Re: Sparse 0.5.1 RC5 released.

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On Sun, Aug 13, 2017 at 3:18 PM, Dibyendu Majumdar
<mobile@xxxxxxxxxxxxxxx> wrote:

>> Care to send your code, I can see where the problem could be?
>
> Yes apologies I should have mentioned the test case:
>
> https://github.com/dibyendumajumdar/dmr_c/blob/master/tests/lcc/cq.c

No problem.

> I am checking whether the slowdown is due to some other factor such as:

I just gave a try and, I was a bit surprised as with the current master,
here it takes me about 5s to get the output of test-linearize (which I find
already a bit slow). It's far far from the time you have.

OTOH with -rc4, it takes only 0.05s !

The situation is really weird, it's an interaction between the patches:
- remove single-store shortcut (first slowdown to 0.8s)
- fix ptrlist corruption while killing unreachable BBs (second slowdown to 2.9s)
- mark pseudo users as deleted instead of removing them (third slowdown to 5.5s)

All three patches were expected to create *some* slowdown,
the first one very obviously and much more than the others.

It's interesting to note that without the 'remove single shortcut' patch, the
two others ones don't seem to have a significative effect on the time.

My guess here is that indeed, with this input, the single-store shortcut
is a huge optimization and without it much much more code is created
(phi-nodes, I suppose) and this impact very negatively the two other fixes.

I'll see what can be done.

-- Luc
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