gistfile1.php

<?php

// [...]

/**
 * pregenerate missing attribute options
 *
 * @param array $products
 */
public function pregenerateAttributeOptions($products)
{
    $attributes = array();
    $config = $this->getConfig()->config;
    foreach (array_merge((array)$config->attributes, (array)$config->attributes_new) as $productAttr => $attr) {
        $attributeInfo = Mage::getSingleton('eav/config')->getAttribute('catalog_product', $attr);
        if (in_array($attributeInfo->getFrontendInput(), array('select', 'multiselect'))) {
            $attributes[$attr] = $productAttr;
        }
    }

    $optionscache = array();
    foreach($attributes as $attr => $productAttr) {
        $attribute = Mage::getSingleton('eav/config')->getAttribute('catalog_product', $attr);
        $sourceModel = $attribute->getSource();
        $sourceModel->setAttribute($attribute);
        foreach($sourceModel->getAllOptions() as $option) {
            $optionscache[$attr][strtolower(trim($option['label']))] = 1;
        }
    }

    foreach ($products as $product) {
        foreach($attributes as $attr => $productAttr) {
            $labels = $product->getData($productAttr);
            if (!is_array($labels)) {
                $labels = array($labels);
            }
            foreach ($labels as $label) {
                $label = strtolower(trim($label));
                if(!isset($optionscache[$attr][$label])) {
                    $installer = new Mage_Eav_Model_Entity_Setup('core_setup');
                    $installer->startSetup();
                    $option = array(
                        'attribute_id' => $installer->getAttributeId(Mage::getModel('catalog/product')->getResource()->getTypeId(), $attr),
                        'value' => array(
                            'x' => array($label),
                        ),
                    );
                    $installer->addAttributeOption($option);
                    $installer->endSetup();
                    $optionscache[$attr][$label] = 1;
                }
            }
        }
    }
}