[llvm-dev] [ELF] Symbol-ordering-file warnings

[Peter Collingbourne via llvm-dev]

These warnings do not seem useful for all users of --symbol-ordering-file.
I am aware of at least one user that uses --symbol-ordering-file as an
opportunistic request for sections to appear in a particular order, rather
than a mandatory request. This user has --fatal-warnings enabled, and would
not want the build to fail if an older --symbol-ordering-file is being used
and a symbol disappears from the final output due to a refactoring.

I imagine that one option would be to put these warnings behind a
default-on flag.

Peter

On Mon, Jan 22, 2018 at 4:28 PM, Rui Ueyama via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> On Mon, Jan 22, 2018 at 2:00 AM, James Henderson via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> Hi,
>>
>>
>>
>> In our proprietary linker, we have a switch which has essentially
>> identical functionality to the --symbol-ordering-file LLD switch. One of
>> the main areas that it differs in is that our linker warns in various
>> circumstances, if there is a problem with the contents of the order file.
>> We would like to propose adding these same warnings to LLD, if there is
>> interest in them. Following are the situations we warn in, and some of the
>> justifications behind them:
>>
>>
>>
>> When a symbol in the order file is not found - might help catch typos in
>> that file.
>>
>> Imported/undefined symbols - symbols in other modules clearly can’t be
>> reordered in the current link.
>>
>> Absolute symbols - these do not have a position in the file, so ordering
>> them makes no sense.
>>
>> Removed symbols (i.e. via --gc-sections) - it doesn’t make much sense to
>> try to order such symbols, since they have no position in the output.
>>
>
> All sound good to me, and these features will be pretty useful.
>
>
>>
>> Would people be interested in these warnings?
>>
>>
>>
>> Regards,
>>
>>
>>
>> James
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>>
>
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>


-- 
-- 
Peter
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