fix: remove UnrolledUtilities dep

Project.toml

@@ -8,7 +8,6 @@ Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"
 Functors = "d9f16b24-f501-4c13-a1f2-28368ffc5196"
 Preferences = "21216c6a-2e73-6563-6e65-726566657250"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
-UnrolledUtilities = "0fe1646c-419e-43be-ac14-22321958931b"
 
 [weakdeps]
 AMDGPU = "21141c5a-9bdb-4563-92ae-f87d6854732e"
@@ -58,7 +57,6 @@ RecursiveArrayTools = "3.8"
 ReverseDiff = "1.15"
 SparseArrays = "1.10"
 Tracker = "0.2.34"
-UnrolledUtilities = "0.1.2"
 Zygote = "0.6.69"
 cuDNN = "1.3"
 julia = "1.10"

src/internal.jl

@@ -3,7 +3,6 @@ module Internal
 using Functors: fmap
 using Preferences: load_preference
 using Random: AbstractRNG
-using UnrolledUtilities: unrolled_mapreduce
 
 using ..MLDataDevices: MLDataDevices, AbstractDevice, CPUDevice, CUDADevice, AMDGPUDevice,
                        MetalDevice, oneAPIDevice, supported_gpu_backends, GPU_DEVICES,
@@ -150,6 +149,34 @@ for op in (:get_device, :get_device_type)
     end
 end
 
+function unrolled_mapreduce(f::F, op::O, itr) where {F, O}
+    return unrolled_mapreduce(f, op, itr, static_length(itr))
+end
+
+function unrolled_mapreduce(::F, ::O, _, ::Val{0}) where {F, O}
+    error("Cannot unroll over an empty iterator.")
+end
+
+unrolled_mapreduce(f::F, ::O, itr, ::Val{1}) where {F, O} = f(only(itr))
+
+@generated function unrolled_mapreduce(f::F, op::O, itr, ::Val{N}) where {F, O, N}
+    syms = [gensym("f_itr_$(i)") for i in 1:N]
+    op_syms = [gensym("op_$(i)") for i in 1:(N - 1)]
+    f_applied = [:($(syms[i]) = f(itr[$i])) for i in 1:N]
+    combine_expr = [:($(op_syms[1]) = op($(syms[1]), $(syms[2])))]
+    for i in 2:(N - 1)
+        push!(combine_expr, :($(op_syms[i]) = op($(op_syms[i - 1]), $(syms[i + 1]))))
+    end
+    return quote
+        $(Expr(:meta, :inline))
+        $(Expr(:inbounds, true))
+        $(Expr(:block, f_applied...))
+        $(Expr(:inbounds, :pop))
+        $(Expr(:block, combine_expr...))
+        return $(op_syms[end])
+    end
+end
+
 function unsafe_free_internal!(x::AbstractArray)
     unsafe_free_internal!(MLDataDevices.get_device_type(x), x)
     return
@@ -162,4 +189,6 @@ function unsafe_free!(x)
     return
 end
 
+static_length(t::Tuple) = Val(length(t))
+
 end