On 14.10.2013 15:02, Dan Carpenter wrote:
> On Fri, Oct 11, 2013 at 02:04:07PM +0200, Peter Oberparleiter wrote:
>> Running smatch on s390x incorrectly reports impossible conditions when
>> comparing variables of type 'char' with constant values larger than 127,
>> even though 'char' is implemented on s390x as unsigned type.
>>
>> A solution to this problem might be to use the __CHAR__UNSIGNED__ macro [1]
>> to determine the correct signedness of the 'char' type at compile time.
>
> Smatch used to try figure out type information manually but these days
> it hopefully should be using the information from Sparse. I'm not sure
> if all the crud has been totally deleted. Does this patch work?
Sorry, my bad - the macro is actually spelled __CHAR_UNSIGNED__ (no double
underscore in the middle). Using the corrected macro name, the patch fixes
the problem (tested on latest git). Thanks!
>
> diff --git a/symbol.c b/symbol.c
> index 0427a23..6ec25c2 100644
> --- a/symbol.c
> +++ b/symbol.c
> @@ -789,6 +789,12 @@ void init_symbols(void)
> }
> }
>
> +#ifdef __CHAR__UNSIGNED__
> +#define CHAR_SIGNEDNESS MOD_UNSIGNED
> +#else
> +#define CHAR_SIGNEDNESS MOD_SIGNED
> +#endif
> +
> #define MOD_ESIGNED (MOD_SIGNED | MOD_EXPLICITLY_SIGNED)
> #define MOD_LL (MOD_LONG | MOD_LONGLONG)
> #define MOD_LLL MOD_LONGLONGLONG
> @@ -806,7 +812,7 @@ static const struct ctype_declare {
> { &incomplete_ctype,SYM_BASETYPE, 0, NULL, NULL, NULL },
> { &bad_ctype, SYM_BASETYPE, 0, NULL, NULL, NULL },
>
> - { &char_ctype, SYM_BASETYPE, MOD_SIGNED | MOD_CHAR, &bits_in_char, &max_int_alignment, &int_type },
> + { &char_ctype, SYM_BASETYPE, CHAR_SIGNEDNESS | MOD_CHAR, &bits_in_char, &max_int_alignment, &int_type },
> { &schar_ctype, SYM_BASETYPE, MOD_ESIGNED | MOD_CHAR, &bits_in_char, &max_int_alignment, &int_type },
> { &uchar_ctype, SYM_BASETYPE, MOD_UNSIGNED | MOD_CHAR, &bits_in_char, &max_int_alignment, &int_type },
> { &short_ctype, SYM_BASETYPE, MOD_SIGNED | MOD_SHORT, &bits_in_short, &max_int_alignment, &int_type },
>
--
Peter Oberparleiter
Linux on System z Development - IBM Germany
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