https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89813
Bug ID: 89813
Summary: bogus warning: ’assume_aligned’ <large integer> is not
an integer constant
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
The warning below that 9223372036854775808 is not an integer constant is
incorrect: the number is an integer constant, it just exceeds the supported
maximum. It's caused by using tree_fits_shwi_p() to detect both excessive
values and non-integers.
The error below is an example of what a better warning should look like.
$ cat b.c && gcc -S b.c
#define N ((__UINT64_TYPE__)1 << 63)
__attribute__ ((assume_aligned (N))) void* f (void);
struct S
{
__attribute__ ((warn_if_not_aligned (N))) int i;
};
b.c:3:1: warning: ‘assume_aligned’ attribute 9223372036854775808 is not an
integer constant [-Wattributes]
3 | __attribute__ ((assume_aligned (N))) void* f (void);
| ^~~~~~~~~~~~~
b.c:7:3: error: requested alignment ‘9223372036854775808’ exceeds maximum
2147483648
7 | __attribute__ ((warn_if_not_aligned (N))) int i;
| ^~~~~~~~~~~~~
