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I can't see that there is any hardware support. It just makes clever use of the CPU. Also 'tagged pointers' is something slightly different than 'tagged data'.
by lispm 12y ago
I can't see that there is any hardware support. It just makes clever use of the CPU. Also 'tagged pointers' is something slightly different than 'tagged data'. Many Lisp systems have been using both, for decades.
- pm215 12y agoThe hardware support is that the CPU ignores the top (tag) byte of the pointer when it's used in eg a load or store instruction, so you don't have to manually mask out the tag to use the value.