Re: ANN: Kickstarter for beginning work on a new open-source Compiler

[Ludovic Brenta <ludovic@ludovic-brenta.org>]

Niklas Holsti <niklas.holsti@tidorum.invalid> writes:
> On 14-03-22 15:59 , Dirk Craeynest wrote:
>> In article <bp5enaF87mnU1@mid.individual.net>,
>> Niklas Holsti  <niklas.holsti@tidorum.invalid> wrote:
>>> The way you worded that suggests that Ada/Ed being an interpreter
>>> would have prevented using it to bootstrap GNAT, but of course that
>>> is not so.  As long as *GNAT* was able to generate an executable,
>>> one could have used Ada/Ed to execute GNAT (albeit through
>>> interpretation) to compile the GNAT source code into an executable
>>> GNAT.
>> 
>> You are right, of course.  Thanks for correcting.  (I don't know
>> where my mind was when I wrote that.)
>> 
>> Dirk
>> 
>> PS: It would've take "quite" some time to bootstrap, though...
>
> Certainly with the SETL version of Ada/Ed, yes. The C version might
> have been fast enough.
>
> But it occurs to me now that perhaps the interpreter nature of Ada/Ed
> was indeed an obstacle to GNAT bootstrapping, because, AIUI, only the
> front-end of GNAT is written in Ada; the rest is C/C++ from GCC. So
> Ada/Ed could execute only the front-end of GNAT. A bootstrap with
> Ada/Ed would have required a file-based (or piped) transfer of the
> intermediate output from the front-end to the back-end. I don't know
> if GCC already had some file-based intermediate representation; if
> not, it would have been extra work for the GNAT team to implement one.

In the olden days, temporary files were the default mechanism that GCC
front-ends used to send their output to the back-end, for memory
allocation reasons.  There was a non-default option, "-pipe", that
allowed the front-end and the back-end to work in parallel.

Still, even the GNAT front-end has parts written in C and Ada/Ed would
not have been able to run them.  But perhaps it would have been possible
to compile those C parts to object code, using a C compiler, and call
them from the interpreted Ada parts?  Anyway, all of this is
theoretical...

-- 
Ludovic Brenta.