Unify meta tensor and fake tensor converter conversion (#87943)
Meta tensor does a lot of work to make sure tensors "look" similar
to the original parts; e.g., if the original was a non-leaf, meta
converter ensures the meta tensor is a non-leaf too. Fake tensor
destroyed some of these properties when it wraps it in a FakeTensor.
This patch pushes the FakeTensor constructor into the meta converter
itself, so that we first create a fake tensor, and then we do various
convertibility bits to it to make it look right.
The two tricky bits:
- We need to have no_dispatch enabled when we allocate the initial meta
tensor, or fake tensor gets mad at us for making a meta fake tensor.
This necessitates the double-callback structure of the callback
arguments: the meta construction happens *inside* the function so
it is covered by no_dispatch
- I can't store tensors for the storages anymore, as that will result
in a leak. But we have untyped storage now, so I just store untyped
storages instead.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
cc @jansel @mlazos @soumith @voznesenskym @yanboliang @penguinwu @anijain2305 @EikanWang @jgong5 @Guobing-Chen @chunyuan-w @XiaobingSuper @zhuhaozhe @blzheng @Xia-Weiwen @wenzhe-nrv @jiayisunx
Pull Request resolved: https://github.com/pytorch/pytorch/pull/87943
Approved by: https://github.com/eellison, https://github.com/albanD
