llama.cpp · b11980

[SYCL] add DPAS flash attention kernel for quantized KV cache (#31125) * sycl : add DPAS flash attention kernel for quantized KV cache Decode and small batches (1 to 31 query tokens) now run flash attention straight on q4_0 and q8_0 KV blocks, instead of scalar dequant or converting the whole cache to f16 per call. Q.K uses s8 x s4 and s8 x s8 DPAS on XMX, V.P stays f16. dpas.s4.s8 is inline vISA since joint_matrix has no s4. Covers head sizes 64 to 512, GQA up to 32 and attention sinks. Prompts stay on the existing kernels. GGML_SYCL_FA_DPAS=0 turns it off. B580, Llama 3.1 8B Q4_K_M, q4_0 KV, tg128: 31.3 to 54.2 t/s at 16K context. FLASH_ATTN_EXT 4582/4584, same 2 failures as master. Assisted-by: Claude * sycl : 192 head dropped, Wildcat Lake added to docs Assisted-by: Claude * sycl : str