Fix #129596: Always use multithreaded BVH building in Cycles again

The workaround of forcing BVH building into single thread
execution on the Blender side is not needed anymore,
because the problem was properly fixed in the upstream
since Embree upgrade in Blender 4.5

This reverts commit c0f0e2ca6f.

Pull Request: https://projects.blender.org/blender/blender/pulls/146859

intern/cycles/device/device.cpp

@@ -831,17 +831,4 @@ bool GPUDevice::is_shared(const void *shared_pointer,
 
 /* DeviceInfo */
 
-bool DeviceInfo::contains_device_type(const DeviceType type) const
-{
-  if (this->type == type) {
-    return true;
-  }
-  for (const DeviceInfo &info : multi_devices) {
-    if (info.contains_device_type(type)) {
-      return true;
-    }
-  }
-  return false;
-}
-
 CCL_NAMESPACE_END

intern/cycles/device/device.h

@@ -119,8 +119,6 @@ class DeviceInfo {
   {
     return !(*this == info);
   }
-
-  bool contains_device_type(const DeviceType type) const;
 };
 
 /* Device */

intern/cycles/scene/geometry.cpp

@@ -957,12 +957,6 @@ void GeometryManager::device_update(Device *device,
       }
     });
 
-    /* Work around Embree/oneAPI bug #129596 with BVH updates. */
-    /* Also note the use of #bvh_task_pool_, see its definition for details. */
-    const bool use_multithreaded_build = first_bvh_build ||
-                                         !device->info.contains_device_type(DEVICE_ONEAPI);
-    first_bvh_build = false;
-
     size_t i = 0;
     size_t num_bvh = 0;
     for (Geometry *geom : scene->geometry) {
@@ -974,14 +968,10 @@ void GeometryManager::device_update(Device *device,
           num_bvh++;
         }
 
-        if (use_multithreaded_build) {
-          bvh_task_pool_.push([geom, device, dscene, scene, &progress, i, &num_bvh] {
-            geom->compute_bvh(device, dscene, &scene->params, &progress, i, num_bvh);
-          });
-        }
-        else {
+        /* Note the use of #bvh_task_pool_, see its definition for details. */
+        bvh_task_pool_.push([geom, device, dscene, scene, &progress, i, &num_bvh] {
           geom->compute_bvh(device, dscene, &scene->params, &progress, i, num_bvh);
-        }
+        });
       }
     }
 

intern/cycles/scene/geometry.h

@@ -237,7 +237,6 @@ class GeometryManager {
 
   /* Update Flags */
   bool need_flags_update;
-  bool first_bvh_build = true;
 
   /* Constructor/Destructor */
   GeometryManager();