On Wed, Jun 8, 2016 at 10:04 AM, Alexander Cherepanov
<ch3r...@openwall.com> wrote:
> On 2016-06-08 10:29, Richard Biener wrote:
>>
>> On Wed, Jun 8, 2016 at 8:36 AM, Alexander Cherepanov
>> <ch3r...@openwall.com> wrote:
>
> [skip]
>>>
>>> But my question is about the following example:
>>>
>>> ----------------------------------------------------------------------
>>> #include <stdio.h>
>>>
>>> int main()
>>> {
>>> _Bool b;
>>> *(char *)&b = 123;
>>> printf("%d\n", *(char *)&b);
>>> }
>>> ----------------------------------------------------------------------
>>>
>>> Results:
>>>
>>> ----------------------------------------------------------------------
>>> $ gcc -std=c11 -pedantic -Wall -Wextra test.c && ./a.out
>>> 123
>>>
>>> $ gcc -std=c11 -pedantic -Wall -Wextra -O3 test.c && ./a.out
>>> 1
>>> ----------------------------------------------------------------------
>
> [skip]
>>
>> Another explanation is that this is a bug. It manifests itself at the
>> time
>> we re-write 'b' into SSA form, disregarding the fact that we access it
>> via a type that while matching in size does not match in precision.
>
>
> Oh, that's much more boring outcome:-)
;-)
>> Can you open a bugreport?
>
>
> Sure, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71452 .
Patch posted / in testing.
Richard.
> --
> Alexander Cherepanov
