1 /*
   2  * Copyright (c) 2001, 2015, 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
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  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
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  24 
  25 #ifndef SHARE_VM_GC_SHARED_BARRIERSET_INLINE_HPP
  26 #define SHARE_VM_GC_SHARED_BARRIERSET_INLINE_HPP
  27 
  28 #include "gc/shared/barrierSet.hpp"
  29 #include "gc/shared/cardTableModRefBS.inline.hpp"
  30 
  31 // Inline functions of BarrierSet, which de-virtualize certain
  32 // performance-critical calls when the barrier is the most common
  33 // card-table kind.
  34 
  35 inline bool BarrierSet::devirtualize_reference_writes() const {
  36   switch (kind()) {
  37   case CardTableForRS:
  38   case CardTableExtension:
  39     return true;
  40   default:
  41     return false;
  42   }
  43 }
  44 
  45 template <class T> void BarrierSet::write_ref_field_pre(T* field, oop new_val) {
  46   if (devirtualize_reference_writes()) {
  47     barrier_set_cast<CardTableModRefBS>(this)->inline_write_ref_field_pre(field, new_val);
  48   } else {
  49     write_ref_field_pre_work(field, new_val);
  50   }
  51 }
  52 
  53 void BarrierSet::write_ref_field(void* field, oop new_val, bool release) {
  54   if (devirtualize_reference_writes()) {
  55     barrier_set_cast<CardTableModRefBS>(this)->inline_write_ref_field(field, new_val, release);
  56   } else {
  57     write_ref_field_work(field, new_val, release);
  58   }
  59 }
  60 
  61 // count is number of array elements being written
  62 void BarrierSet::write_ref_array(HeapWord* start, size_t count) {
  63   assert(count <= (size_t)max_intx, "count too large");
  64   HeapWord* end = (HeapWord*)((char*)start + (count*heapOopSize));
  65   // In the case of compressed oops, start and end may potentially be misaligned;
  66   // so we need to conservatively align the first downward (this is not
  67   // strictly necessary for current uses, but a case of good hygiene and,
  68   // if you will, aesthetics) and the second upward (this is essential for
  69   // current uses) to a HeapWord boundary, so we mark all cards overlapping
  70   // this write. If this evolves in the future to calling a
  71   // logging barrier of narrow oop granularity, like the pre-barrier for G1
  72   // (mentioned here merely by way of example), we will need to change this
  73   // interface, so it is "exactly precise" (if i may be allowed the adverbial
  74   // redundancy for emphasis) and does not include narrow oop slots not
  75   // included in the original write interval.
  76   HeapWord* aligned_start = align_ptr_down(start, HeapWordSize);
  77   HeapWord* aligned_end   = align_ptr_up  (end,   HeapWordSize);
  78   // If compressed oops were not being used, these should already be aligned
  79   assert(UseCompressedOops || (aligned_start == start && aligned_end == end),
  80          "Expected heap word alignment of start and end");
  81   write_ref_array_work(MemRegion(aligned_start, aligned_end));
  82 }
  83 
  84 
  85 inline void BarrierSet::write_region(MemRegion mr) {
  86   if (devirtualize_reference_writes()) {
  87     barrier_set_cast<CardTableModRefBS>(this)->inline_write_region(mr);
  88   } else {
  89     write_region_work(mr);
  90   }
  91 }
  92 
  93 #endif // SHARE_VM_GC_SHARED_BARRIERSET_INLINE_HPP