Fix GH-13988: Storing DOMElement consume 4 times more memory in PHP 8.1 than in PHP 8.0

We avoid creating backing storage by using the feature introduced in
f78d5cfcd2.

Closes GH-15593.

NEWS

@@ -2,6 +2,9 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? ????, PHP 8.4.0beta5
 
+- DOM:
+  . Fixed bug GH-13988 (Storing DOMElement consume 4 times more memory in
+    PHP 8.1 than in PHP 8.0). (nielsdos)
 
 27 Aug 2024, PHP 8.4.0beta4
 

UPGRADING

@@ -1083,6 +1083,7 @@ PHP 8.4 UPGRADE NOTES
     an xpath query. This can give a time improvement of easily two order of
     magnitude for documents with tens of thousands of nodes.
   . Improved performance and reduce memory consumption of XML serialization.
+  . Reduced memory usage of node classes.
 
 - FTP:
   . Improved the performance of FTP uploads up to a factor of 10x for large

ext/dom/element.c

@@ -182,7 +182,7 @@ URL: https://dom.spec.whatwg.org/#dom-element-classlist
 */
 zend_result dom_element_class_list_read(dom_object *obj, zval *retval)
 {
-	const uint32_t PROP_INDEX = 20;
+	const uint32_t PROP_INDEX = 0;
 
 #if ZEND_DEBUG
 	zend_string *class_list_str = ZSTR_INIT_LITERAL("classList", false);

ext/dom/html_document.c

@@ -83,7 +83,7 @@ typedef struct dom_decoding_encoding_ctx {
 /* https://dom.spec.whatwg.org/#dom-document-implementation */
 zend_result dom_modern_document_implementation_read(dom_object *obj, zval *retval)
 {
-	const uint32_t PROP_INDEX = 14;
+	const uint32_t PROP_INDEX = 0;
 
 #if ZEND_DEBUG
 	zend_string *implementation_str = ZSTR_INIT_LITERAL("implementation", false);

ext/dom/tests/bug69846.phpt

@@ -28,9 +28,9 @@ foreach ($dataNodes AS $node) {
 }
 
 ?>
---EXPECT--
+--EXPECTF--
 int(3)
-object(DOMText)#7 (23) {
+object(DOMText)#%d (23) {
   ["wholeText"]=>
   string(3) "
   "
@@ -82,15 +82,15 @@ object(DOMText)#7 (23) {
   string(3) "
   "
 }
-object(DOMElement)#7 (27) {
-  ["schemaTypeInfo"]=>
-  NULL
+object(DOMElement)#%d (27) {
   ["tagName"]=>
   string(5) "form1"
   ["className"]=>
   string(0) ""
   ["id"]=>
   string(0) ""
+  ["schemaTypeInfo"]=>
+  NULL
   ["firstElementChild"]=>
   string(22) "(object value omitted)"
   ["lastElementChild"]=>
@@ -146,7 +146,7 @@ object(DOMElement)#7 (27) {
     Value C
   "
 }
-object(DOMText)#7 (23) {
+object(DOMText)#%d (23) {
   ["wholeText"]=>
   string(1) "
 "

ext/dom/tests/bug80602_3.phpt

@@ -24,14 +24,14 @@ var_dump($target);
 --EXPECTF--
 <a>barfoobaz<last/></a>
 object(DOMElement)#3 (27) {
-  ["schemaTypeInfo"]=>
-  NULL
   ["tagName"]=>
   string(4) "last"
   ["className"]=>
   string(0) ""
   ["id"]=>
   string(0) ""
+  ["schemaTypeInfo"]=>
+  NULL
   ["firstElementChild"]=>
   NULL
   ["lastElementChild"]=>
@@ -81,14 +81,14 @@ object(DOMElement)#3 (27) {
 }
 <a><last/>barfoobaz</a>
 object(DOMElement)#2 (27) {
-  ["schemaTypeInfo"]=>
-  NULL
   ["tagName"]=>
   string(4) "last"
   ["className"]=>
   string(0) ""
   ["id"]=>
   string(0) ""
+  ["schemaTypeInfo"]=>
+  NULL
   ["firstElementChild"]=>
   NULL
   ["lastElementChild"]=>