Re: [PATCH 01/28] tcg: Add flags argument to bswap opcodes

[Peter Maydell]

On Mon, 14 Jun 2021 at 09:43, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> This will eventually simplify front-end usage, and will allow
> backends to unset TCG_TARGET_HAS_MEMORY_BSWAP without loss of
> optimization.
>
> The argument is added during expansion, not currently exposed
> to the front end translators.  Non-zero values are not yet
> supported by any backends.

Here we say non-zero values are not yet supported by the backend...

> diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c
> index dcc2ed0bbc..dc65577e2f 100644
> --- a/tcg/tcg-op.c
> +++ b/tcg/tcg-op.c
> @@ -1005,7 +1005,8 @@ void tcg_gen_ext16u_i32(TCGv_i32 ret, TCGv_i32 arg)
>  void tcg_gen_bswap16_i32(TCGv_i32 ret, TCGv_i32 arg)
>  {
>      if (TCG_TARGET_HAS_bswap16_i32) {
> -        tcg_gen_op2_i32(INDEX_op_bswap16_i32, ret, arg);
> +        tcg_gen_op3i_i32(INDEX_op_bswap16_i32, ret, arg,
> +                         TCG_BSWAP_IZ | TCG_BSWAP_OZ);
>      } else {
>          TCGv_i32 t0 = tcg_temp_new_i32();

...but here we pass a non-zero value...

> @@ -1661,7 +1662,8 @@ void tcg_gen_bswap16_i64(TCGv_i64 ret, TCGv_i64 arg)
>          tcg_gen_bswap16_i32(TCGV_LOW(ret), TCGV_LOW(arg));
>          tcg_gen_movi_i32(TCGV_HIGH(ret), 0);
>      } else if (TCG_TARGET_HAS_bswap16_i64) {
> -        tcg_gen_op2_i64(INDEX_op_bswap16_i64, ret, arg);
> +        tcg_gen_op3i_i64(INDEX_op_bswap16_i64, ret, arg,
> +                         TCG_BSWAP_IZ | TCG_BSWAP_OZ);
>      } else {
>          TCGv_i64 t0 = tcg_temp_new_i64();
>

...and again here...

> @@ -1680,7 +1682,8 @@ void tcg_gen_bswap32_i64(TCGv_i64 ret, TCGv_i64 arg)
>          tcg_gen_bswap32_i32(TCGV_LOW(ret), TCGV_LOW(arg));
>          tcg_gen_movi_i32(TCGV_HIGH(ret), 0);
>      } else if (TCG_TARGET_HAS_bswap32_i64) {
> -        tcg_gen_op2_i64(INDEX_op_bswap32_i64, ret, arg);
> +        tcg_gen_op3i_i64(INDEX_op_bswap32_i64, ret, arg,
> +                         TCG_BSWAP_IZ | TCG_BSWAP_OZ);
>      } else {
>          TCGv_i64 t0 = tcg_temp_new_i64();
>          TCGv_i64 t1 = tcg_temp_new_i64();

...and here.

thanks
-- PMM