Re: [PATCH v2 0/9] pahole: Support cross-CU type references and dwz alternate debug files

[Alan Maguire <alan.maguire@oracle.com>]

On 26/08/2026 01:52, Arnaldo Carvalho de Melo wrote:
> On Fri, Aug 21, 2026 at 06:34:59PM -0300, Arnaldo Carvalho de Melo wrote:
>> From: Arnaldo Carvalho de Melo <acme@redhat.com>
>>
>> Add support for cross-CU type references and dwz alternate debug
>> files so pahole can process binaries (e.g. a perf binary with rust
>> objects, or Firefox) that use DW_FORM_ref_addr inter-CU references or
>> dwz-compressed .dwz alternate debug files.
>>
>> Cross-CU type references:
>>
>>   Force-merge CUs that contain inter-CU references (DW_FORM_ref_addr)
>>   so type lookups resolve correctly.  Handle same-file partial units
>>   where types are shared across CUs via DW_TAG_imported_unit.  Fix
>>   cus__merging_cu failing to detect DW_FORM_ref_addr when
>>   DW_FORM_implicit_const causes dwarf_getabbrevattr() to fail.
> 
> I did a lot of test runs, and with the patches that are waiting for this
> series to be landed that stress even more this series, so I'll merge
> this tomorrow unless anybody have anything against it.
> 
> And then as a followup I'll land a series of test patches that don't
> affect the functioning of these tools, just do coverage analysis and add
> lots more tests for its features.
> 
> We need to release a new version as there are people asking for features
> developed and not yet released, so I'll make sure we get the goodies in
> and the release out ASAP,
> 
> Best regards,
> 
> - Arnaldo

Changes look good CI-wise, one issue that we see (not just for this series)
is that perf on some systems is a shell script that selects the kernel-version-specific
binary, so the result is tests relying on perf being a binary get skipped.
Not a big deal now but maybe we could come up with variants in the future that
generate inter-cu references reliably locally.

I tried a few other approaches where we handle inter-cu references, but all seemed
like they were a bit too complex or involved multiple traversals of the CU set and
were too expensive time-wise.

I can land these if you'd prefer, whatever works. Thanks!

Alan