RE: "Unknown pragma ivdep and pragma vector" errors when compiling on BlueGene

From: Joshua D. Moore (jdmoore_at_unity.ncsu.edu)
Date: Fri Feb 02 2007 - 21:09:23 CST

It seems that the IBM XL C/C++ compiler doesn't have ivdep and vector in the
available pragmas for BlueGeneL (at least from the compiler reference from
IBM). Can anyone confirm?

So what is the best option to use these compilers in the ComputeEwald.C and
ComputeNonbondedBase2.h and ComputeNonbondedBase.h files? Just to remove
these #pragma vector and #pragma ivdep and hope the compiler will vectorize
appropriately? Or is there a better substitute?

Thanks.

Josh

-----Original Message-----
From: owner-namd-l_at_ks.uiuc.edu [mailto:owner-namd-l_at_ks.uiuc.edu] On Behalf
Of Joshua D. Moore
Sent: Friday, February 02, 2007 12:30 AM
To: namd-l_at_ks.uiuc.edu
Subject: namd-l: "Unknown pragma ivdep and pragma vector" errors when
compiling on BlueGene

I am getting "An unknown "pragma ivdep" is specified" on BlueGene when
trying to compile out of ComputeNonbondedBase2.h and ComputeNonbondedBase.h.

I am also getting "An unknown "pragma vector" is specified" out of
ComputeEwald.C.

The first pragma vector message doesn't seems to stop the compiling, but the
last messages with pragma ivdep do.

Main question: Is this an error with the compiler? All I could find
suggested that these pragma's (ivdep and vector) were very good to introduce
to the IBM Bluegene compilers.

I was going to comment this out of the source as I think it is optimization,
but it seems like this would be a very bad thing to do with NAMD.

Currently SDSC's compile of NAMD seems kind of slow, so I was hoping to
compile it myself to see if I could get any improvement. Maybe they took
these lines out so that it would compile?

Thanks.

Joshua Moore

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