Note: this list is generated by looking for the string for this theme hook, so it may include some references that are not actually using this theme hook.

hook_search_page in core/modules/search/search.api.php
Override the rendering of search results.
search_data in core/modules/search/search.module
Performs a search by calling hook_search_execute().
search_embedded_form_preprocess_search_results in core/modules/search/tests/search_embedded_form/search_embedded_form.module
Adds the test form to search results.
search_extra_type_search_page in core/modules/search/tests/search_extra_type/search_extra_type.module
Implements hook_search_page().
search_theme in core/modules/search/search.module
Implements hook_theme().
search_view in core/modules/search/search.pages.inc
Menu callback; presents the search form and/or search results.
template_preprocess_search_results in core/modules/search/search.theme.inc
Process variables for search-results.tpl.php.
template_preprocess_search_results in core/modules/search/search.theme.inc
Process variables for search-results.tpl.php.