gpu::StereoConstantSpaceBP:

fixed some bugs in init_data_cost on first level (added non-reduction version for first level)
  optimized compute_data_cost like init_data_cost (used reduction scheme)
  avoid temp matrix

modules/gpu/include/opencv2/gpu/gpu.hpp

@@ -473,7 +473,7 @@ namespace cv
             GpuMat data_cost;
             GpuMat data_cost_selected;
 
-            GpuMat temp1, temp2;
+            GpuMat temp;
 
             GpuMat out;
         };