https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89798
Bug ID: 89798
Summary: excessive vector_size silently accepted and truncated
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: ---
In the following test case the declaration of v0 is accepted and its size
matches the size specified by the vector_size attribute. The declaration of v1
is also accepted but its size does not match that specified by the same
attribute. See also pr89797 for a similar test case that triggers an ICE.
GCC should validate the attribute argument against its internal maximum and
reject excessive arguments with a descriptive error.
$ cat z.c && gcc -S -Wall -Wextra z.c
#define N0 (1LU << 30)
__attribute__ ((vector_size (N0))) char v0;
_Static_assert (N0 == sizeof v0); // passes
#define N1 (1LU << 34)
__attribute__ ((vector_size (N1))) char v1;
_Static_assert (N1 == sizeof v1); // fails
z.c:10:1: error: static assertion failed
10 | _Static_assert (N1 == sizeof v1); // fails
| ^~~~~~~~~~~~~~
