-O/-O2 causes program to run too slow
jan.stolarek at p.lodz.pl
Mon Dec 8 09:18:12 UTC 2014
While I don't know how to help with your problem I encourage you to attach your code example to
#1168. This will certainly be helpful in working on that bug.
Dnia niedziela, 7 grudnia 2014, David Spies napisał:
> Ok, so I found that it was an instance of this:
> and I read through this whole thread:
> I don't understand the state-hack optimization. It's clearly not safe and
> I'm not convinced that it actually is an optimization. In what
> circumstances does the state-hack identify a single-entry function that
> can't be identified as single-entry by some other (safe) method?
> On Sun, Dec 7, 2014 at 10:52 AM, David Spies <dnspies at gmail.com> wrote:
> > I have a program I wrote to submit for the Car Game problem on Kattis:
> > https://open.kattis.com/problems/cargame
> > but it runs over the 5-second time-limit
> > I downloaded the test data and found that on GHC 7.8.3, if I switch from
> > -O2 to -O0, it runs three times faster (almost certainly fast enough for
> > Kattis to accept). Can someone tell me what's going on? Is this a bug?
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