https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86196
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Known to work| |8.1.0
Keywords| |diagnostic
Last reconfirmed| |2018-06-18
CC| |msebor at gcc dot gnu.org
Blocks| |84774
Ever confirmed|0 |1
Summary|Bogus -Wrestrict on memcpy |[9 Regression] Bogus
| |-Wrestrict on memcpy
| |between array elements at
| |unequal indices
Known to fail| |9.0
--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
Confirmed with the simplified test case below. The "offset [0, 8]" notation
indicates the range the offset into an array is determined to be in. The bug
is caused by GCC incorrectly computing the offset to be between 0 and 8 bytes
(the 8 is the size of the struct).
$ cat pr86196.c && gcc -O2 -S -Wall pr86196.c
struct S { int i; void *p; };
void g (struct S *a, int i, int j)
{
if (i != j)
__builtin_memcpy (&a[j], &a[i], sizeof (struct S));
}
pr86196.c: In function ‘g’:
pr86196.c:6:5: warning: ‘__builtin_memcpy’ accessing 16 bytes at offsets [0, 8]
and [0, 8] overlaps between 8 and 16 bytes at offset [0, 8] [-Wrestrict]
__builtin_memcpy (&a[j], &a[i], sizeof (struct S));
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The regression was introduced in r260280:
r260280 | msebor | 2018-05-15 22:30:38 -0400 (Tue, 15 May 2018) | 15 lines
PR tree-optimization/85753 - missing -Wrestrict on memcpy into a member array
gcc/ChangeLog:
PR tree-optimization/85753
* gimple-ssa-warn-restrict.c (builtin_memref::builtin_memref): Handle
RECORD_TYPE in addition to ARRAY_TYPE.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84774
[Bug 84774] [meta-bug] bogus/missing -Wrestrict
