Re: [PATCH 28/67] target/arm: Convert BFCVT to decodetree

[Peter Maydell]

On Sun, 1 Dec 2024 at 15:11, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  target/arm/tcg/translate-a64.c | 24 ++++++------------------
>  target/arm/tcg/a64.decode      |  3 +++
>  2 files changed, 9 insertions(+), 18 deletions(-)
>
> @@ -8661,21 +8664,6 @@ static void disas_fp_1src(DisasContext *s, uint32_t 
> insn)
>          break;
>
>      case 0x6:
> -        switch (type) {
> -        case 1: /* BFCVT */

Here we decode BFCVT when the 'ftype' field (bits [23:22]) is 0b01...

> -            if (!dc_isar_feature(aa64_bf16, s)) {
> -                goto do_unallocated;
> -            }
> -            if (!fp_access_check(s)) {
> -                return;
> -            }
> -            handle_fp_1src_single(s, opcode, rd, rn);
> -            break;
> -        default:
> -            goto do_unallocated;
> -        }
> -        break;
> -
>      default:
>      do_unallocated:
>          unallocated_encoding(s);
> diff --git a/target/arm/tcg/a64.decode b/target/arm/tcg/a64.decode
> index fbfdf96eb3..476989c1b4 100644
> --- a/target/arm/tcg/a64.decode
> +++ b/target/arm/tcg/a64.decode
> @@ -45,6 +45,7 @@
>  &qrrrr_e        q rd rn rm ra esz
>
>  @rr_h           ........ ... ..... ...... rn:5 rd:5     &rr_e esz=1
> +@rr_s           ........ ... ..... ...... rn:5 rd:5     &rr_e esz=2
>  @rr_d           ........ ... ..... ...... rn:5 rd:5     &rr_e esz=3
>  @rr_sd          ........ ... ..... ...... rn:5 rd:5     &rr_e esz=%esz_sd
>  @rr_hsd         ........ ... ..... ...... rn:5 rd:5     &rr_e esz=%esz_hsd
> @@ -1337,6 +1338,8 @@ FRINTA_s        00011110 .. 1 001100 10000 ..... .....  
>     @rr_hsd
>  FRINTX_s        00011110 .. 1 001110 10000 ..... .....      @rr_hsd
>  FRINTI_s        00011110 .. 1 001111 10000 ..... .....      @rr_hsd
>
> +BFCVT_s         00011110 10 1 000110 10000 ..... .....      @rr_s

...but this decode pattern has them as 0b10.


--- a/target/arm/tcg/a64.decode
+++ b/target/arm/tcg/a64.decode
@@ -1338,7 +1338,7 @@ FRINTA_s        00011110 .. 1 001100 10000 .....
.....      @rr_hsd
 FRINTX_s        00011110 .. 1 001110 10000 ..... .....      @rr_hsd
 FRINTI_s        00011110 .. 1 001111 10000 ..... .....      @rr_hsd

-BFCVT_s         00011110 10 1 000110 10000 ..... .....      @rr_s
+BFCVT_s         00011110 01 1 000110 10000 ..... .....      @rr_s

 # Floating-point Immediate

should fix this.

thanks
-- PMM