IVGCVSW-4440 : Add HARD_SWISH Support to Activation in CpuRef

* Add a new Activiation type of HardSwish.
* Add CpuRef support and tests.

Signed-off-by: Colm Donelan <Colm.Donelan@arm.com>
Change-Id: I68c3840aa45b7a27d5e416a5d50fe8f99f003ce8

3 files changed, 13 insertions, 0 deletions

diff --git a/src/backends/reference/RefLayerSupport.cpp b/src/backends/reference/RefLayerSupport.cpp
index 25334c3b52..7d5c3b509e 100644
--- a/src/backends/reference/RefLayerSupport.cpp
+++ b/src/backends/reference/RefLayerSupport.cpp
@@ -109,6 +109,7 @@ bool RefLayerSupport::IsActivationSupported(const TensorInfo& input,
                 case ActivationFunction::Abs:
                 case ActivationFunction::BoundedReLu:
                 case ActivationFunction::Elu:
+                case ActivationFunction::HardSwish:
                 case ActivationFunction::LeakyReLu:
                 case ActivationFunction::Linear:
                 case ActivationFunction::ReLu:
diff --git a/src/backends/reference/test/RefLayerTests.cpp b/src/backends/reference/test/RefLayerTests.cpp
index ed2b995bd5..40bf600331 100644
--- a/src/backends/reference/test/RefLayerTests.cpp
+++ b/src/backends/reference/test/RefLayerTests.cpp
@@ -466,6 +466,10 @@ ARMNN_AUTO_TEST_CASE(TanhInt16, TanhInt16Test)
 ARMNN_AUTO_TEST_CASE(Elu, EluTest)
 ARMNN_AUTO_TEST_CASE(EluUint8, EluUint8Test)
 ARMNN_AUTO_TEST_CASE(EluInt16, EluInt16Test)
+// HardSwish Activation
+ARMNN_AUTO_TEST_CASE(HardSwish, HardSwishTest)
+ARMNN_AUTO_TEST_CASE(HardSwishUint8, HardSwishUint8Test)
+ARMNN_AUTO_TEST_CASE(HardSwishInt16, HardSwishInt16Test)
 
 // Fully Connected
 ARMNN_AUTO_TEST_CASE(SimpleFullyConnected, FullyConnectedFloat32Test, false, false)
diff --git a/src/backends/reference/workloads/Activation.cpp b/src/backends/reference/workloads/Activation.cpp
index 82dd919de9..798c6e48d5 100644
--- a/src/backends/reference/workloads/Activation.cpp
+++ b/src/backends/reference/workloads/Activation.cpp
@@ -9,6 +9,7 @@
 
 namespace armnn
 {
+
 float Activation(float in,
                  ActivationFunction function,
                  float a,
@@ -74,6 +75,13 @@ float Activation(float in,
             output = (in >= 0) ? in : a * (expf(in) - 1);
             break;
         }
+        case ActivationFunction::HardSwish:
+        {
+            // hard_swish(x) = x * relu6(x+3) / 6
+            // relu6(x) = min(max(x,0),6)
+            output = in * (std::min(std::max((in + 3),0.0f),6.0f)) / 6;
+            break;
+        }
         default:
         {
             throw InvalidArgumentException("Unsupported activation function");