For a compiler writer, generating good machine code for a variety of platforms is hard work. One might try to reuse a retargetable code generator, but code generators are complex and difficult to use, and they limit one's choice of implementation language. One might try to use C as a portable assembly language, but C limits the compiler writer's flexibility and the performance of the resulting code. The wide use of C, despite these drawbacks, argues for a portable assembly language. C-- is a new language designed expressly for this purpose. The use

For a compiler writer, generating good machine code for a variety of platforms is hard work. One might try to reuse a retargetable code generator from another compiler, but code generators are complex and difficult to use, and they limit one's choice of implementation language. One might try to use C as a portable assembly language, but C limits the compiler writer's flexibility and the performance of the resulting code. The wide use of C, despite these drawbacks, argues for a portable assembly language. C-- is a new language designed expressly as a portable assembly language. C-- eliminates some of the performance problems associated with C, but in its originallyproposed form it does not provide adequate support for garbage collection, exception handling, and debugging. The problem is that neither the high-level compiler nor the C-- compiler has all of the information needed to support these run-time features. This paper proposes a three-part solution: new language constructs for C--,...

In the presence of ever-changing computer architectures, highquality optimising compiler backends are moving targets that require specialist knowledge and sophisticated algorithms. In this paper, we explore a new backend for the Glasgow Haskell Compiler (GHC) that leverages the Low Level Virtual Machine (LLVM), a new breed of compiler written explicitly for use by other compiler writers, not high-level programmers, that promises to enable outsourcing of low-level and architecture-dependent aspects of code generation. We discuss the conceptual challenges and our backend design. We also provide an extensive quantitative evaluation of the performance of the backend and of the code it produces.