at-roc: Add boundscheck flag

[jpsamaroo]

Similar to Julia's --check-bounds flag, this flag (used like @roc boundscheck=false ...) allows the user to entirely disable boundschecking within their code.

[luraess]

Testing on MI250x, @roc boundscheck=false seems not to work.

Testing following kernel:

function diff2D_step!(T2, T, Ci, lam, dt, _dx, _dy)
    ix = (workgroupIdx().x - 1) * workgroupDim().x + workitemIdx().x
    iy = (workgroupIdx().y - 1) * workgroupDim().y + workitemIdx().y
    if (ix>1 && ix<size(T2,1) && iy>1 && iy<size(T2,2))
        @inbounds T2[ix,iy] = T[ix,iy] + dt*(Ci[ix,iy]*(
                              - ((-lam*(T[ix+1,iy] - T[ix,iy])*_dx) - (-lam*(T[ix,iy] - T[ix-1,iy])*_dx))*_dx
                              - ((-lam*(T[ix,iy+1] - T[ix,iy])*_dy) - (-lam*(T[ix,iy] - T[ix,iy-1])*_dy))*_dy ))
    end
    return
end

• using @inbounds: T_tot diff2D = 1182.223 GB/s
• disabling @inbounds: T_tot diff2D = 635.3999 GB/s
• disabling @inbounds but setting @roc boundscheck=false: T_tot diff2D = 635.7766 GB/s

[luraess]

Here is a reproducer https://gist.github.com/luraess/5e697f857a7aa4d1d00e99ca02cbbb3d (@jpsamaroo)

Running it on LUMI MI250x produces:

               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.9.0-beta4 (2023-02-07)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

julia> include("amd_bench_inbounds.jl")
Process selecting device 1
Problem size: nx=24575, ny=24575, nz=1, Float64
ROCm grid=(24576, 24576), threads=(128, 2, 1)
T_tot Lap2D inbounds = 1173.402 GB/s
T_tot Lap2D no inbounds = 638.4716 GB/s
T_tot Lap2D boundscheck=false = 639.0676 GB/s

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