Re: [PATCH v2 2/8] Add support for emulation of CRC32 instructions

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Hi Aleksandar,

On 18/10/24 10:19, Aleksandar Rakic wrote:
> Add emulation of MIPS' CRC32 (Cyclic Redundancy Check) instructions.
> Reuse zlib crc32() and Linux crc32c().
> 
> Cherry-picked 4cc974938aee1588f852590509004e340c072940
> from https://github.com/MIPS/gnutools-qemu
> 
> Signed-off-by: Yongbok Kim <yongbok.kim@mips.com>
> Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
> Signed-off-by: Aleksandar Rakic <aleksandar.rakic@htecgroup.com>
> ---
>   target/mips/helper.h        |  2 ++
>   target/mips/meson.build     |  1 +
>   target/mips/tcg/op_helper.c | 26 ++++++++++++++++++++++++++
>   target/mips/tcg/translate.c | 37 +++++++++++++++++++++++++++++++++++++
>   target/mips/tcg/translate.h |  1 +
>   5 files changed, 67 insertions(+)


> diff --git a/target/mips/tcg/translate.c b/target/mips/tcg/translate.c
> index 333469b268..256fa0893e 100644
> --- a/target/mips/tcg/translate.c
> +++ b/target/mips/tcg/translate.c
> @@ -430,6 +430,7 @@ enum {
>       OPC_LWE            = 0x2F | OPC_SPECIAL3,
>   
>       /* R6 */
> +    OPC_CRC32          = 0x0F | OPC_SPECIAL3,
>       R6_OPC_PREF        = 0x35 | OPC_SPECIAL3,
>       R6_OPC_CACHE       = 0x25 | OPC_SPECIAL3,
>       R6_OPC_LL          = 0x36 | OPC_SPECIAL3,


> @@ -13705,6 +13730,17 @@ static void decode_opc_special3_r6(CPUMIPSState *env, DisasContext *ctx)
>   
>       op1 = MASK_SPECIAL3(ctx->opcode);
>       switch (op1) {
> +    case OPC_CRC32:
> +        if (unlikely(!ctx->crcp) ||
> +            unlikely((extract32(ctx->opcode, 6, 2) == 3) &&
> +                     (!(ctx->hflags & MIPS_HFLAG_64))) ||
> +            unlikely((extract32(ctx->opcode, 8, 3) >= 2))) {
> +            gen_reserved_instruction(ctx);
> +        }
> +        gen_crc32(ctx, rt, rs, rt,
> +                  extract32(ctx->opcode, 6, 2),
> +                  extract32(ctx->opcode, 8, 3));
> +        break;

New opcode must be implemented in decodetree format, please
add these in target/mips/tcg/rel6* files (the change should be
trivial and should only involve modifying few lines -- see for
example commit 675bf34a6fe and around).

Thanks,

Phil.