Update the free_slots count of the original page

When invalidating a page during compaction, the free_slots count should
be updated for the page of the object and not the page of the forwarding
address (since the object gets moved back to the forwarding address).

gc.c

@@ -5818,7 +5818,7 @@ gc_sweep_continue(rb_objspace_t *objspace, rb_size_pool_t *sweep_size_pool, rb_h
 }
 
 static void
-invalidate_moved_plane(rb_objspace_t *objspace, struct heap_page *page, uintptr_t p, bits_t bitset, struct gc_sweep_context *ctx)
+invalidate_moved_plane(rb_objspace_t *objspace, struct heap_page *page, uintptr_t p, bits_t bitset)
 {
     if (bitset) {
         do {
@@ -5834,17 +5834,15 @@ invalidate_moved_plane(rb_objspace_t *objspace, struct heap_page *page, uintptr_
 
                     object = rb_gc_location(forwarding_object);
 
-                    if (FL_TEST(forwarding_object, FL_FROM_FREELIST)) {
-                        ctx->empty_slots++; /* already freed */
-                    }
-                    else {
-                        ctx->freed_slots++;
-                    }
-
                     gc_move(objspace, object, forwarding_object, page->size_pool->slot_size);
                     /* forwarding_object is now our actual object, and "object"
                      * is the free slot for the original page */
-                    heap_page_add_freeobj(objspace, GET_HEAP_PAGE(object), object);
+                    struct heap_page *orig_page = GET_HEAP_PAGE(object);
+                    orig_page->free_slots++;
+                    if (!FL_TEST_RAW(object, FL_FROM_FREELIST)) {
+                        objspace->profile.total_freed_objects++;
+                    }
+                    heap_page_add_freeobj(objspace, orig_page, object);
 
                     GC_ASSERT(MARKED_IN_BITMAP(GET_HEAP_MARK_BITS(forwarding_object), forwarding_object));
                     GC_ASSERT(BUILTIN_TYPE(forwarding_object) != T_MOVED);
@@ -5870,16 +5868,10 @@ invalidate_moved_page(rb_objspace_t *objspace, struct heap_page *page)
 
     p = page->start;
 
-    struct gc_sweep_context ctx;
-    ctx.page = page;
-    ctx.final_slots = 0;
-    ctx.freed_slots = 0;
-    ctx.empty_slots = 0;
-
     // Skip out of range slots at the head of the page
     bitset = pin_bits[0] & ~mark_bits[0];
     bitset >>= NUM_IN_PAGE(p);
-    invalidate_moved_plane(objspace, page, (uintptr_t)p, bitset, &ctx);
+    invalidate_moved_plane(objspace, page, (uintptr_t)p, bitset);
     p += (BITS_BITLENGTH - NUM_IN_PAGE(p));
 
     for (i=1; i < HEAP_PAGE_BITMAP_LIMIT; i++) {
@@ -5887,12 +5879,9 @@ invalidate_moved_page(rb_objspace_t *objspace, struct heap_page *page)
          * to indicate there is a moved object in this slot. */
         bitset = pin_bits[i] & ~mark_bits[i];
 
-        invalidate_moved_plane(objspace, page, (uintptr_t)p, bitset, &ctx);
+        invalidate_moved_plane(objspace, page, (uintptr_t)p, bitset);
         p += BITS_BITLENGTH;
     }
-
-    page->free_slots += (ctx.empty_slots + ctx.freed_slots);
-    objspace->profile.total_freed_objects += ctx.freed_slots;
 }
 
 static void