Is it possible to use nvstd::function inside an RTC agent function?

[society-research]

Hello there! :)

I would love some hints/clarifications/help for using additional std-library or cuda C++ headers in agent functions.
It says here [1] #include-directives are supported in RTC functions, but when including nvfunctional [2]

#include <nvfunctional>

I get the following error:

(venv) [me@cgpu01-002 model-socix-py]$ python sx.py -s 2
crt/nvfunctional(50): warning: new: [jitify] File not found
---------------------------------------------------
--- JIT compile log for human_behavior_program ---
---------------------------------------------------
crt/nvfunctional(86): error: namespace "std" has no member "is_move_constructible"

crt/nvfunctional(86): error: type name is not allowed

crt/nvfunctional(87): error: expected a "," or ">"

crt/nvfunctional(87): error: the global scope has no "value"

crt/nvfunctional(87): error: expected a ";"

crt/nvfunctional(118): warning: parsing restarts here after previous syntax error

human_behavior_impl.cu(47): warning: variable "actions" was declared but never referenced

5 errors detected in the compilation of "human_behavior_program".

---------------------------------------------------
Traceback (most recent call last):
  File "/work/me/model-socix-py/sx.py", line 304, in <module>
    main()
  File "/work/me/model-socix-py/sx.py", line 290, in main
    simulation.initialise(sys.argv)
  File "/work/me/model-socix-py/venv/lib/python3.11/site-packages/pyflamegpu/pyflamegpu.py", line 8830, in initialise
    return _pyflamegpu.Simulation_initialise(self, argc)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
pyflamegpu.pyflamegpu.FLAMEGPURuntimeException: (InvalidAgentFunc) /__w/FLAMEGPU2/FLAMEGPU2/src/flamegpu/detail/JitifyCache.cu(422): Error compiling runtime agent function (or function condition) ('human_behavior'): function had compilation errors (see std::cout), in JitifyCache::buildProgram().

So the header is found but there are some compilation errors. Note that #include <type_traits> before including nvfunctional doesn't change the error message.

Just loading functional results in

RuntimeError: human_behavior_impl.cu not in loaded sources! This may be due to a header being loaded by NVRTC without Jitify's knowledge.

So maybe the std::function is just not supposed to be used in CUDA code? Or is this a restriction of FLAMEGPU's JIT compilation code?

Would love to get some input! :)

[1] https://docs.flamegpu.com/guide/agent-functions/defining-agent-functions.html
[2] https://docs.nvidia.com/cuda/cuda-c-programming-guide/#polymorphic-function-wrappers

[Robadob]

We use Jitify to handle runtime compilation (RTC).

RTC does not have access to the C++ standard library includes. For this reason, Jitify provides shims for a subset of the standard library headers.

It would appear that nvfunctional uses something that is not currently shimmed by Jitify (std::is_move_constructible).

You could submit an issue or pull request to jitify requesting/providing the shim. Myself and others have provided PRs to extend the shims in the past. We currently use Jitify1, but hope to move to Jitify2 in the near future when their pre-processor PR is merged. In their repository, they maintain the versions in two separate branches.

[Robadob]

I've created an issue to improve the documentation regarding RTC includes.

I think when we documented includes, we were only considering users creating their own headers common to multiple agent functions. Hence, explaining Jitify's use of Shims was overlooked.

FLAMEGPU/FLAMEGPU2-docs#177

[Robadob]

I suppose, rather than waiting for a shim to be merged into Jitify. You could implement it yourself in your code prior to the include.