Support Optional shapes (#26164)
This pull request introduces a new mechanism for handling tensor shape
information in ONNX Runtime, improving the representation and querying
of shape and symbolic dimension data. The changes add support for
tensors that may not have shape information, update APIs to reflect
this, and refactor internal shape handling logic for improved
consistency and extensibility.
### API and Core Logic Improvements
* Added a new API method `TensorTypeAndShape_HasShape` to `OrtApi` and
corresponding C++ wrapper `HasShape()` in `TensorTypeAndShapeInfoImpl`,
allowing users to check if a tensor has shape information.
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* Updated all shape-related API implementations (e.g.,
`GetDimensionsCount`, `GetDimensions`, `GetSymbolicDimensions`,
`GetTensorShapeElementCount`) to properly handle the case when a tensor
does not have shape information, returning zero or empty values as
appropriate.
### Refactoring and Consistency
* Refactored `OrtTensorTypeAndShapeInfo` to store shape information in
an optional structure, and updated all related methods to use pointers
instead of direct objects, improving consistency and future
extensibility.
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* Updated methods for constructing shape/type info to accept pointers
and handle cases where shape may be absent, including changes in
`onnxruntime_typeinfo.cc` and related API calls.
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### Graph and Proto Serialization
* Modified graph-to-proto conversion logic to propagate and respect the
presence or absence of shape information, ensuring that ONNX graph
serialization accurately reflects tensor shape status.
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These changes collectively improve the robustness and flexibility of
ONNX Runtime's handling of tensor shape information, and lay the
groundwork for supporting more dynamic and symbolic tensor shapes in
future development.
