Re: Implementing an Ada compiler and libraries.

[Lucretia <lucretia9@lycos.co.uk>]

On May 9, 9:48 pm, Robert A Duff <bobd...@shell01.TheWorld.com> wrote:
> Presumably by storing information (symbol tables and whatnot) in
> permanent disk files.  If you do that, I think you should design it as a
> _pure_ optimization.  That is, the system should behave exactly as if
> everything is compiled from source every time, except that it's faster.
> Don't mimic the Ada 83 compilers that had a notion of "compiling things
> into the library", where a source file sitting right there in the source
> directory is ignored, unless "compiled into...".

Yes, I have no intention of having to add stuff to the library before
it can compile. I'm looking at a hybrid of what GNAT does combined
with the ability to use precompiled units in binary form.

> If you do this, you need to design a permanent (on disk) representation
> that is small.  I think it's possible, but it's not easy -- the
> "obvious" representation of symbol tables will be 10 times larger than
> the source code.  If it's 10 times larger, then it defeats the purpose
> -- reading it in from disk will be slower than re-analyzing the original
> source code.
>
> You also suggested storing the info in the object files.  Yes, that is
> possible, given a reasonable object file format that allows arbitrary
> information to be stored, in addition to the actual machine code.

DWARF?

> Building a complete Ada implementation is a daunting task (many
> person-years).  You said you're doing a subset of Ada 2005, and I assume
> you're doing this "just for fun".  Keep your subset small, or you will
> never finish.

Nope, just a subset.

Luke.