adding attempt to force inbounds at the kernel level

Co-authored-by: Valentin Churavy <vchuravy@users.noreply.github.com>

src/KernelAbstractions.jl

@@ -53,28 +53,44 @@ synchronize(backend)
 ```
 """
 macro kernel(expr)
-    __kernel(expr, #=generate_cpu=#true)
+    __kernel(expr, #=generate_cpu=#true, #=force_inbounds=#false)
 end
 
 """
-    @kernel cpu=false function f(args) end
+    @kernel config function f(args) end
 
-Disable code-generation of the CPU function. This relaxes semantics such that
-KernelAbstractions primitives can be used in non-kernel functions.
+This allows for two different configurations:
+
+1. `cpu={true, false}`: Disables code-generation of the CPU function. This relaxes semantics such that KernelAbstractions primitives can be used in non-kernel functions.
+2. `inbounds={false, true}`: Enables a forced `@inbounds` macro around the function definition in the case the user is using too many `@inbounds` already in their kernel. Note that this can lead to incorrect results, crashes, etc and is fundamentally unsafe. Be careful!
 
 - [`@context`](@ref)
 
 !!! warn
     This is an experimental feature.
 """
-macro kernel(config, expr)
-    if config isa Expr && config.head == :(=) &&
-        config.args[1] == :cpu && config.args[2] isa Bool
-        generate_cpu = config.args[2]
+macro kernel(ex...)
+    if length(ex) == 1
+        __kernel(ex[1], true, false)
     else
-        error("Configuration should be of form `cpu=false` got $config")
+        generate_cpu = true
+        force_inbounds = false
+        for i = 1:length(ex)-1
+            if ex[i] isa Expr && ex[i].head == :(=) &&
+                ex[i].args[1] == :cpu && ex[i].args[2] isa Bool
+                generate_cpu = ex[i].args[2]
+            elseif ex[i] isa Expr && ex[i].head == :(=) &&
+                ex[i].args[1] == :inbounds && ex[i].args[2] isa Bool
+                force_inbounds = ex[i].args[2]
+            else
+                error("Configuration should be of form:\n"*
+                      "* `cpu=true`\n"*
+                      "* `inbounds=false`\n"*
+                      "got `", ex[i], "`")
+            end
+        end
+        __kernel(ex[end], generate_cpu, force_inbounds)
     end
-    __kernel(expr, generate_cpu)
 end
 
 """

src/macros.jl

@@ -10,10 +10,16 @@ function find_return(stmt)
 end
 
 # XXX: Proper errors
-function __kernel(expr, generate_cpu=true)
+function __kernel(expr, generate_cpu=true, force_inbounds=false)
     def = splitdef(expr)
     name = def[:name]
     args = def[:args]
+    if force_inbounds
+        body_qt = quote
+            @inbounds $(def[:body])
+        end
+        def[:body] = body_qt
+    end
 
     find_return(expr) && error("Return statement not permitted in a kernel function $name")
 

test/runtests.jl

@@ -21,6 +21,22 @@ kern_static(CPU(static=true), (1,))(A, ndrange=length(A))
 end
 @test_throws ErrorException("This kernel is unavailable for backend CPU") my_no_cpu_kernel(CPU())
 
+# testing multiple configurations at the same time
+@kernel cpu=false inbounds=false function my_no_cpu_kernel2(a)
+end
+@test_throws ErrorException("This kernel is unavailable for backend CPU") my_no_cpu_kernel2(CPU())
+
+if Base.JLOptions().check_bounds == 0 || Base.JLOptions().check_bounds == 1
+    # testing bounds errors
+    @kernel inbounds=false my_bounded_kernel(a) = a[1]
+    @test_throws BoundsError(Int64[],(1,)) my_bounded_kernel(CPU())(Int[], ndrange=1)
+end
+
+if Base.JLOptions().check_bounds == 0 || Base.JLOptions().check_bounds == 2
+    @kernel inbounds=true my_inbounds_kernel(a) = a[1]
+    @test nothing == my_inbounds_kernel(CPU())(Int[], ndrange=1)
+end
+
 struct NewBackend <: KernelAbstractions.GPU end
 @testset "Default host implementation" begin
     backend = NewBackend()