Add query function for if we are executing on a GPU

Project.toml

@@ -1,7 +1,7 @@
 name = "KernelAbstractions"
 uuid = "63c18a36-062a-441e-b654-da1e3ab1ce7c"
 authors = ["Valentin Churavy <v.churavy@gmail.com> and contributors"]
-version = "0.9.8"
+version = "0.10.0"
 
 [deps]
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"

src/KernelAbstractions.jl

@@ -535,6 +535,14 @@ function priority!(::Backend, prio::Symbol)
     return nothing
 end
 
+
+"""
+    ongpu()
+
+Returns if this kernel is currently executing on a GPU.
+"""
+function ongpu end
+
 include("nditeration.jl")
 using .NDIteration
 import .NDIteration: get

src/cpu.jl

@@ -158,6 +158,8 @@ end
     end
 end
 
+ongpu() = false
+
 ###
 # CPU implementation of shared memory
 ###