Merge pull request opencv#17624 from dkurt:dnn_optimize_mish

alalek · alalek · commit 2e165053ef02 · 2020-06-23T18:43:51.000Z
diff --git a/modules/dnn/src/layers/elementwise_layers.cpp b/modules/dnn/src/layers/elementwise_layers.cpp
@@ -667,8 +667,11 @@ struct MishFunctor : public BaseFunctor
         {
             for( int i = 0; i < len; i++ )
             {
+                // Use fast approximation introduced in https://github.com/opencv/opencv/pull/17200
                 float x = srcptr[i];
-                dstptr[i] = x * tanh(log(1.0f + exp(x)));
+                float eX = exp(std::min(x, 20.f));
+                float n = (eX + 2) * eX;
+                dstptr[i] = (x * n) / (n + 2);
             }
         }
     }

Original file line number	Diff line number	Diff line change
`@@ -667,8 +667,11 @@ struct MishFunctor : public BaseFunctor`
`667`	`667`	`{`
`668`	`668`	`for( int i = 0; i < len; i++ )`
`669`	`669`	`{`
	`670`	`+ // Use fast approximation introduced in https://github.com/opencv/opencv/pull/17200`
`670`	`671`	`float x = srcptr[i];`
`671`		`- dstptr[i] = x * tanh(log(1.0f + exp(x)));`
	`672`	`+ float eX = exp(std::min(x, 20.f));`
	`673`	`+ float n = (eX + 2) * eX;`
	`674`	`+ dstptr[i] = (x * n) / (n + 2);`
`672`	`675`	`}`
`673`	`676`	`}`
`674`	`677`	`}`