Re: [PATCH] tools/memory-model: Weaken ctrl dependency definition in explanation.txt

From: Paul Heidekrüger
Date: Fri Sep 02 2022 - 16:53:57 EST


On 2. Sep 2022, at 16:18, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:

> On Fri, Sep 02, 2022 at 10:40:34AM +0200, Paul Heidekrüger wrote:
>> On 31. Aug 2022, at 19:38, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
>>>>> Finally, a read event X and another memory access event Y are linked by a
>>>>> control dependency if Y syntactically lies within an arm of an if
>>>>> statement and X affects the evaluation of the if condition via a data or
>>>>> address dependency. Similarly for switch statements.
>>>>
>>>> What do you think?
>>>
>>> I like the second one. How about combining the last two sentences?
>>>
>>> ... via a data or address dependency (or similarly for a switch
>>> statement).
>>
>> Yes, sounds good!
>>
>>> Now I suppose someone will pipe up and ask about the conditional
>>> expressions in "for", "while" and "do" statements... :-)
>>
>> Happy to have obliged :-)
>> https://lore.kernel.org/all/20F4C097-24B4-416B-95EE-AC11F5952B44@xxxxxxxxx/
>>
>> Do you think the text should explicitly address control dependencies in the
>> context of loops as well? If yes, would it be a separate patch, or would it
>> make sense to combine it with this one?
>
> Anything else should be a separate patch.
>
> For the time being, I'm happy not to worry about loops. In the end
> we'll probably have to describe them as though they were unrolled,
> with all the complications that entails.

OK, sounds good!

Since there aren't any other immediate objections, I'll go ahead an resubmit
a v3 version of the patch with all the changes we discussed then.

Many thanks,
Paul

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