Implement at::has_internal_overlap helper function (#17926)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17926
ghimport-source-id: 9f7572b5d43e474492363fa17dcb86a6c27ca13c
Stack:
* **#17926 Implement at::has_internal_overlap helper function**
* #17927 Error out on in-place (unary) ops on tensors that have internal overlap
On the way to #17935.
Checks if a tensor's sizes/strides indicate that multiple elements share
the same memory location. This problem in general is hard so
at::has_internal_overlap implements two heuristics and avoids solving
the general problem:
if a tensor is contiguous, it cannot have internal overlap
if a tensor has any zero strides, it does have internal overlap
otherwise, return MemOverlap::kTooHard to indicate that there might be
overlap, but we don't know.
Reviewed By: ezyang
Differential Revision: D14438858
fbshipit-source-id: 607ab31771315921ab6165b2a1f072ac3e75925a
