Re: [Qemu-arm] [PATCH v1 03/12] target/arm: Decode aa64 armv8.1 scalar three same extra

["Alex Bennée" <alex.bennee@linaro.org>]

Richard Henderson <richard.henderson@linaro.org> writes:

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  target/arm/helper.h         |   4 ++
>  target/arm/advsimd_helper.c | 105 ++++++++++++++++++++++++++++++++++++++++++++
>  target/arm/translate-a64.c  |  90 +++++++++++++++++++++++++++++++++++++
>  target/arm/Makefile.objs    |   2 +-
>  4 files changed, 200 insertions(+), 1 deletion(-)
>  create mode 100644 target/arm/advsimd_helper.c
>
> diff --git a/target/arm/helper.h b/target/arm/helper.h
> index 64afbac59f..ec098d8337 100644
> --- a/target/arm/helper.h
> +++ b/target/arm/helper.h
> @@ -350,8 +350,12 @@ DEF_HELPER_FLAGS_1(neon_rbit_u8, TCG_CALL_NO_RWG_SE, i32, i32)
>
>  DEF_HELPER_3(neon_qdmulh_s16, i32, env, i32, i32)
>  DEF_HELPER_3(neon_qrdmulh_s16, i32, env, i32, i32)
> +DEF_HELPER_4(neon_qrdmlah_s16, i32, env, i32, i32, i32)
> +DEF_HELPER_4(neon_qrdmlsh_s16, i32, env, i32, i32, i32)
>  DEF_HELPER_3(neon_qdmulh_s32, i32, env, i32, i32)
>  DEF_HELPER_3(neon_qrdmulh_s32, i32, env, i32, i32)
> +DEF_HELPER_4(neon_qrdmlah_s32, i32, env, s32, s32, s32)
> +DEF_HELPER_4(neon_qrdmlsh_s32, i32, env, s32, s32, s32)

Hmm are these really NEON or should they be advsimd_qrdm....?

>
>  DEF_HELPER_1(neon_narrow_u8, i32, i64)
>  DEF_HELPER_1(neon_narrow_u16, i32, i64)
> diff --git a/target/arm/advsimd_helper.c b/target/arm/advsimd_helper.c
> new file mode 100644
> index 0000000000..583c2b0dce
> --- /dev/null
> +++ b/target/arm/advsimd_helper.c
> @@ -0,0 +1,105 @@
> +/*
> + *  ARM AdvSIMD Vector Operations
> + *
> + *  Copyright (c) 2017 Linaro
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "cpu.h"
> +#include "exec/exec-all.h"
> +#include "exec/helper-proto.h"
> +#include "tcg/tcg-gvec-desc.h"
> +
> +
> +#define SET_QC() env->vfp.xregs[ARM_VFP_FPSCR] |= CPSR_Q
> +
> +static uint16_t inl_qrdmlah_s16(CPUARMState *env, int16_t src1,
> +                                int16_t src2, int16_t src3)
> +{
> +    /* Simplify:
> +     * = ((a3 << 16) + ((e1 * e2) << 1) + (1 << 15)) >> 16
> +     * = ((a3 << 15) + (e1 * e2) + (1 << 14)) >> 15
> +     */
> +    int32_t ret = (int32_t)src1 * src2;
> +    ret = ((int32_t)src3 << 15) + ret + (1 << 14);
> +    ret >>= 15;
> +    if (ret != (int16_t)ret) {
> +        SET_QC();
> +        ret = (ret < 0 ? -0x8000 : 0x7fff);
> +    }
> +    return ret;
> +}
> +
> +uint32_t HELPER(neon_qrdmlah_s16)(CPUARMState *env, uint32_t src1,
> +                                  uint32_t src2, uint32_t src3)
> +{
> +    uint16_t e1 = inl_qrdmlah_s16(env, src1, src2, src3);
> +    uint16_t e2 = inl_qrdmlah_s16(env, src1 >> 16, src2 >> 16, src3 >> 16);
> +    return deposit32(e1, 16, 16, e2);
> +}
> +
> +static uint16_t inl_qrdmlsh_s16(CPUARMState *env, int16_t src1,
> +                                int16_t src2, int16_t src3)
> +{
> +    /* Similarly, using subtraction:
> +     * = ((a3 << 16) - ((e1 * e2) << 1) + (1 << 15)) >> 16
> +     * = ((a3 << 15) - (e1 * e2) + (1 << 14)) >> 15
> +     */
> +    int32_t ret = (int32_t)src1 * src2;
> +    ret = ((int32_t)src3 << 15) - ret + (1 << 14);
> +    ret >>= 15;
> +    if (ret != (int16_t)ret) {
> +        SET_QC();
> +        ret = (ret < 0 ? -0x8000 : 0x7fff);
> +    }
> +    return ret;
> +}
> +
> +uint32_t HELPER(neon_qrdmlsh_s16)(CPUARMState *env, uint32_t src1,
> +                                  uint32_t src2, uint32_t src3)
> +{
> +    uint16_t e1 = inl_qrdmlsh_s16(env, src1, src2, src3);
> +    uint16_t e2 = inl_qrdmlsh_s16(env, src1 >> 16, src2 >> 16, src3 >> 16);
> +    return deposit32(e1, 16, 16, e2);
> +}
> +
> +uint32_t HELPER(neon_qrdmlah_s32)(CPUARMState *env, int32_t src1,
> +                                  int32_t src2, int32_t src3)
> +{
> +    /* Simplify similarly to int_qrdmlah_s16 above.  */
> +    int64_t ret = (int64_t)src1 * src2;
> +    ret = ((int64_t)src3 << 31) + ret + (1 << 30);
> +    ret >>= 31;
> +    if (ret != (int32_t)ret) {
> +        SET_QC();
> +        ret = (ret < 0 ? INT32_MIN : INT32_MAX);
> +    }
> +    return ret;
> +}
> +
> +uint32_t HELPER(neon_qrdmlsh_s32)(CPUARMState *env, int32_t src1,
> +                                  int32_t src2, int32_t src3)
> +{
> +    /* Simplify similarly to int_qrdmlsh_s16 above.  */
> +    int64_t ret = (int64_t)src1 * src2;
> +    ret = ((int64_t)src3 << 31) - ret + (1 << 30);
> +    ret >>= 31;
> +    if (ret != (int32_t)ret) {
> +        SET_QC();
> +        ret = (ret < 0 ? INT32_MIN : INT32_MAX);
> +    }
> +    return ret;
> +}
> diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
> index a4380bbb15..182853e3bb 100644
> --- a/target/arm/translate-a64.c
> +++ b/target/arm/translate-a64.c
> @@ -7596,6 +7596,95 @@ static void disas_simd_scalar_three_reg_same(DisasContext *s, uint32_t insn)
>      tcg_temp_free_i64(tcg_rd);
>  }
>
> +/* AdvSIMD scalar three same extra
> + *  31 30  29 28       24 23  22  21 20  16  15 14    11  10 9  5 4  0
> + * +-----+---+-----------+------+---+------+---+--------+---+----+----+
> + * | 0 1 | U | 1 1 1 1 0 | size | 0 |  Rm  | 1 | opcode | 1 | Rn | Rd |
> + * +-----+---+-----------+------+---+------+---+--------+---+----+----+
> + */
> +static void disas_simd_scalar_three_reg_same_extra(DisasContext *s,
> +                                                   uint32_t insn)
> +{
> +    int rd = extract32(insn, 0, 5);
> +    int rn = extract32(insn, 5, 5);
> +    int opcode = extract32(insn, 11, 4);
> +    int rm = extract32(insn, 16, 5);
> +    int size = extract32(insn, 22, 2);
> +    bool u = extract32(insn, 29, 1);
> +    TCGv_i32 ele1, ele2, ele3;
> +    TCGv_i64 res;
> +    int feature;
> +
> +    if (!u) {
> +        unallocated_encoding(s);
> +        return;
> +    }
> +
> +    switch (opcode) {
> +    case 0x0: /* SQRDMLAH (vector) */
> +    case 0x1: /* SQRDMLSH (vector) */
> +        if (size != 1 && size != 2) {
> +            unallocated_encoding(s);
> +            return;
> +        }
> +        feature = ARM_FEATURE_V8_1_SIMD;
> +        break;
> +    default:
> +        unallocated_encoding(s);
> +        return;
> +    }
> +
> +    if (!arm_dc_feature(s, feature)) {
> +        unallocated_encoding(s);
> +        return;
> +    }

I guess this is because we are expecting additional features to be added
to the encoding space...

> +    if (!fp_access_check(s)) {
> +        return;
> +    }
> +
> +    /* Do a single operation on the lowest element in the vector.
> +     * We use the standard Neon helpers and rely on 0 OP 0 == 0
> +     * with no side effects for all these operations.
> +     * OPTME: special-purpose helpers would avoid doing some
> +     * unnecessary work in the helper for the 16 bit cases.
> +     */
> +    ele1 = tcg_temp_new_i32();
> +    ele2 = tcg_temp_new_i32();
> +    ele3 = tcg_temp_new_i32();
> +
> +    read_vec_element_i32(s, ele1, rn, 0, size);
> +    read_vec_element_i32(s, ele2, rm, 0, size);
> +    read_vec_element_i32(s, ele3, rd, 0, size);
> +
> +    switch (opcode) {
> +    case 0x0: /* SQRDMLAH */
> +        if (size == 1) {
> +            gen_helper_neon_qrdmlah_s16(ele3, cpu_env, ele1, ele2, ele3);
> +        } else {
> +            gen_helper_neon_qrdmlah_s32(ele3, cpu_env, ele1, ele2, ele3);
> +        }
> +        break;
> +    case 0x1: /* SQRDMLSH */
> +        if (size == 1) {
> +            gen_helper_neon_qrdmlsh_s16(ele3, cpu_env, ele1, ele2, ele3);
> +        } else {
> +            gen_helper_neon_qrdmlsh_s32(ele3, cpu_env, ele1, ele2, ele3);
> +        }
> +        break;
> +    default:
> +        g_assert_not_reached();
> +    }
> +    tcg_temp_free_i32(ele1);
> +    tcg_temp_free_i32(ele2);
> +
> +    res = tcg_temp_new_i64();
> +    tcg_gen_extu_i32_i64(res, ele3);
> +    tcg_temp_free_i32(ele3);
> +
> +    write_fp_dreg(s, rd, res);
> +    tcg_temp_free_i64(res);
> +}
> +
>  static void handle_2misc_64(DisasContext *s, int opcode, bool u,
>                              TCGv_i64 tcg_rd, TCGv_i64 tcg_rn,
>                              TCGv_i32 tcg_rmode, TCGv_ptr tcg_fpstatus)
> @@ -11184,6 +11273,7 @@ static const AArch64DecodeTable data_proc_simd[] = {
>      { 0x0e000800, 0xbf208c00, disas_simd_zip_trn },
>      { 0x2e000000, 0xbf208400, disas_simd_ext },
>      { 0x5e200400, 0xdf200400, disas_simd_scalar_three_reg_same },
> +    { 0x5e008400, 0xdf208400, disas_simd_scalar_three_reg_same_extra },
>      { 0x5e200000, 0xdf200c00, disas_simd_scalar_three_reg_diff },
>      { 0x5e200800, 0xdf3e0c00, disas_simd_scalar_two_reg_misc },
>      { 0x5e300800, 0xdf3e0c00, disas_simd_scalar_pairwise },
> diff --git a/target/arm/Makefile.objs b/target/arm/Makefile.objs
> index 847fb52ee0..c2d32988f9 100644
> --- a/target/arm/Makefile.objs
> +++ b/target/arm/Makefile.objs
> @@ -5,7 +5,7 @@ obj-$(call land,$(CONFIG_KVM),$(call lnot,$(TARGET_AARCH64))) += kvm32.o
>  obj-$(call land,$(CONFIG_KVM),$(TARGET_AARCH64)) += kvm64.o
>  obj-$(call lnot,$(CONFIG_KVM)) += kvm-stub.o
>  obj-y += translate.o op_helper.o helper.o cpu.o
> -obj-y += neon_helper.o iwmmxt_helper.o
> +obj-y += neon_helper.o iwmmxt_helper.o advsimd_helper.o

Given this is AArch64 only it makes me wonder if we should be using helper-a64.h?

>  obj-y += gdbstub.o
>  obj-$(TARGET_AARCH64) += cpu64.o translate-a64.o helper-a64.o gdbstub64.o
>  obj-y += crypto_helper.o


--
Alex Bennée