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  1. JDK
  2. JDK-8308504

C2: "malformed control flow" after JDK-8303466

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    • b20
    • 21

      The attached Java Fuzzer test (Test.java and Reduced2.java) starts to fail after JDK-8303466:

      To reproduce:

      $ java -Xcomp -XX:CompileOnly=Test -XX:-TieredCompilation Test.java
      $ java -Xcomp -XX:CompileOnly=Reduced -XX:-TieredCompilation Reduced.java (this reduced version starts to fail after JDK-8292088 which only reveals an existing issue)
      $ java -Xcomp -XX:CompileOnly=Reduced2 -XX:-TieredCompilation Reduced2.java

      Since Reduced.java is only slightly different compared to Reduced2.java, it suggests that JDK-8303466 also just revealed an existing issue as JDK-8292088 does.

      Maybe this bug is still related to the case reported in JDK-8308392.

      dist dump
      ---------------------------------------------
         0 1108 If === 1018 1107 [[ 1110 ]] P=0.000001, C=-1.000000 !orig=[1022]
         1 1110 IfTrue === 1108 [[ 1102 ]] #1 !orig=[994],[391],[390],[328] !jvms: Reduced2::test @ bci:34 (line 16)
      #
      # A fatal error has been detected by the Java Runtime Environment:
      #
      # Internal Error (/opt/mach5/mesos/work_dir/slaves/741e9afd-8c02-45c3-b2e2-9db1450d0832-S24789/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/3b2db3c6-2d3e-49c7-b1a7-865f1c6e16a3/runs/77b7bb02-69ed-459f-8e92-803916ef508e/workspace/open/src/hotspot/share/opto/compile.cpp:4003), pid=685778, tid=685793
      # assert(false) failed: malformed control flow
      #
      # JRE version: Java(TM) SE Runtime Environment (21.0+20) (fastdebug build 21-ea+20-LTS-1677)
      # Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 21-ea+20-LTS-1677, compiled mode, sharing, compressed oops, compressed class ptrs, g1 gc, linux-amd64)
      # Problematic frame:
      # V [libjvm.so+0x9b5332] Compile::final_graph_reshaping()+0x1262

        1. Test2.java
          0.5 kB
          Emanuel Peter
        2. Test.java
          8 kB
          Christian Hagedorn
        3. Reduced4.java
          0.5 kB
          Emanuel Peter
        4. Reduced3.java
          0.5 kB
          Emanuel Peter
        5. Reduced2.java
          0.7 kB
          Christian Hagedorn
        6. Reduced.java
          0.7 kB
          Christian Hagedorn
        7. FuzzerUtils.java
          13 kB
          Christian Hagedorn

            chagedorn Christian Hagedorn
            chagedorn Christian Hagedorn
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              Created:
              Updated:
              Resolved: