We motivate the design of a typed assembly language (TAL) and present a type-preserving translation from System F to TAL. The typed assembly language we present is based on a conventional RISC assembly language, but its static type system provides support for enforcing high-level language abstractions, such as closures, tuples, and user-defined abstract data types. The type system ensures that well-typed programs cannot violate these abstractions. In addition, the typing constructs admit many low-level compiler optimizations. Our translation to TAL is specified as a sequence of type-preserving transformations, including CPS and closure conversion phases; type-correct source programs are mapped to type-correct assembly language. A key contribution is an approach to polymorphic closure conversion that is considerably simpler than previous work. The compiler and typed assembly language provide a fully automatic way to produce certified code, suitable for use in systems where untrusted and potentially malicious code must be checked for safety before execution.

We motivate the design of a typed assembly language (TAL) and present a type-preserving translation from System F to TAL. The typed assembly language we present is based on a conventional RISC assembly language, but its static type system provides support for enforcing high-level language abstractions, such as closures, tuples, and user-defined abstract data types. The type system ensures that well-typed programs cannot violate these abstractions. In addition, the typing constructs admit many low-level compiler optimizations. Our translation to TAL is specified as a sequence of type-preserving transformations, including CPS and closure conversion phases; type-correct source programs are mapped to type-correct assembly language. A key contribution is an approach to polymorphic closure conversion that is considerably simpler than previous work. The compiler and typed assembly language provide a fully automatic way to produce certified code, suitable for use in systems where untrusted and potentially malicious code must be checked for safety before execution.

This paper presents a new protocol for certified email. The protocol aims to combine security, scalability, easy implementation, and viable deployment. The protocol relies on a light on-line trusted third party; it can be implemented without any special software for the receiver beyond a standard email reader and web browser, and does not require any public-key infrastructure.

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SUMMARYThe Open Runtime Platform (ORP) is a high-performance managed runtime environment (MRTE) that features exact generational garbage collection, fast thread synchronization, and multiple coexisting justin-time compilers (JITs). ORP was designed for flexibility in order to support experiments in dynamic compilation, garbage collection, synchronization, and other technologies. It can be built to run either Java or Common Language Infrastructure (CLI) applications, to run under the Windows or Linux operating systems, and to run on the IA-32 or Itanium processor family (IPF) architectures. Achieving high performance in a MRTE presents many challenges, particularly when flexibility is a major goal. First, to enable the use of different garbage collectors and JITs, each component must be isolated from the rest of the environment through a well-defined software interface. Without careful attention, this isolation could easily harm performance. Second, MRTEs have correctness and safety requirements that traditional languages such as C++ lack. These requirements, including null pointer checks, array bounds checks, and type checks, impose additional runtime overhead. Finally, the dynamic nature of MRTEs makes some traditional compiler optimizations, such as devirtualization of method calls, more difficult to implement or more limited in applicability. To get full performance, JITs and the core virtual machine (VM) must cooperate to reduce or eliminate (where possible) these MRTE-specific overheads. In this paper, we describe the structure of ORP in detail, paying particular attention to how it supports flexibility while preserving high performance. We describe the interfaces between the garbage collector, the JIT, and the core VM; how these interfaces enable multiple garbage collectors and JITs without sacrificing performance; and how they allow the JIT and the core VM to reduce or eliminate MRTE-specific performance issues.