Defining neutral_element for xor (⊻) and fix it for and (&). (#602)

* Defining zero(T) as the neutral element for xor.

* Modify neutral_element for & to ~zero(T). Included logical operators in the test suite.

Author: Hamiltonian-Action

src/host/mapreduce.jl

@@ -15,9 +15,10 @@ neutral_element(op, T) =
              Please pass it as an explicit argument to `GPUArrays.mapreducedim!`,
              or register it globally by defining `GPUArrays.neutral_element(::typeof($op), T)`.""")
 neutral_element(::typeof(Base.:(|)), T) = zero(T)
+neutral_element(::typeof(Base.:(⊻)), T) = zero(T)
+neutral_element(::typeof(Base.:(&)), T) = ~zero(T)
 neutral_element(::typeof(Base.:(+)), T) = zero(T)
 neutral_element(::typeof(Base.add_sum), T) = zero(T)
-neutral_element(::typeof(Base.:(&)), T) = one(T)
 neutral_element(::typeof(Base.:(*)), T) = one(T)
 neutral_element(::typeof(Base.mul_prod), T) = one(T)
 neutral_element(::typeof(Base.min), T) = typemax(T)

test/testsuite/reductions.jl

@@ -66,6 +66,11 @@ end
                           (0,)=>[1]]
             @test compare(A->reduce(+, A; dims=dims, init=zero(ET)), AT, rand(range, sz))
             @test compare(A->reduce(*, A; dims=dims, init=one(ET)), AT, rand(range, sz))
+            if ET <: Integer
+                @test compare(A->reduce(&, A; dims=dims, init=~zero(ET)), AT, rand(range, sz))
+                @test compare(A->reduce(|, A; dims=dims, init=zero(ET)), AT, rand(range, sz))
+                @test compare(A->reduce(⊻, A; dims=dims, init=zero(ET)), AT, rand(range, sz))
+            end
         end
     end
 end