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LibJS+js+test-js: Add GC debug mode that keeps cells "alive" as zombies

This patch adds a `-z` option to js and test-js. When run in this mode,
garbage cells are never actually destroyed. We instead keep them around
in a special zombie state.

This allows us to validate that zombies don't get marked in future GC
scans (since there were not supposed to be any more references!) :^)

Cells get notified when they become a zombie (via did_become_zombie())
and this is used by WeakContainer cells to deregister themselves from
the heap.
This commit is contained in:
Andreas Kling 2021-09-11 16:44:40 +02:00
parent 57371f7608
commit c364520c24
10 changed files with 33 additions and 1 deletions

View file

@ -34,6 +34,7 @@ public:
private:
virtual void visit_edges(Visitor& visitor) override;
virtual void did_become_zombie() override { deregister(); }
FunctionObject* m_cleanup_callback { nullptr };

View file

@ -30,6 +30,8 @@ public:
virtual void remove_swept_cells(Badge<Heap>, Span<Cell*>) override;
private:
virtual void did_become_zombie() override { deregister(); }
HashMap<Cell*, Value> m_values; // This stores Cell pointers instead of Object pointers to aide with sweeping
};

View file

@ -31,6 +31,7 @@ public:
private:
virtual void visit_edges(Visitor&) override;
virtual void did_become_zombie() override { deregister(); }
Object* m_value { nullptr };
u32 m_last_execution_generation { 0 };

View file

@ -30,6 +30,8 @@ public:
virtual void remove_swept_cells(Badge<Heap>, Span<Cell*>) override;
private:
virtual void did_become_zombie() override { deregister(); }
HashTable<Cell*> m_values; // This stores Cell pointers instead of Object pointers to aide with sweeping
};