have DECLARE_CCTK_ARGUMENTS_CHECKED hide cctkGH members that do not exist in LEVEL mode etc.

[Roland Haas]

Certain cctkGH members (eg nghostzones) do not contain useful values in all modes, eg not in LEVEL mode. This causes problems every once in a while, eg: #2288.

Using the CHECKED macros we can actually avoid defining C / Fortran variables for those members when a scheduled functions is scheduled only in a given mode and turn a runtime error into a compile time error.

[Steven R. Brandt]

Is there a PR?

[Roland Haas]

oh no. this is an enhancement request, not a review request. Ie a note that this might be good to have and suggestion that anyone who feel inclined to implement this could find themselves with an appreciative audience.

[Steven R. Brandt]

@Roland Haas how do you envision this working? Does it read the mode from schedule.ccl and generate accordingly?

[Roland Haas]

yes, that was my idea. Since the presync code in rdwr.pl already reads and parses schedule.ccl and controls what goes into DECLARE_CCTK_ARGUMENTS_FunctionName it could also do that. Namely I am only thinking about the plain cctk_nghostzones variable (as an example) that DECLARE_CCTK_ARGUMENTS provides and not the actual member of the structure pointed to be cctkGH.

[Erik Schnetter]

This macro could have a different name, e.g. having “level” or “global” in its name. I don’t know whether this is a good idea. Of course, grid functions should not be declared in level or global mode.

‌

-erik

[Roland Haas]

There may be some issues to consider. Eg one use of “options: GLOBAL” is if the scheduled function does its own looping over components etc. Something like (I cannot remember the exact syntax of the various mode changing macros):

schedule MyThorn_Func
{
  options: global

  READS: mygf

  lang: C
} "do something with the data on the grid"

and then

void MyTHorn_Func(CCTK_ARGUMENTS)
{
  BEGIN_REFLEVEL_LOOP(cctkGH) {
    BEGIN_LOCAL_MAP_LOOP{(cctkGH, reflevel)}
      BEGIN_LOCAL_COMPONENT_LOOP(cctkGH, map) {
        DECLARE_CCTK_ARGUTMENTS_MyThorn_Fun;
        for(int i = 0 ; i < cctk_lsh[0] ; i++) {
          int idx = CCTK_GFINDEX3D(cctkGH, i,0,0);
          double value = mygf[idx];
        }
      } END_LOCAL_COMPONENT_LOOP;
    } END_LOCAL_MAP_LOOP
  } END_REFLEVEL_LOOP;

which is perfectly valid code and ends up using the cctkGH members cctk_lsh etc. that are not normally valid for a globally scheduled function since the function itself enters local mode.