IVGCVSW-8055 Add support for GELU activation function.

* Add support to CpuRef, CpuAcc and GpuAcc
* Add support to tflite parser, classic and opaque tflite delegates
* Add support to serializer and deserializer
* Add Unit tests

Signed-off-by: Teresa Charlin <teresa.charlinreyes@arm.com>
Change-Id: Ibc60ef2ef2a051e6d9af6e15d24c46316ec19de4

3 files changed, 14 insertions, 0 deletions

diff --git a/src/backends/reference/RefLayerSupport.cpp b/src/backends/reference/RefLayerSupport.cpp
index defdf0d807..167639a733 100644
--- a/src/backends/reference/RefLayerSupport.cpp
+++ b/src/backends/reference/RefLayerSupport.cpp
@@ -588,6 +588,7 @@ bool RefLayerSupport::IsActivationSupported(const TensorInfo& input,
                 case ActivationFunction::Abs:
                 case ActivationFunction::BoundedReLu:
                 case ActivationFunction::Elu:
+                case ActivationFunction::Gelu:
                 case ActivationFunction::HardSwish:
                 case ActivationFunction::LeakyReLu:
                 case ActivationFunction::Linear:
diff --git a/src/backends/reference/test/RefLayerTests.cpp b/src/backends/reference/test/RefLayerTests.cpp
index af4ed966b2..cfe85594b3 100644
--- a/src/backends/reference/test/RefLayerTests.cpp
+++ b/src/backends/reference/test/RefLayerTests.cpp
@@ -770,11 +770,17 @@ ARMNN_AUTO_TEST_CASE_WITH_THF(TanhInt16, TanhInt16Test)
 ARMNN_AUTO_TEST_CASE_WITH_THF(Elu, EluTest)
 ARMNN_AUTO_TEST_CASE_WITH_THF(EluUint8, EluUint8Test)
 ARMNN_AUTO_TEST_CASE_WITH_THF(EluInt16, EluInt16Test)
+
 // HardSwish Activation
 ARMNN_AUTO_TEST_CASE_WITH_THF(HardSwish, HardSwishTest)
 ARMNN_AUTO_TEST_CASE_WITH_THF(HardSwishUint8, HardSwishUint8Test)
 ARMNN_AUTO_TEST_CASE_WITH_THF(HardSwishInt16, HardSwishInt16Test)
 
+// Gelu Activation
+ARMNN_AUTO_TEST_CASE_WITH_THF(Gelu, GeluTest)
+ARMNN_AUTO_TEST_CASE_WITH_THF(GeluUint8, GeluUint8Test)
+ARMNN_AUTO_TEST_CASE_WITH_THF(GeluInt16, GeluInt16Test)
+
 // Fully Connected
 ARMNN_AUTO_TEST_CASE_WITH_THF(SimpleFullyConnected, FullyConnectedFloat32Test, false, false)
 ARMNN_AUTO_TEST_CASE_WITH_THF(FullyConnectedUint8, FullyConnectedTest<DataType::QAsymmU8>, false, true)
diff --git a/src/backends/reference/workloads/Activation.cpp b/src/backends/reference/workloads/Activation.cpp
index 8de0e8b3b2..1577543fe4 100644
--- a/src/backends/reference/workloads/Activation.cpp
+++ b/src/backends/reference/workloads/Activation.cpp
@@ -82,6 +82,13 @@ float Activation(float in,
             output = in * (std::min(std::max((in + 3),0.0f),6.0f)) / 6;
             break;
         }
+        case ActivationFunction::Gelu:
+        {
+            // gelu(x) = x * 1/2 * (1 + erf(x / sqrt(2))),
+            // where erf is Gaussian error function
+            output = in * (0.5f * (1.0f + erff(static_cast<float>(in / std::sqrt(2)))));
+            break;
+        }
         default:
         {
             throw InvalidArgumentException("Unsupported activation function");