[9] RFR(XS): 8148564: compiler/intrinsics/string/TestStringIntrinsics2.java times out

[Tobias Hartmann]

Hi Volker,

On 12.02.2016 10:31, Volker Simonis wrote:
> Hi Tobias,
> 
> thanks for fixing the test. I can confirm that the intrinsics are
> still inlined with -XX:MaxInlineSize=70.

Thanks for verifying.

> I'm only a little confused why we need -Xmixed. This should be the
> default anyway. Or do you run jtreg tests by setting -Xcomp
> explicitly?

Yes, our nightly tests run with different (explicit) flag combinations. Adding -Xmixed to the test overrides the -Xcomp flag.

Thanks,
Tobias

> 
> Thumbs up from me as well,
> Volker
> 
> 
> On Thu, Feb 11, 2016 at 3:29 PM, Tobias Hartmann
> <tobias.hartmann at oracle.com> wrote:
>> Hi,
>>
>> please review the following patch.
>>
>> https://bugs.openjdk.java.net/browse/JDK-8148564
>> http://cr.openjdk.java.net/~thartmann/8148564/webrev.00/
>>
>> The test times out with a fastdebug build and -Xcomp after 356 seconds. The profile shows that most time is spent in C1:
>> 40.06% java libjvm.so [.] RangeCheckEliminator::Verification::can_reach(BlockBegin*, BlockBegin*, BlockBeg
>> 20.08% java libjvm.so [.] LinearScan::is_sorted(IntervalArray*)
>> 4.47% java libc-2.19.so [.] memset
>>
>> LinearScan::is_sorted() is known to be very slow (JDK-8067014). It seems that RangeCheckEliminator::Verification::can_reach() also slows down performance significantly.
>> Without these checks the runtime drops down to 126 seconds.
>>
>> The accumulated compiler times also show that most time is spent in C1 (see [1]):
>> C1 Compile Time: 326.983 s
>> C2 Compile Time: 3.241 s
>>
>> A product build is significantly faster, i.e. the slowdown is caused by additional C1 verification code in fastdebug builds:
>> C1 Compile Time: 8.463 s
>> C2 Compile Time: 1.619 s
>>
>> The problem is that the test specifies -XX:MaxInlineSize=100 to trigger inlining of intrinsics. With -Xcomp, this also causes many other methods to be inlined, blowing up the graphs and significantly slowing down compilation. Since the test uses the Whitebox API to trigger compilation, -Xcomp is not required.
>>
>> I verified that -XX:MaxInlineSize=70 is enough to inline all intrinsics and added -Xmixed to the test to avoid compilation of unrelated methods.
>>
>> Thanks,
>> Tobias
>>
>> [1] https://bugs.openjdk.java.net/secure/attachment/57052/CITime.log
>>