avoid strlen in common case

Author: weltling

Zend/zend_compile.c

@@ -6503,9 +6503,9 @@ static zend_bool zend_try_ct_eval_magic_const(zval *zv, zend_ast *ast) /* {{{ */
 			zend_string *filename = CG(compiled_filename);
 			zend_string *dirname = zend_string_init(ZSTR_VAL(filename), ZSTR_LEN(filename), 0);
 #ifdef ZEND_WIN32
-			php_win32_ioutil_dirname(ZSTR_VAL(dirname), ZSTR_LEN(dirname));
+			ZSTR_LEN(dirname) = php_win32_ioutil_dirname(ZSTR_VAL(dirname), ZSTR_LEN(dirname));
 #else
-			zend_dirname(ZSTR_VAL(dirname), ZSTR_LEN(dirname));
+			ZSTR_LEN(dirname) = zend_dirname(ZSTR_VAL(dirname), ZSTR_LEN(dirname));
 #endif
 
 			if (strcmp(ZSTR_VAL(dirname), ".") == 0) {
@@ -6515,9 +6515,9 @@ static zend_bool zend_try_ct_eval_magic_const(zval *zv, zend_ast *ast) /* {{{ */
 #elif HAVE_GETWD
 				ZEND_IGNORE_VALUE(VCWD_GETWD(ZSTR_VAL(dirname)));
 #endif
+				ZSTR_LEN(dirname) = strlen(ZSTR_VAL(dirname));
 			}
 
-			ZSTR_LEN(dirname) = strlen(ZSTR_VAL(dirname));
 			ZVAL_STR(zv, dirname);
 			break;
 		}