cleanup broadcast implementation

Author: vchuravy

src/broadcast.jl

@@ -1,33 +1,13 @@
 using Base.Broadcast
-import Base.Broadcast: Broadcasted
 
-import Base.Broadcast: BroadcastStyle, AbstractArrayStyle, Broadcasted, broadcast_axes
-import Base.Broadcast: DefaultArrayStyle, materialize!, flatten, ArrayStyle, combine_styles
+import Base.Broadcast: BroadcastStyle, Broadcasted, ArrayStyle
 
 BroadcastStyle(::Type{T}) where T <: GPUArray = ArrayStyle{T}()
-BroadcastStyle(::Type{Any}, ::Type{T}) where T <: GPUArray = ArrayStyle{T}()
-BroadcastStyle(::Type{T}, ::Type{Any}) where T <: GPUArray = ArrayStyle{T}()
-BroadcastStyle(::Type{T1}, ::Type{T2}) where {T1 <: GPUArray, T2 <: GPUArray} = ArrayStyle{T}()
 
-const GPUBroadcast = Broadcasted{<: ArrayStyle{<: GPUArray}}
-
-function Base.similar(bc::Broadcasted{ArrayStyle{GPU}}, ::Type{ElType}) where {GPU <: GPUArray, ElType}
+function Base.similar(bc::Broadcasted{<:ArrayStyle{GPU}}, ::Type{ElType}) where {GPU <: GPUArray, ElType}
     similar(GPU, ElType, axes(bc))
 end
 
-@inline function Base.copyto!(dest::GPUArray, bc::GPUBroadcast)
-    axes(dest) == axes(bc) || Broadcast.throwdm(axes(dest), axes(bc))
-    bc′ = Broadcast.preprocess(dest, bc)
-    gpu_call(dest, (dest, bc′)) do state, dest, bc′
-        let I = CartesianIndex(@cartesianidx(dest))
-            @inbounds dest[I] = bc′[I]
-        end
-    end
-
-    return dest
-end
-
-# the same?
 @inline function Base.copyto!(dest::GPUArray, bc::Broadcasted{Nothing})
     axes(dest) == axes(bc) || Broadcast.throwdm(axes(dest), axes(bc))
     bc′ = Broadcast.preprocess(dest, bc)