Remove constexpr from ringOrder

[davidlt]

ICC segfaults due to to constexpr on ringOrder. This is reported and
due to be fixed in forthcoming ICC releases (2016).

Removal of constexpr did not change assembly in any significant,
actually compiler generated 5 instructions less for this function.

Signed-off-by: David Abdurachmanov David.Abdurachmanov@cern.ch

[cmsbuild]

A new Pull Request was created by @davidlt for CMSSW_7_6_X.

Remove constexpr from ringOrder

It involves the following packages:

RecoTracker/TkDetLayers

@cmsbuild, @cvuosalo, @slava77 can you please review it and eventually sign? Thanks.
@ghellwig, @makortel, @GiacomoSguazzoni, @rovere, @VinInn, @mschrode, @istaslis, @gpetruc, @cerati, @dgulhan this is something you requested to watch as well.
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[slava77]

can we keep "const" here?
This is logically what it was before the change proposed here.

[davidlt]

Yes, I don't know how that got away from me.

[VinInn]

Can we stop modifying production code to support development platform used only for R&D?
We need a policy here. I strongly oppose to change any code with the only purpose to support R&D on HW/Software that has close to negligible chance to become a production platform in the medium future.

[davidlt]

@VinInn I am happy to add ifdef here if required. It's L2 decision. But technically there seems to be no gain in constexpr here.

[cmsbuild]

Pull request #11848 was updated. @cmsbuild, @cvuosalo, @slava77 can you please check and sign again.

[davidlange6]

if I understand correctly that we are patching around an ICC bug (which indeed is not likely a production cms platform..) - an ifdef sounds like the best approach.

[cmsbuild]

Pull request #11848 was updated. @cmsbuild, @cvuosalo, @slava77 can you please check and sign again.

[davidlt]

I added ifdefs, but again constexpr aren't giving any benefits here.

[slava77]

@cmsbuild please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/8958/console

[cmsbuild]

+1
Tested at: 9d76170
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-11848/8958/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-11848/8958/summary.html

[cvuosalo]

+1

For #11848 9d76170

Adding #ifdef for a special R&D compiler that has a bug with constexpr to allow it to compile CMSSW. This compiler bug might get fixed in 2016.

There should be no change in run-time behavior.

The code changes are satisfactory, and standard compilation is successful. Jenkins tests against baseline CMSSW_7_6_X_2015-10-16-1100 show no significant differences, as expected.

[cvuosalo]

@davidlt:
It would be nice if you could remove these #ifdefs next year when you get a new version of ICC without the bug.

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_6_X IBs (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @Degano, @smuzaffar

[davidlange6]

+1