RFR(S): 8214352: C1: Unnecessary "compilation bailout: block join failed" with JVMTI

[Igor Veresov]

So how and why does it happen that a phi has different input types?

igor



> On Dec 3, 2018, at 2:24 AM, Doerr, Martin <martin.doerr at sap.com> wrote:
> 
> Hi Vladimir,
> 
> thanks for reviewing. I hope a C1 expert can find some time to take a look.
> 
> Best regards,
> Martin
> 
> 
> -----Original Message-----
> From: hotspot-compiler-dev <hotspot-compiler-dev-bounces at openjdk.java.net> On Behalf Of Vladimir Kozlov
> Sent: Sonntag, 2. Dezember 2018 01:50
> To: hotspot-compiler-dev at openjdk.java.net
> Subject: Re: RFR(S): 8214352: C1: Unnecessary "compilation bailout: block join failed" with JVMTI
> 
> Seems fine to me but I am not C1 expert.
> 
> Regards,
> Vladimir
> 
> On 11/27/18 3:03 AM, Doerr, Martin wrote:
>> Hi,
>> 
>> C1 currently bails out when a local value is derived from a Phi with different types.
>> 
>> According to comments, this case is supposed to be very rare, but it's not so rare when a JVMTI agent is used 
>> (capability "can_access_local_variables").
>> 
>> I'd like to fix this.
>> 
>> Issue with more detailed description:
>> 
>> https://bugs.openjdk.java.net/browse/JDK-8214352
>> 
>> Webrev:
>> 
>> http://cr.openjdk.java.net/~mdoerr/8214352_c1_phi/webrev.00/ 
>> <http://cr.openjdk.java.net/%7Emdoerr/8214352_c1_phi/webrev.00/>
>> 
>> Patch successfully ran through a substantial amount of tests with enabled "can_access_local_variables". Please review.
>> 
>> Best regards,
>> 
>> Martin
>> 

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