Move executable and device to thunk from expr (EnzymeAD#855)

* Move executable and device to thunk from expr

* fix err

* fix err

* fixup

* Apply suggestions from code review

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: wsmoses

src/Compiler.jl

@@ -1391,14 +1391,11 @@ Generate Julia code to call the XLA executable.
 
 # Arguments
 
-- `exec`: The XLA executable to call.
 - `flatten_names`: A list of `Symbol`s representing the names of the flattened linear arguments.
 - `donated_args_mask`: A list of `UInt8`s representing whether the argument is donated.
 - `nresults`: The number of results to expect.
 """
 function codegen_xla_call(
-    exec,
-    device,
     flatten_names,
     donated_args_mask,
     nresults,
@@ -1420,7 +1417,7 @@ function codegen_xla_call(
             quote
                 GC.@preserve $(flatten_names...) begin
                     linearized_results = XLA.execute(
-                        $exec,
+                        thunk.exec,
                         ($(flatten_buffer_refs...),),
                         $(Tuple(donated_args_mask)),
                         Val($nresults),
@@ -1433,8 +1430,8 @@ function codegen_xla_call(
             quote
                 GC.@preserve $(flatten_names...) begin
                     linearized_results = XLA.execute_sharded(
-                        $exec,
-                        $(device),
+                        thunk.exec,
+                        thunk.device,
                         ($(flatten_buffer_refs...),),
                         $(Tuple(donated_args_mask)),
                         Val($nresults),
@@ -1600,8 +1597,6 @@ function compile(f, args; sync=false, kwargs...)
     )
 
     concretized_res_names, xla_call_code = codegen_xla_call(
-        exec,
-        device,
         flatten_arg_names,
         donated_args_mask,
         length(linear_results),
@@ -1653,15 +1648,23 @@ function compile(f, args; sync=false, kwargs...)
     end
 
     return register_thunk(
-        fname, Tuple{map(Core.Typeof, args)...}, body, f, mlir_fn_res.fnwrapped
+        fname,
+        Tuple{map(Core.Typeof, args)...},
+        body,
+        f,
+        mlir_fn_res.fnwrapped,
+        exec,
+        mlir_fn_res.is_sharded ? nothing : device,
     )
 end
 
 # inspired by RuntimeGeneratedFunction.jl
 const __thunk_body_cache = Dict{Symbol,Expr}()
 
-struct Thunk{FTy,tag,IsClosure,ArgTypes}
+struct Thunk{FTy,tag,IsClosure,ArgTypes,ExecTy,DeviceTy}
     f::FTy
+    exec::ExecTy
+    device::DeviceTy
 end
 
 struct MisMatchedThunkTypeError{ThunkTy,FoundTypes} <: Base.Exception end
@@ -1687,14 +1690,16 @@ function Base.showerror(
     )
 end
 
-@generated function (thunk::Thunk{FTy,tag,ArgTypes,IsClosure})(
+@generated function (thunk::Thunk{FTy,tag,ArgTypes,IsClosure,ExecTy,DeviceTy})(
     args...
-) where {FTy,tag,ArgTypes,IsClosure}
+) where {FTy,tag,ArgTypes,IsClosure,ExecTy,DeviceTy}
     FoundTypes = Tuple{args...}
     if ArgTypes != FoundTypes
         return quote
             throw(
-                $(MisMatchedThunkTypeError{Thunk{FTy,tag,ArgTypes,IsClosure},FoundTypes}())
+                $(MisMatchedThunkTypeError{
+                    Thunk{FTy,tag,ArgTypes,IsClosure,ExecTy,DeviceTy},FoundTypes
+                }()),
             )
         end
     end
@@ -1710,10 +1715,18 @@ end
 end
 
 function register_thunk(
-    tag::Symbol, @nospecialize(argtys::Type), body::Expr, @nospecialize(f), isclosure::Bool
+    tag::Symbol,
+    @nospecialize(argtys::Type),
+    body::Expr,
+    @nospecialize(f),
+    isclosure::Bool,
+    exec,
+    device,
 )
     __thunk_body_cache[tag] = body
-    return Thunk{Core.Typeof(f),tag,argtys,isclosure}(f)
+    return Thunk{Core.Typeof(f),tag,argtys,isclosure,Core.Typeof(exec),Core.Typeof(device)}(
+        f, exec, device
+    )
 end
 
 for cache_type in (:callcache, :sdycache)