Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-8240576

JVM crashes after transformation in C2 IdealLoopTree::merge_many_backedges

    Details

    • Subcomponent:
    • Resolved In Build:
      b14
    • CPU:
      generic
    • OS:
      generic
    • Verification:
      Verified

      Backports

        Description

        Test case which triggers C2 OSR compilation:

        public class Test {

            private int mI = 0;
            private long mJ = 0;
            private float mF = 0f;

            public void testMethod() {
                for (int i0 = 0; i0 < 100; i0++) {
                    if (mF != 0) {
                        // do nothing
                    } else {
                        try {
                            mJ = Long.MAX_VALUE;
                            for (int i1 = 0; i1 < 101; i1++) {
                                for (int i2 = 0; i2 < 102; i2++) {
                                    mI = new Integer(0x1234);
                                }
                            }
                        } catch (Exception ignored) {}
                    }
                }
            }

            public static void main(String[] args) {
                Test t = new Test();
                t.testMethod();
            }
        }

        Command line:
            java -XX:-TieredCompilation -XX:CompileCommand=compileonly,Test::testMethod -XX:+PrintCompilation Test


        Error messages:

        CompileCommand: compileonly Test.testMethod
        ### Excluding compile: java.lang.Object::<init>
        made not compilable on level 4 java.lang.Object::<init> (1 bytes) excluded by CompileCommand
        ### Excluding compile: java.lang.Number::<init>
        made not compilable on level 4 java.lang.Number::<init> (5 bytes) excluded by CompileCommand
        ### Excluding compile: java.lang.Integer::<init>
        made not compilable on level 4 java.lang.Integer::<init> (10 bytes) excluded by CompileCommand
        ### Excluding compile: java.lang.Integer::intValue
        made not compilable on level 4 java.lang.Integer::intValue (5 bytes) excluded by CompileCommand
            296 1 % ! Test::testMethod @ 37 (83 bytes)
        # To suppress the following error report, specify this argument
        # after -XX: or in .hotspotrc: SuppressErrorAt=/multnode.cpp:49
        #
        # A fatal error has been detected by the Java Runtime Environment:
        #
        # Internal Error (/home/yangfei/openjdk-jdk/src/hotspot/share/opto/multnode.cpp:49), pid=37756, tid=37768
        # assert((Opcode() != Op_If && Opcode() != Op_RangeCheck) || outcnt() == 2) failed: bad if #1
        #
        # JRE version: OpenJDK Runtime Environment (15.0) (slowdebug build 15-internal+0-adhoc.yangfei.openjdk-jdk)
        # Java VM: OpenJDK 64-Bit Server VM (slowdebug 15-internal+0-adhoc.yangfei.openjdk-jdk, mixed mode, sharing, compressed oops, g1 gc, linux-amd64)
        # Problematic frame:
        # V [libjvm.so+0xe4de5a] MultiNode::proj_out_or_null(unsigned int) const+0xf4
        #
        # Core dump will be written. Default location: Core dumps may be processed with "/usr/share/apport/apport %p %s %c %d %P" (or dumping to /home/yangfei/1806/core.37756)
        #
        # An error report file with more information is saved as:
        # /home/yangfei/1806/hs_err_pid37756.log
        #
        # Compiler replay data is saved as:
        # /home/yangfei/1806/replay_pid37756.log
        #
        # If you would like to submit a bug report, please visit:
        # https://bugreport.java.com/bugreport/crash.jsp
        #
        Current thread is 37768
        Dumping core ...
        Aborted (core dumped)


        After some analysis, we propose the following fix which is currently under testing:

        diff -r 67cc6f3948e3 src/hotspot/share/opto/loopnode.cpp
        --- a/src/hotspot/share/opto/loopnode.cpp Wed Mar 04 15:34:53 2020 -0800
        +++ b/src/hotspot/share/opto/loopnode.cpp Thu Mar 05 09:32:57 2020 +0800
        @@ -2091,7 +2091,7 @@
           // If I am a shared header (multiple backedges), peel off the many
           // backedges into a private merge point and use the merge point as
           // the one true backedge.
        - if( _head->req() > 3 ) {
        + if (_head->req() > 3 && !_irreducible) {
             // Merge the many backedges into a single backedge but leave
             // the hottest backedge as separate edge for the following peel.
             merge_many_backedges( phase );

          Attachments

            Issue Links

              Activity

                People

                • Assignee:
                  fyang Fei Yang
                  Reporter:
                  fyang Fei Yang
                • Votes:
                  0 Vote for this issue
                  Watchers:
                  4 Start watching this issue

                  Dates

                  • Created:
                    Updated:
                    Resolved: