Request for review (S) 6588413: Use -fvisibility=hidden for gcc compiles

[Coleen Phillimore]

I need another review, please!
Thanks,
Coleen

On 1/24/2011 2:15 PM, Coleen Phillimore wrote:
> Summary: Add option for gcc 4 and above, define JNIEXPORT and JNIIMPORT
>
> open webrev at http://cr.openjdk.java.net/~coleenp/6588413_2/
>
> This is an update to the code review.  I found symbols that we should 
> have exported. I also found exported symbols that were old and unused 
> and removed them.  Embedded question for Igor.
>
> Tested with some SA tests and others.
>
> Coleen
>
> On 1/21/2011 3:39 PM, Coleen Phillimore wrote:
>> On 1/21/2011 12:47 PM, Dmitry Samersoff wrote:
>>> Coleen,
>>>
>>> 1. Hotspot uses a mapfile to hide unused symbols -
>>>    could we just change the mapfile?
>> Thanks Dmitry for this question because it prompted me to do more 
>> searching and there were some definitions that should have JNIEXPORT 
>> on them in the VM (AsyncGetCallTrace would have been broken!).   The 
>> option -fvisibility=hidden does more than hide the symbols as the 
>> mapfile does, it also allows the compiler to optimize the address 
>> calculations for internal functions it calls.  I believe that is 
>> where we get our performance improvements.
>>>
>>> 2. JNICALL is empty in both parts of #ifdef.
>>
>> Thanks, I fixed that.
>>
>> Coleen
>>>
>>> -Dmitry
>>>
>>>
>>> On 2011-01-21 19:57, Coleen Phillimore wrote:
>>>> Summary: Add option for gcc 4 and above, define JNIEXPORT and 
>>>> JNIIMPORT
>>>> to visibility=default, add for jio_snprintf and others since
>>>> -fvisibility=hidden overrides --version-script definitions.
>>>>
>>>> Performance increases measured by Volker and Tom;
>>>>
>>>> 5% (JBB2005) and 2% (JVM98) on Linux/IA64 and 1,5% (JBB2005) and
>>>> 0,5% (JVM98) on Linux/PPC64
>>>>
>>>>
>>>> on intel hardware:
>>>>
>>>> specjvm98 15 314.61 0.00 0.33 0.006 Yes
>>>> javac 15 248.88 0.01 1.72 0.000 Yes
>>>> jack 15 294.44 0.01 1.38 0.000 Yes
>>>>
>>>>
>>>> open webrev at http://cr.openjdk.java.net/~coleenp/6588413/
>>>> bug link at http://bugs.sun.com/view_bug.do?bug_id=6588413
>>>>
>>>> Tested with jmap for any serviceability impact, and tested hs_err_file
>>>> decoding still works.
>>>>
>>>> Thanks,
>>>> Coleen
>>>>
>>>
>>>
>>
>