ggml-cpu: Use tiled FA for prompt-processing (#19012)

* ggml-cpu: Use tiled FA for prompt-processing

the FA performance is gimped on CPU on long contexts because it essentially uses a vector kernel. This PR adds a tiled FA for PP. Perf tuning for tile sizes done on a AMD EPYC single-socket 64-c machine.

* fix out of bounds for mask

* skip rows where there are all masks

* skip tile if mask is inf

* store mask in worksize

* check inf tile earlier

ggml/src/ggml-cpu/common.h

@@ -6,6 +6,9 @@
 #include "ggml-impl.h"
 #include "simd-mappings.h"
 
+#define GGML_FA_TILE_Q  32
+#define GGML_FA_TILE_KV 16
+
 #ifdef __cplusplus
 
 #include <utility>
@@ -84,4 +87,9 @@ static std::pair<int64_t, int64_t> get_thread_range(const struct ggml_compute_pa
     return {ir0, ir1};
 }
 
+struct ggml_fa_tile_config {
+    static constexpr size_t Q  = GGML_FA_TILE_Q;
+    static constexpr size_t KV = GGML_FA_TILE_KV;
+};
+
 #endif