b5377
vulkan: KHR_coopmat flash attention (#13506) This shader uses coopmat1 to do the Q*K^T multiply. The P*V multiply is more difficult for various reasons so I haven't done it. Performance for this shader is around 2.5x better than for the scalar shader when doing prompt processing. Some of the benefit may be from other optimizations like staging through shared memory, or splitting by rows.