hexagon: Flash Attention optimizations (dma, mpyacc, multi-row) and MatMul updates (#20118)
* ggml-hexagon: enhance hvx_dot_f16_f16_aa_rx4 for improved performance by expanding vector handling and optimizing accumulation
# Conflicts:
# ggml/src/ggml-hexagon/htp/flash-attn-ops.c
* ggml-hexagon: optimize hvx_dot_f16_f16_aa_rx4 and enhance hvx_vec_reduce_sum_f32x4 for improved performance and reduced complexity
* ggml-hexagon: add hvx_dot_f16_f16_aa_rx32 for enhanced vector processing in flash attention
# Conflicts:
# ggml/src/ggml-hexagon/htp/flash-attn-ops.c
* optimize hvx_dot_f16_f16_aa_rx4 and hvx_dot_f16_f16_aa_rx32 by removing unused scale parameter and improving vector accumulation
# Conflicts:
# ggml/src/ggml-hexagon/htp/flash-attn-ops.c
* ggml-hexagon: refactor hvx_dot_f16_f16_aa_rx4 for improved readability and return HVX_Vector for better integration
# Conflicts:
# ggml/src/ggml-hexagon/htp/flash-attn-ops.c
* ggml-hexagon: initialize sums variable in hvx_dot_f16_f16_aa_rx32 for clarity
* ggml-hexagon: fix compiling error
* fix hvx_dot_f16_f16_aa_rx4 to handle leftover elements correctly using masking
* refactor hvx_dot_f16_f16_aa_rx4 to accept vector and leftover element counts as parameters for improved clarity and flexibility
* wip
* fa: instrumentation and dma reordering
* hex-fa: use block-size 64 to improve DMA pipelining
* hex-fa: optimize vec-dot for v79 and above
* hex-fa: use block size 64
* hex-fa: avoid scalar fp32->fp16 conversions
* hex-fa: simplify dot_f16 functions using optimized vec_mpyacc
* hex-fa: rewrite mad_f32_f16 using hvx_vec_mpyacc
* hex-mm: use mpyacc in matmul dot functions
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Co-authored-by: chraac <chraac@gmail.com>