On 27/06/2022 20:05, Luc Van Oostenryck wrote:
> Currently, the only value bitwise types can act on is 0
> because the this value is anyway invariant for all bitwise
s/the this/this/
s/anyway//
ATB,
Ramsay Jones
> operations and endianness conversions.
>
> But, a bit-pattern of all ones has the same properties and
> is also very often used.
>
> So, accept all ones as a valid value for bitwise operations.
>
> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
> ---
> evaluate.c | 2 +-
> validation/bitwise-cast.c | 13 +++++++++++++
> 2 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/evaluate.c b/evaluate.c
> index 61f59ee3908e..bcbcdf1ef0cc 100644
> --- a/evaluate.c
> +++ b/evaluate.c
> @@ -417,7 +417,7 @@ static int restricted_value(struct expression *v, struct symbol *type)
> {
> if (v->type != EXPR_VALUE)
> return 1;
> - if (v->value != 0)
> + if (v->value != 0 && v->value != bits_mask(type->bit_size))
> return 1;
> return 0;
> }
> diff --git a/validation/bitwise-cast.c b/validation/bitwise-cast.c
> index 0583461cb745..1075a3e9410c 100644
> --- a/validation/bitwise-cast.c
> +++ b/validation/bitwise-cast.c
> @@ -35,6 +35,19 @@ static __be32 quuy(void)
> return (__attribute__((force)) __be32) 1730;
> }
>
> +/* Implicit casts of all ones, legal */
> +static __be32 foo1(void)
> +{
> + __be32 x = 0xffffffff;
> + return x;
> +}
> +
> +/* Explicit cast of all ones, legal */
> +static __be32 bar1(void)
> +{
> + return (__be32)0xffffffff;
> +}
> +
> /*
> * check-name: conversions to bitwise types
> * check-command: sparse -Wbitwise $file
