Provide conservative marking interface.

GC now exports a function for marking something that might not
be an object, instead of a function for testing.
The previous way wasn't integrated with Valgrind properly,
and didn't observe the FREE flag.

* gc.c (gc_is_heap_obj): Function removed.
(mark_obj_maybe): New static function, with body consisting
of code moved from mark_mem_region.
(mark_mem_region): Moved code replaced by call to mark_obj_maybe.
(gc_conservative_mark): New function, wraps mark_obj_maybe.

* gc.h (gc_conservative_mark): Declared.
(gc_is_heap_obj): Declaration removed.

* parser.c (yy_tok_mark): Use gc_conservative_mark
instead of gc_is_heap_obj check and gc_mark.

3 files changed, 28 insertions, 29 deletions

diff --git a/gc.c b/gc.c
index c4ae9274..01931840 100644
--- a/gc.c
+++ b/gc.c
@@ -395,9 +395,26 @@ static int in_heap(val ptr)
   return 0;
 }
 
-int gc_is_heap_obj(union obj *ptr)
+static void mark_obj_maybe(val maybe_obj)
 {
-  return in_heap(ptr);
+#if HAVE_VALGRIND
+  VALGRIND_MAKE_MEM_DEFINED(&maybe_obj, sizeof maybe_obj);
+#endif
+  if (in_heap(maybe_obj)) {
+#if HAVE_VALGRIND
+    if (opt_vg_debug)
+      VALGRIND_MAKE_MEM_DEFINED(maybe_obj, SIZEOF_PTR);
+#endif
+    type_t t = maybe_obj->t.type;
+    if ((t & FREE) == 0) {
+      mark_obj(maybe_obj);
+    } else {
+#if HAVE_VALGRIND
+      if (opt_vg_debug)
+        VALGRIND_MAKE_MEM_NOACCESS(maybe_obj, sizeof *maybe_obj);
+#endif
+    }
+  }
 }
 
 static void mark_mem_region(val *low, val *high)
@@ -408,28 +425,8 @@ static void mark_mem_region(val *low, val *high)
     low = tmp;
   }
 
-  while (low < high) {
-    val maybe_obj = *low;
-#if HAVE_VALGRIND
-    VALGRIND_MAKE_MEM_DEFINED(&maybe_obj, sizeof maybe_obj);
-#endif
-    if (in_heap(maybe_obj)) {
-#if HAVE_VALGRIND
-      if (opt_vg_debug)
-        VALGRIND_MAKE_MEM_DEFINED(maybe_obj, SIZEOF_PTR);
-#endif
-      type_t t = maybe_obj->t.type;
-      if ((t & FREE) == 0) {
-        mark_obj(maybe_obj);
-      } else {
-#if HAVE_VALGRIND
-        if (opt_vg_debug)
-          VALGRIND_MAKE_MEM_NOACCESS(maybe_obj, sizeof *maybe_obj);
-#endif
-      }
-    }
-    low++;
-  }
+  for (; low < high; low++)
+    mark_obj_maybe(*low);
 }
 
 static void mark(mach_context_t *pmc, val *gc_stack_top)
@@ -718,6 +715,11 @@ void gc_mark(val obj)
   mark_obj(obj);
 }
 
+void gc_conservative_mark(val maybe_obj)
+{
+  mark_obj_maybe(maybe_obj);
+}
+
 int gc_is_reachable(val obj)
 {
   type_t t;
diff --git a/gc.h b/gc.h
index b24b470e..255171f5 100644
--- a/gc.h
+++ b/gc.h
@@ -33,8 +33,8 @@ val make_obj(void);
 void gc(void);
 int gc_state(int);
 void gc_mark(val);
+void gc_conservative_mark(val);
 int gc_is_reachable(val);
-int gc_is_heap_obj(union obj *ptr);
 
 #if CONFIG_GEN_GC
 val gc_set(loc, val);
diff --git a/parser.c b/parser.c
index c5342ae9..bb5205f2 100644
--- a/parser.c
+++ b/parser.c
@@ -54,10 +54,7 @@ static val stream_parser_hash;
 
 static void yy_tok_mark(struct yy_token *tok)
 {
-  obj_t *ptr = tok->yy_lval.val;
-
-  if (gc_is_heap_obj(ptr))
-    gc_mark(ptr);
+  gc_conservative_mark(tok->yy_lval.val);
 }
 
 static void parser_mark(val obj)