[Bug middle-end/80823] New: [8 Regression] ICE: verify_flow_info failed

[trippels at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80823

            Bug ID: 80823
           Summary: [8 Regression] ICE: verify_flow_info failed
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: trippels at gcc dot gnu.org
  Target Milestone: ---

trippels@gcc2-power8 linux % cat book3s_pr_papr.i
int a, c;
int b[1];
int fn1() {
  switch (a)
  case 0:
  case 2:
    return 1;
  return 0;
}
void fn2() {
  int i;
  for (;; ++i) {
    c = b[i];
    int d = !fn1();
    if (d)
      __asm__("");
  }
}

trippels@gcc2-power8 linux % gcc -c -O3 book3s_pr_papr.i
book3s_pr_papr.i: In function ‘fn2’:
book3s_pr_papr.i:10:6: error: missing edge 2->4
 void fn2() {
      ^~~
book3s_pr_papr.i:10:6: internal compiler error: verify_flow_info failed
0x10359553 verify_flow_info()
        ../../gcc/gcc/cfghooks.c:260
0x1094081b checking_verify_flow_info
        ../../gcc/gcc/cfghooks.h:198
0x1094081b cleanup_tree_cfg_noloop
        ../../gcc/gcc/tree-cfgcleanup.c:837
0x1094081b cleanup_tree_cfg()
        ../../gcc/gcc/tree-cfgcleanup.c:883
0x107bbfc7 execute_function_todo
        ../../gcc/gcc/passes.c:1922
0x107bcd53 do_per_function
        ../../gcc/gcc/passes.c:1653
0x107bcfd3 execute_todo
        ../../gcc/gcc/passes.c:2023