feat: specialize dispatches for faster concrete array generation (#213)

* feat: specialize dispatches for faster concrete array generation

* chore: apply formatting suggestion

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: avik-pal

src/Tracing.jl

@@ -563,7 +563,29 @@ end
 
 @inline function to_rarray(@nospecialize(x); track_numbers::Union{Bool,Tuple}=())
     track_numbers isa Bool && (track_numbers = track_numbers ? (Number,) : ())
+    return to_rarray_internal(x, track_numbers)
+end
+
+@inline function to_rarray_internal(@nospecialize(x), track_numbers::Tuple)
     return make_tracer(OrderedIdDict(), x, (), Reactant.ArrayToConcrete; track_numbers)
 end
 
-to_rarray(x::ReactantPrimitive) = ConcreteRArray(x)
+function to_rarray_internal(@nospecialize(::TracedRArray), ::Tuple)
+    return error("Cannot convert TracedRArray to ConcreteRArray")
+end
+@inline to_rarray_internal(@nospecialize(x::ConcreteRArray), ::Tuple) = x
+@inline function to_rarray_internal(
+    @nospecialize(x::AbstractArray{<:ReactantPrimitive}), ::Tuple
+)
+    return ConcreteRArray(x)
+end
+
+@inline to_rarray_internal(@nospecialize(x::ConcreteRNumber), ::Tuple) = x
+@inline function to_rarray_internal(
+    @nospecialize(x::ReactantPrimitive), track_numbers::Tuple
+)
+    for T in track_numbers
+        typeof(x) <: T && return ConcreteRNumber(x)
+    end
+    return x
+end

test/tracing.jl

@@ -100,4 +100,18 @@ using Test
             end
         end
     end
+
+    @testset "specialized dispatches" begin
+        @test @inferred Union{Float64,ConcreteRArray{Float64}} Reactant.to_rarray(
+            1.0; track_numbers=(Number,)
+        ) isa ConcreteRNumber
+        @test @inferred Reactant.to_rarray(1.0) isa Float64
+        @test @inferred Reactant.to_rarray(rand(3)) isa ConcreteRArray
+
+        x_ra = Reactant.to_rarray(rand(3))
+        @test @inferred Reactant.to_rarray(x_ra) isa ConcreteRArray
+
+        x_ra = Reactant.to_rarray(1.0; track_numbers=(Number,))
+        @test @inferred Reactant.to_rarray(x_ra) isa ConcreteRNumber
+    end
 end