6 files changed, 20 insertions, 17 deletions

diff --git a/gc.c b/gc.c
index 18c65915..15384794 100644
--- a/gc.c
+++ b/gc.c
@@ -820,25 +820,27 @@ int gc_is_reachable(val obj)
 
 #if CONFIG_GEN_GC
 
-val gc_set(loc lo, val obj)
+void gc_assign_check(val p, val c)
 {
-  val *ptr = valptr(lo);
-
-  if (lo.obj && is_ptr(obj) && lo.obj->t.gen == 1 && obj->t.gen == 0 && !full_gc) {
+  if (p && is_ptr(c) && p->t.gen == 1 && c->t.gen == 0 && !full_gc) {
     if (checkobj_idx < CHECKOBJ_VEC_SIZE) {
-      obj->t.gen = -1;
-      checkobj[checkobj_idx++] = obj;
+      c->t.gen = -1;
+      checkobj[checkobj_idx++] = c;
     } else if (gc_enabled) {
       gc();
-      /* obj can't be in gen 0 because there are no baby objects after gc */
+      /* c can't be in gen 0 because there are no baby objects after gc */
     } else {
       /* We have no space to in checkobj record this backreference, and gc is
          not available to promote obj to gen 1. We must schedule a full gc. */
       full_gc = 1;
     }
   }
+}
 
-  *ptr = obj;
+val gc_set(loc lo, val obj)
+{
+  gc_assign_check(lo.obj, obj);
+  *valptr(lo) = obj;
   return obj;
 }
 
@@ -862,7 +864,6 @@ val gc_mutated(val obj)
   return obj;
 }
 
-
 val gc_push(val obj, loc plist)
 {
   return gc_set(plist, cons(obj, deref(plist)));
diff --git a/gc.h b/gc.h
index 4c3bc042..7025fa59 100644
--- a/gc.h
+++ b/gc.h
@@ -43,6 +43,7 @@ val gc_call_finalizers(val obj);
 #if CONFIG_GEN_GC
 val gc_set(loc, val);
 val gc_push(val, loc);
+void gc_assign_check(val p, val c);
 val gc_mutated(val);
 extern int full_gc;
 #endif
diff --git a/lib.c b/lib.c
index 761646ff..52320dfe 100644
--- a/lib.c
+++ b/lib.c
@@ -2857,9 +2857,8 @@ val cons(val car, val cdr)
   if (recycled_conses) {
     obj = recycled_conses;
     recycled_conses = recycled_conses->c.cdr;
-#if CONFIG_GEN_GC
-    gc_mutated(obj);
-#endif
+    setcheck(obj, car);
+    setcheck(obj, cdr);
   } else {
     obj = make_obj();
     obj->c.type = CONS;
diff --git a/lib.h b/lib.h
index 718e2c86..ff432bea 100644
--- a/lib.h
+++ b/lib.h
@@ -337,6 +337,7 @@ INLINE loc mkloc_fun(val *ptr, val obj)
 #define deref(lo) (*(lo).ptr)
 #define valptr(lo) ((lo).ptr)
 #define set(lo, val) (gc_set(lo, val))
+#define setcheck(tgt, src) (gc_assign_check(tgt, src))
 #define mut(obj) (gc_mutated(obj));
 #define mpush(val, lo) (gc_push(val, lo))
 #else
@@ -348,6 +349,7 @@ typedef val *loc;
 #define deref(lo) (*(lo))
 #define valptr(lo) (lo)
 #define set(lo, val) (*(lo) = (val))
+#define setcheck(tgt, src) ((void) 0)
 #define mut(obj) ((void) (obj))
 #define mpush(val, lo) (push(val, lo))
 #endif
diff --git a/struct.c b/struct.c
index 2acc0b65..94f53b6b 100644
--- a/struct.c
+++ b/struct.c
@@ -697,7 +697,7 @@ val clear_struct(val strct, val value)
   for (i = 0; i < st->nslots; i++)
     si->slot[i] = clear_val;
 
-  mut(strct);
+  setcheck(strct, clear_val);
 
   return strct;
 }
diff --git a/vm.c b/vm.c
index 26d73304..774124a4 100644
--- a/vm.c
+++ b/vm.c
@@ -271,7 +271,7 @@ static val vm_make_closure(struct vm *vm, int frsz)
         cdi->mem = heap_vec->v.vec;
         memcpy(cdi->mem, mem, size);
         memset(mem, 0, size);
-        mut(closure);
+        setcheck(closure, heap_vec);
         *sdi = *cdi;
         break;
       }
@@ -357,7 +357,7 @@ INLINE void vm_set(struct vm_env *dspl, unsigned ref, val newval)
   env->mem[i] = newval;
 
   if (is_ptr(env->vec))
-    mut(env->vec);
+    setcheck(env->vec, newval);
 }
 
 INLINE void vm_sm_set(struct vm_env *dspl, unsigned ref, val newval)
@@ -372,7 +372,7 @@ INLINE void vm_sm_set(struct vm_env *dspl, unsigned ref, val newval)
   env->mem[i] = newval;
 
   if (is_ptr(env->vec))
-    mut(env->vec);
+    setcheck(env->vec, newval);
 }
 
 
@@ -505,7 +505,7 @@ static loc vm_stab(struct vm *vm, unsigned fun,
     eval_error(vd->bytecode,
                lit("~a ~s is not defined"), kind_str,
                vecref(vd->symvec, num(fun)), nao);
-  gc_mutated(vd->self);
+  setcheck(vd->self, fe->bind);
   return (fe->bindloc = cdr_l(fe->bind));
 }