This paper presents an environment that integrates the tasks of translating a source program to machine instructions for a proposed architecture, imitating the execution of these instructions, and collecting measurements. The environment, which is easily retargeted and quickly collects detailed measurements, facilitates experimentation with a proposed architecture and a compiler.

This article describes the key principles behind the design and implementation of a global code improver that has been use to construct several high-quality compilers and other program transformation and analysis tools. The code improver, called vpo, employs a paradigm of compilation that has proven to be flexible and adaptable---all code improving transformations are performed on a target-specific representation of the program. The aggressive use of this paradigm yields a code improver with several valuable properties. Four properties stand out. First, vpo is language and compiler independent. That is, it has been used to implement compilers for several different computer languages. For the C programming language, it has been used with several front ends each of which generates a different intermediate language. Second, because all code improvements are applied to a single low-level intermediate representation, phase ordering programs are minimized. Third, vpo is easily retargeted and handles a wide variety of architectures. In particular, vpo's structure allows new architectures and new implementations of existing architectures to be accommodated quickly and easily. Fourth and finally, because of its flexible structure, vpo has several other interesting uses in addition to its primary use in an optimizing compiler. This article describes the principles that have driven the design of vpo and the implications of these principles on vpo's implementation. The article concludes with a brief description of vpo's use as a back end with front ends for several different languages, and its use as a key component

This paper describes an environment called ease

To attain peak efficiency, high performance processors must anticipate changes in the flow of control before they actually occur. Branch prediction is the method of determining the most likely path to be taken at branch decision points in the program. Many branch prediction mechanisms have been proposed. The most effective of these use a single tabular data structure in hardware to hold historical information regarding the behaviors of branches. The table is a limited resource, and is managed in a manner that can result in multiple branches attempting to share locations in the table in a conflicting manner.