The Virtual Execution System

The Virtual Execution System (VES) provides an environment for executing managed code. It provides direct support for a set of built-in data types, and it defines a hypothetical machine with an associated machine model and state, a set of control flow constructs, and an exception handling model. To a large extent, the purpose of the VES is to provide the support required to execute the Common Intermediate Language instruction set, described in Partition III (Chapter 6 of this book).

Understanding the VES is important not only to those interested in implementing a VES, but to compiler designers. Compiler designers need to know what the VES does and does not do. This book clearly lays out those lines. Although there is information on the VES throughout the standard, section 12 of Partition I, and all of its subsections, contains important information on the VES, as does Partition III. The early sections of Partition IV (Chapter 7 of this book) are valuable for VES developers because they explain what must be implemented if a staged development is required.

For VES developers, there is a suggested order for reading the standard. If you understand the basic notion of a Virtual Execution System and managed code, read Partition III (Chapter 6) first, because it describes the instructions of the CIL, which are at the heart of the VES. Then go back and read Partition I, and try to fill in the architectural details. Finally, go on to the other sections.