feat: make FromPrimitive wrappers public

DifferentiationInterface/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Make `AutoForwardFromPrimitive` and `AutoReverseFromPrimitive` public ([#825])
+
 ### Fixed
 
 - Replace `one` with `oneunit` in basis computation ([#826])
@@ -67,6 +71,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 [0.6.53]: https://github.com/JuliaDiff/DifferentiationInterface.jl/compare/DifferentiationInterface-v0.6.52...DifferentiationInterface-v0.6.53
 
 [#826]: https://github.com/JuliaDiff/DifferentiationInterface.jl/pull/826
+[#825]: https://github.com/JuliaDiff/DifferentiationInterface.jl/pull/825
 [#823]: https://github.com/JuliaDiff/DifferentiationInterface.jl/pull/823
 [#818]: https://github.com/JuliaDiff/DifferentiationInterface.jl/pull/818
 [#812]: https://github.com/JuliaDiff/DifferentiationInterface.jl/pull/812

DifferentiationInterface/docs/src/api.md

@@ -132,6 +132,13 @@ MixedMode
 DenseSparsityDetector
 ```
 
+### From primitive
+
+```@docs
+DifferentiationInterface.AutoForwardFromPrimitive
+DifferentiationInterface.AutoReverseFromPrimitive
+```
+
 ## Internals
 
 The following is not part of the public API.

DifferentiationInterface/src/DifferentiationInterface.jl

@@ -126,6 +126,7 @@ export AutoSparse
 ## Public but not exported
 
 @public inner, outer
+@public AutoForwardFromPrimitive, AutoReverseFromPrimitive
 
 include("init.jl")
 

DifferentiationInterface/src/first_order/mixed_mode.jl

@@ -41,3 +41,10 @@ Appropriate mode type for `MixedMode` backends.
 """
 struct ForwardAndReverseMode <: ADTypes.AbstractMode end
 ADTypes.mode(::MixedMode) = ForwardAndReverseMode()
+
+function threshold_batchsize(backend::MixedMode, B::Integer)
+    return MixedMode(
+        threshold_batchsize(forward_backend(backend), B),
+        threshold_batchsize(reverse_backend(backend), B),
+    )
+end

DifferentiationInterface/src/misc/from_primitive.jl

@@ -3,26 +3,45 @@ abstract type FromPrimitive{inplace} <: AbstractADType end
 check_available(backend::FromPrimitive) = check_available(backend.backend)
 inplace_support(::FromPrimitive{true}) = InPlaceSupported()
 inplace_support(::FromPrimitive{false}) = InPlaceNotSupported()
-function inner_preparation_behavior(backend::FromPrimitive)
-    return inner_preparation_behavior(backend.backend)
+
+function pick_batchsize(backend::FromPrimitive, x_or_y::AbstractArray)
+    return pick_batchsize(backend.backend, x_or_y)
 end
 
 function pick_batchsize(backend::FromPrimitive, N::Integer)
     return pick_batchsize(backend.backend, N)
 end
 
+function inner_preparation_behavior(backend::FromPrimitive)
+    return inner_preparation_behavior(backend.backend)
+end
+
+function overloaded_input(::typeof(pushforward), f, backend::FromPrimitive, x, tx::NTuple)
+    return overloaded_input(pushforward, f, backend.backend, x, tx)
+end
+
+function overloaded_input(
+    ::typeof(pushforward), f!, y, backend::FromPrimitive, x, tx::NTuple
+)
+    return overloaded_input(pushforward, f!, y, backend.backend, x, tx)
+end
+
 """
-    AutoForwardFromPrimitive
+    AutoForwardFromPrimitive(backend::AbstractADType)
 
-Wrapper which forces a given backend to act as a reverse-mode backend.
+Wrapper which forces a given backend to act as a forward-mode backend, using only its native `value_and_pushforward` primitive and re-implementing the rest from scratch.
 
-Used in internal testing.
+!!! tip
+    This can be useful to circumvent high-level operators when they have impractical limitations.
+    For instance, ForwardDiff.jl's `jacobian` does not support GPU arrays but its `pushforward` does, so `AutoForwardFromPrimitive(AutoForwardDiff())` has a GPU-friendly `jacobian`.
 """
 struct AutoForwardFromPrimitive{inplace,B<:AbstractADType} <: FromPrimitive{inplace}
     backend::B
 end
 
-function AutoForwardFromPrimitive(backend::AbstractADType; inplace=true)
+function AutoForwardFromPrimitive(
+    backend::AbstractADType; inplace::Bool=Bool(inplace_support(backend))
+)
     return AutoForwardFromPrimitive{inplace,typeof(backend)}(backend)
 end
 
@@ -133,17 +152,17 @@ function value_and_pushforward!(
 end
 
 """
-    AutoReverseFromPrimitive
-
-Wrapper which forces a given backend to act as a reverse-mode backend.
+    AutoReverseFromPrimitive(backend::AbstractADType)
 
-Used in internal testing.
+Wrapper which forces a given backend to act as a reverse-mode backend, using only its native `value_and_pullback` implementation and rebuilding the rest from scratch.
 """
 struct AutoReverseFromPrimitive{inplace,B<:AbstractADType} <: FromPrimitive{inplace}
     backend::B
 end
 
-function AutoReverseFromPrimitive(backend::AbstractADType; inplace=true)
+function AutoReverseFromPrimitive(
+    backend::AbstractADType; inplace::Bool=Bool(inplace_support(backend))
+)
     return AutoReverseFromPrimitive{inplace,typeof(backend)}(backend)
 end
 

DifferentiationInterface/src/utils/batchsize.jl

@@ -112,13 +112,6 @@ function threshold_batchsize(backend::SecondOrder, B::Integer)
     )
 end
 
-function threshold_batchsize(backend::MixedMode, B::Integer)
-    return MixedMode(
-        threshold_batchsize(forward_backend(backend), B),
-        threshold_batchsize(reverse_backend(backend), B),
-    )
-end
-
 """
     reasonable_batchsize(N::Integer, Bmax::Integer)
 

DifferentiationInterface/test/Back/ForwardDiff/test.jl

@@ -8,6 +8,7 @@ import DifferentiationInterface as DI
 import DifferentiationInterfaceTest as DIT
 using ForwardDiff: ForwardDiff
 using StaticArrays: StaticArrays, @SVector
+using JLArrays: JLArrays
 using Test
 
 using ExplicitImports
@@ -75,6 +76,9 @@ end
 @testset "Weird" begin
     test_differentiation(AutoForwardDiff(), component_scenarios(); logging=LOGGING)
     test_differentiation(AutoForwardDiff(), static_scenarios(); logging=LOGGING)
+    test_differentiation(
+        DI.AutoForwardFromPrimitive(AutoForwardDiff()), gpu_scenarios(); logging=LOGGING
+    )
 
     @testset "Batch size" begin
         @test DI.pick_batchsize(AutoForwardDiff(), rand(7)) isa DI.BatchSizeSettings{7}

DifferentiationInterface/test/Core/SimpleFiniteDiff/test.jl

@@ -141,6 +141,12 @@ end
 
 @testset "Weird arrays" begin
     test_differentiation(
-        AutoSimpleFiniteDiff(), vcat(static_scenarios(), gpu_scenarios()); logging=LOGGING
+        [
+            AutoSimpleFiniteDiff(),
+            AutoForwardFromPrimitive(AutoSimpleFiniteDiff()),
+            AutoReverseFromPrimitive(AutoSimpleFiniteDiff()),
+        ],
+        vcat(static_scenarios(), gpu_scenarios());
+        logging=LOGGING,
     )
 end;