Make the VM accumulator look like an OCaml block.

We allocate an additional header so that the accumulator is not a naked
pointer. Indeed, it is contained in accumulator blocks which are scanned by
the GC as their tags is 0.

1 files changed, 6 insertions, 2 deletions

diff --git a/kernel/byterun/coq_memory.c b/kernel/byterun/coq_memory.c
index 9102af702..3cf5fc092 100644
--- a/kernel/byterun/coq_memory.c
+++ b/kernel/byterun/coq_memory.c
@@ -99,8 +99,12 @@ value init_coq_vm(value unit) /* ML */
     /* Initialing the interpreter */
     init_coq_interpreter();
     
-    /* Some predefined pointer code */
-    accumulate = (code_t) coq_stat_alloc(sizeof(opcode_t));
+    /* Some predefined pointer code.
+     * It is typically contained in accumlator blocks whose tag is 0 and thus
+     * scanned by the GC, so make it look like an OCaml block. */
+    value accu_block = (value) coq_stat_alloc(2 * sizeof(value));
+    Hd_hp (accu_block) = Make_header (1, Abstract_tag, Caml_black);        \
+    accumulate = (code_t) Val_hp(accu_block);
     *accumulate = VALINSTR(ACCUMULATE);
 
   /* Initialize GC */