Module fuse_readers 

fuse_readers — reader fusion / multicast as a GENERAL pass, decided by the cost model.

Sites whose Load stages read the identical tile stream (a mesh row shares its A blocks, a column its B blocks) form a GROUP: one site keeps its Load and becomes the sender (it multicasts each block after landing it), the others become receivers whose Load is replaced by a Recv. Every group gets a semaphore pair (ready counter at the sender, valid flag at the receivers) and its members’ NOCs follow the target’s direction rule. The decision is the cost model’s comparison of the fused and unfused arrangements of the SAME plan — the comparison tile already made — never a flag.

Functions

fuse_readers

The pass: fuse iff the cost model says so.

fuse_readers_forced

Fuse (or not) regardless of the cost model — a calibration facility, never a pass.

fusion_wins

Whether the cost model prefers the fused (multicast) arrangement for this placed plan.