[onert_micro] workaround for tanh for tizenrt (#14094)

* [onert_micro] workaround for tanh for tizenrt

- TizenRT platform produces tanh(x) NaN for large x
- reason behind this patch is that tanh(x) is almost 1 for x > 15

ONE-DCO-1.0-Signed-off-by: Chunseok Lee <[email protected]>

* fix format

onert-micro/onert-micro/include/pal/common/PALGRUCommon.h

@@ -144,7 +144,18 @@ void calculateGRU(const float *input_data, const float *weight_input_data,
   }
   for (int i = 0; i < num_elements; ++i)
   {
-    second_hidden_part[i] = std::tanh(second_hidden_part[i]);
+    if (second_hidden_part[i] > 19)
+    {
+      second_hidden_part[i] = 1;
+    }
+    else if (second_hidden_part[i] < -19)
+    {
+      second_hidden_part[i] = -1;
+    }
+    else
+    {
+      second_hidden_part[i] = std::tanh(second_hidden_part[i]);
+    }
   }
 
   // If train mode - save mul input (left and right)

onert-micro/onert-micro/include/pal/common/PALGRUWeightGrad.h

@@ -62,6 +62,15 @@ void calculateGRUWeightGrads(
     float tanh_grad_value;
     {
       float tanh = std::tanh(tanh_data[i]);
+      if (tanh_data[i] > 19)
+      {
+        tanh = 1;
+      }
+      else if (tanh_data[i] < -19)
+      {
+        tanh = -1;
+      }
+
       tanh_grad_value = (1 - tanh * tanh) * right_middle_mul;
     }