[Bug tree-optimization/52028] [4.7 Regression] wrong code with -O2 -ftree-loop-distribution

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52028

--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-01-30 
14:16:51 UTC ---
Virtual SSA form is corrupt (and we don't detect that - bah).

<bb 3>:
  # .MEM_723 = PHI <.MEM_666(3), .MEM_661(D)(2)>
  # ivtmp.297_722 = PHI <ivtmp.297_648(3), ivtmp.297_1354(2)>
  D.2523_1353 = (void *) ivtmp.297_722;
  # .MEM_666 = VDEF <.MEM_723>
  MEM[base: D.2523_1353, offset: 0B] = 0;
  ivtmp.297_648 = ivtmp.297_722 + 4;
  if (ivtmp.297_648 != D.2525_653)
    goto <bb 3>;
  else
    goto <bb 4>;

<bb 4>:
...

<bb 5>:
  # K_1035 = PHI <&MEM[(void *)&k + 64B](5), &k(4)>
  # .MEM_703 = PHI <.MEM_562(5), .MEM_666(4)>
...
  # .MEM_562 = VDEF <.MEM_561>
  MEM[(unsigned int *)K_1035 + 52B] = pretmp.262_1186;
  D.1989_556 = D.1916_553 + 512;
  D.1990_563 = D.1989_556 * 4;
  D.1991_566 = &CAST_S_table + D.1990_563;
  # VUSE <.MEM_562>
  D.1992_567 = *D.1991_566;
  if (&k != K_1035)
    goto <bb 6>;
  else
    goto <bb 5>;

<bb 6>:
  K_1352 = &k;
  X$0_719 = 0;

<bb 7>:
  # K_1147 = PHI <&k(6), &MEM[(void *)&k + 64B](7)>
  # .MEM_1141 = PHI <.MEM_666(6), .MEM_1343(7)>
...

We have overlapping life-ranges for .MEM_666 and .MEM_562  (at least).

I have a patch.