[Bug tree-optimization/70128] Linux kernel div patching optimized away

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70128

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
*.mergephi1 has (just the first half, the second one is analogous):
  __aeabi_uidiv.0_1 = (long unsigned int) __aeabi_uidiv;
  fn_addr_2 = __aeabi_uidiv.0_1 & 4294967294;
  fn_addr.1_3 = (unsigned int *) fn_addr_2;
  *fn_addr.1_3 = 3878744336;
  _6 = fn_addr_2 + 4;
  _7 = (unsigned int *) _6;
  *_7 = 3778019102;
  _9 = fn_addr_2 + 8;
  v7_coherent_kern_range (fn_addr_2, _9);
Now, dse1 details say:
  Deleted dead store '*fn_addr.1_3 = 3878744336;
and indeed, that is what happened:
  __aeabi_uidiv.0_1 = (long unsigned int) __aeabi_uidiv;
  fn_addr_2 = __aeabi_uidiv.0_1 & 4294967294;
  fn_addr.1_3 = (unsigned int *) fn_addr_2;
  _6 = fn_addr_2 + 4;
  _7 = (unsigned int *) _6;
  *_7 = 3778019102;
  _9 = fn_addr_2 + 8;
  v7_coherent_kern_range (fn_addr_2, _9);