Merge pull request #568 from N5N3/cbfix

Some recursion tuning to allow more eager inference.

Project.toml

@@ -1,6 +1,6 @@
 name = "Interpolations"
 uuid = "a98d9a8b-a2ab-59e6-89dd-64a1c18fca59"
-version = "0.15.0"
+version = "0.15.1"
 
 [deps]
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"

src/Interpolations.jl

@@ -278,25 +278,34 @@ struct InterpGetindex{N,A<:AbstractArray{<:Any,N}}
     InterpGetindex(A::AbstractArray) = new{ndims(A),typeof(A)}(A)
 end
 @inline Base.getindex(A::InterpGetindex{N}, I::Vararg{Union{Int,WeightedIndex},N}) where {N} =
-    interp_getindex(A.coeffs, ntuple(_ -> 0, Val(N)), map(indexflag, I)...)
-indexflag(I::Int) = I
-@inline indexflag(I::WeightedIndex) = indextuple(I), weights(I)
+    interp_getindex(A.coeffs, ntuple(zero, Val(N)), map(indexflag, I)...)
+@inline indexflag(I) = indextuple(I), weights(I)
+
+# Direct recursion would allow more eager inference before julia 1.11.
+# Normalize all index into the same format.
+struct One end  # Singleton for express weights of no-interp dims
+indextuple(I::Int) = (I,)
+weights(::Int) = (One(),)
+
+struct Zero end # Singleton for dim expansion termination
 
 # A recursion-based `interp_getindex`, which follows a "move processed indexes to the back" strategy
 # `I` contains the processed index, and (wi1, wis...) contains the yet-to-be-processed indexes
-# Here we meet a no-interp dim, just append the index to `I`'s end.
-@inline interp_getindex(A, I, wi1::Int, wis...) =
-    interp_getindex(A, (Base.tail(I)..., wi1), wis...)
 # Here we handle the expansion of a single dimension.
-@inline interp_getindex(A, I, wi1::NTuple{2,Tuple{Any,Vararg{Any,N}}}, wis...) where {N} =
-    wi1[2][end] * interp_getindex(A, (Base.tail(I)..., wi1[1][end]), wis...) +
-    interp_getindex(A, I, map(Base.front, wi1), wis...)
-@inline interp_getindex(A, I, wi1::NTuple{2,Tuple{Any}}, wis...) =
-    wi1[2][1] * interp_getindex(A, (Base.tail(I)..., wi1[1][1]), wis...)
+@inline function interp_getindex(A, I, (is, ws)::NTuple{2,Tuple}, wis...)
+    itped1 = interp_getindex(A, (Base.tail(I)..., is[end]), wis...)
+    witped = interp_getindex(A, I, (Base.front(is), Base.front(ws)), wis...)
+    _weight_itp(ws[end], itped1, witped)
+end
+interp_getindex(_, _, ::NTuple{2,Tuple{}}, ::Vararg) = Zero()
 # Termination
 @inline interp_getindex(A::AbstractArray{T,N}, I::Dims{N}) where {T,N} =
     @inbounds A[I...] # all bounds-checks have already happened
 
+_weight_itp(w, i, wir) = w * i + wir
+_weight_itp(::One, i, ::Zero) = i
+_weight_itp(w, i, ::Zero) = w * i
+
 """
     w = value_weights(degree, δx)
 

src/b-splines/indexing.jl

@@ -102,10 +102,12 @@ function weightedindexes(parts::Vararg{Union{Int,GradParts},N}) where N
     slot_substitute(parts, map(positions, parts), map(valuecoefs, parts), map(gradcoefs, parts))
 end
 
-# Skip over NoInterp dimensions
-slot_substitute(kind::Tuple{Int,Vararg{Any}}, p, v, g) = slot_substitute(Base.tail(kind), p, v, g)
 # Substitute the dth dimension's gradient coefs for the remaining coefs
-slot_substitute(kind, p, v, g) = (map(maybe_weightedindex, p, substitute_ruled(v, kind, g)), slot_substitute(Base.tail(kind), p, v, g)...)
+function slot_substitute(kind, p, v, g)
+    rest = slot_substitute(Base.tail(kind), p, v, g)
+    kind[1] isa Int && return rest # Skip over NoInterp dimensions
+    (map(maybe_weightedindex, p, substitute_ruled(v, kind, g)), rest...)
+end
 # Termination
 slot_substitute(kind::Tuple{}, p, v, g) = ()
 
@@ -132,15 +134,14 @@ function _column(kind1::K, kind2::K, p, v, g, h) where {K<:Tuple}
     ss = substitute_ruled(v, kind1, h)
     (map(maybe_weightedindex, p, ss), _column(Base.tail(kind1), kind2, p, v, g, h)...)
 end
+_column(kind1::K, kind2::K, p, v, g, h) where {K<:Tuple{Int,Vararg}} = () # Skip over NoInterp dimensions
 function _column(kind1::Tuple, kind2::Tuple, p, v, g, h)
+    rest = _column(Base.tail(kind1), kind2, p, v, g, h)
+    kind1[1] isa Int && return rest # Skip over NoInterp dimensions
     ss = substitute_ruled(substitute_ruled(v, kind1, g), kind2, g)
-    (map(maybe_weightedindex, p, ss), _column(Base.tail(kind1), kind2, p, v, g, h)...)
+    (map(maybe_weightedindex, p, ss), rest...)
 end
 _column(::Tuple{}, ::Tuple, p, v, g, h) = ()
-# Skip over NoInterp dimensions
-slot_substitute(kind::Tuple{Int,Vararg{Any}}, p, v, g, h) = slot_substitute(Base.tail(kind), p, v, g, h)
-_column(kind1::Tuple{Int,Vararg{Any}}, kind2::Tuple, p, v, g, h) =
-    _column(Base.tail(kind1), kind2, p, v, g, h)
 
 weightedindex_parts(fs::F, itpflag::BSpline, ax, x) where F =
     weightedindex_parts(fs, degree(itpflag), ax, x)

test/issues/runtests.jl

@@ -156,7 +156,7 @@ using Interpolations, Test, ForwardDiff
     end
     @testset "issue 469" begin
         # We have different inference result on different version.
-        max_dim = VERSION < v"1.3" ? 3 : isdefined(Base, :Any32) ? 7 : 5
+        max_dim = isdefined(Base, :Any32) ? 7 : 5
         for dims in 3:max_dim
             A = zeros(Float64, ntuple(_ -> 5, dims))
             itp = interpolate(A, BSpline(Quadratic(Reflect(OnCell()))))

test/nointerp.jl

@@ -14,3 +14,15 @@
     # @test ae[0,1] === NaN
     # @test_throws InexactError ae(1.5,2)
 end
+
+@testset "Stability of mixtrue with NoInterp and Interp" begin
+    A = zeros(Float64, 5, 5, 5, 5, 5, 5, 5)
+    st = BSpline(Quadratic(Reflect(OnCell()))), NoInterp(),
+         BSpline(Linear()), NoInterp(),
+         BSpline(Quadratic()), NoInterp(),
+         BSpline(Quadratic(Reflect(OnCell())))
+    itp = interpolate(A, st)
+    @test (@inferred Interpolations.hessian(itp, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0)) == zeros(4,4)
+    @test (@inferred Interpolations.gradient(itp, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0)) == zeros(4)
+    @test (@inferred itp(1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0)) == 0
+end