PAGODE: A back end generator using attribute abstract syntaxes and term rewritings

Abstract

A major problem in deriving a compiler from a formal definition is the production of correct and efficient object code. We propose a solution to this problem in the framework of a compiler writing system where the compilation process may be viewed as successive translations from an attributed abstract syntax to another abstract syntax. The code-generator generator needs two kinds of specifications: -an attributed abstract syntax (AAS) of the target machine: it is the description of the I.R. given as input to the code-generator. -a target machine description where the basic concepts are hierarchically described by tree-patterns. These tree patterns are terms of the target abstract syntax. The code generation process is divided into two steps: the instructions selection process and the register allocation one. The instruction selection process applies a set of rewriting rules driven by tree templates derived from the target machine specification to the I.R. term. The register allocation process consists of several evaluation passes of an attributed grammar derived automatically from the target machine specification. The first one sets the constraints on temporaries according to the whole context, the second one does life-time analysis and packing on temporaries, the last one assigns effective resources to temporaries.