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  1. JDK
  2. JDK-8367627

C2: Missed Ideal() optimization opportunity in PhaseIterGVN

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      There is a missed Ideal() optimization opportunity when running RunThese30M.java with -XX:VerifyIterativeGVN=1110. Can also be reproduced with the attached replay file.

      Missed Ideal optimization (can_reshape=true):
      The node was reshaped by Ideal.
      The result after Ideal:
      dist dump
      ---------------------------------------------
         1 133 MergeMem === _ 1 7 40 40 40 40 [[ 139 ]] { N40:rawptr:BotPTR N40:java/lang/Object * N40:java/lang/Object+8 * [narrowklass] N40:java/util/concurrent/atomic/AtomicLong (java/io/Serializable)+16 * } Memory: @BotPTR *+bot, idx=Bot; !jvms: AtomicLong::get @ bci:-1 (line 91) AtomicLong::intValue @ bci:1 (line 358) AtomicLongTest::testIntValue @ bci:10 (line 229)
         1 1 Con === 0 [[ ]] #top
         1 39 Proj === 38 [[ 139 42 ]] #0 !jvms: AtomicLongTest::testIntValue @ bci:0 (line 228)
         0 139 MemBarAcquire === 39 1 133 1 1 [[ 140 141 ]] !jvms: AtomicLong::get @ bci:1 (line 91) AtomicLong::intValue @ bci:1 (line 358) AtomicLongTest::testIntValue @ bci:10 (line 229)

      igvn.worklist[0] 138 ConL === 0 [[ ]] #long:0
      Previously optimized:
       139 MemBarAcquire === 39 1 133 1 1 [[ 140 141 ]] !jvms: AtomicLong::get @ bci:1 (line 91) AtomicLong::intValue @ bci:1 (line 358) AtomicLongTest::testIntValue @ bci:10 (line 229)


      #
      # A fatal error has been detected by the Java Runtime Environment:
      #
      # Internal Error (c:\sb\prod\1757679546\workspace\open\src\hotspot\share\opto\phaseX.cpp:1127), pid=8312, tid=50872
      # assert(false) failed: igvn worklist must still be empty after verify
      #
      # JRE version: Java(TM) SE Runtime Environment (26.0+1) (fastdebug build 26-valhalla+1-12)
      ..............
      C2:809089 68445 b 4 javasoft.sqe.tests.api.java.util.concurrent.StampedLockTest::testValidate0 (17 bytes)

        1. replay.log
          579 kB
          Christian Hagedorn

            Unassigned Unassigned
            chagedorn Christian Hagedorn
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              Created:
              Updated: