Fixed bug in free and some small testing additions

src/GC/lib/heap.cpp

@@ -133,18 +133,27 @@ namespace GC {
         heap->m_freed_chunks.pop_back();
         delete chunk;
       }
-    } else {
+    } 
+    else if (heap->m_freed_chunks.size()) {
       free_overlap(heap);
     }
+    // No freed chunks, nothing to free
+    else {
+      return;
+    } 
   }
 
   void Heap::free_overlap(Heap *heap) {
     std::vector<Chunk *> filtered;
     size_t i = 0;
     filtered.push_back(heap->m_freed_chunks.at(i++));
+    //cout << filtered.back()->start << endl;
     for (; i < heap->m_freed_chunks.size(); i++) {
       auto prev = filtered.back();
+      cout << "Previous start:\t" << prev->start << endl;
+      cout << "Previous end:\t" << prev->start + prev->size << endl;
       auto next = heap->m_freed_chunks.at(i);
+      cout << "Next start:\t" << next->start << endl;
       if (next->start > (prev->start + prev->size)) {
         filtered.push_back(next);
       }
@@ -167,7 +176,7 @@ namespace GC {
 
     // get the frame adress, whwere local variables and saved registers are located
     auto stack_start = reinterpret_cast<uintptr_t *>(__builtin_frame_address(0));
-    cout << "Stack start:\t" << stack_start << endl;
+    cout << "Stack start in collect:\t" << stack_start << endl;
     uintptr_t *stack_end;
 
     if (heap->m_stack_end != nullptr)
@@ -175,7 +184,7 @@ namespace GC {
     else
       stack_end = (uintptr_t *) stack_start - 80; // dummy value
 
-    cout << "Stack end in collect: " << stack_end << endl;
+    cout << "Stack end in collect:\t " << stack_end << endl;
     auto work_list = heap->m_allocated_chunks;
     //print_worklist(work_list);
 

src/GC/tests/h_test.cpp

@@ -65,8 +65,25 @@ void test_some_types() {
 int main() {
     auto stack_start = reinterpret_cast<uintptr_t *>(__builtin_frame_address(0));
     std::cout << "Stack start from main:\t" << stack_start << std::endl;
-    test_chain(10, false);
+    // This is allocated outside of the scope of the GC, thus garbage
-    gc->collect(MARK); // some bug in free (vector out of range)
+    for (int i = 0; i < 10; i++) {
+        gc->alloc(sizeof(int));
+    }
+    /* int depth = 10;
+    Node* nodes[depth];
+    Node *last_node = static_cast<Node *>(gc->alloc(sizeof(Node)));
+    last_node->id = depth;
+    last_node->child = nullptr;
+    nodes[0] = last_node;
+    for (int i = 1; i < depth; i++) {
+        Node *node = static_cast<Node *>(gc->alloc(sizeof(Node)));
+        node->id = depth-i;
+        node->child = nodes[i-1];
+        nodes[i] = node;
+    } */
+    //test_chain(10, false);
+    //test_some_types();
+    gc->collect(MARK | SWEEP | FREE); // free misses some chunks
     gc->print_contents();
     return 0;
 }

src/GC/todo.md

@@ -8,6 +8,9 @@ Goal for next week (24/2):
 ## GC TODO:
 - Merge to main branch
 - Fix singleton references
+- Get a good grasp of how the adressing of stack frames actually works.
+- Debug "free()", sometimes it skips chunks that should be freed.
+- Check alignment of chunks.
 - Think about how we want to determine if some object is a pointer or not, probably will have to discuss that with Samuel. Since it is not ideal to determine in the GC if an object is a pointer or not. It should preferably be done in a previous stage.
 
 ## Tests TODO