You don't need the hardware UAI/LAM to make use of the high pointer bits. The most common technique is to use `shl reg, 16; sar reg, 16`, which will shift in on

You don't need the hardware UAI/LAM to make use of the high pointer bits. The most common technique is to use `shl reg, 16; sar reg, 16`, which will shift in ones or zeros from the left depending on the 47th bit. Several runtimes use high bits tagging combined with NaN-boxing, and have been doing so since before LAM/UAI existed.