Revert bug fix.

asm-commons/src/main/java/org/objectweb/asm/commons/LocalVariablesSorter.java

@@ -65,6 +65,8 @@ public class LocalVariablesSorter extends MethodVisitor {
   /** Index of the next local variable to be created by {@link #newLocal}. */
   protected int nextLocal;
 
+  private boolean changed;
+
   /**
    * Constructs a new {@link LocalVariablesSorter}. <i>Subclasses must not use this constructor</i>.
    * Instead, they must use the {@link #LocalVariablesSorter(int, int, String, MethodVisitor)}
@@ -186,6 +188,10 @@ public class LocalVariablesSorter extends MethodVisitor {
       throw new IllegalStateException(
           "ClassReader.accept() should be called with EXPAND_FRAMES flag");
     }
+    if (!changed) { // optimization for the case where mapping = identity
+      mv.visitFrame(type, nLocal, local, nStack, stack);
+      return;
+    }
 
     // creates a copy of newLocals
     Object[] oldLocals = new Object[newLocals.length];
@@ -281,6 +287,7 @@ public class LocalVariablesSorter extends MethodVisitor {
     int local = newLocalMapping(type);
     setLocalType(local, type);
     setFrameLocal(local, t);
+    changed = true;
     return local;
   }
 
@@ -338,6 +345,9 @@ public class LocalVariablesSorter extends MethodVisitor {
     } else {
       value--;
     }
+    if (value != var) {
+      changed = true;
+    }
     return value;
   }