pytorch

4cbf18cc - Enables integer -> float type promotion in TensorIterator (#42359)

Enables integer -> float type promotion in TensorIterator (#42359) Summary: Many ufuncs (mostly unary ufuncs) in NumPy promote integer inputs to float. This typically occurs when the results of the function are not representable as integers. For example: ``` a = np.array([1, 2, 3], dtype=np.int64) np.sin(a) : array([0.84147098, 0.90929743, 0.14112001]) ``` In PyTorch we only have one function, `torch.true_divide`, which exhibits this behavior today, and it did it by explicitly pre-casting its inputs to the default (float) scalar type where necessary before calling TensorIterator. This PR lets TensorIterator understand and implement this behavior directly, and it updates `torch.true_divide` to verify the behavior is properly implemented. This will be convenient when implementing more integer->float promotions later (like with `torch.sin`), and also saves copies on CUDA, where the cast from one dtype to another is fused with the computation. The mechanism for this change is simple. A new flag, `promote_integer_inputs_to_float_` is added to TensorIteratorConfig, and it requires `promote_integer_inputs_to_float_` be true if it's set. When the new flag is set, after the TensorIterator's "common dtype" (AKA "computation type") is computed it's checked for being an integral (boolean included) type and, if it is, changed to the default (float) scalar type, instead. Only `torch.true_divide` sets this flag (for now). In the future we'll likely... - provide helpers (`binary_float_op`, `unary_float_op`) to more easily construct functions that promote int->float instead of requiring they build their own TensorIteratorConfigs. - update torch.atan2 to use `binary_float_op` - update many unary ufuncs, like `torch.sin` to use `unary_float_op` and support unary ops having different input and result type (this will also require a small modification to some of the "loops" code) Pull Request resolved: https://github.com/pytorch/pytorch/pull/42359 Reviewed By: ngimel Differential Revision: D22878394 Pulled By: mruberry fbshipit-source-id: b8de01e46be859321522da411aed655e2c40e5b9