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  1. JDK
  2. JDK-8323274

C2: array load may float above range check

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    Backports

      Description

        Attached test case run with:

        java -XX:-TieredCompilation -XX:-BackgroundCompilation TestArrayAccessAboveRCAfterSplitIf

        fails with:

        # SIGSEGV (0xb) at pc=0x00007fd5d9056204, pid=2781800, tid=2781801
        #
        # JRE version: OpenJDK Runtime Environment (23.0) (slowdebug build 23-internal-adhoc.roland.jdk-jdk2)
        # Java VM: OpenJDK 64-Bit Server VM (slowdebug 23-internal-adhoc.roland.jdk-jdk2, mixed mode, compressed oops, compressed class ptrs, serial gc, linux-amd64)
        # Problematic frame:
        # J 13 c2 TestArrayAccessAboveRCAfterSplitIf.test([I[IIIZ)I (68 bytes) @ 0x00007fd5d9056204 [0x00007fd5d90561e0+0x0000000000000024]

        In that case, split if inserts a Region between a range check and a dependent array load. The array load becomes dependent on some unrelated condition after the Region is later optimized out. That unrelated condition is subsumed by a dominating identical condition and the array load floats above the range check.

        I expect some other transformation can cause similar failures.

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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-8334370 C2: array load may float above range check

            • 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-8334176 C2: array load may float above range check

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

            Bug - A problem which impairs or prevents the functions of the product. JDK-8319793 C2 compilation fails with "Bad graph detected in build_loop_late" after JDK-8279888

            • P3 - Major loss of function.
            • Resolved

            Bug - A problem which impairs or prevents the functions of the product. JDK-8336729 C2: Div/Mod nodes without zero check could be split through iv phi of outer loop of long counted loop nest resulting in SIGFPE

            • P3 - Major loss of function.
            • Resolved

            Enhancement - null JDK-8324976 C2: allow array loads known to be within bounds to float

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

            Commit Commit openjdk/jdk21u-dev/a1e43d90

            Commit Commit openjdk/jdk/4406915e

            Review Review openjdk/jdk21u-dev/727

            Review Review openjdk/jdk/17635

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                roland Roland Westrelin
                roland Roland Westrelin
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                  Created:
                  Updated:
                  Resolved: