FUTHARK-CUDA(1)

📦
version 0.25.32 · 5 versions
, in ubuntu resolute, ubuntu stonking

💅 futhark-cuda — the CUDA-flavored Futhark compiler, bestie 💖

okay so like. this is futhark-cuda, bestie. it's part of the Futhark fam and it compiles your Futhark programs to CUDA 🎀

✨ SYNOPSIS ✨

futhark cuda [options...] <program.fut>

🌸 DESCRIPTION 🌸

no cap</p>, futhark cuda translates a Futhark program into C code that calls CUDA kernels ✨ and then it does one of two iconic things:

  • it compiles that C code with a C compiler into a whole executable binary, or
  • it hands you a .h and a .c file that you can link with your other code 🫶

and yes it runs the standard Futhark optimisation pipeline, because obviously 💅

ok and listen: futhark cuda links with -lcuda -lcudart -lnvrtc. so if you're using --library, you have to do the same thing yourself when you link the final binary. like, that's on you now bestie 😭

the generated CUDA code is actually built different — it can be called from multiple CPU threads at once, because it brackets every single API operation with cuCtxPushCurrent() and cuCtxPopCurrent(). slay 💅

👑 OPTIONS 👑

  • Accepts the same options as futhark-c — literally identical. same options, same energy 💖

🌈 ENVIRONMENT VARIABLES 🌈

  • CC — the C compiler used to compile the program. defaults to cc if it's unset ✨
  • CFLAGS — a space-separated list of options passed to the C compiler. defaults to -O -std=c99 if unset 🌸

🦋 EXECUTABLE OPTIONS 🦋

the executables you generate accept the same options as the ones generated by futhark-c 👑 and also — heads up — the -t option behaves exactly as it does with futhark-opencl 💫

and then there's MORE. the following extra options are accepted too 🎀

  • -h, --help — print help text to standard output and exit. periodt 💅
  • --default-thread-block-size=INT — the default size of the thread blocks that get launched. it gets capped to the hardware limit if it has to ✨
  • --default-num-thread-blocks=INT — the default number of thread blocks that get launched 🍓
  • --default-threshold=INT — the default parallelism threshold used for comparisons when it's picking between code versions generated by incremental flattening. intuitively? it's the amount of parallelism you need to saturate the GPU 🔥
  • --default-tile-size=INT — the default tile size used when doing two-dimensional tiling. (the workgroup size is gonna be the square of the tile size, jsyk 👀)
  • --dump-cuda=FILE — doesn't run the program, it just dumps the embedded CUDA kernels into the file you name. super useful if you wanna see what's actually being executed 🙈
  • --dump-ptx=FILE — again, doesn't run anything — it dumps the PTX-compiled version of your embedded kernels into the indicated file 💜
  • --load-cuda=FILE — instead of using the embedded CUDA kernels, load them from the file you indicate 🌸
  • --load-ptx=FILE — load PTX code from the indicated file ✨
  • --nvrtc-option=OPT — adds another build option to the string passed to NVRTC. go check the CUDA docs for which options are supported, bestie. and be careful — some options can very easily get you invalid results 💀

💜 ENVIRONMENT 💜

if you run it without --library, futhark cuda will invoke a C compiler to compile the generated C program into a binary. now — this only works if the C compiler can actually find the CUDA libraries it needs 😭

on most systems, CUDA lives in /usr/local/cuda, which is usually not part of the default compiler search path. so you might need to set these environment variables before running futhark cuda:

LIBRARY_PATH=/usr/local/cuda/lib64
LD_LIBRARY_PATH=/usr/local/cuda/lib64/
CPATH=/usr/local/cuda/include

and at runtime, your generated program has to be able to find the CUDA installation directory, which is normally at /usr/local/cuda 🌈 if you have CUDA installed somewhere else, set any of the CUDA_HOME, CUDA_ROOT, or CUDA_PATH environment variables to the proper directory 🫶

🎀 SEE ALSO 🎀

  • futhark-opencl 💖

2013-2020, DIKU, University of Copenhagen

ok that's the whole page bestie, you ate that 💅 this was FUTHARK-CUDA(1), version 0.25.32, dated Mar 11, 2026, from the Futhark fam — now go compile something iconic, mwah 🎀✨🦋💖

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