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  1. JDK
  2. JDK-8317346

assert(is_Loop()) failed: invalid node class

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    • x86_64
    • linux_ubuntu

    Description

      ADDITIONAL SYSTEM INFORMATION :
      # JRE version: OpenJDK Runtime Environment (8.0_392) (build 1.8.0_392-internal-fastdebug--b00)
      # Java VM: OpenJDK 64-Bit Server VM (25.392-b00-fastdebug compiled mode linux-amd64 compressed oops)

      A DESCRIPTION OF THE PROBLEM :
      I ran a modified regression testcase on JDK8u392 and found that the JVM crashed with -Xcomp -XX:-TieredCompilation options.

      #
      # A fatal error has been detected by the Java Runtime Environment:
      #
      # Internal Error (/data//jdk8u/hotspot/src/share/vm/opto/node.hpp:792), pid=84055, tid=0x00007f9f7a252700
      # assert(is_Loop()) failed: invalid node class
      #
      # JRE version: OpenJDK Runtime Environment (8.0_392) (build 1.8.0_392-internal-fastdebug--b00)
      # Java VM: OpenJDK 64-Bit Server VM (25.392-b00-fastdebug compiled mode linux-amd64 compressed oops)
      # Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
      #
      # If you would like to submit a bug report, please visit:
      # http://bugreport.java.com/bugreport/crash.jsp
      #

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      java -Xcomp -XX:-TieredCompilation compiler.loopopts.TestIterationSplitWithRegionHead

      ACTUAL -
      # To suppress the following error report, specify this argument
      # after -XX: or in .hotspotrc: SuppressErrorAt=/node.hpp:792
      #
      # A fatal error has been detected by the Java Runtime Environment:
      #
      # Internal Error (/data//jdk8u/hotspot/src/share/vm/opto/node.hpp:792), pid=84055, tid=0x00007f9f7a252700
      # assert(is_Loop()) failed: invalid node class
      #
      # JRE version: OpenJDK Runtime Environment (8.0_392) (build 1.8.0_392-internal-fastdebug--b00)
      # Java VM: OpenJDK 64-Bit Server VM (25.392-b00-fastdebug compiled mode linux-amd64 compressed oops)
      # Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
      #
      # An error report file with more information is saved as:
      # /home//repository//toreport/TestIterationSplitWithRegionHead_09_24_02_02_31/hs_err_pid84055.log
      #
      # Compiler replay data is saved as:
      # /home//repository//toreport/TestIterationSplitWithRegionHead_09_24_02_02_31/replay_pid84055.log
      #
      # If you would like to submit a bug report, please visit:
      # http://bugreport.java.com/bugreport/crash.jsp
      #

      ---------- BEGIN SOURCE ----------
      package compiler.loopopts;

      public class TestIterationSplitWithRegionHead {

          static boolean flagFalse = false;

          public static void main(String[] args) {

      // modified code
      try {
      Class <?> Class0 = Class.forName("compiler.loopopts.TestIterationSplitWithRegionHead");
      Class0.getDeclaredMethod("test").invoke(null);
      }catch (Exception eeeeeeee){throw new RuntimeException(eeeeeeee);}
      // test();

          }

          public static void test() {
              // 1) The loop tree is built. We find that nested loop N2 is an infinite loop and add a NeverBranch
              // to the inner loop to make it reachable. But the current loop tree does not have N2, yet. The
              // resulting loop tree is:
              //
              // Loop: N0/N0 has_call has_sfpt
              // Loop: N77/N121 has_call // N1 outer
              // Loop: N77/N111 has_call sfpts={ 111 97 } // N1 inner
              //
              // 2) beautify_loops() finds that the outer loop head of N1 is shared and thus adds a new region
              // in merge_many_backedges(). As a result, the loop tree is built again. This time, the NeverBranch
              // in the inner loop of N2 allows that a loop tree can be built for it:
              //
              // Loop: N0/N0 has_call has_sfpt
              // Loop: N216/N213 limit_check profile_predicated predicated has_call sfpts={ 111 97 } // N1 shared loop head
              // Loop: N196/N201 sfpts={ 201 } // N2 inner loop now discovered with the new NeverBranch
              //
              // However, a LoopNode is only added by beautify_loops() which won't be called until the next iteration of loop opts.
              // This means that we have a Region node (N196) as head in the loop tree which cannot be handled by iteration_split_impl()
              // resulting in an assertion failure.

              // Nested loop N1
              while (flagFalse) {
                  while (dontInlineFalse()) {
                  }
              }
              dontInlineFalse();

              // Nested loop N2
              while (flagFalse) {
                  while (true) ; // Detected as infinite inner loop by C2 -> NeverBranch added
              }
          }

          public static boolean dontInlineFalse() {
              return false;
          }
      }

      ---------- END SOURCE ----------

      FREQUENCY : always


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              thartmann Tobias Hartmann
              webbuggrp Webbug Group
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                Created:
                Updated:
                Resolved: