Why does JET give these "runtime dispatch detected" lines for some LDLFactorizations calls in Tulip

[aviatesk]

@nsajko

Why does JET say %143::typeof(LinearAlgebra.ldiv!) instead of just LinearAlgebra.ldiv! ? Likewise with ldl_factorize! .

Some frontend issue. This printing is “correct” since LinearAlgebra.ldiv!::typeof(LinearAlgebra.ldiv!) holds true. But I agree with this is better printed as LinearAlgebra.ldiv!(...) instead. If anyone interested in working on this issue, here is code we want to improve: JET.jl/src/abstractinterpret/inferenceerrorreport.jl at 071d3108bb20fd15571f7294aad28c99e20e798a · aviatesk/JET.jl · GitHub

@nsajko

1. Why the runtime dispatch at all, the types indicated by JET for the call are neither abstract (I think) nor unions?

I’m not familiar with LDLFactorizations codebase, but it seems like LDLFactorizations.LDLFactorization{BigFloat} is not really concrete (there seems to be missing type parameters)?

help?> LDLFactorizations.LDLFactorization
  No documentation found.

  Summary
  ≡≡≡≡≡≡≡≡≡

  mutable struct LDLFactorizations.LDLFactorization{T<:Real, Ti<:Integer, Tn<:Integer, Tp<:Integer}

@mtanneau

For instance, I saw a large number of such messages from JET:

││┌ @ broadcast.jl:516 Base.Broadcast.length(%157)
│││ runtime dispatch detected: Base.Broadcast.length(%157::Base.OneTo{Int64})

This seems to be a bug of JET (as the call seems to be fully concrete and should be resolved at compile time). Could you please provide me a reproducer?