# Problem with CUDAv3

**URL:** <https://discourse.julialang.org/t/problem-with-cudav3/71118>\
**Category:** GPU\
**Created:** [November 7, 2021, 11:47pm UTC](https://discourse.julialang.org/t/problem-with-cudav3/71118 "2021-11-07T23:47:48Z")\
**Posts on this page:** 1\
**Showing post:** 9

<div class="post-metadata">

**Author:** ![shiroghost](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@shiroghost](https://discourse.julialang.org/u/shiroghost)\
**Post date:** [November 8, 2021, 1:14pm UTC](https://discourse.julialang.org/t/problem-with-cudav3/71118/9 "2021-11-08T13:14:25Z")

</div>

Ok, sorry. I will try to be more concise.

I have two problems:

1. Routines that were dispatching based on the type returned by threadIdx() are now broken. MWE:

```julia
import Pkg
Pkg.activate(".")
using CUDA

Pkg.status()

idx(i::Int64) = zero(i)*1.0

function krnl_foo!(ac)
    b, r = CUDA.threadIdx().x, CUDA.blockIdx().x

    ac[b,r] = idx(b)
 return nothing
end

A = randn(10,10)
ac = CuArray(A)

CUDA.@sync begin
  @device_code_warntype CUDA.@cuda threads=10 blocks=10 krnl_foo!(ac)
end

A = Array(ac)
A .== zero(A)

```

works in CUDAv3.3.3, but fails in CUDAv3.5.0.

1. Even if this is corrected by changing the type expected by idx(), the code works, but @device\_code\_warntype does not find the correct types. MWE:

```julia

import Pkg
Pkg.activate(".")
using CUDA

Pkg.status()

idx(i::Int32) = zero(i)*1.0 # Change type for CUDAv3.5.0

function krnl_foo!(ac)
    b, r = CUDA.threadIdx().x, CUDA.blockIdx().x

    ac[b,r] = idx(b)
 return nothing
end

A = randn(10,10)
ac = CuArray(A)

CUDA.@sync begin
  @device_code_warntype CUDA.@cuda threads=10 blocks=10 krnl_foo!(ac)
end

A = Array(ac)
A .== zero(A)

```

works in CUDAv3.5.0, but claims that b,r are of type Union:

```julia
 Activating environment at `~/code/CUDAv3.5.0/Project.toml`
      Status `~/code/CUDAv3.5.0/Project.toml`
  [052768ef] CUDA v3.5.0
PTX CompilerJob of kernel krnl_foo!(CuDeviceMatrix{Float64, 1}) for sm_70

Variables
  #self#::Core.Const(krnl_foo!)
  ac::CuDeviceMatrix{Float64, 1}
  r::Union{}
  b::Union{}

Body::Union{}
1 ─ %1 = CUDA.threadIdx::Core.Const(CUDA.threadIdx)
│ (%1)()
│ Core.Const(:(Base.getproperty(%2, :x)))
│ Core.Const(:(CUDA.blockIdx))
│ Core.Const(:((%4)()))
│ Core.Const(:(Base.getproperty(%5, :x)))
│ Core.Const(:(b = %3))
│ Core.Const(:(r = %6))
│ Core.Const(:(Main.idx(b)))
│ Core.Const(:(Base.setindex!(ac, %9, b, r)))
└── Core.Const(:(return Main.nothing))
10×10 BitMatrix:
 1 1 1 1 1 1 1 1 1 1
 1 1 1 1 1 1 1 1 1 1
 1 1 1 1 1 1 1 1 1 1
 1 1 1 1 1 1 1 1 1 1
 1 1 1 1 1 1 1 1 1 1
 1 1 1 1 1 1 1 1 1 1
 1 1 1 1 1 1 1 1 1 1
 1 1 1 1 1 1 1 1 1 1
 1 1 1 1 1 1 1 1 1 1
 1 1 1 1 1 1 1 1 1 1

```

In my particular case, because of 1), a substantial part of my codes are broken in CUDAv3.5.0.

Many thanks!

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