Add support for dictionary with torch object keys. (#103158)
Fixes: #101979
This PR adds support for dictionaries with torch object as keys in dynamo.
The main problem was that, for example, the source built for `d[torch.float]` (`d` being a
dictionary) was `ODictGetItemSource(GlobalSource('d'), index=torch.float)`. When
`Source.name` method was called, we got `odict_getitem(G['d'], torch.float)`. Evaluating
that string raised an error, since `torch` was only available in the global dictionary `G`
as `G["torch"]`.
Instead, this PR builds the source:
`ODictGetItemSource(GlobalSource('d'), index=AttrSource(GlobalSource('torch'), 'float'))`.
The to-be-evaluated string is correctly generated as:
`odict_getitem(G['d'], G['torch'].float)`.
Here's a minimal example that reproduces the error, before this PR:
```python
import torch
d = {
torch.float16: torch.float32,
}
@torch.compile
def f():
return torch.randn(3, dtype=d[torch.float16])
f()
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/103158
Approved by: https://github.com/mlazos
