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

[Alexey Samsonov via llvm-dev]

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).


>
> -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
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