[WIP] Improve performance of array_walk()

We never need to use refcounted copies for arguments because the copy to
the call frame already increments the refcount.

Author: ndossche

ext/standard/array.c

@@ -1457,7 +1457,7 @@ static zend_result php_array_walk(
 	/* Set up known arguments */
 	ZVAL_UNDEF(&args[1]);
 	if (userdata) {
-		ZVAL_COPY(&args[2], userdata);
+		ZVAL_COPY_VALUE(&args[2], userdata);
 	}
 
 	fci.retval = &retval;
@@ -1531,21 +1531,16 @@ static zend_result php_array_walk(
 			}
 			zval_ptr_dtor(&ref);
 		} else {
-			ZVAL_COPY(&args[0], zv);
+			ZVAL_COPY_VALUE(&args[0], zv);
 
 			/* Call the userland function */
 			result = zend_call_function(&fci, &context->fci_cache);
 			if (result == SUCCESS) {
 				zval_ptr_dtor(&retval);
 			}
-
-			zval_ptr_dtor(&args[0]);
 		}
 
-		if (Z_TYPE(args[1]) != IS_UNDEF) {
-			zval_ptr_dtor(&args[1]);
-			ZVAL_UNDEF(&args[1]);
-		}
+		zval_ptr_dtor_str(&args[1]);
 
 		if (result == FAILURE) {
 			break;
@@ -1565,9 +1560,6 @@ static zend_result php_array_walk(
 		}
 	} while (!EG(exception));
 
-	if (userdata) {
-		zval_ptr_dtor(&args[2]);
-	}
 	zend_hash_iterator_del(ht_iter);
 	return result;
 }