RFR(S) 8251271- C2: Compile::_for_igvn list is corrupted after RenumberLiveNodes

[Liu, Xin]

hi, Nhat and Christian, 

I reviewed this patch. I feel resuming the old worklist looks suspicious. 
PhaseRenumberLive renumbers nodes associates with gvn. old _worklist might have wrong idx  and types. 

Instead of resuming old _worklist,  you can copy out nodes from new_worklist to your current _worklist. 

diff --git a/src/hotspot/share/opto/compile.cpp b/src/hotspot/share/opto/compile.cpp
--- a/src/hotspot/share/opto/compile.cpp
+++ b/src/hotspot/share/opto/compile.cpp
@@ -2089,7 +2089,10 @@
       ResourceMark rm;
       PhaseRenumberLive prl = PhaseRenumberLive(initial_gvn(), for_igvn(), &new_worklist);
     }
-    set_for_igvn(&new_worklist);
+    for_igvn()->clear();
+    while (new_worklist.size() > 0) {
+     for_igvn()->push(new_worklist.rpop());
+    }
     igvn = PhaseIterGVN(initial_gvn());
     igvn.optimize();
   }


thanks, 
--lx

________________________________________
From: hotspot-compiler-dev <hotspot-compiler-dev-retn at openjdk.java.net> on behalf of Christian Hagedorn <christian.hagedorn at oracle.com>
Sent: Thursday, August 27, 2020 7:54 AM
To: Nhat Nguyen; hotspot-compiler-dev at openjdk.java.net
Subject: RE: [EXTERNAL] RFR(S) 8251271- C2: Compile::_for_igvn list is corrupted after RenumberLiveNodes

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Hi Nhat

Looks good to me!

Just make sure you that next time you assign the bug to you or a sponsor
and/or leave a comment that you intend to work on it to avoid the
possibility of some duplicated work (was no problem in this case) ;-)

Best regards,
Christian

On 26.08.20 20:55, Nhat Nguyen wrote:
> Hi hotspot-compiler-dev,
>
> Please review the following patch to address https://bugs.openjdk.java.net/browse/JDK-8251271
> The bug is currently assigned to Christian Hagedorn, but he was supportive of me submitting the patch instead.
> I have run hotspot/tier1 and jdk/tier1 tests to make sure that the change is working as intended.
>
> webrev: http://cr.openjdk.java.net/~burban/nhat/JDK-8251271/webrev.00/
>
> Thank you,
> Nhat
>