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Re: asm volatile statement reordering


On Tue, Oct 17, 2017 at 4:12 AM, Andrew Haley <aph@redhat.com> wrote:
> On 17/10/17 09:01, Jeffrey Walton wrote:
>> On Tue, Oct 17, 2017 at 3:58 AM, Andrew Haley <aph@redhat.com> wrote:
>>> On 17/10/17 08:32, Jeffrey Walton wrote:
>>>> GCC guesses wrong on occasion. It will remove code that has value that
>>>> but does not produce an output because the language does not allow us
>>>> to express it.
>>>>
>>>> The C language lacks what we need to express what we need to do. Its a
>>>> failure of the C (and C++) committees. Its not a GCC failure.
>>>
>>> I disagree.  If you want a bunch of asms to execute in a particular
>>> order, add a memory clobber or some dependencies.  It's not difficult
>>> once you have the understanding.  In this particular case, fixing it
>>> is trivial, and there are many ways to do it.
>>
>> Forgive my ignorance... How does one do it without ASM and in a
>> cross-platform fashion?
>
> I don't understand what you are asking.

Sorry about that Andrew. I had two or three other use cases in mind
when I wrote that. The use case offered by Brown requires it.

Sorry again.

Jeff


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