Re: [PATCH v10 77/77] target/riscv: rvv-1.0: Add ELEN checks for widening and narrowing instructions

[Alistair Francis]

On Mon, Nov 29, 2021 at 1:54 PM <frank.chang@sifive.com> wrote:
>
> From: Frank Chang <frank.chang@sifive.com>
>
> SEW has the limitation which cannot exceed ELEN.
>
> Widening instructions have a destination group with EEW = 2*SEW
> and narrowing instructions have a source operand with EEW = 2*SEW.
> Both of the instructions have the limitation of: 2*SEW <= ELEN.
>
> Signed-off-by: Frank Chang <frank.chang@sifive.com>

Acked-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/insn_trans/trans_rvv.c.inc | 17 +++++++++++------
>  target/riscv/translate.c                |  2 ++
>  2 files changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/target/riscv/insn_trans/trans_rvv.c.inc 
> b/target/riscv/insn_trans/trans_rvv.c.inc
> index 47eb3119cbe..5e3f7fdb77c 100644
> --- a/target/riscv/insn_trans/trans_rvv.c.inc
> +++ b/target/riscv/insn_trans/trans_rvv.c.inc
> @@ -386,9 +386,10 @@ static bool vext_check_mss(DisasContext *s, int vd, int 
> vs1, int vs2)
>   *      can not be greater than 8 vector registers (Section 5.2):
>   *      => LMUL < 8.
>   *      => SEW < 64.
> - *   2. Destination vector register number is multiples of 2 * LMUL.
> + *   2. Double-width SEW cannot greater than ELEN.
> + *   3. Destination vector register number is multiples of 2 * LMUL.
>   *      (Section 3.4.2)
> - *   3. Destination vector register group for a masked vector
> + *   4. Destination vector register group for a masked vector
>   *      instruction cannot overlap the source mask register (v0).
>   *      (Section 5.3)
>   */
> @@ -396,6 +397,7 @@ static bool vext_wide_check_common(DisasContext *s, int 
> vd, int vm)
>  {
>      return (s->lmul <= 2) &&
>             (s->sew < MO_64) &&
> +           ((s->sew + 1) <= (s->elen >> 4)) &&
>             require_align(vd, s->lmul + 1) &&
>             require_vm(vm, vd);
>  }
> @@ -409,11 +411,12 @@ static bool vext_wide_check_common(DisasContext *s, int 
> vd, int vm)
>   *      can not be greater than 8 vector registers (Section 5.2):
>   *      => LMUL < 8.
>   *      => SEW < 64.
> - *   2. Source vector register number is multiples of 2 * LMUL.
> + *   2. Double-width SEW cannot greater than ELEN.
> + *   3. Source vector register number is multiples of 2 * LMUL.
>   *      (Section 3.4.2)
> - *   3. Destination vector register number is multiples of LMUL.
> + *   4. Destination vector register number is multiples of LMUL.
>   *      (Section 3.4.2)
> - *   4. Destination vector register group for a masked vector
> + *   5. Destination vector register group for a masked vector
>   *      instruction cannot overlap the source mask register (v0).
>   *      (Section 5.3)
>   */
> @@ -422,6 +425,7 @@ static bool vext_narrow_check_common(DisasContext *s, int 
> vd, int vs2,
>  {
>      return (s->lmul <= 2) &&
>             (s->sew < MO_64) &&
> +           ((s->sew + 1) <= (s->elen >> 4)) &&
>             require_align(vs2, s->lmul + 1) &&
>             require_align(vd, s->lmul) &&
>             require_vm(vm, vd);
> @@ -2806,7 +2810,8 @@ GEN_OPIVV_TRANS(vredxor_vs, reduction_check)
>  /* Vector Widening Integer Reduction Instructions */
>  static bool reduction_widen_check(DisasContext *s, arg_rmrr *a)
>  {
> -    return reduction_check(s, a) && (s->sew < MO_64);
> +    return reduction_check(s, a) && (s->sew < MO_64) &&
> +           ((s->sew + 1) <= (s->elen >> 4));
>  }
>
>  GEN_OPIVV_WIDEN_TRANS(vwredsum_vs, reduction_widen_check)
> diff --git a/target/riscv/translate.c b/target/riscv/translate.c
> index 68edaaf6ac7..5df6c0d800b 100644
> --- a/target/riscv/translate.c
> +++ b/target/riscv/translate.c
> @@ -96,6 +96,7 @@ typedef struct DisasContext {
>      int8_t lmul;
>      uint8_t sew;
>      uint16_t vlen;
> +    uint16_t elen;
>      target_ulong vstart;
>      bool vl_eq_vlmax;
>      uint8_t ntemp;
> @@ -705,6 +706,7 @@ static void riscv_tr_init_disas_context(DisasContextBase 
> *dcbase, CPUState *cs)
>      ctx->ext_zfh = cpu->cfg.ext_zfh;
>      ctx->ext_zfhmin = cpu->cfg.ext_zfhmin;
>      ctx->vlen = cpu->cfg.vlen;
> +    ctx->elen = cpu->cfg.elen;
>      ctx->mstatus_hs_fs = FIELD_EX32(tb_flags, TB_FLAGS, MSTATUS_HS_FS);
>      ctx->mstatus_hs_vs = FIELD_EX32(tb_flags, TB_FLAGS, MSTATUS_HS_VS);
>      ctx->hlsx = FIELD_EX32(tb_flags, TB_FLAGS, HLSX);
> --
> 2.25.1
>
>