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From: Apache Wiki <wikidiffs@apache.org>
To: commits@harmony.apache.org
Date: Tue, 06 May 2008 08:43:30 -0000
Message-ID: <20080506084330.18260.34734@eos.apache.org>
Subject: [Harmony Wiki] Update of "Jitrino OPT/bbp" by George Timoshenko

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The following page has been changed by George Timoshenko:
http://wiki.apache.org/harmony/Jitrino_OPT/bbp

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  Back-Branch Polling is for yield points insertion at back branches of certain kinds of loops to enable safe thread suspension. Several approaches are implemented there:
  
-     //  0 - the feature is turned off
+  * 0 - the feature is turned off
-     //  1 - insert interruptable subgraph at all backedges except those going from initiallyInterruptable nodes
+  * 1 - insert interruptable subgraph at all backedges except those going from initiallyInterruptable nodes
-     //      (initialInterruptability is not being propagated to the successors. This is the feature of version 5)
+   (initialInterruptability is not being propagated to the successors. This is the feature of version 5)
-     //  2 - path analysis based on searching of pairs [isOnThreadInterruptablePath]->[!isOnThreadInterruptablePath]
+  * 2 - path analysis based on searching of pairs [isOnThreadInterruptablePath]->[!isOnThreadInterruptablePath]
-     //  3 - recursive version of "2"
+  * 3 - recursive version of "2"
-     //  4 - "1" + suspension flag addr [TLS base + offset] is calculated before the loop header
+  * 4 - "1" + suspension flag addr [TLS base + offset] is calculated before the loop header
-     //  5 - like "1" but some backedges are not patched (if all paths through it are uninteruptable)
+  * 5 - like "1" but some backedges are not patched (if all paths through it are uninteruptable)
-     //  6 - "4" + "5"
+  * 6 - "4" + "5"
  
  
- They can be switched using the following:
+ They can be switched using the following: ["-XX:jit.arg.bbp=[0-6]"]
  
- - XX:jit.arg.bbp=[0-6]
+ '''Possible improvement'''
  
+ It may have sence to try BBPolling at earlier stages - in HLO.
- Possible improvement
- 
- It may have sence BBPolling is worth to be done earlier - in HLO.
  To clarify one need to implemet HLO pass for this and find the best position (from the performance POV) for it in the HLO path.