[PATCH] D113741: [RFC][DwarfDebug][AsmPrinter] Support emitting function-local declaration for a lexical block

Mon May 23 16:40:44 PDT 2022

dblaikie added a comment.

In D113741#3516038 <https://reviews.llvm.org/D113741#3516038>, @krisb wrote:

> There is an alternative implementation that relies on addition field of DISubprogram/DILexicalScope that tracks static locals, local imports and types D125693 <https://reviews.llvm.org/D125693>.

Ah, OK - so that 5-part sequence is an alternative to this one?

Might be good to figure out the issue here before debating which direction to go in, etc. (hmm, one of the patches in that series I've already approved? So am I reviewing alternatives here? Given the complexity here that's a bit costly for me/end up feeling like I'm drowning under trying to figure out all these moving parts... - a linear sequence is generally OK/good, I can review the easy parts and focus on the difficult ones, but multiple large alternatives can be a bit daunting)

> ---
>
> In D113741#3448685 <https://reviews.llvm.org/D113741#3448685>, @jmorse wrote:
>
>> Drive-by comment on the topic of the gnu pubnames error,
>>
>> In D113741#3439940 <https://reviews.llvm.org/D113741#3439940>, @krisb wrote:
>>
>>> If I remember correctly, this issue with .debug_gnu_pubnames was caused by another patch (https://reviews.llvm.org/rG78d15a112cbd545fbb6e1aa37c221ef5aeffb3f2). 
>>> Did I understand you right that the same issue is reproduced with w/o that patch?
>>
>> I've run into that error myself when trying to alter which unit a subprogram definition goes in -- see the comment at D94976#2543257 <https://reviews.llvm.org/D94976#2543257> . That patch never landed in the end because I couldn't figure out exactly what was wrong. IMHO, there's some latent weirdness that triggers that error, exactly how is unclear though. IMO, it's not specific to rG78d15a112cbd5 <https://reviews.llvm.org/rG78d15a112cbd545fbb6e1aa37c221ef5aeffb3f2> .
>>
>> [0] "(.debug_gnu_pubnames): name lookup table at offset (...) has a terminator at offset (...) before the expected end at (...)"
>
> I've tried to reproduce the issue using the example from D94976 <https://reviews.llvm.org/D94976> (and with this patch), it compiled fine and didn't show the mentioned problem with pubnames. 
> Another question is about the combination of FullLTO and split-dwarf which has been already discussed in this thread and which isn't (fully) supported by LLVM mainline (yet, at least in a way that doesn't violate DWARF specification).
>
> So, I'm still looking for a reproducer for the issue with pubnames. Any help will be appreciated.

Yeah, I still need to figure out how to do that/get you that. :/

(is this at all/possibly related to https://reviews.llvm.org/D124892 ?)

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