Summary: Currently OpKind is stored as an object field called op_ for each IR
node, and one usage of op_ is to avoid dynamic_cast in NodeCast when we
need to downcast a base-node pointer into a concrete sub-node pointer.
As a result, we need to construct and pass in an op when downcasting
nodes, and this becomes quite anonnying when we start to implement the
trie-based IR node reusing. More importantly, the op for each subclass
should be unique for that subclass and thus making it a const static field
is a more logical design.
In this PR, we still keep the object-level op_ for easier XLA adoption. As
furture work, we can come back to remove op_, make the op() method
virtual, and get rid of OpKind in all the node constructors.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/76711
Approved by: https://github.com/wconstab, https://github.com/JackCaoG
Summary: TrieCache provides a way to look up an IR node before we
actually create it. If the lookup hits in TrieCache, we reuse the
existing node and move the current pointer in TrieCache to point to that
node; if the lookup misses, we create a new node and insert it into TrieCache.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/76542
Approved by: https://github.com/wconstab, https://github.com/JackCaoG
