Christian,
Thanks much for looking into this. I would be really interested to know
the crux of the bug.
I believe that the float variables are using Boost.Interval for the
calculations, right? There are rounding policies that can be used with
that library (that should guarantee specific precision and rounding
behavior), but I'm not sure what overhead there is associated with that
and whether/how it interferes with compiler settings.
Since it appears that in my particular case there are problems with the
FLOAT_VAL_SPLIT_MAX branching, I wonder whether there are some
invariants/assumptions in the branching code that the SSE2 breaks.
But you're saying that SSE2 has been the default for quite some time, so
I wonder why this hasn't been a problem with MSVC 2013 too.
Cheers
Filip
Dne 18. 9. 2015 v 12:22 Christian Schulte napsal(a):
Your environment is fine, it is really MSVC 2015. I can re-produce your
problems with both x86 and x64... And it appears to be really bad.
But I think I found at least something: by default, MSVC uses SSE2
arithmetic (has been since quite some time, in particular for x64). If you
force the compiler to use x87 arithmetic instead (which is really bad as it
also has an impact on integer performance) by -ARCH:IA32 then at least the
tests seem to work (you can pass by make CXXUSR=-ARCH:IA32 when you build
Gecode).
However your test still does not work (terminates immediately with bringing
up Gist).
I think we will have to fix the Gecode build to use x87 for the float stuff.
Cheers
Christian
--
Christian Schulte, www.gecode.org/~schulte
Professor of Computer Science, KTH, cschu...@kth.se
Expert Researcher, SICS, cschu...@sics.se
-----Original Message-----
From: users-boun...@gecode.org [mailto:users-boun...@gecode.org] On Behalf
Of Filip Konvicka
Sent: Thursday, September 17, 2015 05:43 PM
To: users@gecode.org
Subject: Re: [gecode-users] Freeze with MSVC 2015 optimized build
...and "Float::Arithmetic::Div::Sol::A" seems to be failing fast with any
seed.
So it might really be my build setup - although I hope it's not as it is
basically the same as that I've been using for years :)
Cheers,
Filip
It only happens with Gecode compiled in release mode with MSVC 2015.
There are no such official Gecode binaries, so I wasn't sure whether
my build environment was set up correctly - but it probably is.
This is an excerpt from my original post that explains what seems to
be triggering the problem:
> In the test case source code there is a constant >
"8686.9666660000003". Changing it to "8686" seems to fix the problem
- but even "8686.9" makes dfs freeze. It also seems that it is the
branching strategy 'FLOAT_VAL_SPLIT_MAX' that is causing problems.
Regarding the build environment, I tried running some tests, and it
seems to fail "Float::Arithmetic::Div::C":
...
Float::Arithmetic::Div::B +++++
Float::Arithmetic::Div::C -
Options: -seed 71643696 -test Float::Arithmetic::Div::C
I wonder whether this passes in your environment. The "Div" tests
seem to run slow. The same test with the seed 71643693 seems to pass.
Cheers,
Filip
Uuups, gosh. That I did not know. Right now I cannot try MSV 2013
easily as I am travelling. But maybe I'll check somehow.
Cheers
Christian
--
Christian Schulte, www.gecode.org/~schulte Professor of Computer
Science, KTH, cschu...@kth.se Expert Researcher, SICS,
cschu...@sics.se
-----Original Message-----
From: users-boun...@gecode.org
[mailto:users-boun...@gecode.org] On Behalf Of Filip Konvicka
Sent: Thursday, September 17, 2015 05:02 PM
To: users@gecode.org
Subject: Re: [gecode-users] Freeze with MSVC 2015 optimized build
Hi Christian,
Thanks! OK - I just know that the official Gecode 4.4.0 distribution
(MSVC
2013) works OK, and so does the debug (non-optimized) version built
from trunk using MSVC 2015.
Cheers,
Filip
Hi Filip,
This seems to be an issue with Gecode and not the compiler... Guido
promised me that he will look into floats. Real soon, he said ;-)
Cheers
Christian
--
Christian Schulte, www.gecode.org/~schulte Professor of Computer
Science, KTH, cschu...@kth.se Expert Researcher, SICS,
cschu...@sics.se
-----Original Message-----
From: users-boun...@gecode.org
[mailto:users-boun...@gecode.org] On Behalf Of Filip Konvicka
Sent: Thursday, September 17, 2015 03:39 PM
To: users@gecode.org
Subject: Re: [gecode-users] Freeze with MSVC 2015 optimized build
Sure, it's the script from my original post. I'm re-attaching it now.
I also used Gecode trunk (updated about September 1st) with Qt-5.5,
built in my Cygwin environment with MSVC 2015 RTM x64 compiler.
Thanks,
Filip
Hi Filip,
If you tell me which script you tried, I can try here (even though
Gist works for me with MSVC 2015 and Qt-5.5.0, using the trunk).
Cheers
Christian
--
Christian Schulte, www.gecode.org/~schulte Professor of Computer
Science, KTH, cschu...@kth.se Expert Researcher, SICS,
cschu...@sics.se
-----Original Message-----
From: users-boun...@gecode.org
[mailto:users-boun...@gecode.org] On Behalf Of Filip Konvicka
Sent: Thursday, September 17, 2015 03:24 PM
To: users@gecode.org
Subject: Re: [gecode-users] Freeze with MSVC 2015 optimized build
I was trying to use the Qt installer but Qt does not seem to be
visible in the cygwin environment. I'll try the source package as
you suggest, that sounds better to me.
So in the end I finished using the pre-built version of Qt and I'm
now able to run the script in Gist (Gist::dfs). The issue is still
there.
I ran 'Next Solution' - this apparently runs the search in a
separate thread but never finishes (and 'Stop' does not stop the
search, you have to kill the program). Inspecting the nodes one by
one freezes the program during the 3rd expansion, and in this case
the program stops
responding altogether.
So my guess is this is really some tight loop somewhere in Gecode
(maybe caused by a new optimization or bug in the new compiler?)
Cheers,
Filip
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