RFR(XS) 8046289: compiler/6340864/TestLongVect.java timeout with

[Rickard Bäckman]

Vladimir, Tobias

I've looked into something that tries to find out when we have "good
enough" profiling information. Since the bug I've been working on only
happens with the -Xcomp flag, I've tried to special case that instead so
that we don't put uncommon traps when running with -Xcomp since the
profiling information usually is pretty bad.

Updated webrev: http://cr.openjdk.java.net/~rbackman/8046289.3/

Thanks
/R

On 07/01, Tobias Hartmann wrote:
> Hi,
> 
> >Some background: Tobias and me have been looking at JDK-8014830
> >[1] and JDK-8030976 fixed the problem. I suspect that this change
> >will return 8014830.
> 
> I just tested the changes and the bug (JDK-8014830) appears again.
> The problem is that no uncommon trap is added after the first loop
> and therefore the second loop, especially the call to inc(), is not
> profiled. The compiler assumes that the call site is never executed
> and does not inline inc().
> 
> I agree with Vladimir that we should not special case loop exits but
> find a solution for the case were we only have limited or no profile
> information.
> 
> Best,
> Tobias
> 
> >
> >Best regards,
> >Vladimir Ivanov
> >
> >[1] https://bugs.openjdk.java.net/browse/JDK-8014830
> >
> >On 6/30/14 11:26 AM, Rickard Bäckman wrote:
> >>Reviews please?
> >>
> >>Thanks
> >>/R
> >>
> >>On 06/23, Rickard Bäckman wrote:
> >>>Hi,
> >>>
> >>>a test started to timeout after JDK-8030976 was pushed. The
> >>>test was run
> >>>with -Xcomp flag, so the profiling data available is non-existing or
> >>>small. For some cases that meant that if a loop had at least 1
> >>>iteration
> >>>executed it would look like the loop would always take the backedge and
> >>>never end and we would generate an uncommon trap on the loop exit.
> >>>
> >>>The small change checks if the block we are considering turning into an
> >>>uncommon trap is a loop exit.
> >>>
> >>>Bug: https://bugs.openjdk.java.net/browse/JDK-8046289
> >>>Webrev: http://cr.openjdk.java.net/~rbackman/8046289/
> >>>
> >>>Thanks
> >>>/R
> >>
> >>
> 
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