Sym reshapes

[shivadbhavsar]

Motivation

Refactor reshape ops to use dim-like variant to handle symbolic shapes. This will be required when trying to enable simplification passes for symbolic shapes.

Technical Details

Add dim_like variant that works out of the box for current int64 representation for static shapes but can be extended to dyn_dims for symbolic shapes to allow symbolic target dims.

compute_shape will be modified in a later PR, the purpose here is to just introduce the new variant and ensure it causes no regressions with existing static shape compilation.

Later we would want to use this similarly for other ops such as slice, resize, etc. We can also consider refactoring broadcast ops to consolidate the current dual attribute implementation with out_lens and out_dyn_dims

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.

[codecov]

Codecov Report

❌ Patch coverage is 95.12195% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/include/migraphx/op/reshape.hpp	93.33%	1 Missing ⚠️
src/include/migraphx/op/reshape_lazy.hpp	92.31%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4832      +/-   ##
===========================================
- Coverage    92.66%   92.66%   -0.00%     
===========================================
  Files          588      590       +2     
  Lines        30412    30437      +25     
===========================================
+ Hits         28180    28203      +23     
- Misses        2232     2234       +2     

Files with missing lines	Coverage Δ
src/dim_like.cpp	100.00% <100.00%> (ø)
src/include/migraphx/dim_like.hpp	100.00% <100.00%> (ø)
src/include/migraphx/picked_variant.hpp	100.00% <ø> (ø)
src/include/migraphx/op/reshape.hpp	98.81% <93.33%> (-1.19%)	⬇️
src/include/migraphx/op/reshape_lazy.hpp	96.92% <92.31%> (-1.41%)	⬇️

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[pfultz2]

I would like to merge in #3753 first which unifies the reshape calculation for both reshape and reshape_lazy and it also propagates the permutation.

[Copilot]

Pull request overview

This PR introduces a new dim_like attribute element type (int64 or shape::dynamic_dimension) and refactors reshape operators to store dims as std::vector<dim_like>, with accompanying serialization support and tests. This is a foundational change to enable future symbolic-shape reshape support without regressing existing static-shape behavior.

Changes:

• Add migraphx::dim_like (picked-variant) plus to_value/from_value serialization support.
• Refactor reshape / reshape_lazy ops to use std::vector<dim_like> for dims.
• Add unit tests for dim_like behavior and update an ONNX reshape parse test accordingly.

Reviewed changes

Copilot reviewed 7 out of 8 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
test/onnx/parse/reshape_test.cpp	Adjust test to populate reshape::dims with the new dim_like element type.
test/dim_like_test.cpp	New unit tests covering construction, equality, streaming, and serialization round-trips for dim_like.
src/include/migraphx/op/reshape.hpp	Switch dims to std::vector<dim_like>; update shape inference logic to accommodate the new representation.
src/include/migraphx/op/reshape_lazy.hpp	Switch dims to std::vector<dim_like>; update lazy reshape shape inference logic accordingly.
src/include/migraphx/dim_like.hpp	New public header defining dim_like, stream support, and serialization declarations.
src/dim_like.cpp	Implements dim_like serialization (migraphx_to_value/migraphx_from_value).
src/CMakeLists.txt	Adds dim_like.cpp to the core library build.
.gitignore	Adds ignores for local caches/venv-related directories.

[pfultz2]

We should update the picked_variant constructor to propagate the substitution failure instead, Picker::apply(vector<...>) is a substitution failure which is fine, but not when using the picked_variant constructor where it becomes a error(the AI says hard-fail which is a really confusing term).