Re: [PATCH v4 2/9] Remove single-store shortcut

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On Thu, Aug 10, 2017 at 1:32 AM, Dibyendu Majumdar
<mobile@xxxxxxxxxxxxxxx> wrote:
>
> Yes I suppose that is what it is. LLVM complains that 'instruction
> does not dominate all uses'.
> The unsimplified IR works fine
> (https://github.com/dibyendumajumdar/dmr_c/blob/master/tests/bugs/simplifybug.lin).
> The simplified IR has an issue
> (https://github.com/dibyendumajumdar/dmr_c/blob/master/tests/bugs/simplifybug_O1.lin).

Yes, I saw now. It's hopeless.
It's a problem with the SSA construction (happen between linearization
and simplification), basically, it puts the phi-nodes where there is a load
but it's often too late, they need to be put where paths join.

>> You may try the new SSA construction at :
>>    https://github.com/lucvoo/sparse/tree/sssa
>> It will help a lot.
>>
>
> Is that a standalone change I can apply?

Arf ... in a sense yes but it's really a 40 patches series
(but most changes are isolated, maybe not too much work for you
I don't know).

> I think that this is a very good idea. Since the official sparse repo
> is so behind - it will be good if you maintain a branch in your repo
> that has all the things that you have tested thoroughly and are happy
> with - this can be the "next sparse version" for testing. I would
> suggest aggregating only changes that you are 100% confident about. It
> will allow me (and others like me) to test the changes and report back
> if any issues are found.

It's the idea.
Only that the 100% confident will be "confident that it won't break but
improve situations I know about".

Regards,
-- Luc
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