Akram Ahmad <akram.ah...@arm.com> writes:
> Hi Richard,
>
> Thanks for the feedback. I've copied in the resulting patch here- if
> this is okay, please could it be committed on my behalf? The patch
> continues below.
>
> Many thanks,
>
> Akram
Thanks. LGTM. Pushed to trunk.
Richard
> ---
>
> GIMPLE code which performs a narrowing truncation on the result of a
> vector concatenation currently results in an unnecessary XTN being
> emitted following a UZP1 to concate the operands. In cases such as this,
> UZP1 should instead use a smaller arrangement specifier to replace the
> XTN instruction. This is seen in cases such as in this GIMPLE example:
>
> int32x2_t foo (svint64_t a, svint64_t b)
> {
> vector(2) int vect__2.8;
> long int _1;
> long int _3;
> vector(2) long int _12;
>
> <bb 2> [local count: 1073741824]:
> _1 = svaddv_s64 ({ -1, 0, 0, 0, 0, 0, 0, 0, ... }, a_6(D));
> _3 = svaddv_s64 ({ -1, 0, 0, 0, 0, 0, 0, 0, ... }, b_7(D));
> _12 = {_1, _3};
> vect__2.8_13 = (vector(2) int) _12;
> return vect__2.8_13;
>
> }
>
> Original assembly generated:
>
> bar:
> ptrue p3.b, all
> uaddv d0, p3, z0.d
> uaddv d1, p3, z1.d
> uzp1 v0.2d, v0.2d, v1.2d
> xtn v0.2s, v0.2d
> ret
>
> This patch therefore defines the *aarch64_trunc_concat<mode> insn which
> truncates the concatenation result, rather than concatenating the
> truncated operands (such as in *aarch64_narrow_trunc<mode>), resulting
> in the following optimised assembly being emitted:
>
> bar:
> ptrue p3.b, all
> uaddv d0, p3, z0.d
> uaddv d1, p3, z1.d
> uzp1 v0.2s, v0.2s, v1.2s
> ret
>
> This patch passes all regression tests on aarch64 with no new failures.
> A supporting test for this optimisation is also written and passes.
>
> OK for master? I do not have commit rights so I cannot push the patch
> myself.
>
> gcc/ChangeLog:
>
> * config/aarch64/aarch64-simd.md: (*aarch64_trunc_concat)
> new insn definition.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/aarch64/sve/truncated_concatenation_1.c: new test
> for the above example and other modes covered by insn
> definitions.
> ---
> gcc/config/aarch64/aarch64-simd.md | 16 ++++++++++
> .../aarch64/sve/truncated_concatenation_1.c | 32 +++++++++++++++++++
> 2 files changed, 48 insertions(+)
> create mode 100644
> gcc/testsuite/gcc.target/aarch64/sve/truncated_concatenation_1.c
>
> diff --git a/gcc/config/aarch64/aarch64-simd.md
> b/gcc/config/aarch64/aarch64-simd.md
> index cfe95bd4c31..6c129d6c4a8 100644
> --- a/gcc/config/aarch64/aarch64-simd.md
> +++ b/gcc/config/aarch64/aarch64-simd.md
> @@ -1872,6 +1872,22 @@
> [(set_attr "type" "neon_permute<q>")]
> )
>
> +(define_insn "*aarch64_trunc_concat<mode>"
> + [(set (match_operand:<VNARROWQ> 0 "register_operand" "=w")
> + (truncate:<VNARROWQ>
> + (vec_concat:VQN
> + (match_operand:<VHALF> 1 "register_operand" "w")
> + (match_operand:<VHALF> 2 "register_operand" "w"))))]
> + "TARGET_SIMD"
> +{
> + if (!BYTES_BIG_ENDIAN)
> + return "uzp1\\t%0.<Vntype>, %1.<Vntype>, %2.<Vntype>";
> + else
> + return "uzp1\\t%0.<Vntype>, %2.<Vntype>, %1.<Vntype>";
> +}
> + [(set_attr "type" "neon_permute<q>")]
> +)
> +
> ;; Packing doubles.
>
> (define_expand "vec_pack_trunc_<mode>"
> diff --git a/gcc/testsuite/gcc.target/aarch64/sve/truncated_concatenation_1.c
> b/gcc/testsuite/gcc.target/aarch64/sve/truncated_concatenation_1.c
> new file mode 100644
> index 00000000000..95577a1a9ef
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/sve/truncated_concatenation_1.c
> @@ -0,0 +1,32 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -Wall -march=armv8.2-a+sve" } */
> +
> +#include <arm_neon.h>
> +#include <arm_sve.h>
> +
> +int8x8_t f1 (int16x4_t a, int16x4_t b) {
> + int8x8_t ab = vdup_n_s8 (0);
> + int16x8_t ab_concat = vcombine_s16 (a, b);
> + ab = vmovn_s16 (ab_concat);
> + return ab;
> +}
> +
> +int16x4_t f2 (int32x2_t a, int32x2_t b) {
> + int16x4_t ab = vdup_n_s16 (0);
> + int32x4_t ab_concat = vcombine_s32 (a, b);
> + ab = vmovn_s32 (ab_concat);
> + return ab;
> +}
> +
> +int32x2_t f3 (svint64_t a, svint64_t b) {
> + int32x2_t ab = vdup_n_s32 (0);
> + ab = vset_lane_s32 ((int)svaddv_s64 (svptrue_b64 (), a), ab, 0);
> + ab = vset_lane_s32 ((int)svaddv_s64 (svptrue_b64 (), b), ab, 1);
> + return ab;
> +}
> +
> +/* { dg-final { scan-assembler-not {\txtn\t} } }*/
> +/* { dg-final { scan-assembler-not {\tfcvtn\t} } }*/
> +/* { dg-final { scan-assembler-times {\tuzp1\tv[0-9]+\.8b, v[0-9]+\.8b,
> v[0-9]+\.8b} 1 } }*/
> +/* { dg-final { scan-assembler-times {\tuzp1\tv[0-9]+\.4h, v[0-9]+\.4h,
> v[0-9]+\.4h} 1 } }*/
> +/* { dg-final { scan-assembler-times {\tuzp1\tv[0-9]+\.2s, v[0-9]+\.2s,
> v[0-9]+\.2s} 1 } }*/
> \ No newline at end of file
