HotSpot 17 merge

[Andrew John Hughes]

On 17 May 2010 17:29, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
> When we released jdk6u18 (hs16) there were 2 EA critical bugs
> for which we did not have time to fix in 6u18:
>
> http://hg.openjdk.java.net/jdk7/hotspot-comp/hotspot/rev/f96a1a986f7b
> http://hg.openjdk.java.net/jdk7/hotspot-comp/hotspot/rev/7fee0a6cc6d4
>
> In short, with escape analysis the generated code produces NULL(0)
> instead of expected (stored) values.
>
> There was no enough time for full testing in 6u18 and changes were too big.
> I would advice to not use EA with HS16.
>
> In hs17 we enabled EA again and tested it until 6u21 release in which
> the default flag's value is set to false but you can specify the flag
> on command line to enable EA. There are few problems which needs to be
> fixed before we enable EA by default.
>
> Andrew, you are right to not merge changes from hs16. And you can use
> the flag on command line for HS17 instead of patch to enable EA.
> It would be easier for benchmarking.
>

Unfortunately it's not a matter of choosing not to merge the change,
but having to revert it as it's already part of OpenJDK6 from the
earlier hs16 merge (currently showing up as a difference between
OpenJDK6's HotSpot and the hs17 branch).  See the results and
discussion in the mail I just posted.

> Vladimir
>
> Andrew John Hughes wrote:
>>
>> On 16 May 2010 18:22, Andrew Haley <aph at redhat.com> wrote:
>>>
>>> On 05/16/2010 05:14 PM, Andrew John Hughes wrote:
>>>>
>>>> The webrev is here:
>>>>
>>>> http://cr.openjdk.java.net/~andrew/jdk6-hs17-merge/
>>>>
>>>> I'd also like to revert:
>>>>
>>>> 6909480: Disable Escape Analysis in jdk 6u18
>>>> http://hg.openjdk.java.net/hsx/hsx16/master/rev/4ebd3f8407eb
>>>>
>>>> which isn't present in hs17 (and so remains a difference between jdk6
>>>> and hs17) as, unlike jdk6's version, hs17 is based on the main HotSpot
>>>> tree rather than the hs16 master.  I didn't include this in the merge
>>>> because it's clearer what's going on if it appears as a separate
>>>> change.
>>>
>>> Ahh, good catch.
>>>
>>> Do we have any idea why escape analysis is disabled?
>>>
>>> Andrew.
>>>
>>
>> I assume it wasn't stable enough in hs16, but the bug isn't visible.
>> Can someone from the HotSpot team shed more light on this?
>



-- 
Andrew :-)

Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

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