[PyTorch] Devirtualize TensorImpl::dim() with macro (#49770)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49770
Seems like the performance cost of making this commonly-called method virtual isn't worth having use of undefined tensors crash a bit earlier (they'll still fail to dispatch).
ghstack-source-id: 119528065
Test Plan: framework overhead benchmarks
Reviewed By: ezyang
Differential Revision: D25687465
fbshipit-source-id: 89aabce165a594be401979c04236114a6f527b59
