[Bug tree-optimization/124809] [16 Regression] wrong code at -O1 with "-fno-tree-ch -fno-tree-dce" on x86_64-linux-gnu since r16-5322

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124809

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
DOM2 comes up with

   e = 0;

from

  # RANGE [irange] int [0, 65535] MASK 0xffff VALUE 0x0
  k_23 = (int) j_22;
  if (a.0_1 == 0) 
    goto <bb 5>; [50.00%]
  else
    goto <bb 6>; [50.00%]

  <bb 5> [local count: 27903866]:
  iftmp.3_25 = k_23 >> _2;

  <bb 6> [local count: 55807731]:
  # iftmp.3_14 = PHI <iftmp.3_25(5), 0(4)>
  e = iftmp.3_14;

somehow via

Global Exported: j_22 = [irange] short unsigned int [0, 0][2, 2] MASK 0x3 VALUE
0x0
Global Exported: k_23 = [irange] int [0, 0][2, 2] MASK 0x3 VALUE 0x0

Andrew?