[EnzymeTestUtils] Fix batch duplicated return and aliasing return/arg…

…ument (#1079)

* Fix batch duplicated return

* Handle aliasing input and outputs

lib/EnzymeTestUtils/Project.toml

@@ -1,7 +1,7 @@
 name = "EnzymeTestUtils"
 uuid = "12d8515a-0907-448a-8884-5fe00fdf1c5a"
 authors = ["Seth Axen <[email protected]>", "William Moses <[email protected]>", "Valentin Churavy <[email protected]>"]
-version = "0.1.0"
+version = "0.1.1"
 
 [deps]
 ConstructionBase = "187b0558-2788-49d3-abe0-74a17ed4e7c9"

lib/EnzymeTestUtils/src/finite_difference_calls.jl

@@ -156,7 +156,20 @@ function _wrap_reverse_function(f, xs, ignores)
         @assert j == length(sigargs) + 1
         @assert length(callargs) == length(xs)
         @assert length(retargs) == count(!, ignores)
-        return (deepcopy(f)(callargs...), retargs...)
+
+        # if an arg and a return alias, do not consider the contribution from the arg as returned here,
+        # it will already be taken into account. This is implemented using the deepcopy_internal, which
+        # will add all objects inside the return into the dict `zeros`.
+        zeros = IdDict()
+        origRet = Base.deepcopy_internal(deepcopy(f)(callargs...), zeros)
+
+        # we will now explicitly zero all objects returned, and replace any of the args with this
+        # zero, if the input and output alias.
+        for k in keys(zeros)
+            zeros[k] = zero_tangent(k)
+        end
+
+        return (origRet, Base.deepcopy_internal(retargs, zeros)...)
     end
     return fnew
 end

lib/EnzymeTestUtils/src/test_reverse.jl

@@ -94,7 +94,13 @@ function test_reverse(
         else
             # if there's a shadow result, then we need to set it to our random adjoint
             if !(shadow_result === nothing)
-                map_fields_recursive(copyto!, shadow_result, ȳ)
+                if !_any_batch_duplicated(map(typeof, activities)...)
+                    map_fields_recursive(copyto!, shadow_result, ȳ)
+                else
+                    for (sr, dy) in zip(shadow_result, ȳ)
+                        map_fields_recursive(copyto!, sr, dy)
+                    end
+                end
             end
             dx_ad = only(reverse(c_act, activities..., tape))
         end