Refactor rnn ops to op builders

[pfultz2]

Motivation

Technical Details

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.

[pfultz2]

This was a mistake, the test is for lstm, but we were using gru.

[Copilot]

Pull request overview

This PR migrates RNN-family ops (RNN/LSTM/GRU) from dedicated operators + rewrite_rnn pass to OpBuilder-based graph construction, updating ONNX parsing and verification tests accordingly and removing the legacy ops/pass.

Changes:

• Add OpBuilder implementations for rnn, lstm, and gru (plus shared utilities) that directly expand into lower-level ops.
• Update ONNX parsers and many verify tests to use migraphx::op::builder::add(...) results instead of make_op("rnn"/"lstm"/"gru") + rnn_last_* ops.
• Remove rewrite_rnn from target pass pipelines and remove legacy RNN-family operators/headers/registrations; add new OpBuilder-focused tests.

Reviewed changes

Copilot reviewed 96 out of 97 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
test/verify/test_var_sl_gru_forward.cpp	Switch GRU construction to OpBuilder and adjust return ordering to match builder outputs.
test/verify/test_var_sl_gru_bidirct.cpp	Switch bidirectional GRU construction to OpBuilder.
test/verify/test_rnn_sql_2.cpp	Switch RNN construction to OpBuilder; remove unused serialize include.
test/verify/test_rnn_sql_1_layout.cpp	Switch RNN construction to OpBuilder and adapt layout handling to builder outputs.
test/verify/test_rnn_sql_1.cpp	Switch RNN construction to OpBuilder; remove unused serialize include.
test/verify/test_rnn_reverse_layout.cpp	Switch reverse RNN construction to OpBuilder and reuse builder output for layout ops.
test/verify/test_rnn_reverse2.cpp	Switch reverse RNN construction to OpBuilder (no explicit return).
test/verify/test_rnn_reverse.cpp	Switch reverse RNN construction to OpBuilder (no explicit return).
test/verify/test_rnn_forward_layout.cpp	Switch forward RNN construction to OpBuilder and adapt layout handling.
test/verify/test_rnn_forward10.cpp	Switch forward RNN construction to OpBuilder.
test/verify/test_rnn_forward.cpp	Switch forward RNN construction to OpBuilder.
test/verify/test_rnn_bidirectional_layout.cpp	Switch bidirectional RNN construction to OpBuilder and adapt last-output usage.
test/verify/test_rnn_bidirectional10.cpp	Switch bidirectional RNN construction to OpBuilder (no explicit return).
test/verify/test_rnn_bidirectional.cpp	Switch bidirectional RNN construction to OpBuilder (no explicit return).
test/verify/test_rnn_bi_3args_layout.cpp	Switch 3-arg bidirectional RNN construction to OpBuilder and adapt last-output usage.
test/verify/test_rnn_bi_3args.cpp	Switch 3-arg bidirectional RNN construction to OpBuilder.
test/verify/test_rnn_5args.cpp	Switch 5-arg RNN construction to OpBuilder.
test/verify/test_rnn_4args_layout.cpp	Switch 4-arg RNN construction to OpBuilder and adapt layout handling.
test/verify/test_rnn_4args.cpp	Switch 4-arg RNN construction to OpBuilder.
test/verify/test_rnn_3args.cpp	Switch 3-arg RNN construction to OpBuilder.
test/verify/test_lstm_two_outputs.cpp	Switch LSTM construction to OpBuilder and return builder outputs.
test/verify/test_lstm_three_outputs_layout.cpp	Switch LSTM construction to OpBuilder and adapt layout handling for 3 outputs.
test/verify/test_lstm_three_outputs.cpp	Switch LSTM construction to OpBuilder and return 3 builder outputs.
test/verify/test_lstm_reverse_last.cpp	Switch reverse LSTM construction to OpBuilder (no explicit return).
test/verify/test_lstm_reverse_3args_layout.cpp	Switch reverse LSTM construction to OpBuilder and adapt layout handling.
test/verify/test_lstm_reverse_3args_cell_output_layout.cpp	Switch reverse LSTM construction to OpBuilder and adapt cell-output usage.
test/verify/test_lstm_reverse_3args_cell_output.cpp	Switch reverse LSTM construction to OpBuilder (no explicit return).
test/verify/test_lstm_reverse_3args.cpp	Switch reverse LSTM construction to OpBuilder (no explicit return).
test/verify/test_lstm_forward_seq1.cpp	Switch forward LSTM construction to OpBuilder (no explicit return).
test/verify/test_lstm_forward_last_layout.cpp	Switch forward LSTM construction to OpBuilder and adapt layout handling for last output.
test/verify/test_lstm_forward_last.cpp	Switch forward LSTM construction to OpBuilder (no explicit return).
test/verify/test_lstm_forward_hs_layout.cpp	Switch forward LSTM construction to OpBuilder and adapt layout handling for hidden states.
test/verify/test_lstm_forward_hs.cpp	Switch forward LSTM construction to OpBuilder (no explicit return).
test/verify/test_lstm_forward_default_actv1.cpp	Switch forward LSTM construction to OpBuilder with explicit default activation list.
test/verify/test_lstm_forward_default_actv.cpp	Switch forward LSTM construction to OpBuilder with empty activation list.
test/verify/test_lstm_forward_3args_und.cpp	Switch forward LSTM construction to OpBuilder with undefined placeholders.
test/verify/test_lstm_forward_3args.cpp	Switch forward LSTM construction to OpBuilder (no explicit return).
test/verify/test_lstm_bidirct_seq1.cpp	Switch bidirectional LSTM construction to OpBuilder (no explicit return).
test/verify/test_lstm_bidirct_last_layout.cpp	Switch bidirectional LSTM construction to OpBuilder and adapt layout handling for last output.
test/verify/test_lstm_bidirct_last.cpp	Switch bidirectional LSTM construction to OpBuilder (no explicit return).
test/verify/test_lstm_bidirct_hs.cpp	Switch bidirectional LSTM construction to OpBuilder (no explicit return).
test/verify/test_lstm_bidirct_default_actv2.cpp	Switch bidirectional LSTM construction to OpBuilder with 2 default activations.
test/verify/test_lstm_bidirct_default_actv1.cpp	Switch bidirectional LSTM construction to OpBuilder with 1 default activation.
test/verify/test_lstm_bidirct_default_actv.cpp	Switch bidirectional LSTM construction to OpBuilder with empty activation list.
test/verify/test_lstm_bidirct_3args_und.cpp	Switch GRU (file name indicates LSTM) to OpBuilder with undefined placeholders.
test/verify/test_lstm_bidirct_3args_layout.cpp	Switch bidirectional LSTM construction to OpBuilder and adapt layout handling.
test/verify/test_lstm_bidirct_3args.cpp	Switch bidirectional LSTM construction to OpBuilder (no explicit return).
test/verify/test_gru_two_outputs.cpp	Switch GRU construction to OpBuilder and return builder outputs.
test/verify/test_gru_reverse_last_layout.cpp	Switch reverse GRU construction to OpBuilder and adapt layout handling for last output.
test/verify/test_gru_reverse_last.cpp	Switch reverse GRU construction to OpBuilder and return last output directly.
test/verify/test_gru_reverse_3args_layout.cpp	Switch reverse GRU construction to OpBuilder and adapt layout handling.
test/verify/test_gru_reverse_3args.cpp	Switch reverse GRU construction to OpBuilder and return hidden states.
test/verify/test_gru_forward_seq1.cpp	Switch forward GRU construction to OpBuilder and return hidden states.
test/verify/test_gru_forward_layout.cpp	Switch forward GRU construction to OpBuilder and adapt layout handling.
test/verify/test_gru_forward_default_actv1.cpp	Switch forward GRU construction to OpBuilder and return hidden states.
test/verify/test_gru_forward_default_actv.cpp	Switch forward GRU construction to OpBuilder and return hidden states.
test/verify/test_gru_forward_3args_und.cpp	Switch forward GRU construction to OpBuilder with undefined placeholders.
test/verify/test_gru_forward_3args_layout.cpp	Switch forward GRU construction to OpBuilder and adapt layout handling.
test/verify/test_gru_forward_3args.cpp	Switch forward GRU construction to OpBuilder and return hidden states.
test/verify/test_gru_forward.cpp	Switch forward GRU construction to OpBuilder and preserve return ordering.
test/verify/test_gru_bidirct_seq1.cpp	Switch bidirectional GRU construction to OpBuilder and return hidden states.
test/verify/test_gru_bidirct_layout.cpp	Switch bidirectional GRU construction to OpBuilder and adapt layout handling.
test/verify/test_gru_bidirct_default_actv1.cpp	Switch bidirectional GRU construction to OpBuilder and return hidden states.
test/verify/test_gru_bidirct_default_actv.cpp	Switch bidirectional GRU construction to OpBuilder and return hidden states.
test/verify/test_gru_bidirct_3args_und.cpp	Switch bidirectional GRU construction to OpBuilder with undefined placeholders.
test/verify/test_gru_bidirct_3args_layout.cpp	Switch bidirectional GRU construction to OpBuilder and adapt layout handling.
test/verify/test_gru_bidirct_3args.cpp	Switch bidirectional GRU construction to OpBuilder and return hidden states.
test/verify/test_gru_bidirct.cpp	Switch bidirectional GRU construction to OpBuilder and return both outputs.
test/operators.cpp	Remove legacy rnn operator test case (operator no longer present).
test/op/builder/rnn_builder_test.cpp	Add OpBuilder tests for RNN output arity, shapes, and basic eval.
test/op/builder/lstm_builder_test.cpp	Add OpBuilder tests for LSTM output arity, shapes, and basic eval.
test/op/builder/gru_builder_test.cpp	Add OpBuilder tests for GRU output arity, shapes, and basic eval.
src/targets/ref/target.cpp	Remove rewrite_rnn pass from ref target pipeline.
src/targets/gpu/target.cpp	Remove rewrite_rnn pass from GPU target pipeline.
src/targets/fpga/target.cpp	Remove rewrite_rnn pass from FPGA target pipeline.
src/targets/cpu/target.cpp	Remove rewrite_rnn pass from CPU target pipeline.
src/quantization.cpp	Remove rewrite_rnn from quantization pre-pass pipeline.
src/op/builder/rnn.cpp	Add OpBuilder expansion for vanilla RNN into lower-level ops + var-seq-len handling.
src/op/builder/lstm.cpp	Add OpBuilder expansion for LSTM into lower-level ops + var-seq-len handling.
src/op/builder/gru.cpp	Add OpBuilder expansion for GRU into lower-level ops + var-seq-len handling.
src/op/builder/include/migraphx/op/builder/rnn_utils.hpp	Add shared utilities for seq-len handling, padding, and var-seq-len shifting.
src/onnx/parse_rnn.cpp	Parse ONNX RNN via OpBuilder and consume returned outputs.
src/onnx/parse_lstm.cpp	Parse ONNX LSTM via OpBuilder and consume returned outputs.
src/onnx/parse_gru.cpp	Parse ONNX GRU via OpBuilder and consume returned outputs.
src/include/migraphx/rewrite_rnn.hpp	Remove legacy rewrite pass API header.
src/include/migraphx/operators.hpp	Stop including legacy rnn/gru/lstm + last-output operator headers.
src/include/migraphx/op/rnn_last_hs_output.hpp	Remove legacy rnn_last_hs_output operator.
src/include/migraphx/op/rnn_last_cell_output.hpp	Remove legacy rnn_last_cell_output operator.
src/include/migraphx/op/rnn.hpp	Remove legacy rnn operator.
src/include/migraphx/op/lstm.hpp	Remove legacy lstm operator.
src/include/migraphx/op/gru.hpp	Remove legacy gru operator.
src/driver/passes.cpp	Remove rewrite_rnn from driver pass lookup.
src/CMakeLists.txt	Stop building/registering legacy rnn/gru/lstm operators and rewrite_rnn.

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[Copilot]

hidden_size and clip are reflected on lstm_builder, but hidden_size is not validated/used (the implementation derives hs from R), and clip is also unused. This can mask invalid inputs (attribute/weight mismatch) and makes the public builder API misleading. Consider validating these attributes against the provided tensors and either applying clip/hidden_size semantics or throwing when they are inconsistent/non-default.

[Copilot]

input_forget is parsed and reflected on lstm_builder, but it is never used in the LSTM computation. As a result, ONNX models that set input_forget=1 will behave the same as 0. Consider either implementing the input-forget coupling in the cell logic, or explicitly rejecting/ignoring non-zero values with a clear error to avoid silent misbehavior.

[Copilot]

hidden_size (and clip) are accepted as attributes on rnn_builder, but the implementation never uses them or validates them against the provided weight shapes. This can hide malformed inputs (e.g., ONNX attribute/weight mismatch) that previously would have been caught. Consider validating hidden_size and direction against W/R shapes and either using hidden_size for shape decisions or throwing on mismatch.

[Copilot]

hidden_size (and clip) are reflected on gru_builder, but the builder derives hs from the input shapes and does not validate/consume the hidden_size attribute. This makes invalid graphs harder to diagnose (attribute/weight mismatch) and can lead to silent shape inconsistencies. Consider validating hidden_size against R/W and erroring on mismatch (or removing the unused attribute).

[codecov]

Codecov Report

❌ Patch coverage is 99.71751% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/op/builder/lstm.cpp	99.25%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4606      +/-   ##
===========================================
- Coverage    92.21%   92.19%   -0.02%     
===========================================
  Files          567      564       -3     
  Lines        27897    27807      -90     
===========================================
- Hits         25724    25636      -88     
+ Misses        2173     2171       -2     

Files with missing lines	Coverage Δ
src/include/migraphx/serialize.hpp	92.45% <100.00%> (+0.15%)	⬆️
src/onnx/parse_gru.cpp	95.45% <100.00%> (-0.26%)	⬇️
src/onnx/parse_lstm.cpp	94.74% <100.00%> (-0.20%)	⬇️
src/onnx/parse_rnn.cpp	95.24% <100.00%> (-0.15%)	⬇️
src/op/builder/gru.cpp	100.00% <100.00%> (ø)
.../builder/include/migraphx/op/builder/rnn_utils.hpp	100.00% <100.00%> (ø)
src/op/builder/rnn.cpp	100.00% <100.00%> (ø)
src/quantization.cpp	85.33% <100.00%> (ø)
src/targets/ref/target.cpp	100.00% <ø> (ø)
src/op/builder/lstm.cpp	99.25% <99.25%> (ø)

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