Charm++ parallel programming system

[Gengbin Zheng <gzheng AT illinois.edu>]

Charm++'s  interface language was purposely designed to be very simple (so we don't spend too much time on writing a full-fledged compiler).

The readonly syntax as defined in xi-grammar.y is like this:


ArrayDim        : NUMBER
                { $$ = new Value($1); }
                | QualName
                { $$ = new Value($1); }
                ;

QualName        : IDENT
                { $$ = $1; }
                | QualName ':'':' IDENT
                {
                  char *tmp = new char[strlen($1)+strlen($4)+3];
                  sprintf(tmp,"%s::%s", $1, $4);
                  $$ = tmp;
                }
                ;

Dim             : '[' ArrayDim ']'
                { $$ = $2; }
                ;

DimList         : /* Empty */
                { $$ = 0; }
                | Dim DimList
                { $$ = new ValueList($1, $2); }
                ;

Readonly        : READONLY Type QualName DimList
                { $$ = new Readonly(lineno, $2, $3, $4); }


 so in brackets, it pretty much only takes numbers or identifiers, no expressions.


To workaround your problem, you can:

1.  define a macro for your formula and only use the macro in ci file.
     #define WEIGHT_SIZE  (2*RADIUS+1)*(2*RADIUS+1)                    /* write this in a C header file  */

   and then: 
    readonly double weight[WEIGHT_SIZE]
   in ci file.


2.  avoid using readonly in ci file, but use readonly templates in C++ file.
     This is probably not defined in Charm manual, but it is like putting the following in a C++ code:

     roarray<double,  (2*RADIUS+1)*(2*RADIUS+1)>  weight;

    This way, you don't need to write any readonly thing in the ci file.


Gengbin
   

On 9/29/2014 2:47 PM, Van Der Wijngaart, Rob F wrote:

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

 

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