b11703

hexagon: vectorize softplus with HVX (#30435)

softplus_f32 and tile_softplus_f32 ran a scalar logf(1.0f + expf(x)) loop.
Replace both with a shared hvx_softplus_f32_aa() helper built from the
backend's existing hvx_vec_exp_f32 / hvx_vec_log_f32 primitives, so no new
numerical approximation is introduced.

hvx_vec_exp_f32 clamps its input to (-88, 88) before exponentiating, so a
naive log(1 + exp(x)) composition would saturate to ~88.72 for large x
instead of returning x. The Q6_V_vmux_QVV select keeps the scalar
reference's x > 20 guard (ggml_compute_softplus_f32 in ggml-impl.h),
which is what makes the vector path match the CPU result.

Assisted-by: Claude

Website:

• https://llama.app

Attestations:

• https://github.com/ggml-org/llama.cpp/attestations/56858411

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