Functions: improve span buffer reuse in procedure execution

This potentially overallocates buffers so that they are usable
for more data types, which allows buffers to be reused more
easily. That leads to fewer separate allocations and improved
cache usage (in one of my test files the number of separate
allocations went down from 1826 to 1555).

1 files changed, 12 insertions, 4 deletions

diff --git a/source/blender/functions/intern/multi_function_procedure_executor.cc b/source/blender/functions/intern/multi_function_procedure_executor.cc
index d92ce80bceb..7d9b2fcd1f0 100644
--- a/source/blender/functions/intern/multi_function_procedure_executor.cc
+++ b/source/blender/functions/intern/multi_function_procedure_executor.cc
@@ -144,7 +144,8 @@ class ValueAllocator : NonCopyable, NonMovable {
    * The integer key is the size of one element (e.g. 4 for an integer buffer). All buffers are
    * aligned to #min_alignment bytes.
    */
-  Map<int, Stack<void *>> span_buffers_free_list_;
+  Stack<void *> small_span_buffers_free_list_;
+  Map<int, Stack<void *>> span_buffers_free_lists_;
 
   /** Cache buffers for single values of different types. */
   static constexpr inline int small_value_max_size = 16;
@@ -184,9 +185,13 @@ class ValueAllocator : NonCopyable, NonMovable {
       buffer = linear_allocator_.allocate(element_size * size, alignment);
     }
     else {
-      Stack<void *> *stack = span_buffers_free_list_.lookup_ptr(element_size);
+      Stack<void *> *stack = type.can_exist_in_buffer(small_value_max_size,
+                                                      small_value_max_alignment) ?
+                                 &small_span_buffers_free_list_ :
+                                 span_buffers_free_lists_.lookup_ptr(element_size);
       if (stack == nullptr || stack->is_empty()) {
-        buffer = linear_allocator_.allocate(element_size * size, min_alignment);
+        buffer = linear_allocator_.allocate(
+            std::max<int64_t>(element_size, small_value_max_size) * size, min_alignment);
       }
       else {
         /* Reuse existing buffer. */
@@ -243,7 +248,10 @@ class ValueAllocator : NonCopyable, NonMovable {
         if (value_typed->owned) {
           const CPPType &type = data_type.single_type();
           /* Assumes all values in the buffer are uninitialized already. */
-          Stack<void *> &buffers = span_buffers_free_list_.lookup_or_add_default(type.size());
+          Stack<void *> &buffers = type.can_exist_in_buffer(small_value_max_size,
+                                                            small_value_max_alignment) ?
+                                       small_span_buffers_free_list_ :
+                                       span_buffers_free_lists_.lookup_or_add_default(type.size());
           buffers.push(value_typed->data);
         }
         break;