bytecode/native changes

Author: ncik-roberts

ocaml/runtime/obj.c

@@ -331,6 +331,18 @@ struct queue_chunk {
   value entries[ENTRIES_PER_QUEUE_CHUNK];
 };
 
-CAMLprim value caml_reserved (value v) {
+/* Return 0 for uniform blocks and 1+n for a mixed block with scannable prefix
+   len n.
+ */
+CAMLprim value caml_succ_scannable_prefix_len (value v) {
+#ifdef NATIVE_CODE
   return Val_long(Reserved_val(v));
+#else
+  reserved_t reserved = Reserved_val(v);
+  if (reserved == Faux_mixed_block_sentinel) {
+    return Val_long(Scannable_wosize_val(v) + 1);
+  } else {
+    return Val_long(0);
+  }
+#endif /* NATIVE_CODE */
 }

ocaml/runtime4/obj.c

@@ -366,6 +366,18 @@ struct queue_chunk {
   value entries[ENTRIES_PER_QUEUE_CHUNK];
 };
 
-CAMLprim value caml_reserved (value v) {
+/* Return 0 for uniform blocks and 1+n for a mixed block with scannable prefix
+   len n.
+*/
+CAMLprim value caml_succ_scannable_prefix_len (value v) {
+#ifdef NATIVE_CODE
   return Val_long(Reserved_val(v));
+#else
+  reserved_t reserved = Reserved_val(v);
+  if (reserved == Faux_mixed_block_sentinel) {
+    return Val_long(Scannable_wosize_val(v) + 1);
+  } else {
+    return Val_long(0);
+  }
+#endif /* NATIVE_CODE */
 }

ocaml/stdlib/obj.ml

@@ -201,11 +201,14 @@ end
 module Uniform_or_mixed = struct
   type obj_t = t
 
-  (* The raw reserved header bits, which is either 0 if the block is uniform or
-     n+1 if the block has a scannable prefix of length n. *)
+  (* In native code, the raw reserved header bits, which is either 0 if the
+     block is uniform or n+1 if the block has a scannable prefix of length n.
+     In bytecode, this will be size+1 for "faux mixed blocks" representing
+     mixed records, and otherwise 0.
+   *)
   type t = int
 
-  external of_block : obj_t -> t = "caml_reserved" [@@noalloc]
+  external of_block : obj_t -> t = "caml_succ_scannable_prefix_len" [@@noalloc]
 
   type repr =
     | Uniform

ocaml/stdlib/obj.mli

@@ -192,7 +192,7 @@ module Uniform_or_mixed : sig
 
   val repr : t -> repr
 
-  external of_block : obj_t -> t = "caml_reserved" [@@noalloc]
+  external of_block : obj_t -> t = "caml_succ_scannable_prefix_len" [@@noalloc]
 
   val is_uniform : t -> bool
   (** Equivalent to [repr] returning [Uniform]. *)

ocaml/testsuite/tests/lib-obj/uniform_or_mixed.bytecode.reference

@@ -0,0 +1,7 @@
+t_uniform1: uniform
+t_uniform2.0: uniform
+t_uniform2.1: uniform
+t_uniform3: uniform
+t_mixed0: mixed (scannable_prefix_len = 1)
+t_mixed1: mixed (scannable_prefix_len = 2)
+t_mixed2: mixed (scannable_prefix_len = 3)

ocaml/testsuite/tests/lib-obj/uniform_or_mixed.ml

@@ -1,6 +1,19 @@
 (* TEST
-  flags="-extension layouts_beta";
-  native;
+   flags = "-extension layouts_beta";
+   {
+     reference = "${test_source_directory}/uniform_or_mixed.native.reference";
+     compiler_reference2 = "${test_source_directory}/uniform_or_mixed.compiler.reference";
+     native;
+   }{
+     reference = "${test_source_directory}/uniform_or_mixed.bytecode.reference";
+     compiler_reference2 = "${test_source_directory}/uniform_or_mixed.compiler.reference";
+     bytecode;
+   }
+*)
+
+(* Bytecode and native code have slightly different outputs for the scannable prefix
+   of mixed records. The fields of mixed records must be scanned in bytecode.
+   (They are "faux mixed blocks".)
 *)
 
 type t_uniform1 = { x : int }