[Bug tree-optimization/71039] New: [7 Regression] ICE: verify_ssa failed (error: definition in block 4 does not dominate use in block 5) w/ -O1 and above

["asolokha at gmx dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71039

            Bug ID: 71039
           Summary: [7 Regression] ICE: verify_ssa failed (error:
                    definition in block 4 does not dominate use in block
                    5) w/ -O1 and above
           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: asolokha at gmx dot com
  Target Milestone: ---

gcc-7.0.0-alpha20160508 snapshot ICEs when compiling the following reduced
snippet at -O1 and above:

struct wv
{
  int qi;
} qp, *ft;
void *pb;

void
wz (void)
{
  struct wv *vf = pb ? (struct wv *)&pb : &qp;
  *ft = *vf;
}

% x86_64-pc-linux-gnu-gcc-7.0.0-alpha20160508 -c -O1 fo7dullr.c                 
fo7dullr.c: In function 'wz':
fo7dullr.c:8:1: error: definition in block 4 does not dominate use in block 5
 wz (void)
 ^~
for SSA_NAME: ft.2_2 in statement:
# .MEM_7 = VDEF <.MEM_4(D)>
*ft.2_2 = MEM[(struct wv *)&pb];
fo7dullr.c:8:1: internal compiler error: verify_ssa failed