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  1. JDK
  2. JDK-8221083

[ppc64] Wrong oop compare in C1-generated code

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    • b14
    • ppc

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      Description

        The C1 generated code for comparing two oops erroneously emits a 32-bit instead of an 64-bit compare instruction. Because oops are only compared for equality/inequality, this bug only becomes manifests for oops which are equal in their 32 least-significant bits but unequal otherwise. This means the two oops have to be exactly 4GB apart from each other in the heap or their 32 least significant bits have to be zero when compared to 'null'.

        This makes the occurrence of this bug extremely unlikely, but when it happens, the consequences are usually a semantically wrong program execution and not a crash, which makes it very hard to detect.

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            backported by

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8221839 [ppc64] Wrong oop compare in C1-generated code

            • P2 - Crashes, loss of data, severe memory leak.
            • Resolved

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8222587 [ppc64] Wrong oop compare in C1-generated code

            • P2 - Crashes, loss of data, severe memory leak.
            • Resolved

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8221841 [ppc64] Wrong oop compare in C1-generated code

            • P2 - Crashes, loss of data, severe memory leak.
            • Closed
            relates to

            Bug - A problem which impairs or prevents the functions of the product. JDK-8233019 java.lang.Class.isPrimitive() (C1) returns wrong result if Klass* is aligned to 32bit

            • P3 - Major loss of function.
            • Resolved

            Bug - A problem which impairs or prevents the functions of the product. JDK-8221483 TestOopCmp.java fails due to "Multiple garbage collectors selected"

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved

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                simonis Volker Simonis
                simonis Volker Simonis
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                  Updated:
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