.md
> +++ b/gcc/config/aarch64/iterators.md
> @@ -354,6 +354,8 @@
> UNSPEC_SQRDMLSH ; Used in aarch64-simd.md.
> UNSPEC_FMAXNM ; Used in aarch64-simd.md.
> UNSPEC_FMINNM ; Used in aarch64-simd.md.
> + UNSPEC_SDOT ; Used in aarch64-simd.md.
> + UNSPEC_UDOT ; Used in aarch64-simd.md.
> ])
>
> ;; ------------------------------------------------------------------
> @@ -810,6 +812,13 @@
> (define_mode_attr vsi2qi [(V2SI "v8qi") (V4SI "v16qi")])
> (define_mode_attr VSI2QI [(V2SI "V8QI") (V4SI "V16QI")])
>
> +;; Mapping attribute for Dot Product input modes based on result mode.
> +(define_mode_attr DOT_MODE [(V2SI "V8QI") (V4SI "V16QI")])
> +(define_mode_attr dot_mode [(V2SI "v8qi") (V4SI "v16qi")])
Are these not identical to the two lines above in the context?
> (define_mode_attr vsi2qi [(V2SI "v8qi") (V4SI "v16qi")])
> (define_mode_attr VSI2QI [(V2SI "V8QI") (V4SI "V16QI")])
Thanks,
James
