use openmp to thread some common bmesh operations

- BM_mesh_elem_toolflags_ensure / bmo_flag_layer_alloc / bmo_flag_layer_free / bmo_flag_layer_clear
- BM_mesh_select_flush
- EDBM_index_arrays_init

notes:
- mostly use openmp `sections` to split operations on vert/edge/face since this is a fairly minor change.
- split tool flag pool in 3, this means we can allocate exact sizes needed and iterate on them in threads without alloc'ing.

1 files changed, 3 insertions, 2 deletions

diff --git a/source/blender/bmesh/bmesh_class.h b/source/blender/bmesh/bmesh_class.h
index 9d797c1e602..4a370a24c7d 100644
--- a/source/blender/bmesh/bmesh_class.h
+++ b/source/blender/bmesh/bmesh_class.h
@@ -187,8 +187,9 @@ typedef struct BMesh {
 	/*element pools*/
 	struct BLI_mempool *vpool, *epool, *lpool, *fpool;
 
-	/*operator api stuff*/
-	struct BLI_mempool *toolflagpool;
+	/*operator api stuff (must be all NULL or all alloc'd)*/
+	struct BLI_mempool *vtoolflagpool, *etoolflagpool, *ftoolflagpool;
+
 	int stackdepth;
 	struct BMOperator *currentop;