Re: Compiler textbook available online

On Mar 19, 12:38 pm, torb...@app-4.diku.dk (Torben Ęgidius Mogensen)
wrote:
> > PS: I recall some months ago that a Danish univ. released a nice (but
> > old) compiler named Alvilda. Does your work/research have any
> > connection to Alvilda?
>
> No, that was made by some students at another university (Aarhus,
> where I'm from Copnhagen). I can see from their webpage that Alvilda
> ws written in C. I would not choose C as a langauge in which to write
> a compiler.


Assume we're talking about
http://not.meko.dk/Hacks/Alvilda/The%20Alvilda%20Optimizing%20Compiler.html


-1. It wasn't a "Danish univ.", but rather one long-ago graduated
student cleaning old files :-)


0. Jens Palberg (now at UCLA) ran the course, and I am greatful to him
for having allowed us great freedom to go our own way.


1. We _had_ to write in C, and although not necessarily the worlds
greatest programming language, it _is_ hands-down the most portable,
has the most programmers in the world (outside COBOL), and have great
tool support, notably debuggers. I would choose C again for those
reasons, even though I'm fond of Haskell.


2. Our Alvilda compiler was trying out a new internal representation,
CoRTL, that ? had proposed in a Thesis proposal, but never finished.
It was an interesting, but we discovered (Lesson #0) that the
structual constraints of CoRTL were a pain to deal with. Today I would
have gone with Thinned-Gated SSA. ("One" day, I'll do this for a C
subset).


3. Lesson #1 was that going straight from parse actions to our IR was
A Bad Idea. Building an abstract syntax tree as an immediate would
have simplified things enormously. (Obvious to all I hope).


4. I haven't looked at Torben's book (stellar I'm sure), but I'm feel
there all together too much focus, in academia and in this newsgroup,
on a long solved and not so interesting problem. If I were to run a
compiler course, I would _give_ the students the front end. All the
really fun stuff is in the back end.


Regards
Tommy

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