RFR(XXS): 8039348: -XX:+TraceDeoptimization -XX:+Verbose -Xcomp can crash VM

[Vladimir Kozlov]

Hi, Markus

Thank you for fixing this. Please, keep "NULL" output as it was before. 
Otherwise it is good.

Thanks,
Vladimir

On 4/7/14 11:24 AM, Markus Grönlund wrote:
> Hi again,
>
> Updated the webrev to give a bit more descriptive message for debugging
> purposes:
>
> Webrev02: http://cr.openjdk.java.net/~mgronlun/8039348/webrev02/
>
> Thanks again
>
> Markus
>
> *From:*Markus Grönlund
> *Sent:* den 6 april 2014 21:08
> *To:* Staffan Larsen
> *Cc:* serviceability-dev at openjdk.net; hotspot-runtime-dev at openjdk.java.net
> *Subject:* RE: RFR(XXS): 8039348: -XX:+TraceDeoptimization -XX:+Verbose
> -Xcomp can crash VM
>
> Actually, now reflecting a bit more on it, since this uncommon trap
> happens while executing the constructor itself, one could argue that the
> object instance is not yet created.
>
> In addition, the “normal” representation of the java/lang/String  object
> in print() is the value of the [C array – so in that case it might very
> well be that “NULL” is  the value to output, since there is no [C.
>
> I can keep “NULL” as is.
>
> /Markus
>
> *From:*Markus Grönlund
> *Sent:* den 6 april 2014 20:51
> *To:* Staffan Larsen
> *Cc:* serviceability-dev at openjdk.net
> <mailto:serviceability-dev at openjdk.net>;
> hotspot-runtime-dev at openjdk.java.net
> <mailto:hotspot-runtime-dev at openjdk.java.net>
> *Subject:* RE: RFR(XXS): 8039348: -XX:+TraceDeoptimization -XX:+Verbose
> -Xcomp can crash VM
>
> Yes. The java/lang/String object is not NULL but it’s [C field is.
>
> In the local/expression slots output, there is an object there, it’s not
> NULL, it’s being created.
>
> /Markus
>
> *From:*Staffan Larsen
> *Sent:* den 6 april 2014 20:24
> *To:* Markus Grönlund
> *Cc:* serviceability-dev at openjdk.net
> <mailto:serviceability-dev at openjdk.net>;
> hotspot-runtime-dev at openjdk.java.net
> <mailto:hotspot-runtime-dev at openjdk.java.net>
> *Subject:* Re: RFR(XXS): 8039348: -XX:+TraceDeoptimization -XX:+Verbose
> -Xcomp can crash VM
>
> You have changed the output when the ‘value’ field is not set from NULL
> to “”. Was this intentional?
>
> /Staffan
>
> On 6 apr 2014, at 19:05, Markus Grönlund <markus.gronlund at oracle.com
> <mailto:markus.gronlund at oracle.com>> wrote:
>
> Greetings,
>
> Kindly asking for reviews for this small fix:
>
> Bug:https://bugs.openjdk.java.net/browse/JDK-8039348
>
> Webrev:http://cr.openjdk.java.net/~mgronlun/8039348/webrev01/
>
> Found when debugging:
>
> -XX:+TraceDeoptimization -XX:+Verbose –Xcomp
>
> Using –Xcomp can cause an uncommon trap in java/lang/String constructors
> before the [C value field has been assigned.
>
> Thanks
>
> Markus
>