Re: Question about splitting debug information

In the broader build system where I'm using this, we wil indeed have a top
level command line Option called --enable-split-debug, which defaults to
false, and this tool is only loaded if it is set. So it is opt-in. For most
developers doing a compile/test/debug/edit loop, separate debug information
isn't useful, necessary, or worth the additional time. But great for
releases!

On Thu, Oct 25, 2018 at 4:31 PM Jason Kenny <[email protected]> wrote:

> The only suggestion I would have is that you might want a variable to
> control the separation should happen or not.
> The base of the imple used in Parts is here https://tinyurl.com/y7dnvx5c
> as an example
>
> it provided the ability to not make the debug information via an variable
> that can be set in the environment or the command line ( ie IGNORE_PDB =
> True | False)
>
> The form used in Parts extends the env["PDB"]="debug file" used with the
> windows compilers. The one tweak I would make in the Parts version would be
> to tweak the logic to auto add extension such as .pdb or .debug, etc (
> which you do nicely in your version)
>
> Jason
> ------------------------------
> *From:* Scons-users <[email protected]> on behalf of Andrew
> C. Morrow <[email protected]>
> *Sent:* Thursday, October 25, 2018 1:55 PM
> *To:* SCons users mailing list
> *Subject:* Re: [Scons-users] Question about splitting debug information
>
>
> Here is my current state for this. Hasn't yet gone through code review so
> may change. I've also pulled out some unnecessary pieces that relate to
> some other future projects, so it is possible I've slightly broken it in
> the editing of this email:
>
> # Copyright 2018 MongoDB Inc.
> #
> # Licensed under the Apache License, Version 2.0 (the "License");
> # you may not use this file except in compliance with the License.
> # You may obtain a copy of the License at
> #
> # http://www.apache.org/licenses/LICENSE-2.0
> <https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.apache.org%2Flicenses%2FLICENSE-2.0&data=02%7C01%7C%7Cffd583f52a654331732a08d63aab87fc%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636760905722827894&sdata=4dYg4%2FTcUbUg%2BTR8iq0oi%2ByaZJ1QU22VLWc9sk2M9TI%3D&reserved=0>
> #
> # Unless required by applicable law or agreed to in writing, software
> # distributed under the License is distributed on an "AS IS" BASIS,
> # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
> # See the License for the specific language governing permissions and
> # limitations under the License.
>
> import SCons
>
> def _update_builder(env, builder, bitcode):
>
>     base_action = builder.action
>     if not isinstance(base_action, SCons.Action.ListAction):
>         base_action = SCons.Action.ListAction([base_action])
>
>     # TODO: Make variables for dsymutil and strip, and for the action
> strings
>     if env.TargetOSIs('darwin'):
>         base_action.list.append(
>             SCons.Action.Action(
>                 "dsymutil $TARGET -o ${TARGET}.dSYM",
>                 "Generating debug info for $TARGET into ${TARGET}.dSYM"
>             )
>         )
>         base_action.list.append(
>             SCons.Action.Action(
>                 "strip -S ${TARGET}",
>                 "Stripping ${TARGET}"
>             )
>         )
>     elif env.TargetOSIs('posix'):
>         base_action.list.extend([
>             SCons.Action.Action(
>                 "${OBJCOPY} --only-keep-debug $TARGET ${TARGET}.debug",
>                 "Generating debug info for $TARGET into ${TARGET}.debug"
>             ),
>             SCons.Action.Action(
>                 "${OBJCOPY} --strip-debug --add-gnu-debuglink
> ${TARGET}.debug ${TARGET}",
>                 "Stripping debug info from ${TARGET} and adding
> .gnu.debuglink to ${TARGET}.debug"
>             ),
>         ])
>     else:
>         pass
>
>     base_emitter = builder.emitter
>     def new_emitter(target, source, env):
>
>         if env.TargetOSIs('darwin'):
>             debug_file = env.Dir(str(target[0]) + ".dSYM")
>         elif env.TargetOSIs('posix'):
>             debug_file = env.File(str(target[0]) + ".debug")
>         else:
>             pass
>
>         target.append(debug_file)
>
>         return (target, source)
>
>     new_emitter = SCons.Builder.ListEmitter([base_emitter, new_emitter])
>     builder.emitter = new_emitter
>
> def generate(env):
>     if not exists(env):
>         return
>
>     for builder in ['Program', 'SharedLibrary', 'LoadableModule']:
>         _update_builder(env, env['BUILDERS'][builder])
>
> def exists(env):
>     return True
>
> The general idea is to update the relevant builders with emitters that
> describe the separate debug files, and additional actions that produce
> them. By doing it this way, the debug files can move into and be retrieved
> from the cache.
>
> There are some TODOs here. Among the parts that I stripped out as not
> ready to show is an improvement that automatically makes it so that if
> dynamic library A depends on dynamic library B, then the installation (not
> shown here) of the debug information for A depends on the the installation
> of the debug info for library B (as does the installation of A depend on
> the installation of B).
>
> Suggestions welcome. The more complete version of this code is likely to
> land on MongoDB master tomorrow or early next week.
>
> Thanks,
> Andrew
>
>
> On Wed, Oct 24, 2018 at 11:01 AM Martin Ritter <[email protected]>
> wrote:
>
> Hi Gary,
>
> thank you, I overlooked AddPostAction. I now have something which does
> what I want but I'm looking forward to compare that with Andrews
> implementation.
>
> Best Regards,
>
> Martin
>
> On 24/10/2018 15:18, Gary Oberbrunner wrote:
> > The standard approach for this is to use AddPostAction to do your
> > post-build steps, rather than a separate builder. Those operate on the
> > target before its signature is stored.
> >
> > -- Gary
> >
> > On Wed, Oct 24, 2018 at 4:48 AM Martin Ritter <[email protected]
> > <mailto:[email protected]>> wrote:
> >
> >     Hi,
> >
> >     I have a question regarding splitting debug information from binaries
> >     and libraries with SCons: What we want to do is to split the debug
> >     information from libraries and executables and put them into separate
> >     files following
> >     https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
> <https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsourceware.org%2Fgdb%2Fonlinedocs%2Fgdb%2FSeparate-Debug-Files.html&data=02%7C01%7C%7Cffd583f52a654331732a08d63aab87fc%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636760905722827894&sdata=8gt5UHMPO%2BkiRHZQnKt8KXPgWw5wSgF18mVSYwMPpHo%3D&reserved=0>
> >
> >     So we wrote a simple builder which does just that:
> >
> >     strip_debug = Builder(
> >           action='objcopy --only-keep-debug $SOURCE $TARGET && '
> >           'strip --strip-debug --strip-unneeded $SOURCE && '
> >           'objcopy --add-gnu-debuglink=$TARGET $SOURCE',
> >           suffix='.debug', prefix=".debug/")
> >
> >     but obviously this modifies the original $SOURCE. So when running
> scons
> >     again it will notice that the libraries are not up to date and
> >     relink them.
> >
> >     One solution is to first link the library into the build directory
> and
> >     then copy and strip the files to their final destination. But I was
> >     wondering if there is a way to do this without a temporary copy of
> the
> >     binaries (which is quite some disk space in our project)
> >
> >     Best Regards,
> >
> >     Martin
> >
> >
> >     --
> >     Dr. Martin Ritter
> >
> >     LMU München, Excellence Cluster Universe
> >     Boltzmannstrasse 2, 85748 Garching
> >
> >     Tel: (+49) 89 35831-7152
> >     Fax: (+49) 89 3299-4002
> >
> >     _______________________________________________
> >     Scons-users mailing list
> >     [email protected] <mailto:[email protected]>
> >     https://pairlist4.pair.net/mailman/listinfo/scons-users
> <https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpairlist4.pair.net%2Fmailman%2Flistinfo%2Fscons-users&data=02%7C01%7C%7Cffd583f52a654331732a08d63aab87fc%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636760905722984404&sdata=XTLh0arwb6AqwkxRduVT3TP01EPQiu5jJMPAcvLbA%2Bw%3D&reserved=0>
> >
> >
> >
> > --
> > Gary
> >
> > _______________________________________________
> > Scons-users mailing list
> > [email protected]
> > https://pairlist4.pair.net/mailman/listinfo/scons-users
> <https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpairlist4.pair.net%2Fmailman%2Flistinfo%2Fscons-users&data=02%7C01%7C%7Cffd583f52a654331732a08d63aab87fc%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636760905722984404&sdata=XTLh0arwb6AqwkxRduVT3TP01EPQiu5jJMPAcvLbA%2Bw%3D&reserved=0>
> >
>
> --
> Dr. Martin Ritter
>
> LMU München, Excellence Cluster Universe
> Boltzmannstrasse 2, 85748 Garching
>
> Tel: (+49) 89 35831-7152
> Fax: (+49) 89 3299-4002
> _______________________________________________
> Scons-users mailing list
> [email protected]
> https://pairlist4.pair.net/mailman/listinfo/scons-users
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>
>

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