I came here to ask the same thing, did some searching, and still haven't found anything. Edit: Found this in PowerISA_V3.0.pdf Load Doubleword Monitored Instr

I came here to ask the same thing, did some searching, and still haven't found anything. Edit: Found this in PowerISA_V3.0.pdf Load Doubleword Monitored Instruction: Specifies a new instruction and facility that improves the performance of the garbage collection process and eliminates the need to pause all applications during collection. The ldmx instruction loads the same doubleword in storage as the ldx instruction. ldmx is intended for use by applications when loading data objects during times when objects are being moved as part of a garbage collection process. In this type of usage, all loads of object pointers by applications are performed using ldmx. Whenever objects within a given region of memory are to be moved, the garbage collection program sets the Load Monitored Region registers to encompass the region being moved, and sets BESCRGE LME to 0b11 to enable Load Monitored event-based branches. ...