Overhead with nested overdub about cassette.jl

[jrevels]

I think the problem here might just be a bug in the InferenceResult cache - it seems like inference knows the answer here, it's looks like it's just not using that info properly, resulting in ::Any being inferred (maybe not grabbing it due to recursion limiting, though).

Simpler MWE:

julia> f(x) = sin(x)
f (generic function with 1 method)

julia> f2(x) = Cassette.overdub(NoOp(), f, x)
f2 (generic function with 1 method)

julia> f3(x) = Cassette.overdub(NoOp(), f2, x)
f3 (generic function with 1 method)

If you Cthulhu.@descend into this thing, you'll get to the bottom where you hit an invoke typed as:

invoke Cassette.overdub(_2::Cassette.Context{nametype(NoOp),Nothing,Cassette.NoPass,Nothing,Nothing}, Cassette.overdub::typeof(Cassette.overdub), $(QuoteNode(Cassette.Context{nametype(NoOp),Nothing,Cassette.NoPass,Nothing,Nothing}(nametype(NoOp)(), nothing, Cassette.NoPass(), nothing, nothing)))::Cassette.Context{nametype(NoOp),Nothing,Cassette.NoPass,Nothing,Nothing}, Base.AbstractFloat::Type{AbstractFloat}, %9::Int64)::Any

If you then peak into inference's cached result for that by doing one more descent, however, you see that the invoke is actually well-inferred in the cache:

invoke Cassette.overdub(::Cassette.Context{nametype(NoOp),Nothing,Cassette.NoPass,Nothing,Nothing},::typeof(Cassette.overdub),::Cassette.Context{nametype(NoOp),Nothing,Cassette.NoPass,Nothing,Nothing},::Type{AbstractFloat},::Int64)::Float64

Dropping that Float64 for no good reason is what borks inference for the rest of the function call.

@vchuravy is my model of what Cthulhu.jl doing correct - does Cthulhu look at the CodeInfo/InferenceResult that the compiler actually hits in the cache, or is it doing something weirder that would cause my above analysis to be misinformed? EDIT: okay it's calling code_typed recursively, which means this could indeed be just hitting the recursion limiting heuristic

[jrevels]

Okay I think I know how to fix this; just need to leave a note for myself: I need to propagate the primal method_for_inference_limit_heuristics through when overdubbing. Let's try it and see what happens...

[jrevels]

Note that the OP here was actually fixed by #92, which AFAICT is all that was needed for Cassette to fully avoid inference recursion issues.

Extending by one more overdub for this example ends up hitting JuliaLang/julia#28003, though (see the @test_broken here)