[11u] RFR 8240795: [REDO] 8238384 CTW: C2 compilation fails with "assert(store != load->find_exact_control(load->in(0))) failed: dependence cycle found"

[Vladimir Kozlov]

On 12/22/20 4:26 AM, Lindenmaier, Goetz wrote:
> Hi Richard,
> 
> I had a look at this change.
> I assume you need it because the follow up calls is_known_instance().
> 
> The change looks good.

+1

> 
> "JDK-8238691: C2: turn subtype check into macro node" is not really
> a candidate for downport. Else I would fear the omitted chunk gets
> forgotten once that change is downported, as this bug will be marked as
> ported to 11. A solution would be a JBS issue of its own like "Bring parts
> of 8240795 to 11."  But not really necessary here.

I suggest to add comment about this missing part when backport issues is created in JBS.

Regards,
Vladimir K

> 
> Best regards,
>    Goetz.
> 
> 
> 
>> -----Original Message-----
>> From: jdk-updates-dev <jdk-updates-dev-retn at openjdk.java.net> On Behalf
>> Of Reingruber, Richard
>> Sent: Tuesday, December 22, 2020 12:13 PM
>> To: jdk-updates-dev at openjdk.java.net; hotspot-compiler-
>> dev at openjdk.java.net
>> Subject: [11u] RFR 8240795: [REDO] 8238384 CTW: C2 compilation fails with
>> "assert(store != load->find_exact_control(load->in(0))) failed: dependence
>> cycle found"
>>
>> Hi,
>>
>> I would like to downport JDK-8240795 to 11u as prerequisite for the
>> downport of
>> JDK-8243670.
>>
>> I need to be sponsored for this too, please.
>>
>> Please review:
>>
>> Original bug:
>>    https://bugs.openjdk.java.net/browse/JDK-8240795
>>    https://hg.openjdk.java.net/jdk/jdk/rev/993974f21271
>>
>> 11u webrev:
>>
>> http://cr.openjdk.java.net/~rrich/webrevs/8240795_11u_REDO__8238384_
>> CTW__C2_compilation_fails_with__assert_dependence_cycle_found/webre
>> v.0/
>>
>> Modifications:
>>
>>    The 2 hunks for loopnode.cpp were removed from the original patch. They
>> do not
>>    apply because they are based on the enhancement 8238691 which has not
>> been
>>    downported. These hunks introduced a bug which was fixed with 8252292. I
>> don't
>>    intend to downport 8252292 but I have verified that the included test case
>>    succeeds even without it.
>>
>> Testing:
>>
>> test/hotspot/jtreg/compiler/escapeAnalysis/TestMissingAntiDependency.jav
>> a
>>    - from 8252292
>>    - succeeds independently of the patch under review
>>    - will not be downported
>>
>> test/hotspot/jtreg/compiler/escapeAnalysis/TestCopyOfBrokenAntiDepende
>> ncy.java
>>    - included in the patch under review
>>    - fails without patch (assertion "dependence cycle found")
>>    - succeeds with patch
>>
>>
>> CI testing @SAP: JCK and JTREG, also in Xcomp mode, SPECjvm2008,
>> SPECjbb2015, Renaissance Suite,
>> SAP specific tests with fastdebug and release builds on all platforms
>>
>> Thanks, Richard.