Fix dynamic shape conversion semantics

[shivadbhavsar]

Motivation

Goal here is to fix the discrepancies left after integrating symbolic shapes.

1. Preserve original meaning of "to_dynamic" shape method before symbolic integration. For symbolic shape, simply demote to a range-based shape
2. Add a "to_symbolic" shape method to generate a symbolic shape from a static shape by using literal expressions
3. Add a "to_dynamic" static method that returns all inputs shape with a uniform representation

Technical Details

1. for shape to_dynamic(): Revert back to logic before [AIMIGRAPHX-835] integrate symbolic expression in dynamic_dimension #4702. Add block to demote symbolic to pure range-based via interval computation
2. shape to_symbolic(): Convert static shape to symbolic literals. Identity for symbolic shapes. Throws for range-based shapes
3. static vector to_dynamic: Convert all input shapes to symbolic shapes when possible. If there is a range-based shape in the inputs, convert/demote everything to range-based shapes

In practice, there should be no mix between range-based dynamic shapes and symbolic shapes (all dynamic shapes will be represented throughout a model exclusively in one format), the goal here is to have a clear semantic anyway. The static to_dynamic function should be used in compute shapes to create a uniform representation in compute_shape methods of operators.

Changelog Category

Add a CHANGELOG.md entry for any option other than Not Applicable

• • Added: New functionality.
• • Changed: Changes to existing functionality.
• • Removed: Functionality or support that has been removed. (Compared to a previous release)
• • Optimized: Component performance that has been optimized or improved.
• • Resolved Issues: Known issues from a previous version that have been resolved.
• • Not Applicable: This PR is not to be included in the changelog.

[Copilot]

Pull request overview

This PR refines MIGraphX shape conversion semantics after symbolic shape integration, clarifying when shapes should be represented as range-based dynamic vs symbolic dynamic and adding utilities to enforce a uniform representation.

Changes:

• Reworked shape::to_dynamic() to return a range-based dynamic shape (and demote symbolic shapes by evaluating intervals/optimals), restoring pre-symbolic semantics.
• Added shape::to_symbolic() and static shape::to_dynamic(std::vector<shape>) to promote/demote shapes to a uniform representation across inputs (including tuple sub-shapes).
• Extended shape tests for to_symbolic, static to_dynamic, same_lens with symbolic shapes, and is_fixed().

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/shape.cpp	Implements updated to_dynamic(), adds to_symbolic(), adds static to_dynamic(vector), and updates same_lens() via new is_fixed().
src/include/migraphx/shape.hpp	Declares new conversion APIs and adds fixed-dim utilities plus is_fixed() declaration.
test/shape_test.cpp	Updates existing expectations and adds coverage for symbolic promotion/demotion and fixed/same-lens behaviors.

[codecov]

Codecov Report

❌ Patch coverage is 96.07843% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/shape.cpp	96.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4828      +/-   ##
===========================================
- Coverage    92.80%   92.79%   -0.00%     
===========================================
  Files          584      584              
  Lines        30067    30111      +44     
===========================================
+ Hits         27901    27941      +40     
- Misses        2166     2170       +4     

Files with missing lines	Coverage Δ
src/include/migraphx/shape.hpp	91.36% <ø> (ø)
src/sym.cpp	97.11% <100.00%> (+<0.01%)	⬆️
src/shape.cpp	91.71% <96.00%> (-0.07%)	⬇️

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