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Support DiffCache for nonzeroable element types #179

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Merged
ChrisRackauckas merged 1 commit into from
Jul 8, 2026
+21 −1
Merged

Support DiffCache for nonzeroable element types #179

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6 changes: 5 additions & 1 deletion src/PreallocationTools.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -88,12 +88,16 @@ end
function DiffCache(u::AbstractArray{T}, siz, chunk_sizes; warn_on_resize::Bool = true) where {T}
x = adapt(
ArrayInterface.parameterless_type(u),
zeros(T, prod(chunk_sizes .+ 1) * prod(siz))
_zeroed_or_uninitialized(T, prod(chunk_sizes .+ 1) * prod(siz))
)
xany = Any[]
return DiffCache(u, x, xany, warn_on_resize)
end

function _zeroed_or_uninitialized(::Type{T}, dims...) where {T}
return hasmethod(zero, Tuple{Type{T}}) ? zeros(T, dims...) : Array{T}(undef, dims...)
end

"""
`DiffCache(u::AbstractArray, N::Int = forwarddiff_compat_chunk_size(length(u)); levels::Int = 1, warn_on_resize::Bool = true)`
`DiffCache(u::AbstractArray; N::AbstractArray{<:Int}, warn_on_resize::Bool = true)`
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16 changes: 16 additions & 0 deletions test/core_dispatch.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,22 @@ end

Base.zero(::Type{IsbitsPair{T}}) where {T} = IsbitsPair(zero(T), zero(T))

@testset "DiffCache accepts isbits elements without zero" begin
u = [(; a = 1.0, b = (2.0, 3.0)), (; a = 4.0, b = (5.0, 6.0))]
cache = DiffCache(u, 3)
DualT = ForwardDiff.Dual{Nothing, Float64, 3}
tmp = get_tmp(cache, DualT)
expected_eltype = NamedTuple{(:a, :b), Tuple{DualT, Tuple{DualT, DualT}}}

@test eltype(cache.dual_du) == eltype(u)
@test length(cache.dual_du) == 8
@test size(tmp) == size(u)
@test eltype(tmp) == expected_eltype

tmp[1] = (; a = zero(DualT), b = (zero(DualT), zero(DualT)))
@test tmp[1] == (; a = zero(DualT), b = (zero(DualT), zero(DualT)))
end

#Setup Base Array tests
chunk_size = 5
u0 = ones(5, 5)
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