Debugged mark()

Co-authored-by: ValterMiari <ValterMiari@users.noreply.github.com>

src/GC/Makefile

@@ -7,19 +7,23 @@ CFLAGS = -Wall -Wextra -v -g -std=gnu++20 -stdlib=libc++ -I
 VGFLAGS = --leak-check=full --show-leak-kinds=all
 
 heap:
-	$(CC) $(CFLAGS)$(PWD_V) lib/heap.cpp
+	$(CC) $(CFLAGS)$(PWD) lib/heap.cpp
 
 h_test:
 	rm -f tests/h_test.out
-	$(CC) $(CFLAGS)$(PWD_V) tests/h_test.cpp lib/heap.cpp -o tests/h_test.out
+	$(CC) $(CFLAGS)$(PWD) tests/h_test.cpp lib/heap.cpp -o tests/h_test.out
 
 h_test_vg:
 	make h_test
 	valgrind $(VGFLAGS) tests/h_test.out
 
+h_test_dbg:
+	make h_test
+	lldb tests/h_test.out launch
+
 linker:
 	rm -f tests/linker.out
-	$(CC) $(CFLAGS)$(PWD_V) tests/linker.cpp lib/heap.cpp -o tests/linker.out
+	$(CC) $(CFLAGS)$(PWD) tests/linker.cpp lib/heap.cpp -o tests/linker.out
 
 linker_vg:
 	make linker

src/GC/include/heap.hpp

@@ -32,6 +32,7 @@ namespace GC {
     // void compact();
     void mark(uintptr_t *start, const uintptr_t *end, std::vector<Chunk *> worklist);
     void print_line(Chunk *chunk);
+    void print_worklist(std::vector<Chunk *> list);
 
     inline static Heap *m_instance = nullptr;
     const char *m_heap;

src/GC/lib/heap.cpp

@@ -23,6 +23,7 @@ namespace GC {
     }
 
     // kolla freed chunks innan
+    // denna är helt onödig just nu, freed chunks kommer alltid va tom
     for (size_t i = 0; i < m_freed_chunks.size(); i++) {
       auto cp = m_freed_chunks.at(i);
       if (cp->size > size)
@@ -80,7 +81,7 @@ namespace GC {
 
     // We shouldn't do this, since then m_freed_chunks doesnt' have any real purpose,
     // it should be used in alloc, it isn't if we delete *all* of its contentes
-    //release free chunks
+    // release free chunks
     while (m_freed_chunks.size()) {
       auto chunk_pointer = m_freed_chunks.back();
       m_freed_chunks.pop_back();
@@ -90,7 +91,14 @@ namespace GC {
 
   void Heap::collect(uint flags) {
 
-    cout << "DEBUG COLLECT\nFLAGS: " << flags << endl;
+    cout << "DEBUG COLLECT\nFLAGS: ";
+    if (flags & MARK)
+      cout << "\n - MARK";
+    if (flags & SWEEP)
+      cout << "\n - SWEEP";
+    if (flags & FREE)
+      cout << "\n - FREE";
+    cout << endl;
     // 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;
@@ -101,6 +109,7 @@ namespace GC {
     // reinterpret_cast<const uintptr_t *>(__builtin_frame_address(10));
 
     auto work_list = m_allocated_chunks;
+    // print_worklist(work_list);
 
     if (flags & MARK) {
       mark(stack_start, stack_end, work_list);
@@ -136,19 +145,23 @@ namespace GC {
   }
 
   // TODO: return the worklist filtered on mark = true
-  void Heap::mark(uintptr_t *start, const uintptr_t *end, vector<Chunk*> work_list) {
+  // This assumes that there are no chains of pointers, will be fixed later on
+  void Heap::mark(uintptr_t *start, const uintptr_t *end, vector<Chunk*> worklist) {
     for (; start > end; start--) { // to find adresses thats in the worklist
-      cout << "Value of start pointer:\t" << start << endl;
-      for (size_t i = 0; i < work_list.size(); i++) { // fix this
-      auto chunk = work_list.at(i);
-      cout << "Chunk value:\t" << chunk->start << endl;
-      cout << "Chunk pointer value:\t" << &chunk << endl;
-        if (chunk->start <= start && start < chunk->start + chunk->size) {
-          if (!chunk->marked) {
-            chunk->marked = true;
-            work_list.erase(work_list.begin() + i);
-            mark(reinterpret_cast<uintptr_t *>(chunk->start + chunk->size), end, work_list); //
-            return;
+      if (*start % 8 == 0) { // all pointers must be aligned as double words
+        for (size_t i = 0; i < worklist.size(); i++) { // fix this
+          auto chunk = worklist.at(i);
+          uintptr_t c_start = reinterpret_cast<uintptr_t>(chunk->start);
+          uintptr_t c_end = reinterpret_cast<uintptr_t>(chunk->start + chunk->size);
+          if (c_start <= *start && *start < c_end) {
+            uintptr_t c_start = reinterpret_cast<uintptr_t>(chunk->start);
+            if (!chunk->marked) {
+              chunk->marked = true;
+              worklist.erase(worklist.begin() + i);
+              auto new_stack_start = reinterpret_cast<uintptr_t *>(start);
+              mark(new_stack_start, end, worklist); //
+              return;
+            }
           }
         }
       }
@@ -204,6 +217,12 @@ namespace GC {
     cout << "Marked: " << chunk->marked << "\nStart adr: " << chunk->start << "\nSize: " << chunk->size << " B\n" << endl;
   }
 
+  void Heap::print_worklist(std::vector<Chunk *> list) {
+    for (auto cp : list) {
+      cout << "Chunk at:\t" << cp->start << "\nSize:\t\t" << cp->size << endl;
+    }
+  }
+
   void Heap::print_contents() {
     if (m_allocated_chunks.size()) {
       cout << "\nALLOCATED CHUNKS #" << m_allocated_chunks.size() << endl;

src/GC/tests/h_test.cpp

@@ -5,28 +5,26 @@ GC::Heap *gc = GC::Heap::the2();
 void init() {
 
     auto stack_start = reinterpret_cast<uintptr_t *>(__builtin_frame_address(0));
-    auto stack_end = stack_start - 160;
+    auto stack_end = stack_start - 40;
     std::cout << "Stack start from init:\t" << stack_start << std::endl;
     std::cout << "Imaginary stack end:\t" << stack_end << std::endl;
-    int *arr = static_cast<int *>(gc->alloc(sizeof(int) * 300));
-    for (int i = 0; i < (sizeof(int) * 300); i++) {
+    int *arr = static_cast<int *>(gc->alloc(sizeof(int) * 100));
+    std::cout << "Arr_ptr" << std::hex << arr << "\n\n\n" << std::endl;
+    for (int i = 0; i < (sizeof(int) * 100); i++) {
         arr[i] = i;
     }
     std::cout << "First stack pointer:\t" << &arr << std::endl;
+    long a = 20;
     long *l = static_cast<long *>(gc->alloc(sizeof(long)));
-    *l = 20;
-    // This doesn't get allocated on our heap, but how is it viewed on valgr?
-    int *arr2 = new int[1000];
-    for (int i = 0; i < 1000; i++) {
-        arr2[i] = i;
-    }
+    l = &a;
+    //*l = 20;
 }
 
 int main() {
     auto stack_start = reinterpret_cast<uintptr_t *>(__builtin_frame_address(0));
     std::cout << "Stack start from main:\t" << stack_start << std::endl;
     init();
-    gc->collect(MARK | SWEEP);
+    gc->collect(MARK | SWEEP | FREE);
     gc->print_contents();
     //delete gc;
     return 0;

src/GC/todo.md

@@ -6,16 +6,13 @@ Goal for next week (17/2):
 - Functioning garbage collector
 - Test it with valgrind
 
-TODO:
+## GC TODO:
 - Merge to main branch
-
-## Algorithm
-
-Potential algorithms:
-- mark & sweep
+- Don't empty m_free_chunks, reuse in a better way **Victor fixes this**
 
 ## Tests TODO
 ### Library linking
+**Victor fixes this**
 Compile the GC lib and a test separately, link them together
 and evalutate the following:
 
@@ -24,3 +21,17 @@ and evalutate the following:
     __builtin_return_address(0)
     __builtin_return_address(1)
 
+### GC Init and __b_f_a
+1. Save the first stack fram globally as the stack start
+2. For each call to collect, save the prev stack frame as the stack end
+3. Scan through the span
+
+    gc_init()
+        global stack_end = __builtin_frame_address(1)
+
+    collect()
+        global stack_start = __builtin_frame_address(1)
+
+    sweep()
+        for all addr in range(stack_end, stack_start)
+            mark if chunk