support mips elu erf gelu selu

[futz12]

No description provided.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.64%. Comparing base (7237643) to head (91c3405).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6607      +/-   ##
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- Coverage   93.41%   92.64%   -0.78%     
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  Files         868      873       +5     
  Lines      275540   273876    -1664     
==========================================
- Hits       257391   253726    -3665     
- Misses      18149    20150    +2001     

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[Copilot]

Pull request overview

Adds MIPS (MSA-accelerated) implementations for several activation/unary layers to improve performance on MIPS targets, including vectorized erf support needed by GELU.

Changes:

• Introduces new MIPS layer implementations: ELU, SELU, GELU, and Erf (with MSA vector paths + scalar fallback).
• Extends MSA math utilities with a vectorized erf_ps() approximation used by GELU/Erf.
• Adds an MSA helper elu_ps() to the shared MIPS activation utilities.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/layer/mips/selu_mips.h	Declares SELU_mips layer class for MIPS backend.
src/layer/mips/selu_mips.cpp	Implements SELU forward with optional MSA vectorization and packing support.
src/layer/mips/gelu_mips.h	Declares GELU_mips layer class for MIPS backend.
src/layer/mips/gelu_mips.cpp	Implements GELU forward (fast + exact modes) with optional MSA vectorization.
src/layer/mips/erf_mips.h	Declares Erf_mips layer class for MIPS backend.
src/layer/mips/erf_mips.cpp	Implements Erf forward with optional MSA vectorization using erf_ps.
src/layer/mips/elu_mips.h	Declares ELU_mips layer class for MIPS backend.
src/layer/mips/elu_mips.cpp	Implements ELU forward with optional MSA vectorization using elu_ps.
src/layer/mips/msa_mathfun.h	Adds MSA vector erf_ps() and supporting constants.
src/layer/mips/mips_activation.h	Adds MSA helper elu_ps() for reuse in ELU and potentially other codepaths.

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[nihui]

Thanks for your contribution !