Allow use of CPU RNG without scalar iteration. (#378)

Author: maleadt

src/host/random.jl

@@ -109,3 +109,9 @@ function Random.randn!(rng::RNG, A::AnyGPUArray{T}) where T <: Number
     end
     A
 end
+
+# allow use of CPU RNGs without scalar iteration
+Random.rand!(rng::AbstractRNG, A::AnyGPUArray) =
+    copyto!(A, rand(rng, eltype(A), size(A)...))
+Random.randn!(rng::AbstractRNG, A::AnyGPUArray) =
+    copyto!(A, randn(rng, eltype(A), size(A)...))

test/testsuite/random.jl

@@ -4,6 +4,7 @@
     else
         Random.default_rng()
     end
+    cpu_rng = Random.default_rng()
 
     @testset "rand" begin  # uniform
         for T in eltypes, d in (10, (10,10))
@@ -19,6 +20,10 @@
             Random.seed!(rng, 1)
             rand!(rng, B)
             @test all(Array(A) .== Array(B))
+
+            if rng != cpu_rng
+                rand!(cpu_rng, A)
+            end
         end
 
         A = AT{Bool}(undef, 1024)
@@ -46,6 +51,10 @@
             Random.seed!(rng, 1)
             randn!(rng, B)
             @test all(Array(A) .== Array(B))
+
+            if rng != cpu_rng
+                randn!(cpu_rng, A)
+            end
         end
     end
 end