int extraItems = onFpu ? 0 : 1; ensureStackCapacity(os, ec, vstack, extraItems);
    private final static void prepareForOperation(AbstractX86Stream os,            EmitterContext ec, VirtualStack vstack, FPUStack fpuStack, Item left) {        final boolean onFpu = left.isFPUStack();        if (onFpu) {            // Operand is on the FPU stack            if (!fpuStack.isTos(left)) {                // operand not on top, exchange it.                final Register reg = fpuStack.getRegister(left);                os.writeFXCH(reg);                fpuStack.fxch(reg);            }        } else {            // operand is not on FPU stack            left.pushToFPU(ec); // Now left is on top        }    }