AVM2s

AVM2 stands for ActionScript Virtual Machine 2, a virtual machine designed by Adobe Systems to execute ActionScript 3 bytecode within the Flash Player and the Adobe AIR runtime. It is the successor to the earlier AVM1 used for ActionScript 1 and 2, and it is specifically geared toward running the strongly typed, object-oriented features of ActionScript 3.

History and purpose: AVM2 was introduced with the later generations of Flash Player (beginning with Flash Player 9) to provide higher performance, richer language features, and better tooling support for ActionScript 3. The VM executes bytecode compiled from ActionScript 3 source into the ABC (ActionScript ByteCode) format, enabling a more robust and scalable runtime for multimedia, games, and application logic delivered via Flash and AIR.

Architecture and execution model: AVM2 is a stack-based virtual machine with a class-based object model. It processes ABC bytecode that references a comprehensive runtime library and the Flash display APIs. The VM supports features such as strong typing (optional in certain contexts), dynamic properties, namespaces, metadata, and structured exception handling. Programs are run inside an execution environment that manages memory, security, and access to system resources through the Flash/AIR runtime.

Performance and security features: AVM2 includes mechanisms for improving speed, such as a Just-In-Time (JIT) compiler in some environments, and utilizes garbage-collected memory to manage object lifetimes. It enforces security boundaries through sandboxing and policy checks tied to the web or local environments, aligning with the browser-like security model used by Flash Player and AIR.

Legacy status: With the end of official Flash Player support in 2020, practical usage of AVM2 diminished, though AVM2 remains relevant for existing AIR applications and in various maintenance or open-source reimplementation efforts.