[llvm-dev] compatibility with gnu binutils

[Jon Chesterfield via llvm-dev]

On Thu, Feb 6, 2020 at 9:15 AM James Henderson <jh7370.2008 at my.bristol.ac.uk>
wrote:

>
> On Thu, 6 Feb 2020 at 00:24, Jon Chesterfield via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> This doesn't sound right. GNU binutils have a large quantity of legacy
>> cruft, not least the redundancy between tools like readelf and objdump
>> which are capable of doing the same task in exchange for different command
>> line arguments.
>>
>
>> Our from-scratch binutils suite has the opportunity to be much easier to
>> use than GNU's tooling. Where was this policy, which sounds like
>> replicating their design mistakes bug-for-bug, agreed upon and documented?
>>
> Many tools (readelf, objdump, nm, objcopy etc) are used in many people's
> build systems... principle is discussed on multiple reviews of changes for
> the tools too.
>

Thanks for your response. I read through the links but haven't gone looking
for diff reviews.

Yes, I see why people presently using gnu tools would want llvm tools with
corresponding names to behave identically. My concern is that meeting this
goal takes time from the very few binutils developers that could otherwise
be spent producing new binary manipulation tooling. Programmers wanting to
rewrite their binaries doesn't necessarily imply a determination to stick
with the GNU API - your example of generating json instead semi-arbitrarily
delimited text is a good example.

To be clear, if there is a bug in the GNU tool, we don't try to match that.
> We've also made multiple extensions and improvements over what GNU does in
> some tools, some of which were also adopted in the GNU equivalent
> afterwards.
>

Bugs vs features are a bit context dependent but I'm glad to hear dev
effort is also going on improving matters. I'm not in the binutils space
(as a dev or as a user) anymore so haven't been paying much attention to it.


> Note that there are some tools (llvm-readobj, llvm-symbolizer) which are
> not GNU compatible, and go their own way in output styles and command-line
> processing. These both have switches and tool aliases that allow them to be
> used in a GNU-like manner though too.
>

Taking it on faith that the llvm binutils are implemented as a relatively
thin layer on top of libraries, perhaps we should ship 'objdump' which
takes the same arguments as gnu objdump and does our best effort at
matching the semantics, and also ship llvm-objdump which is under no
obligation to match arguments or the precise semantics. Optionally as the
same file which checks the name it was invoked as. That would avoid a
proliferation of strip-all-gnu and similar.

Thanks,

Jon
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20200206/98dee2ba/attachment.html>