On 22/11/2018 13:44, Luc Van Oostenryck wrote:
> From: Ramsay Jones <ramsay@xxxxxxxxxxxxxxxxxxxx>
>
> Currently, when used on the kernel, sparse issues a bunch
> of warnings like:
> warning: constant 0x100000000 is so big it is long
>
> These warning are issued because when there is a discrepancy
> between the type as indicated by the suffix (or the absence
> of a suffix) and the real type as selected by the type
> suffix *and* the value of the constant.
>
> Since there is nothing incorrect with this discrepancy,
> (no bits are lost) these warnings are more annoying than useful.
> So, make them depending on a new warning flag -Wconstant-suffix
> and make it off by default.
>
> Signed-off-by: Ramsay Jones <ramsay@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
Looks *very* good to me! :-D
Thanks for doing that.
ATB,
Ramsay Jones
> ---
> cgcc | 2 +-
> expression.c | 2 +-
> lib.c | 2 ++
> lib.h | 1 +
> sparse.1 | 12 ++++++++++++
> validation/constant-suffix-32.c | 15 +++++++++++++++
> validation/constant-suffix-64.c | 15 +++++++++++++++
> 7 files changed, 47 insertions(+), 2 deletions(-)
> create mode 100644 validation/constant-suffix-32.c
> create mode 100644 validation/constant-suffix-64.c
>
> diff --git a/cgcc b/cgcc
> index 7611dc9ff..736cb704c 100755
> --- a/cgcc
> +++ b/cgcc
> @@ -101,7 +101,7 @@ exit 0;
>
> sub check_only_option {
> my ($arg) = @_;
> - return 1 if $arg =~ /^-W(no-?)?(address-space|bitwise|cast-to-as|cast-truncate|context|decl|default-bitfield-sign|designated-init|do-while|enum-mismatch|init-cstring|memcpy-max-count|non-pointer-null|old-initializer|one-bit-signed-bitfield|override-init-all|paren-string|ptr-subtraction-blows|return-void|sizeof-bool|sparse-all|sparse-error|transparent-union|typesign|undef|unknown-attribute)$/;
> + return 1 if $arg =~ /^-W(no-?)?(address-space|bitwise|cast-to-as|cast-truncate|constant-suffix|context|decl|default-bitfield-sign|designated-init|do-while|enum-mismatch|init-cstring|memcpy-max-count|non-pointer-null|old-initializer|one-bit-signed-bitfield|override-init-all|paren-string|ptr-subtraction-blows|return-void|sizeof-bool|sparse-all|sparse-error|transparent-union|typesign|undef|unknown-attribute)$/;
> return 1 if $arg =~ /^-v(no-?)?(entry|dead)$/;
> return 1 if $arg =~ /^-f(dump-ir|memcpy-max-count|diagnostic-prefix)(=\S*)?$/;
> return 1 if $arg =~ /^-f(mem2reg|optim)(-enable|-disable|=last)?$/;
> diff --git a/expression.c b/expression.c
> index 6f4300b9a..f955fb159 100644
> --- a/expression.c
> +++ b/expression.c
> @@ -324,7 +324,7 @@ static void get_number_value(struct expression *expr, struct token *token)
> show_token(token));
> want_unsigned = 1;
> got_it:
> - if (do_warn)
> + if (do_warn && Wconstant_suffix)
> warning(expr->pos, "constant %s is so big it is%s%s%s",
> show_token(token),
> want_unsigned ? " unsigned":"",
> diff --git a/lib.c b/lib.c
> index 07a5b9cda..5c2059f23 100644
> --- a/lib.c
> +++ b/lib.c
> @@ -251,6 +251,7 @@ int Wbitwise = 1;
> int Wcast_from_as = 0;
> int Wcast_to_as = 0;
> int Wcast_truncate = 1;
> +int Wconstant_suffix = 0;
> int Wconstexpr_not_const = 0;
> int Wcontext = 1;
> int Wdecl = 1;
> @@ -686,6 +687,7 @@ static const struct flag warnings[] = {
> { "cast-from-as", &Wcast_from_as },
> { "cast-to-as", &Wcast_to_as },
> { "cast-truncate", &Wcast_truncate },
> + { "constant-suffix", &Wconstant_suffix },
> { "constexpr-not-const", &Wconstexpr_not_const},
> { "context", &Wcontext },
> { "decl", &Wdecl },
> diff --git a/lib.h b/lib.h
> index cd1af9c4a..cde74e93e 100644
> --- a/lib.h
> +++ b/lib.h
> @@ -141,6 +141,7 @@ extern int Wbitwise;
> extern int Wcast_from_as;
> extern int Wcast_to_as;
> extern int Wcast_truncate;
> +extern int Wconstant_suffix;
> extern int Wconstexpr_not_const;
> extern int Wcontext;
> extern int Wdecl;
> diff --git a/sparse.1 b/sparse.1
> index 3e1352352..64323222b 100644
> --- a/sparse.1
> +++ b/sparse.1
> @@ -101,6 +101,18 @@ Sparse issues these warnings by default. To turn them off, use
> \fB\-Wno\-cast\-truncate\fR.
> .
> .TP
> +.B \-Wconstant\-suffix
> +Warn if an integer constant is larger than the maximum representable value
> +of the type indicated by its type suffix (if any). For example, on a
> +system where ints are 32-bit and longs 64-bit, the constant \fB0x100000000U\fR
> +is larger than can be represented by an \fBunsigned int\fR but fits in an
> +\fBunsigned long\fR. So its type is \fBunsigned long\fR but this is not
> +indicated by its suffix. In this case, the warning could be suppressed by
> +using the suffix \fBUL\fR: \fB0x100000000UL\fR.
> +
> +Sparse does not issue these warnings by default.
> +.
> +.TP
> .B \-Wconstexpr-not-const
> Warn if a non-constant expression is encountered when really expecting a
> constant expression instead.
> diff --git a/validation/constant-suffix-32.c b/validation/constant-suffix-32.c
> new file mode 100644
> index 000000000..dc063a079
> --- /dev/null
> +++ b/validation/constant-suffix-32.c
> @@ -0,0 +1,15 @@
> +#define BIGU 0xfffff00000000000U
> +#define BIGULL 0xfffff00000000000ULL
> +
> +static unsigned long long a = BIGU;
> +static unsigned long long b = BIGULL;
> +
> +/*
> + * check-name: constant-suffix
> + * check-command: sparse -m32 -Wconstant-suffix $file
> + *
> + * check-error-start
> +constant-suffix-32.c:4:31: warning: constant 0xfffff00000000000U is so big it is unsigned long long
> + * check-error-end
> + */
> +
> diff --git a/validation/constant-suffix-64.c b/validation/constant-suffix-64.c
> new file mode 100644
> index 000000000..e65706b02
> --- /dev/null
> +++ b/validation/constant-suffix-64.c
> @@ -0,0 +1,15 @@
> +#define BIGU 0xfffff00000000000U
> +#define BIGUL 0xfffff00000000000UL
> +
> +static unsigned long a = BIGU;
> +static unsigned long b = BIGUL;
> +
> +/*
> + * check-name: constant-suffix
> + * check-command: sparse -m64 -Wconstant-suffix $file
> + *
> + * check-error-start
> +constant-suffix-64.c:4:26: warning: constant 0xfffff00000000000U is so big it is unsigned long
> + * check-error-end
> + */
> +
>
