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

[Philippe Mathieu-Daudé]

On 6/14/21 10:37 AM, Richard Henderson 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.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  include/tcg/tcg-opc.h | 10 +++++-----
>  include/tcg/tcg.h     | 12 ++++++++++++
>  tcg/tcg-op.c          | 13 ++++++++-----
>  tcg/README            | 18 ++++++++++--------
>  4 files changed, 35 insertions(+), 18 deletions(-)

> +/*
> + * Flags for the bswap opcodes.
> + * If IZ, the input is zero-extended, otherwise unknown.
> + * If OZ or OS, the output is zero- or sign-extended respectively,
> + * otherwise the high bits are undefined.
> + */
> +enum {
> +    TCG_BSWAP_IZ = 1,
> +    TCG_BSWAP_OZ = 2,
> +    TCG_BSWAP_OS = 4,

Matter of taste, I find "1 << x" bullet proof for flags.

Otherwise:
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>