Can you please post a working piece of reproducing code? Preferably no more than 20 lines.
Thanks.

The following code gives me 

Fatal error: Invalid opcode 137/1/8. in /home/hartmut/tmp/PECL_Gen.test/pecl-gen on line 24

using latest CVS HEAD on Linux:

<?php

class XML_Parser
{
  var $dummy = "a";


    function parse($data)
    {
    $parser = xml_parser_create();

    xml_set_object($parser, $this);

    xml_set_element_handler($parser, 'startHandler', 'endHandler');

    xml_parse($parser, $data, true);

    xml_parser_free($parser);
    }

  function startHandler($XmlParser, $tag, $attr)
        {
      // commenting out either line prevents the crash
            $this->dummy = "b";
      throw new Exception("ex");
        }

  function endHandler($XmlParser, $tag)
        {
        }
}

  $p1 = new Xml_Parser();
  $p1->parse('<tag1><tag2></tag2></tag1>'); // this crashes
#   $p1->parse('<tag1></tag1>'); // this doesn't crash


?>

Reproduceable using array_walk as well:

<?php
class testc
{
	var $b = "c";

	function crash($val) {
		$this->b = $val;
		throw new Exception("ex");
	}
}

$fruits = array ("d"=>"lemon", "a"=>"orange", "b"=>"banana", "c"=>"apple");
$myobj = new testc();

function test_print ($item2, $key, $userd) {
	$userd->crash($item2);
}
array_walk ($fruits, 'test_print', $myobj);
?>

comment out either line in the crash() method and it works fine otherwise: Invalid opcode when run under HEAD and segfault when run under 5_0 branch. same results as Hartmut's script

This bug has been fixed in CVS.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
http://snaps.php.net/.
 
Thank you for the report, and for helping us make PHP better.