RFR: 8033251: Use DWARF debug symbols for Linux 32-bit as default

[Coleen Phillimore]

On 3/28/14 12:44 PM, Erik Helin wrote:
> Hi Coleen,
>
> thanks for having a look at the patch!
>
> On 2014-03-28 17:30, Coleen Phillimore wrote:
>>
>> I thought you'd be able to remove the DEBUG_BINARIES logic with this
>> change.  It appears there are no platforms left that use stabs with
>> gcc.
>
> Yeah, I also noticed that this change enables cleanups in the 
> Makefiles. However, I think it is better to do these cleanups as a 
> second change after this one, what do you think?

A cleanup CR is fine.
>
> On 2014-03-28 17:30, Coleen Phillimore wrote:
>> Does this change add -g for saproc, adlc and jsig compilations also?
> It seems like saproc uses SA_DEBUG_CFLAGS which only is being set if 
> DEBUG_BINARIES=true. If DEBUG_BINARIES is not true, then it seems like 
> we don't generate debug symbols (please correct me if I'm wrong).
>
> The above also seems to be the case for libjsig.so.
>

These seem broken, but I don't know the makefiles well enough to comment.

I think this change is good.  People have been asking for it for years 
and now that the size problem with dwarf has been fixed, I'm glad you 
are making this change.

Thanks,
Coleen
> Looking in make/linux/makefiles/adlc.make it seems like adlc is using 
> -g for GCC 3.3 or newer.
>
> Thanks,
> Erik
>
>> Coleen
>>
>> On 3/28/14 12:12 PM, Erik Helin wrote:
>>> Hi all,
>>>
>>> this patch changes the Linux Makefiles to use DWARF as the default
>>> debug symbol format for Linux 32-bit instead of STABS. The main
>>> arguments for using DWARF are:
>>>
>>>   - DWARF provides a superior debugging experience compared to STABS.
>>>   - STABS support in GCC/GDB is in maintenance mode [0].
>>>   - External tools (e.g. perf on Linux) often understands DWARF but not
>>>     STABS.
>>>   - Compilation on 32-bit Linux can make use of precompiled headers.
>>>
>>> Webrev:
>>> http://cr.openjdk.java.net/~ehelin/8033251/webrev.00/
>>>
>>> Testing:
>>> - Compiling with GCC 4.3.4, GCC 4.7.3 and GCC 4.8.1
>>> - JPRT
>>>
>>> Thanks,
>>> Erik
>>>
>>> [0]: https://sourceware.org/ml/binutils/2013-01/msg00028.html
>>