Check alignment of ReinterpretView args of custom Triton kernels (#119649)
Summary: Currently, when a custom (user-written) Triton kernel has a ReinterpretView argument in IR, we're always skipping the alignment checking for this argument when preparing the `signature_of` for the AOT compilation of the Triton kernel (via setting `TensorArg.check_alignment` to `False`). This is problematic for user-written kernels where, albeit reinterpreted, the argument of the Triton kernel (the data pointer) can still be aligned to 16. When we skip alignment checking, the performance of the AOT-compiled internal Triton kernels can degrade 2x--3x.
In this PR, we replace `TensorArg.check_alignment` by `TensorArg.offset`, in which we specify the offset of the `ReinterpretView.layout` relative to the underlying `ir.Buffer` (corresponding to the data pointer before reinterpretation). As the size and stride of the layout don't change the alignment properties, those can be skipped. Importantly, for `ReinterpretView` arguments of custom Triton kernels, we use `arg.data.get_name()` as the buffer name. That, together with the offset, is used to check the alignment.
Bonus: the namedtuples in `codegen/common.py` are refactored as `dataclass`es, with nicer type hints and default values (for the newly added `TensorArg.offset`).
Test Plan:
```
$ python test/inductor/test_aot_inductor.py -k test_triton_kernel_reinterpret_view
...
----------------------------------------------------------------------
Ran 6 tests in 27.952s
OK (skipped=4)
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/119649
Approved by: https://github.com/oulgen
