[Bug tree-optimization/114121] wrong code with _BitInt() arithmetics at -O2

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114121

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
As an aside we at -O3 has:
  _87 = .USUBC (_30, 3, 0);
  _93 = IMAGPART_EXPR <_87>;
  _88 = .USUBC (0, 0, _93);
  _29 = IMAGPART_EXPR <_88>;
  _187 = .USUBC (0, 0, _29);
  _217 = IMAGPART_EXPR <_187>;
  _218 = .USUBC (0, 0, _217);
  _214 = IMAGPART_EXPR <_218>;
  _213 = .USUBC (0, 0, _214);
  _212 = IMAGPART_EXPR <_213>;
  _200 = .USUBC (0, 0, _212);
  _34 = IMAGPART_EXPR <_200>;
  _35 = .USUBC (0, 0, _34);
  _36 = IMAGPART_EXPR <_35>;
  _39 = .USUBC (0, 0, _36);
  _40 = REALPART_EXPR <_39>;
  _2 = (signed long) _40;
  _77 = _2 < 0;

isn't `.USUBC (0, 0, _93);` just Complex<-_93, _93!=0> ? Or did I misunderstand
USUBC ?