Merge pull request #7021 from michaellilltokiwa/dfa--remove-unused-_writtenFields-bitset

dfa: remove unused _writtenFields bitset

Author: michaellilltokiwa

src/dev/flang/fuir/analysis/dfa/DFA.java

@@ -1023,14 +1023,6 @@ public static Set<String> supportedIntrinsics()
   TreeSet<Integer> _preEffectsAborted = new TreeSet<>();
 
 
-  /**
-   * All fields that are ever written.  These will be needed even if they are
-   * never read unless the assignments are actually removed (which is currently
-   * not the case).
-   */
-  BitSet _writtenFields = new BitSet();
-
-
   /**
    * All fields that are ever read.
    */

src/dev/flang/fuir/analysis/dfa/Instance.java

@@ -172,7 +172,6 @@ public void setField(DFA dfa, int field, Value v)
           }
         _fields.put(field, v);
       }
-    dfa._writtenFields.set(field);
   }