JuliaGPU / JuliaGPU/KernelAbstractions.jl

tuples with multiple functions cannot be accessed on the GPU with a complicated symbol

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Julia
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1d 11h
Merged PRs (30d)
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Description

MWE:

using KernelAbstractions, CUDA, CUDAKernels

@kernel function f_test_kernel!(input, tuple_thingy, tuple_size)
    tid = @index(Global, Linear)

    meh = tid%tuple_size+1
    input[tid] = tuple_thingy[meh](tid)
end

function test!(input, tuple_thingy, tuple_size; numcores = 4, numthreads = 256)

    if isa(input, Array)
        kernel! = f_test_kernel!(CPU(), numcores)
    else
        kernel! = f_test_kernel!(CUDADevice(), numthreads)
    end

    kernel!(input, tuple_thingy, tuple_size, ndrange=size(input)[1])

end

f(x) = x+1
g(x) = x+2
h(x) = x+3

input = zeros(1024)
tuple_thingy = (f,g,h)
tuple_size = 3

wait(test!(input, tuple_thingy, tuple_size))

d_input = CuArray(zeros(1024))
wait(test!(d_input, tuple_thingy, tuple_size))

Error:

ERROR: LoadError: InvalidIRError: compiling kernel gpu_f_test_kernel!(Cassette.Context{nametype(CUDACtx), Nothing, 
Nothing, KernelAbstractions.var"##PassType#274", Nothing, Cassette.DisableHooks}, typeof(gpu_f_test_kernel!), 
KernelAbstractions.CompilerMetadata{KernelAbstractions.NDIteration.DynamicSize, 
KernelAbstractions.NDIteration.DynamicCheck, Nothing, CartesianIndices{1, Tuple{Base.OneTo{Int64}}}, 
KernelAbstractions.NDIteration.NDRange{1, KernelAbstractions.NDIteration.DynamicSize, 
KernelAbstractions.NDIteration.StaticSize{(256,)}, CartesianIndices{1, Tuple{Base.OneTo{Int64}}}, Nothing}}, 
CuDeviceVector{Float64, 1}, Tuple{typeof(f), typeof(g), typeof(h)}, Int64) resulted in invalid LLVM IR
Reason: unsupported call to an unknown function (call to jl_f_getfield)
Stacktrace:
 [1] getindex(::Tuple{typeof(f), typeof(g), typeof(h)}, ::Int64)
   @ ./tuple.jl:29
 [2] overdub
   @ ./tuple.jl:29
 [3] macro expansion
   @ ~/projects/simuleios/test/tuple_test.jl:7
 [4] overdub
   @ ~/projects/KernelAbstractions.jl/src/macros.jl:80
 [5] overdub
   @ ~/.julia/packages/Cassette/1lyEM/src/overdub.jl:0
Stacktrace:
  [1] check_ir(job::GPUCompiler.CompilerJob{GPUCompiler.PTXCompilerTarget, CUDA.CUDACompilerParams, 
  GPUCompiler.FunctionSpec{typeof(Cassette.overdub), Tuple{Cassette.Context{nametype(CUDACtx), Nothing, Nothing, 
  KernelAbstractions.var"##PassType#274", Nothing, Cassette.DisableHooks}, typeof(gpu_f_test_kernel!), 
  KernelAbstractions.CompilerMetadata{KernelAbstractions.NDIteration.DynamicSize, 
  KernelAbstractions.NDIteration.DynamicCheck, Nothing, CartesianIndices{1, Tuple{Base.OneTo{Int64}}}, 
  KernelAbstractions.NDIteration.NDRange{1, KernelAbstractions.NDIteration.DynamicSize, 
  KernelAbstractions.NDIteration.StaticSize{(256,)}, CartesianIndices{1, Tuple{Base.OneTo{Int64}}}, Nothing}}, 
  CuDeviceVector{Float64, 1}, Tuple{typeof(f), typeof(g), typeof(h)}, Int64}}}, args::LLVM.Module)
    @ GPUCompiler ~/.julia/packages/GPUCompiler/HeCT6/src/validation.jl:111
  [2] macro expansion
    @ ~/.julia/packages/GPUCompiler/HeCT6/src/driver.jl:326 [inlined]
  [3] macro expansion
    @ ~/.julia/packages/TimerOutputs/SSeq1/src/TimerOutput.jl:252 [inlined]
  [4] macro expansion
    @ ~/.julia/packages/GPUCompiler/HeCT6/src/driver.jl:324 [inlined]
  [5] emit_asm(job::GPUCompiler.CompilerJob, ir::LLVM.Module; strip::Bool, validate::Bool, format::LLVM.API.LLVMCodeGenFileType)
    @ GPUCompiler ~/.julia/packages/GPUCompiler/HeCT6/src/utils.jl:64
  [6] cufunction_compile(job::GPUCompiler.CompilerJob)
    @ CUDA ~/.julia/packages/CUDA/sCev8/src/compiler/execution.jl:326
  [7] cached_compilation(cache::Dict{UInt64, Any}, job::GPUCompiler.CompilerJob, compiler::typeof(CUDA.cufunction_compile), linker::typeof(CUDA.cufunction_link))
    @ GPUCompiler ~/.julia/packages/GPUCompiler/HeCT6/src/cache.jl:90
  [8] cufunction(f::typeof(Cassette.overdub), tt::Type{Tuple{Cassette.Context{nametype(CUDACtx), Nothing, Nothing, 
  KernelAbstractions.var"##PassType#274", Nothing, Cassette.DisableHooks}, typeof(gpu_f_test_kernel!), 
  KernelAbstractions.CompilerMetadata{KernelAbstractions.NDIteration.DynamicSize, 
  KernelAbstractions.NDIteration.DynamicCheck, Nothing, CartesianIndices{1, Tuple{Base.OneTo{Int64}}}, 
  KernelAbstractions.NDIteration.NDRange{1, KernelAbstractions.NDIteration.DynamicSize, 
  KernelAbstractions.NDIteration.StaticSize{(256,)}, CartesianIndices{1, Tuple{Base.OneTo{Int64}}}, Nothing}}, 
  CuDeviceVector{Float64, 1}, Tuple{typeof(f), typeof(g), typeof(h)}, Int64}}; name::String, kwargs::Base.Pairs{Symbol, Union{}, 
  Tuple{}, NamedTuple{(), Tuple{}}})
    @ CUDA ~/.julia/packages/CUDA/sCev8/src/compiler/execution.jl:297
  [9] macro expansion
    @ ~/.julia/packages/CUDA/sCev8/src/compiler/execution.jl:102 [inlined]
 [10] (::KernelAbstractions.Kernel{CUDADevice, KernelAbstractions.NDIteration.StaticSize{(256,)}, 
 KernelAbstractions.NDIteration.DynamicSize, typeof(gpu_f_test_kernel!)})(::CuArray{Float64, 1, CUDA.Mem.DeviceBuffer}, 
 ::Vararg{Any}; ndrange::Int64, dependencies::CUDAKernels.CudaEvent, workgroupsize::Nothing, progress::Function)
    @ CUDAKernels ~/projects/KernelAbstractions.jl/lib/CUDAKernels/src/CUDAKernels.jl:194
 [11] test!(input::CuArray{Float64, 1, CUDA.Mem.DeviceBuffer}, tuple_thingy::Tuple{typeof(f), typeof(g), typeof(h)}, 
 tuple_size::Int64; numcores::Int64, numthreads::Int64)
    @ Main ~/projects/simuleios/test/tuple_test.jl:18
 [12] test!(input::CuArray{Float64, 1, CUDA.Mem.DeviceBuffer}, tuple_thingy::Tuple{typeof(f), typeof(g), typeof(h)}, 
 tuple_size::Int64)
    @ Main ~/projects/simuleios/test/tuple_test.jl:12
 [13] top-level scope
    @ ~/projects/simuleios/test/tuple_test.jl:33
 [14] include(fname::String)
    @ Base.MainInclude ./client.jl:451
 [15] top-level scope
    @ REPL[1]:1
in expression starting at /home/leios/projects/simuleios/test/tuple_test.jl:33

Notes:

  1. If meh is 1 or set to a specific integer, there is no error.
  2. This seems to fall back to @eval getindex(@nospecialize(t::Tuple), i::Int) = getfield(t, i, $(Expr(:boundscheck))), so I tried with @inbounds (as that was the only thing I could think of), but I got the same error
  3. If the tuple all has the same function, there is no error

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by running the MWE in test/tuple_test.jl and compare the CPU and CUDA paths. Trace the tuple indexing through src/macros.jl and lib/CUDAKernels/src/CUDAKernels.jl, using the reported invalid LLVM IR as the failure point. Done means a GPU kernel can index a tuple containing multiple functions without this compilation error.

Written by the indexing model from the issue text.

Assessment

Tech stack
julia
Domain
backend
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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