[losewayy]

Summary

Sol now passes the Q/K views of the QKV projection directly to RMSNorm instead of copying them first, and the CUDA backend fuses the non-affine RMSNorm with the following partial RoPE. The kernel preserves the reduction order and rounding of the separate ops.

Related Issue / Discussion

Follow-up to #2317.

Additional Information

Tested on an RTX 5070 Ti Laptop GPU (sm_120) with CUDA 13.4. Decoding an 864×480, 56-frame clip took 13% less time on average than master. CUDA output is byte-for-byte identical to master with fusion on or off, and CPU and Vulkan outputs also match master.

Checklist

• I have read and confirmed this PR follows the contribution guidelines.

Summary by CodeRabbit

• Performance
  • Improved CUDA processing for certain RMS normalization and RoPE operations, including a direct non-affine path for supported 64-channel F32 inputs.
  • Updated SOL attention processing to use its dedicated projection path.
• Documentation
  • Clarified the supported configurations for CUDA RMSNorm/RoPE fusion, including input format, RoPE mode, and weight layout requirements.

[coderabbitai]

Walkthrough

The CUDA backend adds a non-affine RMSNorm-to-RoPE fusion for eligible F32 inputs with 64 channels. The SOL attention path now uses a QKV projection method that applies RMS normalization and RoPE to Q and K.

Changes: CUDA RoPE fusion and SOL projection

Layer / File(s)	Summary
Non-affine CUDA RMSNorm–RoPE fusion src/core/cuda/rope.cu, docs/ggml_extensions.md	The CUDA kernel and graph handling support an eligible two-node non-affine RMSNorm-to-RoPE fusion. The documentation describes its input requirements and distinguishes it from affine fusion.
SOL attention projection src/model/vae/minimax_h3_vae.hpp	DecoderAttention adds project_sol to apply RMS normalization and RoPE to Q and K. The SOL callback uses it; the non-SOL path still uses project.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Refactor

Possibly related issues

• leejet/stable-diffusion.cpp#2264 — The issue requests Sol-H3-VAE support; this change adds a SOL-specific attention projection path.

Possibly related PRs

• leejet/stable-diffusion.cpp#2269 — Extends CUDA RMSNorm–Mul–RoPE fusion in the same implementation.
• leejet/stable-diffusion.cpp#2253 — Moves CUDA RoPE kernels and fusion rules into the backend extension implementation continued here.

Suggested reviewers: leejet

Merge Risk: Minimal · up to e8671

No actionable merge-blocking issue was established; the change is ready for normal merge checks.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentat…	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Title check		The title clearly identifies the CUDA RMSNorm-and-RoPE fusion and its performance focus for Sol-H3-VAE.
Description check		The description includes all required template sections, explains the change, links related work, reports testing and performance results, and completes the checklist.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 6 functions across 2 files. (1 skipped: 1 unsupported.)

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

Finishing Touches

Generate unit tests (beta)

• Create a new PR

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Failed pre-merge checks:
- Docstring Coverage:
Write docstrings for the functions missing them to satisfy the coverage
threshold.

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Commits

Reviewing files that changed from the base of the PR and between 0678d04 and e867115.

Files selected for processing: 3

• docs/ggml_extensions.md
• src/core/cuda/rope.cu
• src/model/vae/minimax_h3_vae.hpp

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