[Bug middle-end/31531] A microoptimization of isnegative of signed integer

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31531

--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-02-12 
04:39:01 UTC ---
forwprop already handles:
int f(int a)
{
  int b = ~a;
  return b<0;
}

It just needs to handle:
int f(unsigned a)
{
  int b = ~a;
  return b<0;
}