[Bug c/114239] New: ice: error: definition in block does not dominate use in block

["dcb314 at hotmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114239

            Bug ID: 114239
           Summary: ice: error: definition in block does not dominate use
                    in block
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

For this C code:

int ip4_getbit_a, ip4_getbit_pos, ip4_clrbit_pos;
void ip4_clrbit(int *a) { *a &= ip4_clrbit_pos; }
typedef struct {
  char pxlen;
  int prefix
} net_addr_ip4;
void fib_get_chain();
int trie_match_longest_ip4();
int trie_match_next_longest_ip4(net_addr_ip4 *n) {
  int __trans_tmp_1;
  while (n->pxlen) {
    n->pxlen--;
    ip4_clrbit(&n->prefix);
    __trans_tmp_1 = ip4_getbit_a >> ip4_getbit_pos;
    if (__trans_tmp_1)
      return 1;
  }
  return 0;
}
void net_roa_check_ip4_trie_tab() {
  net_addr_ip4 px0;
  for (int _n = trie_match_longest_ip4(&px0); _n;
       _n = trie_match_next_longest_ip4(&px0))
    fib_get_chain();
}

on x86_64, does this:

$ ../results/bin/gcc -c -O3 -march=znver3 -w ~/cvise/bug1021.c
/home/dcb38/cvise/bug1021.c: In function ‘net_roa_check_ip4_trie_tab’:
/home/dcb38/cvise/bug1021.c:20:6: error: definition in block 19 does not
dominate use in block 14
   20 | void net_roa_check_ip4_trie_tab() {
      |      ^~~~~~~~~~~~~~~~~~~~~~~~~~
for SSA_NAME: _117 in statement:
px0__lsm.22_47 = PHI <_117(14), _117(19)>
PHI argument
_117
for PHI node
px0__lsm.22_47 = PHI <_117(14), _117(19)>
during GIMPLE pass: vect
/home/dcb38/cvise/bug1021.c:20:6: internal compiler error: verify_ssa failed

The bug first seems to occur sometime between g:1e74ce8983fd4926
and g:71244316cf714725, which is 42 commits.