Fix T44833: Can't use ccl_local space in non-kernel functions

This commit re-shuffles code in split kernel once again and makes it so common
parts which is in the headers is only responsible to making all the work needed
for specified ray index. Getting ray index, checking for it's validity and
enqueuing tasks are now happening in the device specified part of the kernel.

This actually makes sense because enqueuing is indeed device-specified and i.e.
with CUDA we'll want to enqueue kernels from kernel and avoid CPU roundtrip.

TODO:
- Kernel comments are still placed in the common header files, but since queue
  related stuff is not passed to those functions those comments might need to
  be split as well.

  Just currently read them considering that they're also covering the way how
  all devices are invoking the common code path.

- Arguments might need to be wrapped into KernelGlobals, so we don't ened to
  pass all them around as function arguments.

1 files changed, 73 insertions, 26 deletions

diff --git a/intern/cycles/kernel/kernels/opencl/kernel_background_buffer_update.cl b/intern/cycles/kernel/kernels/opencl/kernel_background_buffer_update.cl
index 2d1944d01e6..eff77b89a0a 100644
--- a/intern/cycles/kernel/kernels/opencl/kernel_background_buffer_update.cl
+++ b/intern/cycles/kernel/kernels/opencl/kernel_background_buffer_update.cl
@@ -48,34 +48,81 @@ __kernel void kernel_ocl_path_trace_background_buffer_update(
 #endif
         int parallel_samples)                  /* Number of samples to be processed in parallel */
 {
-	kernel_background_buffer_update(globals,
-	                                data,
-	                                shader_data,
-	                                per_sample_output_buffers,
-	                                rng_state,
-	                                rng_coop,
-	                                throughput_coop,
-	                                PathRadiance_coop,
-	                                Ray_coop,
-	                                PathState_coop,
-	                                L_transparent_coop,
-	                                ray_state,
-	                                sw, sh, sx, sy, stride,
-	                                rng_state_offset_x,
-	                                rng_state_offset_y,
-	                                rng_state_stride,
-	                                work_array,
-	                                Queue_data,
-	                                Queue_index,
-	                                queuesize,
-	                                end_sample,
-	                                start_sample,
+	ccl_local unsigned int local_queue_atomics;
+	if(get_local_id(0) == 0 && get_local_id(1) == 0) {
+		local_queue_atomics = 0;
+	}
+	barrier(CLK_LOCAL_MEM_FENCE);
+
+	int ray_index = get_global_id(1) * get_global_size(0) + get_global_id(0);
+	if(ray_index == 0) {
+		/* We will empty this queue in this kernel. */
+		Queue_index[QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS] = 0;
+	}
+	char enqueue_flag = 0;
+	ray_index = get_ray_index(ray_index,
+	                          QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS,
+	                          Queue_data,
+	                          queuesize,
+	                          1);
+
+#ifdef __COMPUTE_DEVICE_GPU__
+	/* If we are executing on a GPU device, we exit all threads that are not
+	 * required.
+	 *
+	 * If we are executing on a CPU device, then we need to keep all threads
+	 * active since we have barrier() calls later in the kernel. CPU devices,
+	 * expect all threads to execute barrier statement.
+	 */
+	if(ray_index == QUEUE_EMPTY_SLOT) {
+		return;
+	}
+#endif
+
+#ifndef __COMPUTE_DEVICE_GPU__
+	if(ray_index != QUEUE_EMPTY_SLOT) {
+#endif
+		enqueue_flag =
+			kernel_background_buffer_update(globals,
+			                                data,
+			                                shader_data,
+			                                per_sample_output_buffers,
+			                                rng_state,
+			                                rng_coop,
+			                                throughput_coop,
+			                                PathRadiance_coop,
+			                                Ray_coop,
+			                                PathState_coop,
+			                                L_transparent_coop,
+			                                ray_state,
+			                                sw, sh, sx, sy, stride,
+			                                rng_state_offset_x,
+			                                rng_state_offset_y,
+			                                rng_state_stride,
+			                                work_array,
+			                                end_sample,
+			                                start_sample,
 #ifdef __WORK_STEALING__
-	                                work_pool_wgs,
-	                                num_samples,
+			                                work_pool_wgs,
+			                                num_samples,
 #endif
 #ifdef __KERNEL_DEBUG__
-	                                debugdata_coop,
+			                                debugdata_coop,
+#endif
+			                                parallel_samples,
+			                                ray_index);
+#ifndef __COMPUTE_DEVICE_GPU__
+	}
 #endif
-	                                parallel_samples);
+
+	/* Enqueue RAY_REGENERATED rays into QUEUE_ACTIVE_AND_REGENERATED_RAYS;
+	 * These rays will be made active during next SceneIntersectkernel.
+	 */
+	enqueue_ray_index_local(ray_index,
+	                        QUEUE_ACTIVE_AND_REGENERATED_RAYS,
+	                        enqueue_flag,
+	                        queuesize,
+	                        &local_queue_atomics,
+	                        Queue_data,
+	                        Queue_index);
 }