Re: Implementing an Ada compiler and libraries.

[Robert A Duff <bobduff@shell01.TheWorld.com>]

Lucretia <lucretia9@lycos.co.uk> writes:

> But I'm interested in seeing how I can get the compiler to not have to
> reparse other source files (when with'd) in order to compile a unit.

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...".

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.

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.

- Bob