When using the ThisCall calling convention, the first parameter of a method call is the this pointer, which is stored in register ECX. Other parameters of a method call are pushed on the stack. This calling convention is used to call methods on classes exported from an unmanaged DLL.

The classes in System.Runtime.CompilerServices are for compiler writers' use only.

Compilers emit custom modifiers within metadata to change the way that the just-in-time (JIT) compiler handles values when the default behavior is not appropriate. When the JIT compiler encounters a custom modifier, it handles the value in the way that the modifier specifies. Compilers can apply custom modifiers to methods, parameters, and return values. The JIT compiler must respond to required modifiers but can ignore optional modifiers. A C++ compiler could emit a custom modifier to describe how a byte should be treated in cases where the JIT compiler treats bytes in a manner that is not compatible with C++ by default.

You can emit custom modifiers into metadata using one of the following techniques:

• Using methods in the System.Reflection.Emit.TypeBuilder class such as erload:System.Reflection.Emit.TypeBuilder.DefineMethod, erload:System.Reflection.Emit.TypeBuilder.DefineField, erload:System.Reflection.Emit.TypeBuilder.DefineConstructor, and erload:System.Reflection.Emit.TypeBuilder.DefineProperty.

• Generating a Microsoft intermediate language (MSIL) instruction file that contains calls to modopt and modreq, and assembling the file with the MSIL Assembler (Ilasm.exe).

• Using the unmanaged reflection API.

Namespace: System.Runtime.CompilerServices
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0, 4.0.0.0