COMPMID-2264: Implement LOG operator for CL

Change-Id: I95ca659e8884191762b5d611a424a6e8a1d88885
Signed-off-by: Usama Arif <usama.arif@arm.com>
Reviewed-on: https://review.mlplatform.org/c/1189
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Pablo Marquez <pablo.tello@arm.com>
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/core/CL/cl_kernels/elementwise_unary.cl b/src/core/CL/cl_kernels/elementwise_unary.cl
index 89bffed..866b7ee 100644
--- a/src/core/CL/cl_kernels/elementwise_unary.cl
+++ b/src/core/CL/cl_kernels/elementwise_unary.cl
@@ -36,6 +36,8 @@
 #define sin_op(input) sin(input)
 // Calculate abs for floating point values
 #define fabs_op(input) fabs(input)
+// Calculate natural_log
+#define natural_log_op(input) log(input)
 
 /** Applies element wise unary operator in a tensor.
  *
diff --git a/src/core/CL/kernels/CLElementWiseUnaryLayerKernel.cpp b/src/core/CL/kernels/CLElementWiseUnaryLayerKernel.cpp
index 15823b0..8b8d296 100644
--- a/src/core/CL/kernels/CLElementWiseUnaryLayerKernel.cpp
+++ b/src/core/CL/kernels/CLElementWiseUnaryLayerKernel.cpp
@@ -93,6 +93,9 @@
         case ElementWiseUnary::ABS:
             build_opts.add_option("-DOPERATION=fabs_op");
             break;
+        case ElementWiseUnary::LOG:
+            build_opts.add_option("-DOPERATION=natural_log_op");
+            break;
         default:
             ARM_COMPUTE_ERROR("Not implemented");
     }