[Bug tree-optimization/82838] New: [8 Regression] ICE in verify_ssa failed w/ store-merging

["marxin at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82838

            Bug ID: 82838
           Summary: [8 Regression] ICE in verify_ssa failed w/
                    store-merging
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
                CC: jakub at gcc dot gnu.org
  Target Milestone: ---

New ICE starting from r254391:

$ cat /tmp/tmpn_t2ld0o.i
typedef struct
{
  unsigned short a;
  unsigned short b;
  unsigned short c;
} d;

int e;
d f[10];
void g ()
{
  d *a;
  f[e].b = a[e].a;
  f[e].c = a[e].b;
}

$ ./xgcc -B. -fno-ivopts -Os /tmp/tmpn_t2ld0o.i -c
/tmp/tmpn_t2ld0o.i: In function ‘g’:
/tmp/tmpn_t2ld0o.i:10:6: error: missing definition
 void g ()
      ^
for SSA_NAME: _13 in statement:
# .MEM_10 = VDEF <.MEM_7(D)>
MEM[(short unsigned int *)_13 + 2B] = _14;
during GIMPLE pass: store-merging
/tmp/tmpn_t2ld0o.i:10:6: internal compiler error: verify_ssa failed
0x122dbf5 verify_ssa(bool, bool)
        ../../gcc/tree-ssa.c:1188
0xe3b20b execute_function_todo
        ../../gcc/passes.c:2001
0xe3a19c do_per_function
        ../../gcc/passes.c:1659
0xe3b3b4 execute_todo
        ../../gcc/passes.c:2048