From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dibyendu Majumdar <mobile@majumdar.org.uk>
Subject: Re: Sparse 0.5.1 RC5 released.
Date: Sun, 13 Aug 2017 16:00:51 +0100
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To: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Christopher Li <sparse@chrisli.org>, Linux-Sparse <linux-sparse@vger.kernel.org>, Ramsay Jones <ramsay@ramsayjones.plus.com>, Lance Richardson <lrichard@redhat.com>, Michael Stefaniuc <mstefani@mykolab.com>

On 13 August 2017 at 15:44, Dibyendu Majumdar <mobile@majumdar.org.uk> wrote:
> On 13 August 2017 at 15:18, Luc Van Oostenryck
> <luc.vanoostenryck@gmail.com> wrote:
>> On Sun, Aug 13, 2017 at 3:18 PM, Dibyendu Majumdar
>> <mobile@majumdar.org.uk> 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.
>>
>
> Yes, reinstating the single store shortcut reduces time from 8.3 secs
> to 0.16 seconds.
>

In the interest of getting the release out I recommend simply undoing
the single store shortcut change. It was a last minute change and that
is always risky.

Regards
Dibyendu