NET, you will often encounter the term "managed code". This document will explain what this term means and additional information around it. To put it very simply, managed code is just that: code whose execution is managed by a runtime. In this case, the runtime in question is called the Common Language Runtime or CLR, regardless of the implementation for example, Mono ,.
NET Framework, or. CLR is in charge of taking the managed code, compiling it into machine code and then executing it.
On top of that, runtime provides several important services such as automatic memory management, security boundaries, type safety etc. In the unmanaged world, the programmer is in charge of pretty much everything.
The actual program is, essentially, a binary that the operating system OS loads into memory and starts. Everything else, from memory management to security considerations are a burden of the programmer. Managed code is written in one of the high-level languages that can be run on top of. When you compile code written in those languages with their respective compiler, you don't get machine code. You get Intermediate Language code which the runtime then compiles and executes.
What is ASP. NET Core? How to iterate through ArrayList in jQuery? What is the difference between TempData keep and peek function? A class provides a default constructor for me. I write a constructor that takes a string as Can multiple catch blocks be executed in a C program? What Operating Systems Node. JIT compilation converts MSIL to native code on demand at application run time, when the contents of an assembly are loaded and executed. Because the common language runtime supplies a JIT compiler for each supported CPU architecture, developers can build a set of MSIL assemblies that can be JIT-compiled and run on different computers with different machine architectures.
However, if your managed code calls platform-specific native APIs or a platform-specific class library, it will run only on that operating system. JIT compilation takes into account the possibility that some code might never be called during execution. Instead of using time and memory to convert all the MSIL in a PE file to native code, it converts the MSIL as needed during execution and stores the resulting native code in memory so that it is accessible for subsequent calls in the context of that process.
The loader creates and attaches a stub to each method in a type when the type is loaded and initialized. When a method is called for the first time, the stub passes control to the JIT compiler, which converts the MSIL for that method into native code and modifies the stub to point directly to the generated native code. Therefore, subsequent calls to the JIT-compiled method go directly to the native code.
Because the JIT compiler converts an assembly's MSIL to native code when individual methods defined in that assembly are called, it affects performance adversely at run time. In most cases, that diminished performance is acceptable. More importantly, the code generated by the JIT compiler is bound to the process that triggered the compilation.
It cannot be shared across multiple processes. To allow the generated code to be shared across multiple invocations of an application or across multiple processes that share a set of assemblies, the common language runtime supports an ahead-of-time compilation mode.
This ahead-of-time compilation mode uses the Ngen. However, the operation of Ngen. It performs the conversion from MSIL to native code before running the application instead of while the application is running. As part of its compilation to native code, the MSIL code must pass a verification process unless an administrator has established a security policy that allows the code to bypass verification.
Verification examines MSIL and metadata to find out whether the code is type safe, which means that it accesses only the memory locations it is authorized to access. Type safety helps isolate objects from each other and helps protect them from inadvertent or malicious corruption. It also provides assurance that security restrictions on code can be reliably enforced. The runtime relies on the fact that the following statements are true for code that is verifiably type safe:.
During the verification process, MSIL code is examined in an attempt to confirm that the code can access memory locations and call methods only through properly defined types.
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