return !VM.ExplicitlyGuardLowMemory || isStore || ((memOp.index == null) && (memOp.disp < 0));
return !VM.ExplicitlyGuardLowMemory || isStore || ((memOp.index == null) && (memOp.disp.sLT(Offset.zero())));
  private boolean canFold(OPT_Instruction s, OPT_Operand activeGuard, boolean isStore) {    if (GuardCarrier.conforms(s) &&         GuardCarrier.hasGuard(s) &&         activeGuard.similar(GuardCarrier.getGuard(s))) {      if (!VM.ExplicitlyGuardLowMemory) return true;      //-#if RVM_FOR_POWERPC      // TODO: In theory, lowMemory is protected even on AIX.      // However, enabling this causes a large number of failures.      // Figure out why that is the case and enable some variant of this.      // if (isStore) return true; // Even on AIX low memory is write protected      if (MIR_Load.conforms(s)) {        OPT_Operand offset = MIR_Load.getOffset(s);        if (offset instanceof OPT_IntConstantOperand) {          return ((OPT_IntConstantOperand)offset).value < 0;        }      }      //-#endif      return false;    }    for (int i=0, n = s.getNumberOfOperands(); i<n; i++) {      OPT_Operand op = s.getOperand(i);      if (op instanceof OPT_MemoryOperand) {        OPT_MemoryOperand memOp = (OPT_MemoryOperand)op;        if (activeGuard.similar(memOp.guard)) {          return !VM.ExplicitlyGuardLowMemory || isStore || ((memOp.index == null) && (memOp.disp < 0));        }       }    }    return false;  }