[jit] fix trace checking reporting divergent names (#37464)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/37464
Fixes https://github.com/pytorch/pytorch/issues/23993.
There are two fixes here:
1. Previously our name lookup function for the tracer was looking in
f.globals for names. For example:
```
sample = torch.ones(1)
traced = torch.jit.trace(my_mod, ((sample, sample,),))
# produces a graph with something like
# %sample, %sample = prim::TupleUnpack(%input)
```
This is not great if you are, e.g. trace checking, because a non-local
bit of interpreter state is affected the graph produced:
```
traced = torch.jit.trace(my_mod, _clone_inputs((sample, sample,),))
# produces a graph with something like
# %0, %1 = prim::TupleUnpack(%input)
```
I have removed this functionality, as I don't think it provides huge
value. Things that look locally for names will still work, so e.g.
inputs, intermediate variables, and the like will be named correctly.
2. Previously, our input cloning for trace checking didn't do a memoized
deep copy. So:
```
_clone_inputs((sample, sample, sample))
```
produces a tuple with three non-aliased tensors. That's wrong! Use
copy.deepcopy with a memoization argument to fix this.
Test Plan: Imported from OSS
Differential Revision: D21297549
Pulled By: suo
fbshipit-source-id: 981d5879a4a244520dd68489767129ff357f1497
