Add forward AD layout check for storage numel (#68631)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68631
This PR:
- Adds the check that the storage numel of the base and tangent tensors are the same. This is to support the case when as_strided reveals elements that aren't indexable by the input tensor.
- Skips the check when batched tensors are involved, because using as_strided to reveal elements that not indexable by the input tensor is already not allowed vmap.
- Adds tests for the above two cases, as well as an edge case regarding conj bit (what about neg bit?)
For functorch:
- we need to copy the batching rule implemented here
Test Plan: Imported from OSS
Reviewed By: albanD
Differential Revision: D32899678
Pulled By: soulitzer
fbshipit-source-id: 54db9550dd2c93bc66b8fb2d36ce40799ebba794
