[LLVMdev] Debug Info Documentation State

[Erkki Lindpere]

Thanks for the quick reply! I will keep the DIBuilder and Clang's
CGDebugInfo as my reference for now.

At the moment I want to stick with generating .ll -- it's somewhat easier
for me to debug the output of my compiler that way, and I haven't
programmed much in C/C++ for years -- mostly been a JVM guy. But at one
point I may want to look into bindings or even creating a bootstrapped
compiler.


On Wed, Mar 20, 2013 at 11:33 PM, Eric Christopher <echristo at gmail.com>wrote:

>
>
>
> On Wed, Mar 20, 2013 at 2:21 PM, Erkki Lindpere <villane at gmail.com> wrote:
>
>> Hi,
>>
>> I wanted to add debug info to my language (compiler written in Scala,
>> outputs .ll files), but I found it really hard to do based on the
>> documentation provided at http://llvm.org/docs/SourceLevelDebugging.html(I looked at the specific doc for LLVM 3.0 though)
>>
>> With LLVM 3.0, DI version 8 (which is documented there) seemed to work,
>> except DW_TAG_auto_variable for which I used version tag 11 and imitated
>> what clang was doing.
>>
>> Got that working for simple programs, but now I switched to LLVM 3.2 and
>> that debug info doesn't work any more. My best bet seems to be looking at
>> how Clang/LLVM does it internally.
>>
>> PS. For anyone else looking for this, lib/VMCore/DIBuilder.cpp seems to
>> be the best place to look what the structures should look like.
>>
>>
> Yes. You should use DIBuilder if at all possible or construct something
> that does the same thing if you need bindings. But I'd probably just do
> bindings, producing the text is the least portable way.
>
>
>> My question is, any plans to updating the documentation? Documenting
>> different versions of the debug info is probably too much, but the docs
>> should at least be of a working version (of course it's possible that
>> Version 8 works fine and I was just doing something wrong).
>>
>
> We've removed the versioning on debug info recently and it will continue
> to be an unstable format for the foreseeable future. Updating the
> documentation is definitely possible, and should be happening as we move
> around fields and change things. It's possible it hasn't happened of late
> and so that should probably be fixed. A good chunk of the layout still
> looks correct - but will be incorrect against any released version even if
> it was updated. It should reflect top of tree.
>
> That said, looking at how clang emits debug information is guaranteed to
> be the current correct way to emit it so that what you emit is understood
> by the backend and if you've got any specific questions the mailing list
> should work well.
>
> -eric
>
>
>
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