Reorder types in sharing_nodet to optimize for common case

When destructt::destruct() of a small shared n-way pointer is called, it first
determines the type of its pointee. For example, if the parameter pack Ts...
is instantiated to T1, T2, T3, then it first checks if the pointer points to T3,
then to T2, etc. Thus, the least checks are performed if it is most likely that
the pointer points to an object of type T3, then T2, etc.

Author: danpoe

src/util/sharing_node.h

@@ -59,7 +59,7 @@ Author: Daniel Poetzl
 #define SN_TYPE_ARGS keyT, valueT, equalT
 
 #define SN_PTR_TYPE_ARGS \
-  d_internalt<SN_TYPE_ARGS>, d_containert<SN_TYPE_ARGS>, d_leaft<SN_TYPE_ARGS>
+  d_containert<SN_TYPE_ARGS>, d_leaft<SN_TYPE_ARGS>, d_internalt<SN_TYPE_ARGS>
 // clang-format on
 
 typedef small_shared_n_way_pointee_baset<3, unsigned> d_baset;
@@ -132,10 +132,10 @@ SN_TYPE_PAR_DEF class sharing_nodet
 
 #if SN_SHARE_KEYS == 1
     SN_ASSERT(d.k == nullptr);
-    data = make_shared_3<2, SN_PTR_TYPE_ARGS>(
+    data = make_shared_3<1, SN_PTR_TYPE_ARGS>(
       std::make_shared<keyT>(k), std::forward<valueU>(v));
 #else
-    data = make_shared_3<2, SN_PTR_TYPE_ARGS>(k, std::forward<valueU>(v));
+    data = make_shared_3<1, SN_PTR_TYPE_ARGS>(k, std::forward<valueU>(v));
 #endif
   }
 
@@ -174,17 +174,17 @@ SN_TYPE_PAR_DEF class sharing_nodet
 
   bool is_internal() const
   {
-    return data.template is_derived<0>();
+    return data.template is_derived<2>();
   }
 
   bool is_container() const
   {
-    return data.template is_derived<1>();
+    return data.template is_derived<0>();
   }
 
   bool is_leaf() const
   {
-    return data.template is_derived<2>();
+    return data.template is_derived<1>();
   }
 
   bool is_defined_internal() const
@@ -206,21 +206,21 @@ SN_TYPE_PAR_DEF class sharing_nodet
   {
     SN_ASSERT(!empty());
 
-    return *data.template get_derived<0>();
+    return *data.template get_derived<2>();
   }
 
   const d_ct &read_container() const
   {
     SN_ASSERT(!empty());
 
-    return *data.template get_derived<1>();
+    return *data.template get_derived<0>();
   }
 
   const d_lt &read_leaf() const
   {
     SN_ASSERT(!empty());
 
-    return *data.template get_derived<2>();
+    return *data.template get_derived<1>();
   }
 
   // Accessors
@@ -395,7 +395,7 @@ SN_TYPE_PAR_DEF class sharing_nodet
   {
     SN_ASSERT(!data);
 
-    data = make_shared_3<2, SN_PTR_TYPE_ARGS>(k, std::forward<valueU>(v));
+    data = make_shared_3<1, SN_PTR_TYPE_ARGS>(k, std::forward<valueU>(v));
   }
 
   template <class valueU>
@@ -406,11 +406,11 @@ SN_TYPE_PAR_DEF class sharing_nodet
     if(data.use_count() > 1)
     {
       data =
-        make_shared_3<2, SN_PTR_TYPE_ARGS>(get_key(), std::forward<valueU>(v));
+        make_shared_3<1, SN_PTR_TYPE_ARGS>(get_key(), std::forward<valueU>(v));
     }
     else
     {
-      data.template get_derived<2>()->v = std::forward<valueU>(v);
+      data.template get_derived<1>()->v = std::forward<valueU>(v);
     }
 
     SN_ASSERT(data.use_count() == 1);
@@ -422,10 +422,10 @@ SN_TYPE_PAR_DEF class sharing_nodet
 
     if(data.use_count() > 1)
     {
-      data = make_shared_3<2, SN_PTR_TYPE_ARGS>(read_leaf());
+      data = make_shared_3<1, SN_PTR_TYPE_ARGS>(read_leaf());
     }
 
-    mutator(data.template get_derived<2>()->v);
+    mutator(data.template get_derived<1>()->v);
 
     SN_ASSERT(data.use_count() == 1);
   }
@@ -437,16 +437,16 @@ SN_TYPE_PAR_DEF class sharing_nodet
 
     if(!data)
     {
-      data = make_shared_3<0, SN_PTR_TYPE_ARGS>();
+      data = make_shared_3<2, SN_PTR_TYPE_ARGS>();
     }
     else if(data.use_count() > 1)
     {
-      data = make_shared_3<0, SN_PTR_TYPE_ARGS>(read_internal());
+      data = make_shared_3<2, SN_PTR_TYPE_ARGS>(read_internal());
     }
 
     SN_ASSERT(data.use_count() == 1);
 
-    return *data.template get_derived<0>();
+    return *data.template get_derived<2>();
   }
 
   d_ct &write_container()
@@ -455,16 +455,16 @@ SN_TYPE_PAR_DEF class sharing_nodet
 
     if(!data)
     {
-      data = make_shared_3<1, SN_PTR_TYPE_ARGS>();
+      data = make_shared_3<0, SN_PTR_TYPE_ARGS>();
     }
     else if(data.use_count() > 1)
     {
-      data = make_shared_3<1, SN_PTR_TYPE_ARGS>(read_container());
+      data = make_shared_3<0, SN_PTR_TYPE_ARGS>(read_container());
     }
 
     SN_ASSERT(data.use_count() == 1);
 
-    return *data.template get_derived<1>();
+    return *data.template get_derived<0>();
   }
 
   datat data;