ggml : update ggml_prec specification (#26675)

* ggml : update ggml_prec specification

[no ci]

* cont : add GGML_PREC_BF16

* cont : rework API

* cont : use new API

* cont : swap arg order

* cont : support for MUL_MAT_ID

* cont : fix accidental remove of "break;"

* cont : return bools, add doc TAG_GGML_PREC, clean-up

* cont : add search tag

* cont : ws

ggml/src/ggml-impl.h

@@ -160,6 +160,18 @@ static float ggml_get_op_params_f32(const struct ggml_tensor * tensor, uint32_t
     return ((const float *)(tensor->op_params))[i];
 }
 
+// [TAG_GGML_PREC]
+// - GGML_OP_MUL_MAT
+//   0 - acc
+//   1 - hint
+//   2 - src0 precision
+//   3 - src1 precision
+//
+// - GGML_OP_MUL_MAT_ID
+//   0 - acc
+//   1 - hint
+//   2 - src0 precision
+//   3 - src1 precision
 static void ggml_set_op_params_i32(struct ggml_tensor * tensor, uint32_t i, int32_t value) {
     assert(i < GGML_MAX_OP_PARAMS / sizeof(int32_t));
     ((int32_t *)(tensor->op_params))[i] = value;

ggml/src/ggml.c

@@ -3277,6 +3277,57 @@ struct ggml_tensor * ggml_l2_norm_inplace(
     return ggml_l2_norm_impl(ctx, a, eps, true);
 }
 
+// ggml_prec
+
+bool ggml_prec_set_acc(
+        struct ggml_tensor * a,
+        enum ggml_prec       prec) {
+    switch (a->op) {
+        case GGML_OP_MUL_MAT:
+        case GGML_OP_MUL_MAT_ID:
+            {
+                const int32_t prec_i32 = (int32_t) prec;
+                ggml_set_op_params_i32(a, 0, prec_i32);
+            }
+            break;
+        case GGML_OP_FLASH_ATTN_EXT:
+            {
+                const int32_t prec_i32 = (int32_t) prec;
+                ggml_set_op_params_i32(a, 3, prec_i32);
+            }
+            break;
+        default:
+            return false;
+    };
+
+    return true;
+}
+
+bool ggml_prec_set_src(
+        struct ggml_tensor * a,
+        enum ggml_prec       prec,
+        int                  idx) {
+    GGML_ASSERT(idx >= 0 && idx < GGML_MAX_SRC);
+
+    switch (a->op) {
+        case GGML_OP_MUL_MAT:
+        case GGML_OP_MUL_MAT_ID:
+            {
+                if (idx != 1) {
+                    return false;
+                }
+
+                const int32_t prec_i32 = (int32_t) prec;
+                ggml_set_op_params_i32(a, 2 + idx, prec_i32);
+            }
+            break;
+        default:
+            return false;
+    };
+
+    return true;
+}
+
 // ggml_mul_mat
 
 static inline bool ggml_can_mul_mat(const struct ggml_tensor * t0, const struct ggml_tensor * t1) {