OPcache: Add information to the Site Health -> Server

src/wp-admin/includes/class-wp-debug-data.php

@@ -471,6 +471,58 @@ private static function get_wp_server(): array {
 			'debug' => $imagick_loaded,
 		);
 
+		// Opcode Cache.
+		if ( function_exists( 'opcache_get_status' ) ) {
+			$opcache_status = @opcache_get_status( false ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- Warning emitted in failure case.
+
+			if ( false === $opcache_status ) {
+				$fields['opcode_cache'] = array(
+					'label' => __( 'Opcode cache' ),
+					'value' => __( 'Disabled by configuration' ),
+					'debug' => 'not available',
+				);
+			} else {
+				$fields['opcode_cache'] = array(
+					'label' => __( 'Opcode cache' ),
+					'value' => $opcache_status['opcache_enabled'] ? __( 'Enabled' ) : __( 'Disabled' ),
+					'debug' => $opcache_status['opcache_enabled'],
+				);
+
+				if ( true === $opcache_status['opcache_enabled'] ) {
+					$fields['opcode_cache_memory_usage'] = array(
+						'label' => __( 'Opcode cache memory usage' ),
+						'value' => sprintf(
+							/* translators: 1: Used memory, 2: Total memory */
+							__( '%1$s of %2$s' ),
+							size_format( $opcache_status['memory_usage']['used_memory'] ),
+							size_format( $opcache_status['memory_usage']['free_memory'] + $opcache_status['memory_usage']['used_memory'] )
+						),
+						'debug' => sprintf(
+							'%s of %s',
+							$opcache_status['memory_usage']['used_memory'],
+							$opcache_status['memory_usage']['free_memory'] + $opcache_status['memory_usage']['used_memory']
+						),
+					);
+
+					$fields['opcode_cache_hit_rate'] = array(
+						'label' => __( 'Opcode cache hit rate' ),
+						'value' => sprintf(
+							/* translators: %s: Hit rate percentage */
+							__( '%s%%' ),
+							round( $opcache_status['opcache_statistics']['opcache_hit_rate'], 2 )
+						),
+						'debug' => $opcache_status['opcache_statistics']['opcache_hit_rate'],
+					);
+				}
+			}
+		} else {
+			$fields['opcode_cache'] = array(
+				'label' => __( 'Opcode cache' ),
+				'value' => __( 'Disabled' ),
+				'debug' => 'not available',
+			);
+		}
+
 		// Pretty permalinks.
 		$pretty_permalinks_supported = got_url_rewrite();
 

src/wp-admin/includes/class-wp-site-health.php

@@ -2755,6 +2755,52 @@ public function get_test_search_engine_visibility() {
 		return $result;
 	}
 
+	/**
+	 * Tests if opcode cache is enabled and available.
+	 *
+	 * @since 7.0.0
+	 *
+	 * @return array<string, string|array<string, string>> The test result.
+	 */
+	public function get_test_opcode_cache() {
+		$opcode_cache_enabled = false;
+		if ( function_exists( 'opcache_get_status' ) ) {
+			$status = @opcache_get_status( false ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discourage -- Warning emitted in failure case.
+			if ( $status && true === $status['opcache_enabled'] ) {
+				$opcode_cache_enabled = true;
+			}
+		}
+
+		$result = array(
+			'label'       => __( 'Opcode cache is enabled' ),
+			'status'      => 'good',
+			'badge'       => array(
+				'label' => __( 'Performance' ),
+				'color' => 'blue',
+			),
+			'description' => sprintf(
+				'<p>%s</p>',
+				__( 'Opcode cache improves PHP performance by storing precompiled script bytecode in memory, reducing the need for PHP to load and parse scripts on each request.' )
+			),
+			'actions'     => sprintf(
+				'<p><a href="%s" target="_blank">%s<span class="screen-reader-text"> %s</span><span aria-hidden="true" class="dashicons dashicons-external"></span></a></p>',
+				esc_url( 'https://www.php.net/manual/en/book.opcache.php' ),
+				__( 'Learn more about OPcache.' ),
+				/* translators: Hidden accessibility text. */
+				__( '(opens in a new tab)' )
+			),
+			'test'        => 'opcode_cache',
+		);
+
+		if ( ! $opcode_cache_enabled ) {
+			$result['status']       = 'recommended';
+			$result['label']        = __( 'Opcode cache is not enabled' );
+			$result['description'] .= '<p>' . __( 'Enabling this cache can significantly improve the performance of your site.' ) . '</p>';
+		}
+
+		return $result;
+	}
+
 	/**
 	 * Returns a set of tests that belong to the site status page.
 	 *
@@ -2847,6 +2893,10 @@ public static function get_tests() {
 					'label' => __( 'Search Engine Visibility' ),
 					'test'  => 'search_engine_visibility',
 				),
+				'opcode_cache'                 => array(
+					'label' => __( 'Opcode cache' ),
+					'test'  => 'opcode_cache',
+				),
 			),
 			'async'  => array(
 				'dotorg_communication' => array(
@@ -3415,14 +3465,14 @@ public function get_page_cache_headers() {
 			'x-srcache-fetch-status' => $cache_hit_callback,
 
 			// Generic caching proxies (Nginx, Varnish, etc.)
-			'x-cache'           => $cache_hit_callback,
-			'x-cache-status'    => $cache_hit_callback,
-			'x-litespeed-cache' => $cache_hit_callback,
-			'x-proxy-cache'     => $cache_hit_callback,
-			'via'               => '',
+			'x-cache'                => $cache_hit_callback,
+			'x-cache-status'         => $cache_hit_callback,
+			'x-litespeed-cache'      => $cache_hit_callback,
+			'x-proxy-cache'          => $cache_hit_callback,
+			'via'                    => '',
 
 			// Cloudflare
-			'cf-cache-status' => $cache_hit_callback,
+			'cf-cache-status'        => $cache_hit_callback,
 		);
 
 		/**