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- commit d26a40412197ba61a72368c71e8a8582d686d28c
- Author: Willy Tarreau <w@1wt.eu>
- Date: Mon Oct 15 11:53:34 2018 +0200
-
- BUILD: compiler: add a new statement "__unreachable()"
-
- This statement is used as a hint for the compiler so that it knows that
- the location where it's placed cannot be reached. It will mostly be used
- after longjmp() or equivalent statements that deal with error processing
- and that the compiler doesn't know will not return on certain conditions,
- so that it doesn't complain about null dereferences on error paths.
-
- (cherry picked from commit 8d26f02e693121764bfa0cb48c9a7ab31e17225d)
- Signed-off-by: Willy Tarreau <w@1wt.eu>
-
- diff --git a/include/common/compiler.h b/include/common/compiler.h
- index a13aad5c..6f4f5a67 100644
- --- a/include/common/compiler.h
- +++ b/include/common/compiler.h
- @@ -82,6 +82,18 @@
- */
- #define __maybe_unused __attribute__((unused))
-
- +/* This allows gcc to know that some locations are never reached, for example
- + * after a longjmp() in the Lua code, hence that some errors caught by such
- + * methods cannot propagate further. This is important with gcc versions 6 and
- + * above which can more aggressively detect null dereferences. The builtin
- + * below was introduced in gcc 4.5, and before it we didn't care.
- + */
- +#if __GNUC__ >= 5 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
- +#define __unreachable() __builtin_unreachable()
- +#else
- +#define __unreachable()
- +#endif
- +
- /*
- * Gcc >= 3 provides the ability for the programme to give hints to the
- * compiler about what branch of an if is most likely to be taken. This
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