[llvm-dev] elf2yaml document structure, for dynamic symbols

[Rui Ueyama via llvm-dev]

I'm not really pushing back, and I'm not opposing to your idea to add the
feature to obj2yaml/yaml2obj, but if you can do what you want to do using
existing tools, why do you want to write new code?

For tests, you might be able to llvm-objdump which can dump .dynsym
contents. obj2yaml and yaml2obj are the tools to serialize and de-serialize
a binary file, so if you don't need a round-trip conversion, other tool
might fit better.

On Wed, Nov 1, 2017 at 1:11 PM, Dave Lee <davelee.com at gmail.com> wrote:

> > Can't you do that by generating a small assembly file and compile &
> link it to a .so?
>
> I could, though I admit I haven't consider that approach. Thanks for the
> suggestion. If there is opposition to adding support for dynamic symbols,
> then I will try the assembly+linker approach, but if I can add the support
> for dynamic symbols, then I'll continue with yaml2obj, at least for now. We
> also had a test case we wanted to write using obj2yaml but couldn't because
> of the lack of dynamic symbols.
>
> On Wed, Nov 1, 2017 at 12:40 PM, Rui Ueyama <ruiu at google.com> wrote:
>
>> On Wed, Nov 1, 2017 at 11:56 AM, Dave Lee <davelee.com at gmail.com> wrote:
>>
>>> > I wonder why you want to add the new feature to yaml2obj. Maybe,
>>> explaining your motivation would help others understand your problem.
>>>
>>> Thanks for the cue! I am using yaml2obj to generate stub dynamic
>>> libraries.
>>>
>>
>> Can't you do that by generating a small assembly file and compile & link
>> it to a .so?
>>
>>
>>> On Wed, Nov 1, 2017 at 11:29 AM, Rui Ueyama <ruiu at google.com> wrote:
>>>
>>>> I don't have a strong opinion on this. yaml2obj was there when I joined
>>>> to the project, and we are not using it for ELF in lld to test lld's
>>>> features anyway, so I'm not really a user of the bool. But, I wonder why
>>>> you want to add the new feature to yaml2obj. Maybe, explaining your
>>>> motivation would help others understand your problem.
>>>>
>>>> On Wed, Nov 1, 2017 at 10:43 AM, Dave Lee <davelee.com at gmail.com>
>>>> wrote:
>>>>
>>>>> I'm adding support for elf dynamic symbols in yaml2obj/obj2yaml. I'm
>>>>> seeking opinions about how to model dynamic symbols (and symbols in
>>>>> general) in the yaml structure. Currently, symbols in elf are represented
>>>>> by a top level `Symbols` key, within which symbols are grouped by binding
>>>>> type (Global, Weak, Local). The simplest thing to do would be to mirror
>>>>> this structure to a DynamicSymbols (or SymbolsDynamic). Is there other ways
>>>>> people would like to see this structure represented? Saleem suggested
>>>>> symbols be modeled more closely to the elf spec, and that the binding type
>>>>> should be represented as an attribute on each symbol, not as a grouping.
>>>>> For comparison, coff and macho both appear to represent the file format
>>>>> more directly, without much (any?) added abstraction.
>>>>>
>>>>> Short pseudo example of the current symbol structure:
>>>>>
>>>>>     Symbols:
>>>>>       Global:
>>>>>         - Name: ...
>>>>>           Type: ...
>>>>>           Section: ...
>>>>>           ...
>>>>>       Weak:
>>>>>         - Name: ...
>>>>>           Type: ...
>>>>>           Section: ...
>>>>>           ...
>>>>>       Local:
>>>>>         - Name: ...
>>>>>           Type: ...
>>>>>           Section: ...
>>>>>           ...
>>>>>
>>>>> thanks,
>>>>> Dave
>>>>>
>>>>
>>>>
>>>
>>
>
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