ACG Concepts

To understand how adaptive code generation (ACG) works, it is helpful to understand the following concepts.

A hardware feature is a feature that has been added to the family of processors supported by IBM® i. For instance, one new feature available in some processors supported by 6.1, is a new hardware decimal floating-point unit. A processor with this unit is considered by ACG to have the decimal floating-point feature, while a processor without it does not have the decimal floating-point feature. The aggregation of all added features present in a processor is called that processor’s feature set.

A target model is an abstraction of all processors that have the same feature set. An example of a target model would be all processors that conform to the POWER6 level of the PowerPC® AS architecture.

A module or program object also has a feature set that identifies the features required by the object so that the object runs correctly without change. An object is compatible with a target model if all features in the object’s feature set are also present in the target model’s feature set.

Code generation refers to the process of creating hardware instructions for your module and program objects. Code generation is performed by the optimizing translator.

A module or program object can be moved from one system to another. The system on which an object resides is called the current machine.