Author: pfg Date: Thu May 14 15:49:48 2015 New Revision: 282907 URL: https://svnweb.freebsd.org/changeset/base/282907
Log: Add new __unreachable() builtin This is one of the few post gcc4.2 builtins that has been implemented by clang: __builtin_unreachable is used to indicate that a specific point in the program cannot be reached, even if the compiler might otherwise think it can. This is useful to improve optimization and eliminates certain warnings. Hinted by: NetBSD Differential Revision: https://reviews.freebsd.org/D2536 Modified: head/sys/sys/cdefs.h Modified: head/sys/sys/cdefs.h ============================================================================== --- head/sys/sys/cdefs.h Thu May 14 15:14:03 2015 (r282906) +++ head/sys/sys/cdefs.h Thu May 14 15:49:48 2015 (r282907) @@ -388,6 +388,12 @@ #define __alloc_size(x) #endif +#if __has_builtin(__builtin_unreachable) || __GNUC_PREREQ__(4, 6) +#define __unreachable() __builtin_unreachable() +#else +#define __unreachable() do {} while (/*CONSTCOND*/0) +#endif + #if __has_attribute(alloc_align) || __GNUC_PREREQ__(4, 9) #define __alloc_align(x) __attribute__((__alloc_align__(x))) #else _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
