JDK-8192977 : LoopStripMiningIter is set to 1000 if UseCountedLoopSafepoints is enabled
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 10
  • Priority: P3
  • Status: Closed
  • Resolution: Duplicate
  • Submitted: 2017-12-04
  • Updated: 2019-09-13
  • Resolved: 2017-12-06
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JDK 10
10Resolved
Related Reports
Duplicate :  
JDK-8192908 - -XX:+UseCountedLoopSafepoints alone doesn't disable strip mining with G1
Relates :  
JDK-8186027 - C2: loop strip mining
Relates :  
JDK-8154302 - C2 removes safepoint poll from loop
Description
java -XX:+UseCountedLoopSafepoints -XX:+PrintFlagsFinal -version | grep LoopStripMiningIter
Java HotSpot(TM) 64-Bit Server VM warning: When counted loop safepoints are enabled, LoopStripMiningIter must be at least 1 (a safepoint every 1 iteration): setting it to 1
    uintx LoopStripMiningIter                      = 1000                                  {C2 product} {default}
    uintx LoopStripMiningIterShortLoop             = 0                                     {C2 product} {default}
java version "10-internal"
Java(TM) SE Runtime Environment (fastdebug build 10-internal+0-adhoc.tobias.open)
Java HotSpot(TM) 64-Bit Server VM (fastdebug build 10-internal+0-adhoc.tobias.open, mixed mode)

See also Roland's comment in JDK-8154302.
Comments
ILW = Misleading warning and wrong default value (regression in JDK 10), with -XX:+UseCountedLoopSafepoints, set LoopStripMiningIter explicitly to 1 = MMM = P3
04-12-2017