Re: Follow up to stabs deprecation - AIX regressions

[Simon Marchi <simark@simark.ca>]

On 2025-02-13 12:58, Guinevere Larsen wrote:
> On 2/13/25 2:43 PM, Kevin Buettner wrote:
>> On Thu, 13 Feb 2025 14:21:01 -0300
>> Guinevere Larsen <guinevere@redhat.com> wrote:
>>
>>> On 2/13/25 1:48 PM, Kevin Buettner wrote:
>>>> On Thu, 13 Feb 2025 09:25:44 -0300
>>>> Guinevere Larsen <guinevere@redhat.com> wrote:
>>>>  
>>>>> * DWARF reading can sometimes fail in AIX. Currently, reading dwarf for
>>>>> xcoff inferiors is called on it's own, with no warning if dwarf fails
>>>>> (which probably makes sense, considering the default format in aix is
>>>>> still stabs). I added a warning when failing to read dwarf and noticed
>>>>> it being triggered on inferiors compiled with -gdwarf  
>>>> I assume that you mean that stabs is the default when compiling with
>>>> gcc.  Is stabs still also the default format for XLC (IBM Open XL C/C++) ?  
>>> Yes, sorry, I meant gcc. The compile farm had versions 10 and 12, both 
>>> with the same behavior.
>>>
>>> I don't think the compile farm has XLC compilers available for testing, 
>>> or if they do I don't know how to use it, so I couldn't tell you...
>> I think it'd be good to find out XLC's preferred debug format.  If it
>> uses/prefers DWARF, that'd be a good argument for gcc (on AIX)
>> switching to DWARF for it's preferred format too.
>>
>> Kevin
>>
> I just looked over at the GCC releases, and the GCC12 changelog says the following:
> 
>   * *STABS:* Support for emitting the STABS debugging format is deprecated and will be removed in the next release. All ports now default to emit DWARF (version 2 or later) debugging info or are obsoleted.
> 
> Since the default is supposed to have changed *in* gcc 12 - which is the version that AIX has - or the port be obsolete, it looks to me like that gcc on AIX is obsoleted...
> 
> In other words, gcc already knows it should change but seems to have given up on AIX?

Given this commit (present in gcc 11):

https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=56b5d13e27891ed1caec07826a07bb2e0621f914

I would expect gcc 12 to produce DWARF by default, I'm not sure why you
don't see that.

Simon