ggml: add graph_reused (#21764)

* ggml: add graph_reused

* use versioning instead of reuse flag

* increment version with atomic

* use top bits for split numbering

* add assert

* move counter to ggml.c

* set uid in split_graph only

* fix windows

* address further review comments

* get next_uid rather than doing bit manipulation

* rename + add comment about uid

ggml/src/ggml.c

@@ -53,6 +53,16 @@
 
 #define UNUSED GGML_UNUSED
 
+uint64_t ggml_graph_next_uid(void) {
+#ifdef _MSC_VER
+    static volatile long long counter = 1;
+    return (uint64_t) _InterlockedIncrement64(&counter) - 1;
+#else
+    static uint64_t counter = 1;
+    return __atomic_fetch_add(&counter, 1, __ATOMIC_RELAXED);
+#endif
+}
+
 // Needed for ggml_fp32_to_bf16_row()
 #if defined(__AVX512BF16__)
 #if defined(_MSC_VER)
@@ -7098,6 +7108,7 @@ struct ggml_cgraph * ggml_new_graph_custom(struct ggml_context * ctx, size_t siz
         /*.use_counts   =*/ use_counts_ptr,
         /*.hash_table   =*/ { hash_size, hash_used, hash_keys_ptr },
         /*.order        =*/ GGML_CGRAPH_EVAL_ORDER_LEFT_TO_RIGHT,
+        /*.uid          =*/ 0,
     };
 
     ggml_hash_set_reset(&cgraph->visited_hash_set);
@@ -7125,6 +7136,7 @@ struct ggml_cgraph ggml_graph_view(struct ggml_cgraph * cgraph0, int i0, int i1)
         /*.use_counts       =*/ cgraph0->use_counts,
         /*.visited_hash_set =*/ cgraph0->visited_hash_set,
         /*.order            =*/ cgraph0->order,
+        /*.uid              =*/ 0
     };
 
     return cgraph;