Add a hint to the compiler.
If BUG_ON() is used instead of BUG(), it means that probably the
preferred outcome is to not BUG().
The optimization is disabled, in case CONFIG_PROFILE_ANNOTATED_BRANCHES
is turned on.
Signed-off-by: Igor Stoppa <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: [email protected]
Cc: [email protected]
---
include/asm-generic/bug.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 20561a60db9c..bf47584eab2a 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -183,7 +183,11 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
#endif
#ifndef HAVE_ARCH_BUG_ON
+#ifdef CONFIG_PROFILE_ANNOTATED_BRANCHES
#define BUG_ON(condition) do { if (condition) BUG(); } while (0)
+#else
+#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
+#endif
#endif
#ifndef HAVE_ARCH_WARN_ON
--
2.17.1
On Fri, Sep 7, 2018 at 9:21 PM Igor Stoppa <[email protected]> wrote:
>
> Add a hint to the compiler.
> If BUG_ON() is used instead of BUG(), it means that probably the
> preferred outcome is to not BUG().
>
> The optimization is disabled, in case CONFIG_PROFILE_ANNOTATED_BRANCHES
> is turned on.
This sounds like a good idea, as this is one of the more likely causes
of false-positive -Wmaybe-uninitialized warnings with
CONFIG_PROFILE_ANNOTATED_BRANCHES
Could you add a comment about -Wmaybe-uninitialized next to the definition?
Otherwise that is easily lost.
Also, I see that the file has two separate definitions of BUG_ON(), and the
other one does have an unlikely() in it already. Can you change both
to do the same thing with unlikely() or not unlikely()?
Arnd
On 07/09/18 23:41, Arnd Bergmann wrote:
> Could you add a comment about -Wmaybe-uninitialized next to the definition?
> Otherwise that is easily lost.
>
> Also, I see that the file has two separate definitions of BUG_ON(), and the
> other one does have an unlikely() in it already. Can you change both
> to do the same thing with unlikely() or not unlikely()?
ack
--
igor