2nd order AD fails

[avik-pal]

using Reactant, Enzyme, Lux, Random, LinearAlgebra

const xdev = reactant_device()
const cdev = cpu_device()

model = Dense(5 => 5, gelu);
ps, st = Lux.setup(Random.default_rng(), model) |> xdev;
potential = StatefulLuxLayer{true}(model, ps, st)

# Currently EnzymeMLIR doesn't support batching so we force chunksize to 1
function ∇potential(potential, x)
    J = reshape(only(Enzyme.jacobian(Forward, potential, x; chunk=Val(1))), :, length(x))
    J_diag = @allowscalar diag(J)
    return reshape(J_diag, size(x))
end

function ∇²potential(potential, x)
    J = reshape(only(
        Enzyme.jacobian(Forward, Base.Fix1(∇potential, potential), x; chunk=Val(1))
    ), :, length(x))
end

x_ra = randn(Float32, 5, 3) |> xdev

@code_hlo ∇²potential(potential, x_ra)

A non-minimal example taken from LuxDL/Lux.jl#614

[avik-pal]

Error Msg

ERROR: AssertionError: Base.isconcretetype(typ)
Stacktrace:
  [1] abs_typeof(arg::LLVM.LoadInst, partial::Bool, seenphis::Set{LLVM.PHIInst})
    @ Enzyme.Compiler /mnt/.julia/packages/Enzyme/RTS5U/src/absint.jl:557
  [2] abs_typeof(arg::LLVM.LoadInst)
    @ Enzyme.Compiler /mnt/.julia/packages/Enzyme/RTS5U/src/absint.jl:283
  [3] codegen(output::Symbol, job::GPUCompiler.CompilerJob{…}; libraries::Bool, deferred_codegen::Bool, optimize::Bool, toplevel::Bool, strip::Bool, validate::Bool, only_entry::Bool, parent_job::Nothing)
    @ Enzyme.Compiler /mnt/.julia/packages/Enzyme/RTS5U/src/compiler.jl:7066
  [4] codegen
    @ /mnt/.julia/packages/Enzyme/RTS5U/src/compiler.jl:6146 [inlined]
  [5] _thunk(job::GPUCompiler.CompilerJob{Enzyme.Compiler.EnzymeTarget, Enzyme.Compiler.EnzymeCompilerParams}, postopt::Bool)
    @ Enzyme.Compiler /mnt/.julia/packages/Enzyme/RTS5U/src/compiler.jl:8468
  [6] _thunk
    @ /mnt/.julia/packages/Enzyme/RTS5U/src/compiler.jl:8468 [inlined]
  [7] cached_compilation
    @ /mnt/.julia/packages/Enzyme/RTS5U/src/compiler.jl:8509 [inlined]
  [8] thunkbase(ctx::LLVM.Context, mi::Core.MethodInstance, ::Val{…}, ::Type{…}, ::Type{…}, tt::Type{…}, ::Val{…}, ::Val{…}, ::Val{…}, ::Val{…}, ::Val{…}, ::Type{…}, ::Val{…}, ::Val{…})
    @ Enzyme.Compiler /mnt/.julia/packages/Enzyme/RTS5U/src/compiler.jl:8641
  [9] #s2105#19135
    @ /mnt/.julia/packages/Enzyme/RTS5U/src/compiler.jl:8778 [inlined]
 [10] 
    @ Enzyme.Compiler ./none:0
 [11] (::Core.GeneratedFunctionStub)(::UInt64, ::LineNumberNode, ::Any, ::Vararg{Any})
    @ Core ./boot.jl:707
 [12] autodiff
    @ /mnt/.julia/packages/Enzyme/RTS5U/src/Enzyme.jl:633 [inlined]
 [13] autodiff
    @ /mnt/.julia/packages/Enzyme/RTS5U/src/Enzyme.jl:512 [inlined]
 [14] macro expansion
    @ /mnt/.julia/packages/Enzyme/RTS5U/src/Enzyme.jl:2090 [inlined]
 [15] gradient(::ForwardMode{…}, ::StatefulLuxLayer{…}, ::Reactant.TracedRArray{…}; chunk::Val{…}, shadows::Tuple{…})
    @ Enzyme /mnt/.julia/packages/Enzyme/RTS5U/src/Enzyme.jl:1970
 [16] #jacobian#133
    @ /mnt/.julia/packages/Enzyme/RTS5U/src/Enzyme.jl:2177 [inlined]
 [17] jacobian
    @ /mnt/.julia/packages/Enzyme/RTS5U/src/Enzyme.jl:2176 [inlined]
 [18] ∇potential(potential::StatefulLuxLayer{…}, x::Reactant.TracedRArray{…})
    @ Main /mnt/software/lux/Lux.jl/docs/src/manual/nested_autodiff_reactant.md:17
 [19] Fix1
    @ ./operators.jl:1127 [inlined]
 [20] #apply#24
    @ /mnt/software/lux/Reactant.jl/src/utils.jl:37 [inlined]
 [21] apply
    @ /mnt/software/lux/Reactant.jl/src/utils.jl:36 [inlined]
 [22] (::Tuple{})(none::Base.Fix1{typeof(∇potential), StatefulLuxLayer{…}}, none::Tuple{Reactant.TracedRArray{…}})
    @ Base.Experimental ./<missing>:0
 [23] (::Reactant.var"#32#42"{Bool, Bool, typeof(Reactant.apply), Tuple{…}, Vector{…}, Tuple{…}})()
    @ Reactant /mnt/software/lux/Reactant.jl/src/utils.jl:148
 [24] block!(f::Reactant.var"#32#42"{…}, blk::Reactant.MLIR.IR.Block)
    @ Reactant.MLIR.IR /mnt/software/lux/Reactant.jl/src/mlir/IR/Block.jl:201
 [25] make_mlir_fn(f::Function, args::Tuple{…}, kwargs::Tuple{}, name::String, concretein::Bool; toscalar::Bool, return_dialect::Symbol, no_args_in_result::Bool, construct_function_without_args::Bool, do_transpose::Bool)
    @ Reactant /mnt/software/lux/Reactant.jl/src/utils.jl:120
 [26] make_mlir_fn
    @ /mnt/software/lux/Reactant.jl/src/utils.jl:40 [inlined]
 [27] #make_mlir_fn#25
    @ /mnt/software/lux/Reactant.jl/src/utils.jl:53 [inlined]
 [28] make_mlir_fn
    @ /mnt/software/lux/Reactant.jl/src/utils.jl:40 [inlined]
 [29] overload_autodiff(::ForwardMode{…}, f::Const{…}, ::Type{…}, args::Duplicated{…})
    @ Reactant /mnt/software/lux/Reactant.jl/src/Interpreter.jl:373
 [30] autodiff
    @ /mnt/software/lux/Reactant.jl/src/Interpreter.jl:660 [inlined]
 [31] autodiff
    @ /mnt/.julia/packages/Enzyme/RTS5U/src/Enzyme.jl:512 [inlined]
 [32] macro expansion
    @ /mnt/.julia/packages/Enzyme/RTS5U/src/Enzyme.jl:2090 [inlined]
 [33] gradient(::ForwardMode{…}, ::Base.Fix1{…}, ::Reactant.TracedRArray{…}; chunk::Val{…}, shadows::Tuple{…})
    @ Enzyme /mnt/.julia/packages/Enzyme/RTS5U/src/Enzyme.jl:1970
 [34] #jacobian#133
    @ /mnt/.julia/packages/Enzyme/RTS5U/src/Enzyme.jl:2177 [inlined]
 [35] jacobian
    @ /mnt/.julia/packages/Enzyme/RTS5U/src/Enzyme.jl:2176 [inlined]
 [36] ∇²potential
    @ /mnt/software/lux/Lux.jl/docs/src/manual/nested_autodiff_reactant.md:23 [inlined]
 [37] (::Tuple{})(none::StatefulLuxLayer{…}, none::Reactant.TracedRArray{…})
    @ Base.Experimental ./<missing>:0
 [38] (::Reactant.var"#32#42"{Bool, Bool, typeof(∇²potential), Tuple{…}, Vector{…}, Tuple{…}})()
    @ Reactant /mnt/software/lux/Reactant.jl/src/utils.jl:157
 [39] block!(f::Reactant.var"#32#42"{…}, blk::Reactant.MLIR.IR.Block)
    @ Reactant.MLIR.IR /mnt/software/lux/Reactant.jl/src/mlir/IR/Block.jl:201
 [40] make_mlir_fn(f::Function, args::Tuple{…}, kwargs::Tuple{}, name::String, concretein::Bool; toscalar::Bool, return_dialect::Symbol, no_args_in_result::Bool, construct_function_without_args::Bool, do_transpose::Bool)
    @ Reactant /mnt/software/lux/Reactant.jl/src/utils.jl:120
 [41] make_mlir_fn
    @ /mnt/software/lux/Reactant.jl/src/utils.jl:40 [inlined]
 [42] #10
    @ /mnt/software/lux/Reactant.jl/src/Compiler.jl:286 [inlined]
 [43] block!(f::Reactant.Compiler.var"#10#15"{typeof(∇²potential), Tuple{…}}, blk::Reactant.MLIR.IR.Block)
    @ Reactant.MLIR.IR /mnt/software/lux/Reactant.jl/src/mlir/IR/Block.jl:201
 [44] #9
    @ /mnt/software/lux/Reactant.jl/src/Compiler.jl:285 [inlined]
 [45] mmodule!(f::Reactant.Compiler.var"#9#14"{…}, blk::Reactant.MLIR.IR.Module)
    @ Reactant.MLIR.IR /mnt/software/lux/Reactant.jl/src/mlir/IR/Module.jl:92
 [46] compile_mlir!(mod::Reactant.MLIR.IR.Module, f::Function, args::Tuple{…}; optimize::Bool)
    @ Reactant.Compiler /mnt/software/lux/Reactant.jl/src/Compiler.jl:282
 [47] compile_mlir!
    @ /mnt/software/lux/Reactant.jl/src/Compiler.jl:281 [inlined]
 [48] #6
    @ /mnt/software/lux/Reactant.jl/src/Compiler.jl:276 [inlined]
 [49] context!(f::Reactant.Compiler.var"#6#7"{@Kwargs{…}, typeof(∇²potential), Tuple{…}}, ctx::Reactant.MLIR.IR.Context)
    @ Reactant.MLIR.IR /mnt/software/lux/Reactant.jl/src/mlir/IR/Context.jl:76
 [50] compile_mlir(f::Function, args::Tuple{StatefulLuxLayer{…}, ConcreteRArray{…}}; kwargs::@Kwargs{optimize::Bool})
    @ Reactant.Compiler /mnt/software/lux/Reactant.jl/src/Compiler.jl:274
Some type information was truncated. Use `show(err)` to see complete types.

[wsmoses]

just for fun what if you do set_abi(Forward, ReactantABI)

[avik-pal]

That did work!

[wsmoses]

yeah so this is again stemming from "any abstract interpreter based shenanigans fails to go through type unstable code".

Here the actual resolution we did earlier is to make Forward be replaced by set_abi(Forward, ReactantABI) in our absint. This makes things way nicer (including doing the replacement at the callsite of autodiff/jacobian/etc), so any intermediates that are type unstable don't have any issues. Similarly, it means we can natively call it like above. Unfortunately this only applies at the top level absint.

Probably the solution here is to have the absint replace type unstable calls with my_call(...) which itself runs things again in an absint.