abstract boolean isForbidden(OPT_Register symb, OPT_Register r, OPT_Instruction s);
final boolean isForbidden(OPT_Register symb, OPT_Register phys) { if (VM.VerifyAssertions) { VM._assert(symb != null); VM._assert(phys != null); } RestrictedRegisterSet s = getRestrictions(symb); if (s == null) return false; return s.contains(phys); }
  abstract boolean isForbidden(OPT_Register symb, OPT_Register r,                               OPT_Instruction s);