Merge remote-tracking branch 'upstream/3.4' into merge-3.4

diff --cc cmake/OpenCVDetectInferenceEngine.cmake
index 2c0296d,829ddbf..8c6470e
--- 1/cmake/OpenCVDetectInferenceEngine.cmake
--- 2/cmake/OpenCVDetectInferenceEngine.cmake
+++ b/cmake/OpenCVDetectInferenceEngine.cmake
@@@ -134,14 -140,10 +134,14 @@@ endif(
  # Add more features to the target
  
  if(INF_ENGINE_TARGET)
 +  if(InferenceEngine_VERSION VERSION_GREATER_EQUAL "2021.4")
 +    math(EXPR INF_ENGINE_RELEASE "${InferenceEngine_VERSION_MAJOR} * 1000000 + ${InferenceEngine_VERSION_MINOR} * 10000 + ${InferenceEngine_VERSION_PATCH} * 100")
 +  endif()
    if(NOT INF_ENGINE_RELEASE)
-     message(WARNING "InferenceEngine version has not been set, 2021.3 will be used by default. Set INF_ENGINE_RELEASE variable if you experience build errors.")
-     set(INF_ENGINE_RELEASE "2021030000")
+     message(WARNING "InferenceEngine version has not been set, 2021.4 will be used by default. Set INF_ENGINE_RELEASE variable if you experience build errors.")
++    set(INF_ENGINE_RELEASE "2021040000")
    endif()
 -  set(INF_ENGINE_RELEASE "2021040000" CACHE STRING "Force IE version, should be in form YYYYAABBCC (e.g. 2020.1.0.2 -> 2020010002)")
 +  set(INF_ENGINE_RELEASE "${INF_ENGINE_RELEASE}" CACHE STRING "Force IE version, should be in form YYYYAABBCC (e.g. 2020.1.0.2 -> 2020010002)")
    set_target_properties(${INF_ENGINE_TARGET} PROPERTIES
      INTERFACE_COMPILE_DEFINITIONS "HAVE_INF_ENGINE=1;INF_ENGINE_RELEASE=${INF_ENGINE_RELEASE}"
    )

diff --cc modules/dnn/src/ie_ngraph.cpp
Simple merge

diff --cc modules/dnn/src/layers/batch_norm_layer.cpp
Simple merge

diff --cc modules/dnn/src/onnx/onnx_importer.cpp
Simple merge

diff --cc modules/dnn/src/op_inf_engine.hpp
Simple merge

diff --cc modules/dnn/test/test_backends.cpp
index aab4c6f,5426a11..e8c7e70
--- 1/modules/dnn/test/test_backends.cpp
--- 2/modules/dnn/test/test_backends.cpp
+++ b/modules/dnn/test/test_backends.cpp
@@@ -202,11 -194,11 +202,11 @@@ TEST_P(DNNTestNetwork, MobileNet_SSD_Ca
          applyTestTag(CV_TEST_TAG_DNN_SKIP_HALIDE);
      Mat sample = imread(findDataFile("dnn/street.png"));
      Mat inp = blobFromImage(sample, 1.0f / 127.5, Size(300, 300), Scalar(127.5, 127.5, 127.5), false);
 -    float diffScores = (target == DNN_TARGET_OPENCL_FP16 || target == DNN_TARGET_MYRIAD) ? 1.5e-2 : 0.0;
 -    float diffSquares = (target == DNN_TARGET_MYRIAD) ? 0.063  : 0.0;
 +    float scoreDiff = (target == DNN_TARGET_OPENCL_FP16 || target == DNN_TARGET_MYRIAD) ? 1.5e-2 : 0.0;
 +    float iouDiff = (target == DNN_TARGET_MYRIAD) ? 0.063  : 0.0;
-     float detectionConfThresh = (target == DNN_TARGET_MYRIAD) ? 0.252  : FLT_MIN;
+     float detectionConfThresh = (target == DNN_TARGET_MYRIAD) ? 0.262  : FLT_MIN;
           processNet("dnn/MobileNetSSD_deploy.caffemodel", "dnn/MobileNetSSD_deploy.prototxt",
 -                    inp, "detection_out", "", diffScores, diffSquares, detectionConfThresh);
 +                    inp, "detection_out", "", scoreDiff, iouDiff, detectionConfThresh);
      expectNoFallbacksFromIE(net);
  }
  

diff --cc modules/dnn/test/test_ie_models.cpp
Simple merge

diff --cc modules/dnn/test/test_onnx_importer.cpp
Simple merge

diff --cc modules/dnn/test/test_torch_importer.cpp
Simple merge