alias_analysis refactor (#17511)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17511
AliasTracker was doing bookkeeping for three concepts: the points-to graph,
writes, and wildcards.
This PR makes AliasTracker's job clearer: it keeps track of the points-to
graph. Thus it has been renamed MemoryDAG. Write and wildcard information were
pulled back into AliasDb as part of this—I may decide to pull them into their
own little modules since I don't want the alias analysis stuff to get too
bloated.
This refactor is necessary because we want to start tracking information for
aliasing elements that _aren't_ first-class IR Values (e.g. the "stuff" inside
a list). So MemoryDAG can't know too much about Values
Reviewed By: houseroad
Differential Revision: D14231251
fbshipit-source-id: 6cd98ae6fced8d6c1522c2454da77c3c1b2b0504
