Re: [PATCH v2 14/35] tcg/i386: Support TCG_COND_TST{EQ,NE}

[Philippe Mathieu-Daudé]

On 28/10/23 21:45, Richard Henderson wrote:
> Merge tcg_out_testi into tcg_out_cmp and adjust the two uses.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   tcg/i386/tcg-target.c.inc | 83 ++++++++++++++++++++++-----------------
>   1 file changed, 47 insertions(+), 36 deletions(-)


>   #if TCG_TARGET_REG_BITS == 64
> @@ -1422,15 +1424,35 @@ static void tcg_out_jxx(TCGContext *s, int opc, 
> TCGLabel *l, bool small)
>   static int tcg_out_cmp(TCGContext *s, TCGCond cond, TCGArg arg1,
>                          TCGArg arg2, int const_arg2, int rexw)
>   {
> -    if (const_arg2) {
> -        if (arg2 == 0) {
> -            /* test r, r */
> -            tcg_out_modrm(s, OPC_TESTL + rexw, arg1, arg1);
> +    if (is_tst_cond(cond)) {
> +        if (!const_arg2) {
> +            tcg_out_modrm(s, OPC_TESTL + rexw, arg1, arg2);
> +        } else if (arg2 <= 0xff && (TCG_TARGET_REG_BITS == 64 || arg1 < 4)) {
> +            tcg_out_modrm(s, OPC_GRP3_Eb | P_REXB_RM, EXT3_TESTi, arg1);
> +            tcg_out8(s, arg2);
> +        } else if ((arg2 & ~0xff00) == 0 && arg1 < 4) {
> +            tcg_out_modrm(s, OPC_GRP3_Eb, EXT3_TESTi, arg1 + 4);
> +            tcg_out8(s, arg2 >> 8);
>           } else {

For this part, a double-review from x86 developer is welcomed,

> -            tgen_arithi(s, ARITH_CMP + rexw, arg1, arg2, 0);
> +            if (rexw) {
> +                if (arg2 == (uint32_t)arg2) {
> +                    rexw = 0;
> +                } else {
> +                    tcg_debug_assert(arg2 == (int32_t)arg2);
> +                }
> +            }
> +            tcg_out_modrm(s, OPC_GRP3_Ev + rexw, EXT3_TESTi, arg1);
> +            tcg_out32(s, arg2);
>           }
>       } else {

then the rest is OK.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>