Re: [PATCH] target/m68k: Implement atomic test-and-set

[Laurent Vivier <laurent@vivier.eu>]

Le 29/08/2022 à 07:17, Richard Henderson a écrit :
> This is slightly more complicated than cas,
> because tas is allowed on data registers.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   target/m68k/translate.c | 40 ++++++++++++++++++++++++++++++----------
>   1 file changed, 30 insertions(+), 10 deletions(-)
> 
> diff --git a/target/m68k/translate.c b/target/m68k/translate.c
> index 8f3c298ad0..0aef827b38 100644
> --- a/target/m68k/translate.c
> +++ b/target/m68k/translate.c
> @@ -2825,19 +2825,39 @@ DISAS_INSN(illegal)
>       gen_exception(s, s->base.pc_next, EXCP_ILLEGAL);
>   }
>   
> -/* ??? This should be atomic.  */
>   DISAS_INSN(tas)
>   {
> -    TCGv dest;
> -    TCGv src1;
> -    TCGv addr;
> +    int mode = extract32(insn, 3, 3);
> +    int reg0 = REG(insn, 0);
>   
> -    dest = tcg_temp_new();
> -    SRC_EA(env, src1, OS_BYTE, 1, &addr);
> -    gen_logic_cc(s, src1, OS_BYTE);
> -    tcg_gen_ori_i32(dest, src1, 0x80);
> -    DEST_EA(env, insn, OS_BYTE, dest, &addr);
> -    tcg_temp_free(dest);
> +    if (mode == 0) {
> +        /* data register direct */
> +        TCGv dest = cpu_dregs[reg0];
> +        gen_logic_cc(s, dest, OS_BYTE);
> +        tcg_gen_ori_tl(dest, dest, 0x80);
> +    } else {
> +        TCGv src1, addr;
> +
> +        addr = gen_lea_mode(env, s, mode, reg0, OS_BYTE);
> +        if (IS_NULL_QREG(addr)) {
> +            gen_addr_fault(s);
> +            return;
> +        }
> +        src1 = tcg_temp_new();
> +        tcg_gen_atomic_fetch_or_tl(src1, addr, tcg_constant_tl(0x80),
> +                                   IS_USER(s), MO_SB);
> +        gen_logic_cc(s, src1, OS_BYTE);
> +        tcg_temp_free(src1);
> +
> +        switch (mode) {
> +        case 3: /* Indirect postincrement.  */
> +            tcg_gen_addi_i32(AREG(insn, 0), addr, 1);
> +            break;
> +        case 4: /* Indirect predecrememnt.  */
> +            tcg_gen_mov_i32(AREG(insn, 0), addr);
> +            break;
> +        }
> +    }
>   }
>   
>   DISAS_INSN(mull)

Applied to my m68k-for-7.2 branch

Thanks,
Laurent