[JIT] Re-enable alias sensitive peepholes (#65860)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/65860
Re-enable peepholes like `x + 0 == x`. These were at one point enabled, and then disabled because they did not properly account for aliasing, and then re-enabled with reconstructing the alias db everytime which is slow - O(n^2). I've added correctness conditions, and I've also made it so that we avoid using stale aliasing properties for either the input or output of nodes we optimize.
Some of the other code that we have written to avoid re-instantiating the alias db involves internally mutating it, however this is tricky to reason about and we probably have to add some extra invariants...
cc navahgar relevant to graph opts and d1jang alias analysis relevant here
Test Plan: Imported from OSS
Reviewed By: ZolotukhinM
Differential Revision: D31352382
Pulled By: eellison
fbshipit-source-id: 441a27f17dc623d6c24538d1d43cba0412c3c482
