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  1. JDK
  2. JDK-8073480

C2 should optimize explicit range checks

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Details

    • Enhancement
    • Resolution: Fixed
    • P3
    • 9
    • 9
    • hotspot
    • None
    • b64

    Backports

      Description

        See JDK-8042997

        Consider the following code:

           static void setVolatile(ArrayRefHandle handle, Object[] array, int index,
                   Object value) {
               if (index < 0 || index >= array.length) // bounds and null check
                   throw new ArrayIndexOutOfBoundsException();
               UNSAFE.putObjectVolatile(array,
                                        (((long) index) << handle.ashift) + handle.abase,
                                        castReference(handle.componentType, value));
           }

        For such a user written range test the compiler does fully recognize an array access is going on and so certain optimizations tend not to kick in, such as removing or strength reducing range checks, treating "index" as an unsigned value as opposed to a signed value, or coalescing write barriers when loop unrolling.

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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-8082623 C2 should optimize explicit range checks

            • P3 - Major loss of function.
            • Resolved
            relates to

            Bug - A problem which impairs or prevents the functions of the product. JDK-8075663 compiler/rangechecks/TestExplicitRangeChecks.java fails in compiler nightlies

            • P3 - Major loss of function.
            • Resolved

            Bug - A problem which impairs or prevents the functions of the product. JDK-8135069 C2 replaces range checks by unsigned comparison with -1

            • P3 - Major loss of function.
            • Resolved

            Bug - A problem which impairs or prevents the functions of the product. JDK-8261912 Code IfNode::fold_compares_helper more defensively

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

            Bug - A problem which impairs or prevents the functions of the product. JDK-8261914 IfNode::fold_compares_helper faces non-canonicalized bool when running JRuby JSON workload

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

            Enhancement - null JDK-8325443 C2 misses fold_compare opportunity in loops

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

            Enhancement - null JDK-8042997 Make intrinsic some or all check index/range methods

            • P3 - Major loss of function.
            • Resolved

            Enhancement - null JDK-8206932 Add utility methods to check machine word indexes and ranges

            • P3 - Major loss of function.
            • New

            Bug - A problem which impairs or prevents the functions of the product. JDK-8081823 C2 performs unsigned comparison against -1

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

            Bug - A problem which impairs or prevents the functions of the product. JDK-8140574 C2 must re-execute checks after deoptimizing from merged uncommon traps

            • P1 - Blocks development and/or testing work, production could not run.
            • Closed

            Bug - A problem which impairs or prevents the functions of the product. JDK-8080976 Unexpected AIOOB thrown from 1.9.0-ea-b64 on (regression)

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

            Enhancement - null JDK-8329101 Add IR checks to TestExplicitRangeChecks.java

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

            Enhancement - null JDK-8074383 Redundant "compare" in generated code for String.charAt bounds checks

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

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