The following cross compiler crashes:

$ cat amd.i
int _vfwprintf_r_ch;

int btowc();
int __sprint_r();
int iov_len();

void
_vfwprintf_r() {
  int uio_0, buf;
  for (;;) {
    switch (_vfwprintf_r_ch) {
    case L'c':
      int wc = btowc();
      if (wc)
        goto error;
      if (buf)
        if (++uio_0)
          __sprint_r();
    }
    iov_len();
  }
error:
}

$ ./xgcc -B. amd.i -c -O2 
during RTL pass: postreload
amd.i: In function ‘_vfwprintf_r’:
amd.i:23:1: internal compiler error: in require, at machmode.h:297
   23 | }
      | ^
0xc47789 opt_mode<scalar_int_mode>::require() const
	/home/marxin/Programming/gcc/gcc/machmode.h:297
0xcff5c8 void mode_iterator::get_known_wider<scalar_int_mode>(scalar_int_mode*)
	/home/marxin/Programming/gcc/gcc/machmode.h:1124
0xcf9d81 new_cselib_val
	/home/marxin/Programming/gcc/gcc/cselib.cc:1579
0xcfba7a cselib_lookup_1
	/home/marxin/Programming/gcc/gcc/cselib.cc:2315
0xcfc183 cselib_lookup(rtx_def*, machine_mode, int, machine_mode)
	/home/marxin/Programming/gcc/gcc/cselib.cc:2431
0xcfd498 cselib_record_sets
	/home/marxin/Programming/gcc/gcc/cselib.cc:2932
0xcfe00a cselib_process_insn(rtx_insn*)
	/home/marxin/Programming/gcc/gcc/cselib.cc:3159
0x123eac4 reload_cse_regs_1
	/home/marxin/Programming/gcc/gcc/postreload.cc:229
0x123e5b4 reload_cse_regs
	/home/marxin/Programming/gcc/gcc/postreload.cc:72
0x1244156 execute
	/home/marxin/Programming/gcc/gcc/postreload.cc:2347
Please submit a full bug report, with preprocessed source (by using -freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.