为什么CPU寄存器充当垃圾收集器的根？

Question

Why CPU registers act like roots for Garbage Collector? When a mutator pauses, so the garbage collector can scan the roots, the variables contents are flushed to memory (using a memory fence) so the registers dont contain data that isnt in memory... if my understanding is correct...

Why then do you need to scan them? I see this as redundancy...

Answer 1

The flushing to memory is an implementation detail. The important thing is that the data contained in registers at the time a GC cycle is initiated is treated as reachable, regardless of how or where that data is stored in memory during the GC cycle itself.