Re: [Qemu-devel] [PATCH v7 04/20] target/mips: Add and integrate MXU decoding engine placeholder

[Stefan Markovic <smarkovic@wavecomp.com>]

On 24.10.18. 14:18, Aleksandar Markovic wrote:
> From: Aleksandar Markovic <amarkovic@wavecomp.com>
>
> Provide the placeholder and add the invocation logic for MXU
> decoding engine.
>
> Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
> ---
>   target/mips/translate.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
>
> diff --git a/target/mips/translate.c b/target/mips/translate.c
> index fefe9ac..128cabe 100644
> --- a/target/mips/translate.c
> +++ b/target/mips/translate.c
> @@ -23844,6 +23844,12 @@ static void decode_opc_special(CPUMIPSState *env, DisasContext *ctx)
>       }
>   }
>   
> +static void decode_opc_mxu(CPUMIPSState *env, DisasContext *ctx)
> +{
> +    MIPS_INVAL("decode_opc_mxu");
> +    generate_exception_end(ctx, EXCP_RI);
> +}
> +
>   static void decode_opc_special2_legacy(CPUMIPSState *env, DisasContext *ctx)
>   {
>       int rs, rt, rd;
> @@ -26087,6 +26093,8 @@ static void decode_opc(CPUMIPSState *env, DisasContext *ctx)
>       case OPC_SPECIAL2:
>           if ((ctx->insn_flags & INSN_R5900) && (ctx->insn_flags & ASE_MMI)) {
>               decode_tx79_mmi(env, ctx);
> +        } else if (ctx->insn_flags & ASE_MXU) {
> +            decode_opc_mxu(env, ctx);


Is the best way to implement this to include processing of MUL, CLZ, 
CLO, SDDP instructions into decode_opc_mxu as their encodings aren't 
overlaid by MXU instructions

considering MIPS SPECIAL2 instruction pool and MXU Instruction Set?


>           } else {
>               decode_opc_special2_legacy(env, ctx);
>           }