Magento 1.9 - Find what are all functions overwritten magento core function?

Create file into your Magento root folder with the name of find.php and run,

 <?php  
 $foldersToCheck = array('app/code/local/', 'app/code/community/');  
 $configFiles = array();  
 foreach ($foldersToCheck as $folder){  
   $files = glob($folder.'*/*/etc/config.xml');//get all config.xml files in the specified folder  
   $configFiles = array_merge($configFiles, $files);//merge with the rest of the config files  
 }  
 $rewrites = array();//list of all rewrites  
 foreach ($configFiles as $file){  
   $dom = new DOMDocument;  
   $dom->loadXML(file_get_contents($file));  
   $xpath = new DOMXPath($dom);  
     $path = '//rewrite/*';//search for tags named 'rewrite'  
     $text = $xpath->query($path);  
     foreach ($text as $rewriteElement){  
       $type = $rewriteElement->parentNode->parentNode->parentNode->tagName;//what is overwritten (model, block, helper)  
       $parent = $rewriteElement->parentNode->parentNode->tagName;//module identifier that is being rewritten (core, catalog, sales, ...)  
       $name = $rewriteElement->tagName;//element that is rewritten (layout, product, category, order)  
       foreach ($rewriteElement->childNodes as $element){  
         $rewrites[$type][$parent.'/'.$name][] = $element->textContent;//class that rewrites it  
       }  
     }  
 }  
 echo "<pre>";print_r($rewrites);  
 ?>