This particular instruction - XSAVES - isn't the sort of simple building block that most user code is full of like ADD or MOV. It does quite a bit of work (sav

This particular instruction - XSAVES - isn't the sort of simple building block that most user code is full of like ADD or MOV. It does quite a bit of work (saving a chunk of the CPU state) and is implemented more like calling a subroutine within the CPU than the way the normal number-crunching instructions are executed. These updates basically just change that subroutine code within the CPU.