RFR: 8242181: [Linux] Show source information when printing native stack traces in hs_err files [v8]

[Magnus Ihse Bursie]

On Fri, 13 May 2022 08:43:35 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> I'm googling around for some information about -gdwarf-4 but is mostly coming up empty handed. :( I found [this](https://www.phoronix.com/scan.php?page=news_item&px=GCC-11-DWARF-5-Possible-Default) saying that dwarf-5 became default in gcc11. It also claims dwarf-4 is about 10 years old. My guess is that all our supported gcc versions do support -gdwarf-4, but this needs to be verified.
>> 
>> In practice, we only use gcc on linux so I'm not convinced we need to have an addition check for that. If we ever are going to support gcc on other OSes I think we'll have many more, much harder problems, than to remove the -gdwarf-4 flag.
>
> I'm back to work again. I also had a look but could not find something on Google, either. I then skimmed through the old GCC manuals. I found the first occurrence of `-gdwarf-4` in the manual for GCC 4.5.4 [here](https://gcc.gnu.org/onlinedocs/gcc-4.5.4/gcc.pdf):
> 
> 
> - gdwarf-version
>     Produce debugging information in DWARF format (if that is supported). This
>     is the format used by DBX on IRIX 6. The value of version may be either 2, 3
>     or 4; the default version is 2.
> 
> While the manual for GCC 4.4.7 only mentions `-gdwarf-2`:
> 
> -gdwarf-2
>     Produce debugging information in DWARF version 2 format (if that is supported). This is the format used by DBX on 
>     IRIX 6. With this option, GCC
>     uses features of DWARF version 3 when they are useful; version 3 is upward
>     compatible with version 2, but may still cause problems for older debuggers.
> 
> 
> The minimum accepted GCC version is currently 5.0 according to:
> https://github.com/openjdk/jdk/blob/d5ae3833b1b71eb84fadb69c0c92851400f8921c/doc/building.md?plain=1#L341-L344
> 
> This suggests that all our supported GCC versions should accept `-gdwarf-4`.

@chhagedorn Thanks for the research. You provide more than necessary reason to accept `-gdwarf-4` without any further checks.

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PR: https://git.openjdk.java.net/jdk/pull/7126