[Bug tree-optimization/52406] [4.7 Regression] likely wrong code bug

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52406

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-02-28 
10:14:57 UTC ---
Indeed, it is pcom that breaks it.

Before pcom we have:
  MEM[(int *)&a + 4B] = 1;
  D.1723_6 = a[1].f1;
but pcom doesn't consider the first store to be possibly affecting the load:
  a_I_f1_lsm0.14_26 = a[1].f1;

<bb 5>:
  # d_lsm0.12_12 = PHI <d_lsm0.12_18(6), d.13_5(4)>
  MEM[(int *)&a + 4B] = 1;
  D.1723_6 = a_I_f1_lsm0.14_26;