Add dynamic shape support for TopK

[klin2024]

Motivation

The topk operator previously required a constant k and static input shapes, which will block the SSDMobileNetV2 model from running.

AMDMIGraphX/src/onnx/parse_topk.cpp

Line 47 in 93b8849

check_arg_empty(arg_k, "PARSE_TopK: k input must be constant");

This PR adds dynamic input support for the topk op.

Affected model: SSDMobileNetV2

Technical Details

.\bin\migraphx-driver.exe perf .\bin\topk_shape_derived_k.onnx can run success.

onnx file
topk_shape_derived_k.zip

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 84.78261% with 7 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/onnx/parse_topk.cpp	57.14%	6 Missing ⚠️
src/program.cpp	66.67%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4880      +/-   ##
===========================================
+ Coverage    92.86%   92.87%   +0.01%     
===========================================
  Files          585      585              
  Lines        30152    30213      +61     
===========================================
+ Hits         27998    28059      +61     
  Misses        2154     2154              

Files with missing lines	Coverage Δ
src/include/migraphx/dyn_output.hpp	100.00% <100.00%> (ø)
src/include/migraphx/op/topk.hpp	98.72% <100.00%> (+0.28%)	⬆️
src/rewrite_topk.cpp	100.00% <100.00%> (ø)
src/program.cpp	81.05% <66.67%> (-0.08%)	⬇️
src/onnx/parse_topk.cpp	78.57% <57.14%> (-21.43%)	⬇️

... and 12 files with indirect coverage changes

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[Copilot]

Pull request overview

This PR extends MIGraphX’s TopK support to handle dynamic input shapes and cases where k is not a compile-time constant (by using a placeholder k derived from the input shape), and adjusts dynamic-output handling in evaluation/GPU lowering to better support tuple-shaped outputs like TopK.

Changes:

• Update ONNX TopK parsing to allow non-constant k by deriving a placeholder k from the input shape (static lens or dynamic max lens).
• Update op::topk to support dynamic shapes at shape-inference/eval time via dyn_output, including runtime clamping of k.
• Adjust GPU/lowering + dyn-output plumbing for tuple/dynamic shapes, and add tests for dynamic TopK scenarios.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
test/verify/test_topk_dynamic.cpp	Adds a verify test exercising TopK with a dynamic input shape and placeholder k.
test/ref/topk.cpp	Adds reference tests for k > n with dynamic input and for k == n behavior.
src/targets/gpu/lowering.cpp	Switches dynamic-shape detection to any_of_dynamic() to account for tuple outputs.
src/targets/gpu/include/migraphx/gpu/hip.hpp	Minor whitespace-only adjustment.
src/targets/gpu/compile_ops.cpp	Alters dynamic code-object execution to always compute/reshape runtime output shape and adds a skip-on-empty heuristic.
src/rewrite_topk.cpp	Disables large-TopK rewrite when input shape is dynamic.
src/program.cpp	Makes tracing more robust when evaluating submodules from dynamic code-object ops.
src/onnx/parse_topk.cpp	Removes the “k must be constant” restriction; derives placeholder k from input shape when needed.
src/include/migraphx/op/topk.hpp	Adds dynamic-shape support and switches compute to dyn_output, clamping k at runtime.
src/include/migraphx/dyn_output.hpp	Uses any_of_dynamic() so tuple outputs with dynamic subshapes get runtime-computed shapes.

[wendyli-2024]

Hi @pfultz2
Do you have time to check the code change? Thanks