fix xml re-entry

Summary: Before we dive into the XML library, we need to save the JIT state incase we need it later (for example, to raise a warning).

Reviewed By: @alexmalyshev

Differential Revision: D1321974

hphp/runtime/ext/ext_xml.cpp

@@ -712,6 +712,7 @@ int64_t f_xml_parse(const Resource& parser, const String& data, bool is_final /*
 int64_t f_xml_parse_into_struct(const Resource& parser, const String& data, VRefParam values,
                             VRefParam index /* = null */) {
   int ret;
+  JIT::VMRegAnchor _;
   XmlParser * p = parser.getTyped<XmlParser>();
   values = Array::Create();
   p->data.assignRef(values);

hphp/test/slow/ext_xml/depth_limit.php

@@ -1,7 +1,11 @@
 <?php
-$a = array();
-$res = xml_parse_into_struct(
-  xml_parser_create_ns(),
-  str_repeat("<blah>", 100000),
-  $a);
-var_dump(count(array_keys($a)));
+
+function main() {
+  $a = array();
+  $res = xml_parse_into_struct(
+    xml_parser_create_ns(),
+    str_repeat("<blah>", 100000),
+    $a);
+  var_dump(count(array_keys($a)));
+}
+main();

hphp/test/slow/ext_xml/depth_limit.php.expectf

@@ -1,2 +1,2 @@
-Warning: Maximum depth exceeded - Results truncated in %s on line 6
+Warning: Maximum depth exceeded - Results truncated in %s on line 8
 int(255)