adding a comment to Gen::visitBlock

src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/Gen.java

@@ -1074,6 +1074,11 @@ public void visitSkip(JCSkip tree) {
     }
 
     public void visitBlock(JCBlock tree) {
+        /* this method is heavily invoked, as expected, for deeply nested blocks, if blocks doesn't happen to have
+         * patterns there will be an unnecessary tax on memory consumption for these blocks, for this reason we have
+         * created helper methods and here at a higher level we just discriminate depending on the presence, or not,
+         * of patterns in a given block
+         */
         if (tree.patternMatchingCatch != null) {
             visitBlockWithPatterns(tree);
         } else {