Add SEClamp support in CoreNEURON

[pramodk]

• add svclmp.mod mod file from NEURON
• update registeration callbacks
• expose at_time in the header file

[nrnhines]

This seem basically sound. I.e at_time already has an implementation. Also after_cvode likely emits the correct code (just puts the call to the function in the nrn_solve function) and if not I can activate the proper code in mod2c.

[pramodk]

NMODL needs to handle after_cvode. Also, at_time function needs some extra annotation for GPU:

PGCC/x86-64 Linux 19.10-0: compilation completed with warnings
PGCC-S-1000-Call in OpenACC region to procedure '_ZN10coreneuron7at_timeEPNS_9NrnThreadEd' which has no acc routine information (/jenkins/07/workspace/oss.coreneuron.pipeline/build_GPU-non-unified/coreneuron/svclmp.cpp: 434)
PGCC-W-0155-Compiler failed to translate accelerator region (see -Minfo messages): Missing branch target block (/jenkins/07/workspace/oss.coreneuron.pipeline/build_GPU-non-unified/coreneuron/svclmp.cpp: 336)
PGCC-F-0704-Compilation aborted due to previous errors. (/jenkins/07/workspace/oss.coreneuron.pipeline/build_GPU-non-unified/coreneuron/svclmp.cpp)
PGCC/x86-64 Linux 19.10-0: compilation aborted

[cattabiani]

please retest

[cattabiani]

Given the recent work done by @iomaganaris on at_time, I think this PR can be merged too right?

[pramodk]

Yes but nmodl submodule needs to be updated in coreneuron repo.

[pramodk]

Warning: No --target specified on command-line. Using default system target 
3321        "avx512skx-i32x16". 
3322Warning: No --target specified on command-line. Using default system target 
3323        "avx512skx-i32x16". 
3324x86_64/core/mod2c/svclmp.ispc:83:13: Error: Undeclared symbol "at_time". 
3325            at_time(nt, inst->dur1[id]);
3326            ^^^^^^^
3327
3328x86_64/core/mod2c/svclmp.ispc:86:13: Error: Undeclared symbol "at_time". 
3329            at_time(nt, inst->tc2[id]);
3330            ^^^^^^^
3331
3332x86_64/core/mod2c/svclmp.ispc:89:13: Error: Undeclared symbol "at_time". 
3333            at_time(nt, inst->tc3[id]);
3334            ^^^^^^^

I don't remember how to expose "annotate" function for ISPC but @ohm314 or @iomaganaris might remember better.

[pramodk]

Thanks @iomaganaris for all fixes with ISPC!