Can you explain the working principles of JIT compilation mechanisms in virtual machines?

JIT compilation (Just-In-Time compilation) is a mechanism used by virtual machines (e.g., JVM, .NET CLR, Dart VM) to convert bytecode or intermediate code into machine code during runtime.

Working principle:

• When a program starts, code is usually interpreted or compiled into bytecode.
• When the VM detects that a certain code section is executed frequently (hot path), it compiles this section into native machine code.
• The compiled code is cached and executed directly on subsequent calls, significantly improving performance.

Advantages of JIT:

• Optimization based on actual program behavior (e.g., inlining, removal of unused code).
• Balance between startup speed (interpretation) and execution speed (compilation).

In the context of Flutter, Dart VM uses JIT during development for fast startup and hot reload, while AOT compilation (Ahead-Of-Time) is used in release builds for maximum performance.

Simplified scheme example:

Source code -> Bytecode compilation -> Interpretation
                         |
                  JIT compilation of hot paths
                         |
                  Execution of native code