Charm++ parallel programming system

["Van Der Wijngaart, Rob F" <rob.f.van.der.wijngaart AT intel.com>]

But then again, maybe “double weight[4.5+4.5];” is OK. In some parallel universe this must be true.

 

Rob

 

From: Van Der Wijngaart, Rob F
Sent: Monday, September 29, 2014 12:47 PM
To: Hammond, Jeff R; Phil Miller
Cc: Nikhil Jain; Kunzman, David M; Mattson, Timothy G; charm AT cs.illinois.edu
Subject: RE: Global variables in Charm++

 

Eh, that would stink spectacularly. I refuse to accept that “double weight[3+3+3];” may result in a syntax error. I invite the Charm++ team to explain why this would be reasonable.

 

Rob

 

From: Hammond, Jeff R
Sent: Monday, September 29, 2014 12:38 PM
To: Van Der Wijngaart, Rob F; Phil Miller
Cc: Nikhil Jain; Kunzman, David M; Mattson, Timothy G; charm AT cs.illinois.edu
Subject: Re: Global variables in Charm++

 

Can you do something evil where you extern pointer to storage and then declare it in a generic C++ file that will be preprocessed properly?

 

Obviously, may provoke the question “what is that terrible smell?” but I’ve seen far worse workarounds associated with legacy Fortran :-)

 

Jeff

 

From: "<Van Der Wijngaart>", Rob F <rob.f.van.der.wijngaart AT intel.com>
Date: Monday, September 29, 2014 at 9:55 AM
To: Phil Miller <mille121 AT illinois.edu>
Cc: Nikhil Jain <nikhil.life AT gmail.com>, "Kunzman, David M" <david.m.kunzman AT intel.com>, Jeff R Hammond <jeff.r.hammond AT intel.com>, "Mattson, Timothy G" <timothy.g.mattson AT intel.com>, "charm AT cs.illinois.edu" <charm AT cs.illinois.edu>
Subject: RE: Global variables in Charm++

 

OK, it appears not to be the problem of running the preprocessor per se, but of having expressions in array dimensions. I replaced

  readonly double weight[(2*RADIUS+1)*(2*RADIUS+1)];

with

  readonly double weight[3+3+3];

and got another syntax error.

This looks like a pretty serious limitation to me. I am now required to do the array dimension computation for charmc and stuff that into the .ci file explicitly as a constant. This means running another script/preprocessor before I can run charmc.

 

Rob

 

From: Van Der Wijngaart, Rob F
Sent: Friday, September 26, 2014 3:49 PM
To: 'Phil Miller'
Cc: Nikhil Jain; Kunzman, David M; Hammond, Jeff R; Mattson, Timothy G; charm AT cs.illinois.edu
Subject: RE: Global variables in Charm++

 

Thanks Phil. I just added –E to my OPTS parameter, but then all hell breaks loose.

This is what charmc says is happening when it tries to compile my .ci file:

../../../bin/charmc -Ofast -DRADIUS=1 -DSTAR -E  jacobi2d.ci

And this is the line in my .ci file that it complains about:

  readonly double weight[(2*RADIUS+1)*(2*RADIUS+1)];

 

Output:

[rfvander@bar1 PRKstencil5]$ make

../../../bin/charmc -Ofast -DRADIUS=1 -DSTAR -E  jacobi2d.ci

STDIN:8: Charmxi syntax error> syntax error

Invalid construct

Fatal Error by charmc in directory /home/rfvander/charm/examples/charm++/PRKstencil5

   Command ../../../bin/charmxi -orig-file jacobi2d.ci returned error code 1

charmc exiting...

../../../bin/charmc -Ofast -DRADIUS=1 -DSTAR -c jacobi2d.C

jacobi2d.C(1): catastrophic error: cannot open source file "jacobi2d.decl.h"

  #include "jacobi2d.decl.h"

 

By the way, you may wonder about the subject line of this message. It started because I wanted a (small) 2D array as a global variable. I couldn’t get that to work (is that by design?), so made it into a 1D array. And then I ran into the issue I just reported.

 

Rob

 

From:unmobile AT gmail.com [mailto:unmobile AT gmail.com] On Behalf Of Phil Miller
Sent: Friday, September 26, 2014 3:37 PM
To: Van Der Wijngaart, Rob F
Cc: Nikhil Jain; Kunzman, David M; Hammond, Jeff R; Mattson, Timothy G; charm AT cs.illinois.edu
Subject: Re: Global variables in Charm++

 

For historical reasons [1], charmc defaults to *not* running the preprocessor on .ci files. Preprocessing .ci files can be enabled by passing charmc the -E flag when it's working on .ci files.

[1] Enabling pre-processing when it wasn't historically the default risks breaking existing application code by having macros that may have been used as identifiers in .ci files suddenly be subject to expansion/substitution.

 

On Fri, Sep 26, 2014 at 5:31 PM, Van Der Wijngaart, Rob F <rob.f.van.der.wijngaart AT intel.com> wrote:

Hello Nikhil,

 

I have a symbol that I define on the compile line (i.e. I stuff it in OPTS, as below):

OPTS=-DRADIUS=1

CHARMC=../../../bin/charmc $(OPTS)

When I now use RADIUS in my .C file, the C preprocessor does its work nicely and recognizes that I have defined RADIUS, and also what its value is. However, when I use RADIUS in the .ci file, charmc croaks. So is it true that no preprocessor is run on .ci files? Thanks!

 

Rob