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  1. JDK
  2. JDK-8288303

C1: Miscompilation due to broken Class.getModifiers intrinsic

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    • b27

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      Description

        Currently, at least one test is timing out:

        $ CONF=linux-x86-server-fastdebug make images run-test TEST=jdk/jfr/jvm/TestGetEventWriter.java

        It times out only with C1 -Xcomp. It looks as if this loop is reduced to infinite one:

        ```
        package jdk.jfr.internal;

        ...

        public final class Utils {
            ...

            public static void verifyMirror(Class<?> mirror, Class<?> real) {
                Class<?> cMirror = Objects.requireNonNull(mirror);
                Class<?> cReal = Objects.requireNonNull(real);

                Map<String, Field> mirrorFields = new HashMap<>();
                while (cMirror != null) {
                    for (Field f : cMirror.getDeclaredFields()) {
                        if (isSupportedType(f.getType())) {
                            mirrorFields.put(f.getName(), f);
                        }
                    }
                    cMirror = cMirror.getSuperclass();
                }
                ...
             }
          }
        ```

        Unfortunately, that test is inconvenient to use as the bisection test, because it was only recently added. Luckily, other JFR tests fail as well with the same symptoms:

        CONF=linux-x86-server-fastdebug make images run-test TEST=jdk/jfr/api/recording/misc/TestGetStream.java TEST_VM_OPTS="-Xcomp -XX:TieredStopAtLevel=1" JTREG="TIMEOUT_FACTOR=1"

        That allows to bisect the hangup to JDK-8265711, which also makes some sense, as the code above calls `isSupportedType` -> `Class.getModifiers`.

        While this reliably reproduces on x86_32, I believe the bug is actually generic.

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                shade Aleksey Shipilev
                shade Aleksey Shipilev
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