When does @inbounds increase performance?

[jishnub]

E.g. a case where this optimization doesn’t happen is

Is the triple `@inbounds @fastmath @simd` necessary for absolute peak performance?

This is not always the case, unfortunately. Only in simple cases can the compiler elide bounds-checks with eachindex. E.g.: julia> using LinearAlgebra julia> function f(D) s = zero(eltype(D)) for i in eachindex(D) s += D[i] end s end f (generic function with 1 method) julia> D = Diagonal(1:3); julia> @code_llvm f(D) this indicates that the bounds checks are still present. L28: ; preds = %L65, %top …