Software designers face many challenges when developing applications for embedded systems. A major challenge is meeting the conflicting constraints of speed, code density, and power consumption. Traditional optimizing compiler technology is usually of little help in addressing this challenge. To meet speed, power, and size constraints, application developers typically resort to hand-coded assembly language. The results are software systems that are not portable, less robust, and more costly to develop and maintain. This paper describes a new code improvement paradigm implemented in a system called vista that can help achieve the cost/ performance trade-offs that embedded applications demand. Unlike traditional compilation systems where the smallest unit of compilation is typically a function and the programmer has no control over the code improvement process other than what types of code improvements to perform, the vista system opens the code improvement process and gives the application programmer, when necessary, the ability to finely control it. In particular, vista allows the application developer to (1) direct the order and scope in which the code improvement phases are applied, (2) manually specify code transformations, (3) undo previously applied transformations, and (4) view the low-level program representation graphically. vista can be used by embedded systems developers to produce applications, by compiler writers to prototype and debug new lowlevel code transformations, and by instructors to illustrate code transformations (e.g., in a compilers course).

The hardware description language TDL has been designed with the goal to generate machine-dependent postpass optimizers and analyzers from a concise specification of the target processor. TDL is assembly-oriented and provides a generic modeling of irregular hardware constraints that are typical for many embedded processors. The generic modeling supports graph-based and search-based optimization algorithms. An important design goal of Tdl was to achieve extendibility, so that TDL can be easily integrated in different target applications. TDL is at the base

Predicated instructions are a feature more and more common in contemporary instruction set architectures. Machine instructions are only executed if an individual guard register associated with the instruction evaluates to true. This enhances execution efficiency, but comes at a price: the control flow of a program is not explicit any more. Instead instructions from the same basic block may belong to different execution paths if they are subject to disjoint guard predicates. Postpass tools processing machine code with the purpose of program analyses or optimizations require the control flow graph of the input program to be known. The effectiveness of postpass analyses and optimizations strongly depends on the precision of the control ow reconstruction. If traditional reconstruction techniques are applied for processors with predicated instructions, their precision is seriously deteriorated. In this paper a generic algorithm is...

Seeking to resolve many of the problems related to code size in traditional program development environments. In the Java world, libraries are usually available in a bytecode representation that provides high-level semantic information, such as type information. This information is exploited by Java application extractors, as discussed in the article “Extracting Library-based Java Applications ” in this section. By contrast, reusable code in the C/C++ world often is only distributed in the form of native machine code in object archives. Therefore, we cannot rely on the same techniques to avoid code reuse overhead in C/C++ programs.