[Mesa-dev] [PATCH 1/2] util: Make unreachable at least be an assert

[Matt Turner]

On Fri, Dec 5, 2014 at 1:48 PM, Ian Romanick <idr at freedesktop.org> wrote:
> On 12/05/2014 01:42 PM, Matt Turner wrote:
>> On Fri, Dec 5, 2014 at 1:25 PM, Ian Romanick <idr at freedesktop.org> wrote:
>>> On 12/05/2014 01:17 PM, Carl Worth wrote:
>>>> Previously, if __builtin_unreachable() was unavailable, the
>>>> unreachable macro was defined to do nothing. We do better here, by at
>>>> least still making it an assert.
>>>> ---
>>>>  src/util/macros.h | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/src/util/macros.h b/src/util/macros.h
>>>> index 5fc6729..eec8b93 100644
>>>> --- a/src/util/macros.h
>>>> +++ b/src/util/macros.h
>>>> @@ -82,7 +82,7 @@ do {                        \
>>>>  #endif
>>>>
>>>>  #ifndef unreachable
>>>> -#define unreachable(str)
>>>> +#define unreachable(str) assert(!str)
>>>
>>> I'd make this ASSERT.  In Mesa, ASSERT only exists if DEBUG is defined.
>>>  It seems that many distros build without -DDEBUG and without -DNDEBUG.
>>>  I'd rather have no code for these cases in all release builds.
>>
>> I'm surprised by that.
>>
>> I see that we add -DDEBUG with --enable-debug, but from experience
>> assert() does nothing in my regular release build (without
>> --enable-debug). Where is NDEBUG coming from in that case? I don't see
>> it in the macros gcc automatically defines (gcc -g -dM -E - <
>> /dev/null).
>
> Right... and you need NDEBUG to no-op assert.  It has to be added by
> hand, and it seems that the distros don't.

But I don't get assert()s in release builds, and I'm not adding NDEBUG anywhere.