Scheduler Intrinsics

This is the basic scheduler intrinsic set I developed as part of my master's thesis (a very, very tiny part, and there was a fully formal description of the execution model to go along with it), modified for the runtime system. The actual runtime system had a mailbox pointer, which gets passed around. This pointer is a required first argument to anyscheduler function

%thr = spawn %mbox, @func(...)

Spawn the call to func as a thread.

%state, %pri = stat %thr, %mbox

Get the state and priority of the given thread

update %thr [, run | suspend | term] [, %pri], %mbox

Update a thread's state and priority. State changes do not take effect until the next safepoint.

%mbox = safepoint, %mbox'

Possibly deschedule or context switch, and acknowledge any changes in state. This effectively destroys %mbox', replacing it with %mbox.

The cooperative nature of this threading works much nicer with a lock-free scheduler, and lock-free systems in general. It is possible to implement asynchronous channel communications quite simply:

send(%achan, %ptr, %mbox):
%box = getelementptr, %achan, 0
%recv = getelementptr, %achan, 1
%thr = load %recv
store %val, %box
update %thr, run, %mbox
ret

recv(%achan, %ptr, %mbox):
%box = getelementptr, %achan, 0
%recv = getelementptr, %achan, 1
update %self, suspend, %mbox
store %self, %recv
safepoint %mbox
%val = load %box
ret %box

Lastly, it works nicely for doing a TM system as well. The next step is to tie all this in with the GC/TM intrinsics, and wire in all the %mboxes into those as well.