[hipDNN] Add RMSNorm backward CPU reference implementation

[saikubairkota]

Motivation

This PR adds the RMSNorm backward CPU reference implementation to the hipDNN test SDK.

Technical Details

• Added the CPU reference implementation of the RMSNorm backward operation.
• Implemented CpuFpReferenceRMSNorm::backward() that calculates the gradients dx, dscale, and dbias .
• Added RMSNormBwdPlan, RMSNormBwdPlanBuilder, and RMSNormBwdSignatureKey for executing RMSNorm backward graph operations.
• Added unit tests for the plan, signature key, and the CPU reference implementation.

Test Plan

Build hipDNN and run the relevant unit tests with ./bin/hipdnn_test_sdk_tests --gtest_filter="*RMSNormBwd*".

Test Result

All relevant unit tests pass successfully on an MI210.

• ninja check - full test suite

Submission Checklist

• Look over the contributing guidelines at https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 83.48624% with 54 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...ities/cpu_graph_executor/detail/RMSNormBwdPlan.hpp	70.30%	14 Missing and 16 partials ⚠️
...ipdnn_test_sdk/utilities/CpuFpReferenceRMSNorm.hpp	89.92%	9 Missing and 3 partials ⚠️
...u_graph_executor/detail/RMSNormBwdSignatureKey.hpp	88.57%	8 Missing and 4 partials ⚠️

❌ Your project status has failed because the head coverage (77.83%) is below the target coverage (80.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #7494      +/-   ##
===========================================
+ Coverage    61.93%   61.95%   +0.02%     
===========================================
  Files         2084     2086       +2     
  Lines       357263   357576     +313     
  Branches     54006    54043      +37     
===========================================
+ Hits        221253   221521     +268     
- Misses      117207   117231      +24     
- Partials     18803    18824      +21     

Flag	Coverage Δ		*Carryforward flag
TensileLite	25.95% <ø> (ø)		Carriedforward from 06b571e
hipBLAS	90.65% <ø> (ø)		Carriedforward from 06b571e
hipBLASLt	41.27% <ø> (ø)		Carriedforward from 06b571e
hipCUB	82.21% <ø> (ø)		Carriedforward from 06b571e
hipDNN	86.89% <83.49%> (-0.01%)	⬇️
hipFFT	50.00% <ø> (ø)		Carriedforward from 06b571e
hipRAND	76.12% <ø> (ø)		Carriedforward from 06b571e
hipSOLVER	69.24% <ø> (ø)		Carriedforward from 06b571e
hipSPARSE	85.42% <ø> (ø)		Carriedforward from 06b571e
rocBLAS	48.09% <ø> (ø)		Carriedforward from 06b571e
rocFFT	52.07% <ø> (ø)		Carriedforward from 06b571e
rocRAND	57.04% <ø> (ø)		Carriedforward from 06b571e
rocSOLVER	77.83% <ø> (ø)		Carriedforward from 06b571e
rocSPARSE	72.68% <ø> (ø)		Carriedforward from 06b571e

*This pull request uses carry forward flags. Click here to find out more.

Files with missing lines	Coverage Δ
...s/cpu_graph_executor/CpuReferenceGraphExecutor.hpp	82.14% <100.00%> (+0.44%)	⬆️
.../cpu_graph_executor/detail/PlanBuilderRegistry.hpp	100.00% <ø> (ø)
...graph_executor/detail/PlanRegistrySignatureKey.hpp	100.00% <ø> (ø)
...ipdnn_test_sdk/utilities/CpuFpReferenceRMSNorm.hpp	90.71% <89.92%> (+4.81%)	⬆️
...u_graph_executor/detail/RMSNormBwdSignatureKey.hpp	88.57% <88.57%> (ø)
...ities/cpu_graph_executor/detail/RMSNormBwdPlan.hpp	70.30% <70.30%> (ø)

... and 2 files with indirect coverage changes

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[EwanC]

LGTM

[BalintCsala]

LGTM

[adickin-amd]

looked like CI hit some infra errors on your PR. I merged in develop to get it to run again

[adickin-amd]

LGTM, miopen-provider failure is unrelated to these change. the code coverage issue also looks unrelated. Ive brought up the code coverage issue with hipdnn-core to discuss if we can exlude mocks from coverage.