Re: [PATCH 2/3] target/mips: implement Octeon-specific BBIT instructions

[Richard Henderson]

On 6/7/22 01:59, Pavel Dovgalyuk wrote:
> +# Branch on bit set or clear
> +# BBIT0      110010 ..... ..... ................
> +# BBIT032    110110 ..... ..... ................
> +# BBIT1      111010 ..... ..... ................
> +# BBIT132    111110 ..... ..... ................
> +
> +BBIT         11 set:1 shift:1 10 rs:5 p:5 offset:16

shift + p are logically one field -- all you need to do is concatenate them.

%bbit_p         28:1 16:5
BBIT            11 set:1 . 10 rs:5 ..... offset:16  p=%bbit_p

> +    if (ctx->hflags & MIPS_HFLAG_BMASK) {
> +#ifdef MIPS_DEBUG_DISAS
> +        LOG_DISAS("Branch in delay / forbidden slot at PC 0x"
> +                  TARGET_FMT_lx "\n", ctx->base.pc_next);
> +#endif

Ifdef isn't needed -- it's always defined, even to 0.

> +    tcg_gen_andi_tl(t0, t0, 1ULL << p);
> +
> +    /* Jump conditions */
> +    if (a->set) {
> +        tcg_gen_setcondi_tl(TCG_COND_NE, bcond, t0, 0);
> +    } else {
> +        tcg_gen_setcondi_tl(TCG_COND_EQ, bcond, t0, 0);
> +    }

You don't need to produce a boolean, MIPS_HFLAG_BC tests for non-zero.  Thus you can 
simplify this to

    p = tcg_constant_tl(1ull << a->p);
    if (a->set) {
        tcg_gen_and_tl(bcond, rs, p);
    } else {
        tcg_gen_andc_tl(bcond, p, rs);
    }


r~