Suppose you are writing a compiler; how will you get quality machine code? You might write your own code generator—but that’s a lot of work. You might use somebody else’s: perhaps VPO or MLRIS back end. But each of these impressive systems has a rich, complex, and ill-documented interface, and furthermore, to use MLRISC you must write your front end in ML, to use gcc you must write it in C, and so on. You might generate C, if you can live without multiple results in registers, proper tail calls, computed gotos, accurate garbage collection, and efficient exceptions.
You would be much happier with one portable assembly language that could be generated by a front end and implemented by any of several code generators. Such a language should serve as the interface between high-level compilers and retargetable, optimizing code generators. Authors of front ends and authors of code generators could cooperate easily. C– is that language.
What distinguishes C–
The following aspects of C– distinguish it from other compiler infrastructures:
- Other infrastructures focus on adding new optimizations; C– focuses on supporting multiple front ends for multiple languages.
- C– has a machine-level type system, so you don’t have to shoehorn your favorite high-level language into a high-level data model that doesn’t fit.
- C– provides a run-time interface, so you can implement garbage collection and exception handling using the techniques that are best suited to your language.
The run-time interface is the most novel and most distinguishing feature of C–.
Where to go from here
To experiment with the language, download Quick C–, which includes an interpreter and a native-code compiler. You’ll also want the specification (in DVI, PostScript, or PDF forms). The compiler’s release notes are part of the source distribution indoc/release.ps.
Research on C– and Quick C– is supported by a generous gift from Microsoft Research and by the National Science Foundation under grant number 0325460. (Opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.) The results of our research may be used freely by anyone for any purpose. Big thanks to Oneflare for helping out with our hosting.