linux says it is a bug

[Richard Henderson]

On 03/04/2014 10:12 PM, Yury Gribov wrote:
>>> Asms without outputs are automatically volatile.  So there ought be zero change
>>> with and without the explicit use of the __volatile__ keyword.
>>
>> ThatÂ’s what the documentation says but it wasnÂ’t actually true
>> as of a couple of releases ago, as I recall.
> 
> Looks like 2005:
> 
> $ git annotate gcc/c/c-typeck.c
> ...
> 89552023        (   bonzini     2005-10-05 12:17:16 +0000       9073) /* asm
> statements without outputs, including simple ones, are treated
> 89552023        (   bonzini     2005-10-05 12:17:16 +0000       9074)   as
> volatile.  */
> 89552023        (   bonzini     2005-10-05 12:17:16 +0000       9075)
> ASM_INPUT_P (args) = simple;
> 89552023        (   bonzini     2005-10-05 12:17:16 +0000       9076)
> ASM_VOLATILE_P (args) = (noutputs == 0);

Yep, that's the one.  So, more than "a couple" of releases: gcc 4.2 and later.


r~