Cc_backend fixes: setup globals for compile_batch; merge buffer acc…

…esses

arrayjit/lib/cc_backend.ml

@@ -348,6 +348,11 @@ let compile_main ~traced_store info ppf llc : unit =
           ^ "v" ^ Int.to_string id.scope_id
         in
         (v ^ "{=%f}", [ `Value v ])
+    | Get_global (Ops.Merge_buffer { source_node_id }, Some idcs) ->
+        let tn = Option.value_exn @@ Tn.find ~id:source_node_id in
+        let node = get_node tn in
+        let v = sprintf "@[<2>merge_buffer[%s@;<0 -2>]@]" (array_offset_to_string (idcs, node.dims)) in
+        ("merge_buffer[%u]{=%f}", [ `Accessor (idcs, node.dims); `Value v ])
     | Get_global _ -> failwith "Exec_as_cuda: Get_global / FFI NOT IMPLEMENTED YET"
     | Get (tn, idcs) ->
         let ident = info.get_ident tn in
@@ -371,12 +376,18 @@ let compile_main ~traced_store info ppf llc : unit =
   in
   pp_ll ppf llc
 
-let%track_sexp compile_globals ~get_ident ppf info =
+let%track_sexp compile_globals ~get_ident ppf infos =
   let open Stdlib.Format in
-  fprintf ppf {|@[<v 0>#include "stdio.h"@,#include "stdlib.h"@,/* Global declarations. */@,|};
-  Hash_set.to_list info.used_tensors
+  fprintf ppf {|@[<v 0>#include <stdio.h>@,#include <stdlib.h>@,/* Global declarations. */@,|};
+  let infos = Array.filter_opt infos in
+  let used =
+    Array.map infos ~f:(fun i -> i.used_tensors)
+    |> Array.fold ~init:(Hash_set.create (module Tn)) ~f:Hash_set.union
+  in
+  let get_node tn = Array.find_map infos ~f:(fun info -> Hashtbl.find info.nodes tn) in
+  Hash_set.to_list used
   |> List.iter ~f:(fun tn ->
-         let node = Hashtbl.find_exn info.nodes tn in
+         let node = Option.value_exn @@ get_node tn in
          match node.mem with
          | Constant_from_host ->
              let nd = Option.value_exn @@ Lazy.force tn.Tn.array in
@@ -404,8 +415,10 @@ let%track_sexp compile_proc ~name info ppf idx_params Low_level.{ traced_store;
     if Utils.settings.debug_log_from_routines then [ ("const char* log_file_name", Log_file_name) ] else []
   in
   let merge_param =
-    Option.(to_list @@ map merge_node ~f:(fun tn ->
-        ("const " ^ Ops.cuda_typ_of_prec tn.prec ^ " *merge_buffer", Merge_buffer)))
+    Option.(
+      to_list
+      @@ map merge_node ~f:(fun tn ->
+             ("const " ^ Ops.cuda_typ_of_prec tn.prec ^ " *merge_buffer", Merge_buffer)))
   in
   let params = log_file @ merge_param @ idx_params @ params in
   fprintf ppf "@[<v 2>@[<hv 4>void %s(@,@[<hov 0>%a@]@;<0 -4>)@] {@ " name
@@ -475,7 +488,7 @@ let%track_sexp compile ~(name : string) ~opt_ctx_arrays bindings (lowered : Low_
   prepare_nodes info ctx_nodes lowered;
   let pp_file = Utils.pp_file ~base_name:name ~extension:".c" in
   let base_name = Filename_base.chop_extension pp_file.f_name in
-  compile_globals ~get_ident:info.get_ident pp_file.ppf info;
+  compile_globals ~get_ident:info.get_ident pp_file.ppf [| Some info |];
   let params = compile_proc ~name info pp_file.ppf idx_params lowered in
   pp_file.finalize ();
   let log_fname = base_name ^ ".log" in
@@ -528,6 +541,7 @@ let%track_sexp compile_batch ~names ~opt_ctx_arrays bindings (lowereds : Low_lev
       @@ common_prefix (Array.to_list @@ Array.concat_map ~f:Option.to_array names))
   in
   let pp_file = Utils.pp_file ~base_name ~extension:".c" in
+  compile_globals ~get_ident pp_file.ppf infos;
   let params =
     Array.mapi lowereds ~f:(fun i lowered ->
         Option.map2 names.(i) infos.(i) ~f:(fun name info ->