Re: [PATCH dwarves] dwarf_loader: handle subprogram ret type with abstract_origin properly

[Yonghong Song <yhs@fb.com>]

On 4/2/21 11:08 AM, Arnaldo wrote:
> 
> 
> On April 2, 2021 2:42:21 PM GMT-03:00, Yonghong Song <yhs@fb.com> wrote:
>> On 4/2/21 10:23 AM, Yonghong Song wrote:
> :> Thanks. I checked out the branch and did some testing with latest
>> clang
>>> trunk (just pulled in).
>>>
>>> With kernel LTO note support, I tested gcc non-lto, and llvm-lto
>> mode,
>>> it works fine.
>>>
>>> Without kernel LTO note support, I tested
>>>     gcc non-lto  <=== ok
>>>     llvm non-lto  <=== not ok
>>>     llvm lto     <=== ok
>>>
>>> Surprisingly llvm non-lto vmlinux had the same "tcp_slow_start"
>> issue.
>>> Some previous version of clang does not have this issue.
>>> I double checked the dwarfdump and it is indeed has the same reason
>>> for lto vmlinux. I checked abbrev section and there is no cross-cu
>>> references.
>>>
>>> That means we need to adapt this patch
>>>     dwarf_loader: Handle subprogram ret type with abstract_origin
>> properly
>>> for non merging case as well.
>>> The previous patch fixed lto subprogram abstract_origin issue,
>>> I will submit a followup patch for this.
>>
>> Actually, the change is pretty simple,
>>
>> diff --git a/dwarf_loader.c b/dwarf_loader.c
>> index 5dea837..82d7131 100644
>> --- a/dwarf_loader.c
>> +++ b/dwarf_loader.c
>> @@ -2323,7 +2323,11 @@ static int die__process_and_recode(Dwarf_Die
>> *die, struct cu *cu)
>>          int ret = die__process(die, cu);
>>          if (ret != 0)
>>                  return ret;
>> -       return cu__recode_dwarf_types(cu);
>> +       ret = cu__recode_dwarf_types(cu);
>> +       if (ret != 0)
>> +               return ret;
>> +
>> +       return cu__resolve_func_ret_types(cu);
>>   }
>>
>> Arnaldo, do you just want to fold into previous patches, or
>> you want me to submit a new one?
> 
> I can take care of that.
> 
> And I think it's time for to look at Jiri's test suite... :-)
> 
> It's a holiday here, so I'll take some time to get to this, hopefully I'll tag 1.21 tomorrow tho.

Thanks for taking care of this! Right, 1.21 looks very close.

> 
> Cheers,
> 
> - Arnaldo
>