How much can hard-coded indexing be avoided in Julia?

Internals & Design
41

I see. So you use explicit @inbounds or none at all, but never start Julia with --check-bounds=no? How come I see a large difference between functions optE and optEib?

function optE(A)
    for idx in CartesianIndices(A)
        i, j, k = Tuple(idx)
        A[idx] = f(i, g(j, k))
    end
end

function optEib(A)
    for idx in CartesianIndices(A)
        i, j, k = Tuple(idx)
        @inbounds A[idx] = f(i, g(j, k))
    end
end

julia> @benchmark optE(A)
BenchmarkTools.Trial: 
  memory estimate:  0 bytes
  allocs estimate:  0
  --------------
  minimum time:     4.376 ms (0.00% GC)
  median time:      4.516 ms (0.00% GC)
  mean time:        4.578 ms (0.00% GC)
  maximum time:     6.253 ms (0.00% GC)
  --------------
  samples:          1092
  evals/sample:     1

julia> @benchmark optEib(A)
BenchmarkTools.Trial: 
  memory estimate:  0 bytes
  allocs estimate:  0
  --------------
  minimum time:     2.946 ms (0.00% GC)
  median time:      3.239 ms (0.00% GC)
  mean time:        3.259 ms (0.00% GC)
  maximum time:     4.865 ms (0.00% GC)
  --------------
  samples:          1534
  evals/sample:     1