Shulou(Shulou.com)06/03 Report--

Mono refines its just-in-time and static compilers with new ways to run code.

In 2001, the Mono project officially began, with the Mono development team writing an interpreter for the. NET instruction set to boot a self-hosted. NET development environment on Linux.

The interpreter was considered a temporary tool that could be used while building a Just-in-Time (JIT) compiler. The interpreter (mint) and JIT engine (mono) remain synchronized until the JIT engine can be ported to all supported platforms.

When generics were introduced, the engineering cost of keeping both the interpreter and the JIT engine became too high to be worthwhile, so the interpreter was removed.

Fully static compilation of. NET code is described later. This is also the introduction of techniques that prohibit the target platform from generating dynamic code. iOS is the main driver in this regard, opening the door to allowing Mono to run on consoles such as PlayStation and Xbox.

The main disadvantage of fully static compilation is that you have to recreate an entirely new executable every time you update the code. This is a slow process, not suitable for interactive development of practice.

For example, some game developers like to tweak their game code without triggering a full recompile. Static compilation makes this impractical, so they embed scripting languages in the game code to iterate and tweak quickly.

The lack of dynamic functionality in. NET also prevents its use as a teaching or prototyping tool in some environments. Some tools like Xamarin Workbooks or simple scripts cannot use the. NET language and have to resort to other solutions on the platform.

Frank Krueger needed such an environment for iOS when he was building Continuous IDE, so he wrote his own. NET interpreter in F#so he could have a complete. NET development environment for iPad.

To address these issues and support some of the internal Microsoft products, Mono interpreter was brought back.

The new Mono interpreter

Mono's old interpreter is now welcomed back and upgraded to support. NET, and support for generics has been added to upgrade it to run. NET, which is now officially available in 2017. Next Mono will add support for mixed mode execution.

Mono now runs on WebAssembly is one way to do that (the other is static compilation using LLVM).

The interpreter is now an important part of Mono. It has passed most of the tests in a large number of test suites. You can now use it when building Mono from source code, as follows:

$ mono --interpreter yourassembly.exe Mixed mode execution

Although stand-alone interpreters are well established, the Mono development team is currently working on a configuration that can mix interpreted code with statically compiled code or just-in-time compiled code, known as mixed-mode execution.

For platforms like iOS, PlayStation, and Xbox, mixed mode execution means you can precompile core libraries or core apps and still support dynamic loading and executing code. While you have the advantage of optimizing all core libraries with LLVM, you still have the flexibility to run some dynamic code.

This will allow game developers to prototype, experiment, and tweak game code using the. NET language on their systems without having to recompile applications.

This opens the door to scriptable application design on devices that use the. NET language.

future work

The Mono development team is expanding the interpreter's capabilities to handle a variety of interesting scenarios, and here are some current projects:

Upgrade Mono Static Compilation

The full AOT build of Mono does not come with System.Reflection.Emit, which serves several purposes.

The System.Linq.Expressions API has been widely used in many advanced scenarios, such as entity frameworks or users parsing expressions into expression trees using the C#compiler. You may have seen code in the following scenarios:

Expression sum = a + b;var adder = sum.Compile ( );adder ( );

In a full AOT scenario, both the design entity framework and the way this works are integrated into the interpreter via the Expression class above. Although this expression interpreter has limitations, it is also a large interpreter.

By enabling the System.Reflection.Emit interpreter, you can remove a lot of code.

This also enables scripting languages built for. NET to work in statically compiled environments such as IronPython, IronRuby, and IronScheme.

To do this, the Mono development team is completing the mixed-mode implementation. This means that interpreted code complements existing statically compiled. NET code.

better isolation

Having previously failed to address developers 'hot-loading issues when deploying apps, the Mono development team is completing AppDomain support to enable this scenario.

Working on hybrid mode options

The Mono development team found that certain programs run faster when interpreted through an interpreter than when executed using a JIT engine.

So I'm going to look at hybrid execution patterns, or layered compilation. You can have the interpreter execute code that is not performance-sensitive, such as static constructors or other initialization code that can only be run once, in order to reduce memory usage, code usage, and execution time generated.

Another scenario is to run the code in interpreted mode and switch to a JIT-compiled implementation of the method if a certain threshold is exceeded, or use attributes to annotate problems encountered and methods that are not worth optimizing.

Mono download address: www.mono-project.com/download/

Original link: www.mono-project.com/news/

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