[Bug c/88273] New: warning: 'memcpy' offset [-527, -529] is out of the bounds [0, 16] of object 'vrsave' with type 'union ' [-Warray-bounds]

[mathieu.malaterre at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88273

            Bug ID: 88273
           Summary: warning: 'memcpy' offset [-527, -529] is out of the
                    bounds [0, 16] of object 'vrsave' with type 'union
                    <anonymous>' [-Warray-bounds]
           Product: gcc
           Version: 8.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mathieu.malaterre at gmail dot com
  Target Milestone: ---

Created attachment 45127
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45127&action=edit
creduce code

There seems to be a regression in 8.2.0 from the previous release. See original
post at:

* https://lkml.org/lkml/2018/8/16/117

Reduced test case:

$ cat bug.c
typedef struct {
  int a[4]
} b, c;
d, e;
inline f(void *g, int h, int p3) {
  unsigned *i = 0;
  int copy = ({ d ?: p3; });
  g += *i - h;
  memcpy(e, g, copy);
  *i = copy;
}
j() {
  f(j, 0, sizeof(c));
  union {
    b k
  } vrsave;
  f(&vrsave, 33 * sizeof(c), 1);
}


With:

$ powerpc-linux-gnu-gcc -Warray-bounds -mcpu=powerpc
-fno-delete-null-pointer-checks -O2 -c bug.c
...
bug.c:9:3: warning: 'memcpy' offset [-527, -529] is out of the bounds [0, 16]
of object 'vrsave' with type 'union <anonymous>' [-Warray-bounds]
   memcpy(e, g, copy);


For reference:

$ powerpc-linux-gnu-gcc --version
powerpc-linux-gnu-gcc (Debian 8.2.0-9) 8.2.0