[llvm-dev] RFC: Move parts of llvm-symbolizer tool implementation to LLVMSymbolize library

[Eric Christopher via llvm-dev]

On Wed, Oct 21, 2015 at 2:18 PM Alexey Samsonov <vonosmas at gmail.com> wrote:

> On Wed, Oct 21, 2015 at 1:24 PM, Eric Christopher <echristo at gmail.com>
> wrote:
>
>>
>>
>> On Wed, Oct 21, 2015 at 1:21 PM Alexey Samsonov <vonosmas at gmail.com>
>> wrote:
>>
>>> On Wed, Oct 21, 2015 at 12:59 PM, Eric Christopher <echristo at gmail.com>
>>> wrote:
>>>
>>>>
>>>>
>>>> On Wed, Oct 21, 2015 at 12:17 PM Alexey Samsonov <vonosmas at gmail.com>
>>>> wrote:
>>>>
>>>>> We have out-of-tree implementation of llvm-symbolizer-as-a-library,
>>>>> and I still hope to upstream it one day (unfortunately, its build process
>>>>> is really complicated).
>>>>>
>>>>> Mike can probably comment on his plans for using symbolization in
>>>>> coverage-related tools.
>>>>>
>>>>> On Wed, Oct 21, 2015 at 11:34 AM, Eric Christopher <echristo at gmail.com
>>>>> > wrote:
>>>>>
>>>>>> To create unit tests is a pretty good reason IMO :)
>>>>>>
>>>>>> That said, I'd be a fan of trying to encapsulate all of this behind
>>>>>> an interface. I like that most of the tools are exceptionally light weight
>>>>>> and it makes it much more obvious what's "wrapper" versus "functionality"
>>>>>> in something like llvm-symbolize. That said, I'll be interested to see the
>>>>>> library design :)
>>>>>>
>>>>>
>>>>> Do you suggest to design it upfront, or you're fine with moving the
>>>>> existing code first, and gradually updating the interface afterwards?
>>>>>
>>>>
>>>> Don't know, what's the interface look like now? :) Were you just going
>>>> to copy the LLVMSymbolize.[cpp,h] into the directory?
>>>>
>>>
>>> For a start, yes.
>>>
>>
>> OK.
>>
>>
>>>
>>>
>>>> That should be fine I guess. I'd like to see the general ownership of
>>>> objects separated out fairly explicitly from the rest of the code.
>>>>
>>>
>>> I'm not sure what you mean by this.
>>>
>>>
>>
>> Is LLVMSymbolizer owning all of the files the right choice, or what was
>> convenient at the time?
>>
>
> Yeah, I think it's correct to have LLVMSymbolizer own parsed object files
> (although we might factor out a separate "cache" object
> that would be responsible for it).
>

OK. Sounds good to me. It can also be changed in the future if we decide to
go a different way.

-eric


>
>
>>
>> -eric
>>
>>
>>>
>>>> -eric
>>>>
>>>>
>>>>>
>>>>>
>>>>>>
>>>>>> -eric
>>>>>>
>>>>>> On Wed, Oct 21, 2015 at 7:35 AM Rafael Espíndola <
>>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>>
>>>>>>> I would say it is worth it if someone is actually planning on using
>>>>>>> the library in something else.
>>>>>>>
>>>>>>> Moving the code "just in case" or to create unit tests is not a good
>>>>>>> reason IMHO.
>>>>>>>
>>>>>>> On 20 October 2015 at 16:54, Alexey Samsonov <vonosmas at gmail.com>
>>>>>>> wrote:
>>>>>>> > Hi,
>>>>>>> >
>>>>>>> > We have a lot of non-trivial logic accumulated in the
>>>>>>> > implementation of llvm-symbolizer tool
>>>>>>> > (tools/llvm-symbolizer/LLVMSymbolize.{h,cpp}), for instance:
>>>>>>> >
>>>>>>> > * dynamic dispatch between DWARF and PDB debug info;
>>>>>>> > * building address->symbol_name mapping from object file (with
>>>>>>> special cases
>>>>>>> > for PowerPC function descriptor section, and COFF export tables);
>>>>>>> > * finding debug info stored in separate files (.dSYM files on
>>>>>>> Darwin, ELF
>>>>>>> > .gnu_debuglink section, etc.);
>>>>>>> > * demangling (with platform-specific implementations for Windows
>>>>>>> and Unix).
>>>>>>> >
>>>>>>> > I propose to move this code into a separate library LLVMSymbolize
>>>>>>> (stored
>>>>>>> > under lib/DebugInfo/Symbolize), and make llvm-symbolizer a short
>>>>>>> and simple
>>>>>>> > tool using it. This would allow to:
>>>>>>> >
>>>>>>> > * implement in-process symbolized stack trace printers (for the
>>>>>>> cases when
>>>>>>> > it's possible to link in a bunch of LLVM libraries into the
>>>>>>> executable).
>>>>>>> > * easily write more tools that can make use of symbolized code
>>>>>>> locations,
>>>>>>> > such as coverage data visualizers.
>>>>>>> > * (at least sometimes) write unit tests instead of testing
>>>>>>> functionality by
>>>>>>> > running "llvm-symbolizer" executable on pre-built executables
>>>>>>> checked in
>>>>>>> > repository.
>>>>>>> >
>>>>>>> > Any comments/objections?
>>>>>>> >
>>>>>>> > --
>>>>>>> > Alexey Samsonov
>>>>>>> > vonosmas at gmail.com
>>>>>>> _______________________________________________
>>>>>>> LLVM Developers mailing list
>>>>>>> llvm-dev at lists.llvm.org
>>>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Alexey Samsonov
>>>>> vonosmas at gmail.com
>>>>>
>>>>
>>>
>>>
>>> --
>>> Alexey Samsonov
>>> vonosmas at gmail.com
>>>
>>
>
>
> --
> Alexey Samsonov
> vonosmas at gmail.com
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20151021/77d8d681/attachment-0001.html>