Re: [PATCH] Enable GDB build with in-tree GMP and MPFR

Bernd Edlinger
2020-11-18T08:15:02Z

On 11/18/20 4:44 AM, Joel Brobecker wrote:
>> this enables GDB build with in-tree GMP and MPFR.
>>
>> This updated version of my patch added support for in-tree MPFR.
>>
>> While there is no preexisting --with-gmp configure option in gdb,
>> this leaves the current --with-mpfr=yes/no/auto as it is, since it seems
>> to work by accident. The top level config script thinks "no" is
>> a DIR, and skips the detection of in-tree MPFR in that case, while
>> gdb honors --with-mpfr=no, so that is what's expected.
>>
>> The in-tree build works only when no --with-mpfr and no
>> --with-gmp is given. While it does not advertise --with-gmp-prefix=DIR
>> and/or --with-mpfr-prefix=DIR with "./configure --help", I'll leave that
>> for another patch.
>
> I think we better sort the discrepancy between GCC and GDB
> if we can, but this is going to take time. From what you were
> explaining before, I believe you can separate this part of
> your patch (adding the above to GDB's configury) from the part
> where you're adding support for in-tree building?
>

99% of the top-level configury is already there, but it needs
still a dependency between gdb and (in-tree) gmp / mpfr,
and pass the options where to find gmp and mpfr to gdb,
I don't know how to actually resolve the differences ATM.
If the top-level configure script advertises GDB-style options
It will at least have to translate them for in-tree MPFR,
MPC, and ISL.

I believe this change is just the bare minimum and will not
cause additional incompatibilities with GCC.

>> Tested on x86_64-pc-linux-gnu and cross-build for arm.
>> Is it OK for the trunk?
>
> These are changes in areas I am not familiar with, and wouldn't
> have very much time to look into. I talked to Tom yesterday,
> and he kindly agreed to take a look.
>
>> From 503435680f463cf5ed060ce32b902051cb19e801 Mon Sep 17 00:00:00 2001
>> From: Bernd Edlinger <bernd.edlinger@hotmail.de>
>> Date: Sun, 15 Nov 2020 15:37:22 +0100
>> Subject: [PATCH] Enable GDB build with in-tree GMP and MPFR
>>
>> With this patch GDB can be built with in-tree GMP and/or
>> MPFR. This works also for cross-builds.
>>
>> All that is needed, is a sym-link in the source tree,
>> like this:
>>
>> gmp -> ../gmp-6.1.0
>> mpfr -> ../mpfr-3.1.4
>>
>> 2020-11-15 Bernd Edlinger <bernd.edlinger@hotmail.de>
>>
>> * Makefile.def: Prepare for GDB build with intree GMP.
>> * Makefile.in: Regenerate.
>
> I got the answer about approval for toplevel tree changes; we're still
> keeping in sync with GCC. However, Tom said that these kinds of changes
> are OK to discuss and eventually push locally, before we bring them
> to GCC next. It's better the other way around, but discussing them
> here is also an option, because it's a minor change taking advantage
> of infrastructure that's already in place.
>
> In this particular instance, I would indeed _not_ rush discussing
> with GCC, in case the tie with GDB affects the changes we would need
> in toplevel.
>

Yep, agreed.

Thanks
Bernd.