1 /*
   2  * Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_JFR_RECORDER_CHECKPOINT_TYPES_TRACEID_JFRTRACEIDBITS_INLINE_HPP
  26 #define SHARE_JFR_RECORDER_CHECKPOINT_TYPES_TRACEID_JFRTRACEIDBITS_INLINE_HPP
  27 
  28 #include "jfr/utilities/jfrTypes.hpp"
  29 #include "runtime/atomic.hpp"
  30 #include "runtime/orderAccess.hpp"
  31 #include "utilities/macros.hpp"
  32 
  33 #ifdef VM_LITTLE_ENDIAN
  34 static const int low_offset = 0;
  35 static const int meta_offset = low_offset + 1;
  36 #else
  37 static const int low_offset = 7;
  38 static const int meta_offset = low_offset - 1;
  39 #endif
  40 
  41 inline void set_bits(jbyte bits, jbyte volatile* const dest) {
  42   assert(dest != NULL, "invariant");
  43   *dest |= bits;
  44   OrderAccess::storestore();
  45 }
  46 
  47 inline jbyte traceid_and(jbyte current, jbyte bits) {
  48   return current & bits;
  49 }
  50 
  51 inline jbyte traceid_or(jbyte current, jbyte bits) {
  52   return current | bits;
  53 }
  54 
  55 inline jbyte traceid_xor(jbyte current, jbyte bits) {
  56   return current ^ bits;
  57 }
  58 
  59 template <jbyte op(jbyte, jbyte)>
  60 inline void set_bits_cas_form(jbyte bits, jbyte* const dest) {
  61   assert(dest != NULL, "invariant");
  62   do {
  63     const jbyte current = *dest;
  64     const jbyte new_value = op(current, bits);
  65     if (Atomic::cmpxchg(dest, current, new_value) == current) {
  66       return;
  67     }
  68   } while (true);
  69 }
  70 
  71 inline void set_bits_cas(jbyte bits, jbyte* const dest) {
  72   set_bits_cas_form<traceid_or>(bits, dest);
  73 }
  74 
  75 inline void clear_bits_cas(jbyte bits, jbyte* const dest) {
  76   set_bits_cas_form<traceid_xor>(bits, dest);
  77 }
  78 
  79 inline void set_mask(jbyte mask, jbyte* const dest) {
  80   set_bits_cas_form<traceid_and>(mask, dest);
  81 }
  82 
  83 inline void set_traceid_bits(jbyte bits, traceid* dest) {
  84   set_bits(bits, ((jbyte*)dest) + low_offset);
  85 }
  86 
  87 inline void set_traceid_bits_cas(jbyte bits, traceid* dest) {
  88   set_bits_cas(bits, ((jbyte*)dest) + low_offset);
  89 }
  90 
  91 inline void set_traceid_mask(jbyte mask, traceid* dest) {
  92   set_mask(mask, ((jbyte*)dest) + low_offset);
  93 }
  94 
  95 inline void set_meta_bits(jbyte bits, jbyte* const dest) {
  96   assert(dest != NULL, "invariant");
  97   *dest |= bits;
  98 }
  99 
 100 inline void set_traceid_meta_bits(jbyte bits, traceid* dest) {
 101   set_meta_bits(bits, ((jbyte*)dest) + meta_offset);
 102 }
 103 
 104 inline void set_meta_mask(jbyte mask, jbyte* const dest) {
 105   assert(dest != NULL, "invariant");
 106   *dest &= mask;
 107 }
 108 
 109 inline void set_traceid_meta_mask(jbyte mask, traceid* dest) {
 110   set_meta_mask(mask, ((jbyte*)dest) + meta_offset);
 111 }
 112 
 113 // only used by a single thread with no visibility requirements
 114 inline void clear_meta_bits(jbyte bits, jbyte* const dest) {
 115   assert(dest != NULL, "invariant");
 116   *dest ^= bits;
 117 }
 118 
 119 #endif // SHARE_JFR_RECORDER_CHECKPOINT_TYPES_TRACEID_JFRTRACEIDBITS_INLINE_HPP