Re: Target-specific Front-Ends? (Was: front end changes for altivec)

[Bernd Schmidt <bernds at redhat dot com>]

On Tue, 27 Nov 2001, Ziemowit Laski wrote:

> How could we go about step 3?  I'm sure there are a million ways,
> but let me illustrate one possible scenario (for AltiVec):
>    1. We create a file called gcc/config/rs6000/c-parse.in.diff
>       (and something analogous for C++)
>    2. At build time, this diff will be used to patch up
>       gcc/c-parse.in if needed.

When you suggest that there is no harm in that, you think only of the
present, not of the future.

Well, imagine we try to support not one, but fourty-two poorly designed
extensions this way (and it would happen - everyone would go "hey, you
did it for Altivec, why can't I put in my feature too").  Imagine trying
to make any changes to the C parser if you have to make sure none of these
patches break.  It would be impossible - you'd have to build and test as
many toolchains as there are such extensions, rather than building just
one.

Conditional compilation has the same problem.  It's a maintenance
nightmare.  The only way to prevent it is to say "no" right at the
start.


Bernd