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  1. JDK
  2. JDK-8323274

C2: array load may float above range check

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    • b12
    • Verified

        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.

          1. TestArrayAccessAboveRCForArrayCopyLoad.java
            0.7 kB
          2. TestArrayAccessAboveRCAfterUnswitching.java
            2 kB
          3. TestArrayAccessAboveRCAfterSplitIf.java
            2 kB
          4. TestArrayAccessAboveRCAfterSinking.java
            2 kB
          5. TestArrayAccessAboveRCAfterPartialPeeling.java
            3 kB

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