Re: [PATCH v3 14/29] tcg/mips: Support bswap flags in tcg_out_bswap16

["Philippe Mathieu-Daudé" <f4bug@amsat.org>]

On 6/26/21 8:36 AM, Richard Henderson wrote:
> Merge tcg_out_bswap16 and tcg_out_bswap16s.  Use the flags
> in the internal uses for loads and stores.
> 
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  tcg/mips/tcg-target.c.inc | 63 +++++++++++++++++++--------------------
>  1 file changed, 30 insertions(+), 33 deletions(-)

> -static inline void tcg_out_bswap16(TCGContext *s, TCGReg ret, TCGReg arg)
> +static void tcg_out_bswap16(TCGContext *s, TCGReg ret, TCGReg arg, int flags)
>  {
> +    /* ret and arg can't be register tmp0 */
> +    tcg_debug_assert(ret != TCG_TMP0);
> +    tcg_debug_assert(arg != TCG_TMP0);
> +
> +    /* With arg = abcd: */
>      if (use_mips32r2_instructions) {
> -        tcg_out_opc_reg(s, OPC_WSBH, ret, 0, arg);
> -    } else {
> -        /* ret and arg can't be register at */
> -        if (ret == TCG_TMP0 || arg == TCG_TMP0) {
> -            tcg_abort();
> +        tcg_out_opc_reg(s, OPC_WSBH, ret, 0, arg);                 /* badc */
> +        if (flags & TCG_BSWAP_OS) {
> +            tcg_out_opc_reg(s, OPC_SEH, ret, 0, ret);              /* ssdc */
> +        } else if ((flags & (TCG_BSWAP_IZ | TCG_BSWAP_OZ)) == TCG_BSWAP_OZ) {
> +            tcg_out_opc_imm(s, OPC_ANDI, ret, ret, 0xffff);        /* 00dc */
>          }
> -
> -        tcg_out_opc_sa(s, OPC_SRL, TCG_TMP0, arg, 8);
> -        tcg_out_opc_sa(s, OPC_SLL, ret, arg, 8);
> -        tcg_out_opc_imm(s, OPC_ANDI, ret, ret, 0xff00);
> -        tcg_out_opc_reg(s, OPC_OR, ret, ret, TCG_TMP0);
> +        return;
>      }
> -}
>  
> -static inline void tcg_out_bswap16s(TCGContext *s, TCGReg ret, TCGReg arg)
> -{
> -    if (use_mips32r2_instructions) {
> -        tcg_out_opc_reg(s, OPC_WSBH, ret, 0, arg);
> -        tcg_out_opc_reg(s, OPC_SEH, ret, 0, ret);
> +    tcg_out_opc_sa(s, OPC_SRL, TCG_TMP0, arg, 8);                  /* 0abc */
> +    if (!(flags & TCG_BSWAP_IZ)) {
> +        tcg_out_opc_imm(s, OPC_ANDI, TCG_TMP0, TCG_TMP0, 0x00ff);  /* 000c */
> +    }
> +    if (flags & TCG_BSWAP_OS) {
> +        tcg_out_opc_sa(s, OPC_SLL, ret, arg, 24);                  /* d000 */
> +        tcg_out_opc_sa(s, OPC_SRA, ret, ret, 16);                  /* ssd0 */
>      } else {
> -        /* ret and arg can't be register at */
> -        if (ret == TCG_TMP0 || arg == TCG_TMP0) {
> -            tcg_abort();
> +        tcg_out_opc_sa(s, OPC_SLL, ret, arg, 8);                   /* bcd0 */
> +        if (flags & TCG_BSWAP_OZ) {
> +            tcg_out_opc_imm(s, OPC_ANDI, ret, ret, 0xff00);        /* 00d0 */
>          }
> -
> -        tcg_out_opc_sa(s, OPC_SRL, TCG_TMP0, arg, 8);
> -        tcg_out_opc_sa(s, OPC_SLL, ret, arg, 24);
> -        tcg_out_opc_sa(s, OPC_SRA, ret, ret, 16);
> -        tcg_out_opc_reg(s, OPC_OR, ret, ret, TCG_TMP0);
>      }
> +    tcg_out_opc_reg(s, OPC_OR, ret, ret, TCG_TMP0);                /* ssdc */
>  }

Thanks for adding the comments!