Compiler calculates the PciBar[BarIndex] using sizeof (PciBar[0]) * BarIndex, when BarIndex is type of UINT64, the above calculation generates assembly code using _allmul. Change BarIndex to UINTN to avoid the build failure. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com> Reviewed-by: Wu Jiaxin <jiaxin.wu@intel.com>