[P1] Write value into register from const_queue not implemented

[Jackcuii]

Theoritically, the register file could be written by the values from 3 different sources (Xbar, Const queue and FU), but the selection seems not to be implemented, especially from the const queue.

[tancheng]

I think the issue is related to:

VectorCGRA/tile/TileRTL.py

Lines 221 to 222 in 5bac336

	s.register_cluster.recv_data_from_const[i].msg //= DataType()
	s.register_cluster.recv_data_from_const[i].val //= 0

instead of zero, it should be connected to const_queue.

[tancheng]

But actually, we may no need to support that? From application's behavior, it doesn't make sense to send a constant value to a register. The constant will stay in const_queue forever, moving it to another register for later use doesn't make sense. So may be we can remove that s.register_cluster.recv_data_from_const[i].

[Jackcuii]

Make sense~ But if we want to distribute the same const to multiple downstream, we may need a register to pass it?

[tancheng]

Make sense~ But if we want to distribute the same const to multiple downstream, we may need a register to pass it?

Our FU_xbar can multi-cast it, i.e., const_queue -> ConstOp -> multi-cast via FU_xbar. WDYT?