tests/std: Harness CUDA/NVCC

[cbezault]

We need to add nvcc to the set of configurations we test.

• We need to determine which version we need to support.
  • CUDA 10.1 unblocked VS2019 users, however 10.1 Update 2 added if constexpr support. Which we want.
• We need to actually add tests which use nvcc.
  • We have some internally but they aren't fit for external consumption.

Microsoft-internal: Tracked by VSO-750842 / AB#750842. After we add CUDA 10.1 Update 2 coverage to GitHub, we should remove our completely-hacked-up CUDA 9.2 coverage from the MSVC-internal vcr test suite.

[BillyONeal]

I have code to put CUDA on the agents when we're ready to do this from vcpkg.

[StephanTLavavej]

We talked about this, and VS 2019 16.7 can require CUDA 10.1 Update 2, as long as we emit an informative error message for CUDA 10.1 RTW and Update 1.

We already use #ifdef __CUDACC__ to detect CUDA. We should be able to use __CUDACC_VER_MAJOR__ == 10 && __CUDACC_VER_MINOR__ == 1 && __CUDACC_VER_BUILD__ < VALUE_FOR_UPDATE_2.

[StephanTLavavej]

Related to #189.

[StephanTLavavej]

Billy O'Neal (@BillyONeal) If you're ready to put CUDA 10.1 Update 2 on the agents, that would be the first step - then we'd need a modern test (with NVIDIA's help), and finally we can update the STL to use if constexpr everywhere.

[BillyONeal]

Stephan T. Lavavej (@StephanTLavavej) The version I have comes from this URI:

$CudaUrl = 'https://developer.nvidia.com/compute/cuda/10.1/Prod/local_installers/cuda_10.1.105_418.96_win10.exe'
$CudaFeatures = 'nvcc_10.1 cuobjdump_10.1 nvprune_10.1 cupti_10.1 gpu_library_advisor_10.1 memcheck_10.1 ' + `
  'nvdisasm_10.1 nvprof_10.1 visual_profiler_10.1 visual_studio_integration_10.1 cublas_10.1 cublas_dev_10.1 ' + `
  'cudart_10.1 cufft_10.1 cufft_dev_10.1 curand_10.1 curand_dev_10.1 cusolver_10.1 cusolver_dev_10.1 cusparse_10.1 ' + `
  'cusparse_dev_10.1 nvgraph_10.1 nvgraph_dev_10.1 npp_10.1 npp_dev_10.1 nvrtc_10.1 nvrtc_dev_10.1 nvml_dev_10.1 ' + `
  'occupancy_calculator_10.1 fortran_examples_10.1'

Function InstallCuda {
  Param(
    [String]$Url,
    [String]$Features
  )

  try {
    Write-Output 'Downloading CUDA...'
    [string]$installerPath = Get-TempFilePath -Extension 'exe'
    curl.exe -L -o $installerPath -s -S $Url
    Write-Output 'Installing CUDA...'
    $proc = Start-Process -FilePath $installerPath -ArgumentList @('-s ' + $Features) -Wait -PassThru
    $exitCode = $proc.ExitCode
    if ($exitCode -eq 0) {
      Write-Output 'Installation successful!'
    }
    else {
      Write-Output "Installation failed! Exited with $exitCode."
      exit $exitCode
    }
  }
  catch {
    Write-Output "Failed to install CUDA!"
    Write-Output $_.Exception.Message
    exit -1
  }
}

Bryce Adelstein Lelbach (@brycelelbach) Do you know what installer we should be using?

[StephanTLavavej]

After looking at https://developer.nvidia.com/cuda-toolkit-archive , I believe you've found 10.1 RTW. https://developer.nvidia.com/cuda-10.1-download-archive-update2?target_os=Windows&target_arch=x86_64&target_version=10&target_type=exelocal indicates that you can download 10.1 Update 2 from (adding HTTPS):
https://developer.download.nvidia.com/compute/cuda/10.1/Prod/local_installers/cuda_10.1.243_426.00_win10.exe

[BillyONeal]

I'm collecting this and other changes in my branch https://github.com/BillyONeal/STL/tree/cleanup_script -- after I have vcpkg switched over and there stops being churn I'll update here.

[BillyONeal]

#682 adds nvcc since Curtis added my in flight commits.

[brycelelbach]

10.1.43 sounds right. But why not use 10.2?

[StephanTLavavej]

I absolutely love increasing minimum required versions, but users sometimes have different preferences. CUDA 10.1 was the first version that worked with VS 2019, and there are some number of users still using that combination (I don't know numbers/percentages but it is certainly nonzero). By waiting almost a year and telling management that 10.1 Update 2 looked like a highly compatible update (admittedly not from personal experience), plus pointing to our support for side-by-side toolsets and the latency of our release schedule, and promising good error messages, I was able to get approval to increase the minimum required version from 10.1 RTW to 10.1 Update 2 (i.e. allowing us to use if constexpr unconditionally).

Requiring 10.2 would be significantly more aggressive, and while it would presumably fix various compiler bugs, I'm unable to point to specific improvements or features that would dramatically accelerate our development. (Note that I have a pending request for unconditional explicit(bool) support, not sure what the status is there.) I am clueless about how rapidly CUDA users upgrade, but it seems like they explicitly have to download the new version - i.e. there is no auto-upgrader like the VS installer that now offers new production versions as soon as they're released.

If we could somehow require 10.2 without making any of our mutual users hiss, I would love to find a way to do so. Or some kind of predictable policy (e.g. supporting CUDA versions one year old, or something). Currently, the system appears to be that a new VS version can require the corresponding CUDA version that accepts it, except in special circumstances like this 10.1 Update 2 thing. Anyways, please send me an email if you'd like to discuss policy changes, as that's outside the scope of the microsoft/STL repo (whereas getting CUDA 10.1 Update 2 coverage is in scope, and now possible because it's installed on the worker VMs - we just need the actual test, and enhancements to the lit Python machinery to invoke a different compiler driver).