Module Ir.Host_inits

A weakly-owned association from a tensor node to the host buffer holding its initialization data (ndarray-backed literals and persistence-loaded nodes). After gh-ocannl-333 the data is no longer stored on Tnode.t; instead it is registered here at construction and uploaded into a backend context, on demand, at link time.

The table is:

• weak in the key: an entry is reclaimed by the GC once its tensor node becomes unreachable, so constructing-but-never-compiling a literal does not leak its buffer;
• read, not consumed: linking a node into a context reads (does not remove) the entry, so the same node can be initialized into multiple independent contexts / devices;
• lazy in the value: the buffer is shaped only when forced, i.e. after shape inference.