effective machine descriptors for ada
With the impetus provided by the U.S. Department of Defense's support for Ada, serious attention must once again be given to the design of computer architecture for the efficient execution of structured high level languages. Descriptors are one of the more theoretically popular features in a structured machine, yet in practice they do not come up to expectations. This paper examines the deficiencies of current descriptor implementations, and goes on to propose a new approach to descriptors. The design takes into account the relative usage of scalar and structured data in structured programs, and pays due attention to the efficient representation of descriptors as well as to packing, the question of uninitialised values and the contribution which the compiler makes to range and index checking.
effect descriptors support attention design computation architecture efficiency structure language feature practical paper implementation account structural data program representation packing values compilation indexing initialisation subrange checking machine architecture relation