We tackle the problem of checking non-proof-carrying code , i.e. automatically proving type-safety (implying in our type system spatial memory safety) of low-level C code or of machine code resulting from its compilation without modification. This requires a precise static analysis that we obtain by having a type system which (i) is expressive enough to encode common low-level idioms, like pointer arithmetic, discriminating variants by bit-stealing on aligned pointers, storing the size and the base address of a buffer in distinct parts of the memory, or records with flexible array members, among others; and (ii) can be embedded in an abstract interpreter. We propose a new type system that meets these criteria. The distinguishing feature of this type system is a nominal organization of contiguous memory regions, which (i) allows nesting, concatenation, union, and sharing parameters between regions; (ii) induces a lattice over sets of addresses from the type definitions; and (iii) permits updates to memory cells that change their type without requiring one to control aliasing. We provide a semantic model for our type system, which enables us to derive sound type checking rules by abstract interpretation, then to integrate these rules as an abstract domain in a standard flow-sensitive static analysis. Our experiments on various challenging benchmarks show that semantic type-checking using this expressive type system generally succeeds in proving type safety and spatial memory safety of C and machine code programs without modification, using only user-provided function prototypes.

Abstract In this paper, we propose SWARP, a retargetable preprocessor for exploiting multimedia instructions. The system mixes loop distribution, unrolling and pattern matching to exploit complex multimedia instructions. Contrary to all available systems, it can be extended at the user level. Using with a TriMedia processor we show that our system achieves important good code quality with a set of frequently used loop kernels for multimedia applications. Copyright © 2004 John Wiley & Sons, Ltd.

The Arden Syntax was introduced more than 10 years ago, but it is still not in widespread use. One reason might be that for each particular architecture and information system, a different Arden Syntax compiler must be written as well as a program for the runtime execution of the medical logic modules (MLMs). The authors have designed and implemented an architecture that increases the portability of Arden Syntax rules, using the Java platform. The portability to a target information system is achieved by the addition of appropriate adapter components, which they call mappers. These mappers are dynamically selected using explicit and implicit elements of MLMs. Furthermore, they can help translate data from the clinical information system representation into the representation needed by an MLM. This was validated by an experiment in two clinical units. Also, the authors propose a convention to name signals that trigger other MLMs (called intermediate states) so that they remain unique to each institution. The authors implemented this architecture in their clinical system and in an XML-based medical record application that has been used experimentally in their urology and nephrology departments. The Tetrasys company that provided the medical record was able to incorporate their runtime without modifications, and typical MLM execution time was less than 1 sec.