[llvm-dev] Linker Option support for ELF

[James Henderson via llvm-dev]

On 8 January 2018 at 08:14, Rui Ueyama <ruiu at google.com> wrote:

> On Mon, Jan 8, 2018 at 3:55 AM, Sean Silva via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>>
>>
>> On Jan 7, 2018 5:02 PM, "Cary Coutant via llvm-dev" <
>> llvm-dev at lists.llvm.org> wrote:
>>
>> > I think we all agree that blindly allowing the linker to honor the
>> options
>> > would be scary.  I agree that we should whitelist the options, and am
>> of the
>> > opinion that we should force validation on the linker side (use of any
>> > option which the linker doesn't support in this form can be fatal).
>> > Starting small is the best way, with `-l` and `-L` as a starting
>> point.  I
>> > want to retain the ability to add additional options which may not be
>> > available in all linkers.  However, whitelisting obviously requires
>> working
>> > with the linker as would adding such options, so that could be handled
>> at
>> > that time.
>>
>> This is actually why I'd prefer a new "language" over just
>> whitelisting options. With "lib", "file", and "path", as I suggested,
>> there's no question whether an option like "-no-pie" is supported, and
>> no temptation to even try.
>>
>>
>> That's a very simple and elegant solution.
>>
>
> I really like that approach too. Command line options and "embedded
> options" are different, so making them actually look different makes sense.
>

+1 from me. This is very similar to what we have in the Playstation linker
(which uses integers instead of strings to denote the type of directive).
As Paul mentioned earlier, we support "lib" and "export" directives, both
of which would fit nicely into this format.


>
>
>> -- Sean Silva
>>
>>
>> The new language should be tailored for
>> process-to-process communication, rather than user-to-shell
>> communication.
>>
>> > I’m thinking about future enhancements.  MachO does actually provide
>> > something like `-L` -`l` in a single go via `-framework`.  But, no such
>> > option exists for ELF since it doesn’t have the concept of framework
>> bundles
>> > (but the layout itself is interesting), and I just want to try to keep
>> the
>> > door open for such features.
>>
>> This is why I also included "path" in my suggestion. I imagine
>> something very much like -framework, where include files and library
>> search paths are handled together.
>>
>> -cary
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>
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