expression: weak-reference the singleton intern table to bound memory - #1530
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Expr.args2expr (the singleton intern cache) held a STRONG reference to every expression ever created, so it grew without bound on long analyses (symbolic execution of obfuscated code created millions of transient expressions that were never freed -> tens of GB, swapping). Make Expr instances weak-referenceable (add __weakref__ to Expr.__slots__) and change args2expr / canon_exprs to weakref.WeakValueDictionary / WeakSet, so transient expressions are garbage-collected once unreferenced while live ones (still held elsewhere) stay interned -- singleton identity and value equality are preserved. Subclasses now declare only their own slots (base slots, incl. __weakref__, are inherited; the previous `Expr.__slots__ + [...]` redeclared base slots, which both wasted memory and is disallowed for __weakref__). Measured: a long symbolic-execution analysis dropped from ~13GB (and climbing) to ~155MB peak with no change in results.
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Hey @mrexodia ! |
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Claude found this when my deobfuscation script was growing to 50+GB memory usage, works really well!