4 files changed, 39 insertions, 15 deletions

diff --git a/eval.cpp b/eval.cpp
index e21ae7b..7370187 100644
--- a/eval.cpp
+++ b/eval.cpp
@@ -110,13 +110,11 @@ inline bool make_exec(Pair *ptr) {
 }
 
 inline void push(Pair * &pc, FrameObj ** &top_ptr, Environment *envt) {
-    gc.attach(pc);
 //    if (pc->car == NULL)
  //       puts("oops");
     if (pc->car->is_simple_obj())           // Not an opt invocation
     {
-        *top_ptr = envt->get_obj(pc->car);  // Objectify the symbol
-        top_ptr++;
+        *top_ptr++ = gc.attach(envt->get_obj(pc->car));  // Objectify the symbol
         pc = pc->next;                      // Move to the next instruction
 //        if (pc == empty_list)
 //        puts("oops");
@@ -152,6 +150,7 @@ EvalObj *Evaluator::run_expr(Pair *prog) {
     Continuation *cont = NULL;
     // envt is this->envt
     push(pc, top_ptr, envt);
+    gc.attach(prog);
 
     while((*eval_stack)->is_ret_addr())
     {
@@ -163,7 +162,11 @@ EvalObj *Evaluator::run_expr(Pair *prog) {
         {
             Pair *args = empty_list;
             while (!(*(--top_ptr))->is_ret_addr())
-                args = new Pair(static_cast<EvalObj*>(*top_ptr), args);
+            {
+                EvalObj* obj = static_cast<EvalObj*>(*top_ptr);
+                gc.expose(obj);
+                args = new Pair(obj, args);
+            }
             //< static_cast because the while condition
             RetAddr *ret_addr = static_cast<RetAddr*>(*top_ptr);
             if (!ret_addr->addr)
diff --git a/gc.cpp b/gc.cpp
index a5fdc48..5aed8b8 100644
--- a/gc.cpp
+++ b/gc.cpp
@@ -13,39 +13,46 @@ GarbageCollector::GarbageCollector() {
     mapping.clear();
     pend_cnt = 0;
     pending_list = NULL;
+    collecting = false;
 }
 
 GarbageCollector::PendingEntry::PendingEntry(
         EvalObj *_obj, PendingEntry *_next) : obj(_obj), next(_next) {}
 
 
-void GarbageCollector::expose(EvalObj *ptr, bool delay) {
+void GarbageCollector::expose(EvalObj *ptr) {
     bool flag = mapping.count(ptr);
     if (flag)
     {
-        if (!--mapping[ptr] && !delay)
+#ifdef GC_DEBUG
+        fprintf(stderr, "GC: 0x%llx exposed. count = %lu \"%s\"\n", 
+            (ull)ptr, mapping[ptr], ptr->ext_repr().c_str());
+#endif
+        if (!--mapping[ptr] && collecting)
         {
 #ifdef GC_DEBUG
             fprintf(stderr, "GC: 0x%llx pending. \n", (ull)ptr);
 #endif
             pending_list = new PendingEntry(ptr, pending_list);
-            if (++pend_cnt == GC_QUEUE_SIZE >> 1)
-                force();    // the gc queue may overflow
-        }
+        } 
     }
 }
 
 void GarbageCollector::force() {
     EvalObj **l = gcq, **r = l;
-    for (PendingEntry *p = pending_list, *np; p; p = np)
+/*    for (PendingEntry *p = pending_list, *np; p; p = np)
     {
         np = p->next;
         *r++ = p->obj;
         delete p;
     }   // fetch the pending pointers in the list
     // clear the list
-    pending_list = NULL;
+    pending_list = NULL; */
+    for (EvalObj2Int::iterator it = mapping.begin(); 
+            it != mapping.end(); it++)
+        if (it->second == 0) *r++ = it->first;
 
+    collecting = true;
 #ifdef GC_DEBUG
     size_t cnt = 0;
     fprintf(stderr, "GC: Forcing the clear process...\n");
@@ -57,6 +64,7 @@ void GarbageCollector::force() {
         cnt++;
 #endif
         delete *l;
+        mapping.erase(*l);
         // maybe it's a complex structure, 
         // so that more pointers are reported
         for (PendingEntry *p = pending_list, *np; p; p = np)
@@ -70,8 +78,14 @@ void GarbageCollector::force() {
         pending_list = NULL;
     }
 #ifdef GC_DEBUG
-    fprintf(stderr, "GC: Forced clear, %lu objects are freed\n", cnt);
+    fprintf(stderr, "GC: Forced clear, %lu objects are freed, "
+            "%lu remains\n", cnt, mapping.size());
+/*    for (EvalObj2Int::iterator it = mapping.begin();
+            it != mapping.end(); it++)
+        fprintf(stderr, "%llx => %lu\n", (ull)it->first, it->second);
+        */
 #endif
+    collecting = false;
 }
 
 EvalObj *GarbageCollector::attach(EvalObj *ptr) {
diff --git a/gc.h b/gc.h
index c017156..8380210 100644
--- a/gc.h
+++ b/gc.h
@@ -19,11 +19,12 @@ class GarbageCollector {
     EvalObj2Int mapping;
     size_t pend_cnt;
     PendingEntry *pending_list;
+    bool collecting;
 
     public:
     GarbageCollector();
     void force();
-    void expose(EvalObj *ptr, bool delay = false);
+    void expose(EvalObj *ptr);
     EvalObj *attach(EvalObj *ptr);
 };
 
diff --git a/types.cpp b/types.cpp
index 1548805..84106df 100644
--- a/types.cpp
+++ b/types.cpp
@@ -90,9 +90,13 @@ Pair *ProcObj::call(Pair *args, Environment * &genvt,
 
     genvt = _envt;
     cont = _cont;
-    *top_ptr++ = new RetAddr(NULL);   // Mark the entrance of a cont
+
+    gc.expose(static_cast<EvalObj*>(*(top_ptr + 1)));          // release opt obj
+    delete *top_ptr;                    // release ret addr
+
+    *top_ptr++ = new RetAddr(NULL);     // Mark the entrance of a cont
     gc.expose(args);
-    return body;                    // Move pc to the proc entry point
+    return body;                        // Move pc to the proc entry point
 }
 
 ReprCons *ProcObj::get_repr_cons() {
@@ -222,6 +226,8 @@ BuiltinProcObj::BuiltinProcObj(BuiltinProc f, string _name) :
             Continuation * &cont, FrameObj ** &top_ptr) {
 
         Pair *ret_addr = static_cast<RetAddr*>(*top_ptr)->addr;
+        gc.expose(static_cast<EvalObj*>(*(top_ptr + 1)));
+        delete *top_ptr;
         *top_ptr++ = handler(TO_PAIR(args->cdr), name);
         gc.expose(args);
         return ret_addr->next;          // Move to the next instruction