Use faster string construction in ext/dom in some places (#20005)

Many tag names are single characters, so we can use the fast string
construction. In cases where a NULL name is used we can also use the
empty string.
This avoids some allocations and some work.

Author: ndossche

ext/dom/attr.c

@@ -83,7 +83,7 @@ zend_result dom_attr_name_read(dom_object *obj, zval *retval)
 
 	if (php_dom_follow_spec_intern(obj)) {
 		zend_string *str = dom_node_get_node_name_attribute_or_element((xmlNodePtr) attrp, false);
-		ZVAL_NEW_STR(retval, str);
+		ZVAL_STR(retval, str);
 	} else {
 		ZVAL_STRING(retval, (char *) attrp->name);
 	}

ext/dom/documenttype.c

@@ -34,7 +34,11 @@ URL: http://www.w3.org/TR/2003/WD-DOM-Level-3-Core-20030226/DOM3-Core.html#core-
 zend_result dom_documenttype_name_read(dom_object *obj, zval *retval)
 {
 	DOM_PROP_NODE(xmlDtdPtr, dtdptr, obj);
-	ZVAL_STRING(retval, dtdptr->name ? (char *) (dtdptr->name) : "");
+	if (dtdptr->name) {
+		ZVAL_STRING(retval, (const char *) dtdptr->name);
+	} else {
+		ZVAL_EMPTY_STRING(retval);
+	}
 	return SUCCESS;
 }
 

ext/dom/dom_iterators.c

@@ -127,9 +127,9 @@ static void php_dom_iterator_current_key(zend_object_iterator *iter, zval *key)
 		if (intern->ptr != NULL) {
 			xmlNodePtr curnode = ((php_libxml_node_ptr *)intern->ptr)->node;
 			if (curnode->type == XML_ATTRIBUTE_NODE && php_dom_follow_spec_intern(intern)) {
-				ZVAL_NEW_STR(key, dom_node_get_node_name_attribute_or_element(curnode, false));
+				ZVAL_STR(key, dom_node_get_node_name_attribute_or_element(curnode, false));
 			} else {
-				ZVAL_STRINGL(key, (const char *) curnode->name, xmlStrlen(curnode->name));
+				ZVAL_STRINGL_FAST(key, (const char *) curnode->name, xmlStrlen(curnode->name));
 			}
 		} else {
 			ZVAL_NULL(key);

ext/dom/element.c

@@ -122,7 +122,7 @@ zend_result dom_element_tag_name_read(dom_object *obj, zval *retval)
 	bool uppercase = php_dom_follow_spec_intern(obj) && php_dom_ns_is_html_and_document_is_html(nodep);
 
 	zend_string *result = dom_node_get_node_name_attribute_or_element((const xmlNode *) nodep, uppercase);
-	ZVAL_NEW_STR(retval, result);
+	ZVAL_STR(retval, result);
 
 	return SUCCESS;
 }
@@ -375,7 +375,7 @@ PHP_METHOD(DOMElement, getAttributeNames)
 	}
 
 	for (xmlAttrPtr attr = nodep->properties; attr; attr = attr->next) {
-		ZVAL_NEW_STR(&tmp, dom_node_get_node_name_attribute_or_element((const xmlNode *) attr, false));
+		ZVAL_STR(&tmp, dom_node_get_node_name_attribute_or_element((const xmlNode *) attr, false));
 		zend_hash_next_index_insert(ht, &tmp);
 	}
 }

ext/dom/node.c

@@ -52,6 +52,13 @@ zend_string *dom_node_get_node_name_attribute_or_element(const xmlNode *nodep, b
 	if (nodep->ns != NULL && nodep->ns->prefix != NULL) {
 		ret = dom_node_concatenated_name_helper(name_len, (const char *) nodep->name, strlen((const char *) nodep->ns->prefix), (const char *) nodep->ns->prefix);
 	} else {
+		if (name_len == 1) {
+			if (uppercase) {
+				return ZSTR_CHAR(zend_toupper_ascii(*nodep->name));
+			} else {
+				return ZSTR_CHAR((zend_uchar) *nodep->name);
+			}
+		}
 		ret = zend_string_init((const char *) nodep->name, name_len, false);
 	}
 	if (uppercase) {
@@ -89,7 +96,7 @@ zend_result dom_node_node_name_read(dom_object *obj, zval *retval)
 			uppercase = php_dom_follow_spec_intern(obj) && php_dom_ns_is_html_and_document_is_html(nodep);
 			ZEND_FALLTHROUGH;
 		case XML_ATTRIBUTE_NODE:
-			ZVAL_NEW_STR(retval, dom_node_get_node_name_attribute_or_element(nodep, uppercase));
+			ZVAL_STR(retval, dom_node_get_node_name_attribute_or_element(nodep, uppercase));
 			break;
 		case XML_NAMESPACE_DECL: {
 			xmlNsPtr ns = nodep->ns;
@@ -635,7 +642,7 @@ zend_result dom_node_local_name_read(dom_object *obj, zval *retval)
 	DOM_PROP_NODE(xmlNodePtr, nodep, obj);
 
 	if (nodep->type == XML_ELEMENT_NODE || nodep->type == XML_ATTRIBUTE_NODE || nodep->type == XML_NAMESPACE_DECL) {
-		ZVAL_STRING(retval, (char *) (nodep->name));
+		ZVAL_STRING_FAST(retval, (const char *) (nodep->name));
 	} else {
 		ZVAL_NULL(retval);
 	}