Mercurial > jdk8-mips64-public > hotspot / changeset

     1.1 --- a/src/share/vm/jfr/periodic/sampling/jfrThreadSampler.cpp	Thu Dec 13 14:36:54 2018 +0100
     1.2 +++ b/src/share/vm/jfr/periodic/sampling/jfrThreadSampler.cpp	Fri Jan 11 23:32:52 2019 +0900
     1.3 @@ -1,5 +1,5 @@
     1.4  /*
     1.5 - * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
     1.6 + * Copyright (c) 2012, 2019, Oracle and/or its affiliates. All rights reserved.
     1.7   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
     1.8   *
     1.9   * This code is free software; you can redistribute it and/or modify it
    1.10 @@ -499,8 +499,17 @@
    1.11  
    1.12      jlong now_ms = get_monotonic_ms();
    1.13  
    1.14 -    jlong next_j = java_interval + last_java_ms - now_ms;
    1.15 -    jlong next_n = native_interval + last_native_ms - now_ms;
    1.16 +    /*
    1.17 +     * Let I be java_interval or native_interval.
    1.18 +     * Let L be last_java_ms or last_native_ms.
    1.19 +     * Let N be now_ms.
    1.20 +     *
    1.21 +     * Interval, I, might be max_jlong so the addition
    1.22 +     * could potentially overflow without parenthesis (UB). Also note that
    1.23 +     * L - N < 0. Avoid UB, by adding parenthesis.
    1.24 +     */
    1.25 +    jlong next_j = java_interval + (last_java_ms - now_ms);
    1.26 +    jlong next_n = native_interval + (last_native_ms - now_ms);
    1.27  
    1.28      jlong sleep_to_next = MIN2<jlong>(next_j, next_n);
    1.29