Re: [RFC] Adding Python as a possible language and it's usage

[Richard Biener <richard.guenther@gmail.com>]

On Tue, Jul 17, 2018 at 2:49 PM Martin Liška <mliska@suse.cz> wrote:
>
> Hi.
>
> I've recently touched AWK option generate machinery and it's quite unpleasant
> to make any adjustments. My question is simple: can we starting using a scripting
> language like Python and replace usage of the AWK scripts? It's probably question
> for Steering committee, but I would like to see feedback from community.
>
> There are some bulletins why I would like to replace current AWK scripts:
>
> 1) gcc/optc-save-gen.awk is full of copy&pasted code, due to lack of flags type classes multiple
> global variables are created (var_opt_char, var_opt_string, ...)
>
> 2) similar happens in gcc/opth-gen.awk
>
> 3) we do very many regex matches (mainly in gcc/opt-functions.awk), I believe
>    we should come up with a structured option format that will make parsing and
>    processing much simpler.
>
> 4) we can come up with new sanity checks of options:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81397
>
> 5) there are various targets that generate *.opt files, one example is ARM:
> gcc/config/arm/parsecpu.awk
>
> where transforms:
> ./gcc/config/arm/arm-cpus.in
>
> I guess having a well-defined structured format for *.opt files will make
> it easier to write generated opt files?
>
> I'm attaching a prototype that can transform optionlist into options-save.c
> that can be compiled and works.
>
> I'm looking forward to a feedback.

I guess we either need to document python as build requirement in
install.texi then,
it currently has

@item A POSIX or SVR4 awk

Necessary for creating some of the generated source files for GCC@.
If in doubt, use a recent GNU awk version, as some of the older ones
are broken.  GNU awk version 3.1.5 is known to work.

alternatively we could handle the generated files like those we still
need flex for:

@item --enable-generated-files-in-srcdir
Neither the .c and .h files that are generated from Bison and flex nor the
info manuals and man pages that are built from the .texi files are present
in the SVN development tree.  When building GCC from that development tree,
or from one of our snapshots, those generated files are placed in your
build directory, which allows for the source to be in a readonly
directory.

If you configure with @option{--enable-generated-files-in-srcdir} then those
generated files will go into the source directory.  This is mainly intended
for generating release or prerelease tarballs of the GCC sources, since it
is not a requirement that the users of source releases to have flex, Bison,
or makeinfo.

We already conditionally require Perl for building for some targets so I wonder
if using perl would be better ...

Do we get rid of the AWK build requirement with your changes?

Richard.

> Martin