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8131330: G1CollectedHeap::verify_dirty_young_list fails with assert

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Use assembly loop to avoid compiler optimization into memset

Reviewed-by: ecaspole, tschatzl
This commit is contained in:
Kim Barrett 2015-08-31 13:06:01 -04:00
parent 673798137b
commit 15196341a5
9 changed files with 341 additions and 71 deletions
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46
hotspot/src/share/vm/gc/shared/blockOffsetTable.hpp
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@ -25,9 +25,12 @@
#ifndef SHARE_VM_GC_SHARED_BLOCKOFFSETTABLE_HPP
#define SHARE_VM_GC_SHARED_BLOCKOFFSETTABLE_HPP
#include "gc/shared/memset_with_concurrent_readers.hpp"
#include "memory/memRegion.hpp"
#include "memory/virtualspace.hpp"
#include "runtime/globals.hpp"
#include "utilities/globalDefinitions.hpp"
#include "utilities/macros.hpp"
// The CollectedHeap type requires subtypes to implement a method
// "block_start". For some subtypes, notably generational
@ -126,6 +129,19 @@ class BlockOffsetSharedArray: public CHeapObj<mtGC> {
VirtualSpace _vs;
u_char* _offset_array; // byte array keeping backwards offsets
void fill_range(size_t start, size_t num_cards, u_char offset) {
void* start_ptr = &_offset_array[start];
#if INCLUDE_ALL_GCS
// If collector is concurrent, special handling may be needed.
assert(!UseG1GC, "Shouldn't be here when using G1");
if (UseConcMarkSweepGC) {
memset_with_concurrent_readers(start_ptr, offset, num_cards);
return;
}
#endif // INCLUDE_ALL_GCS
memset(start_ptr, offset, num_cards);
}
protected:
// Bounds checking accessors:
// For performance these have to devolve to array accesses in product builds.
@ -160,20 +176,7 @@ class BlockOffsetSharedArray: public CHeapObj<mtGC> {
assert(left < right, "Heap addresses out of order");
size_t num_cards = pointer_delta(right, left) >> LogN_words;
// Below, we may use an explicit loop instead of memset()
// because on certain platforms memset() can give concurrent
// readers "out-of-thin-air," phantom zeros; see 6948537.
if (UseMemSetInBOT) {
memset(&_offset_array[index_for(left)], offset, num_cards);
} else {
size_t i = index_for(left);
const size_t end = i + num_cards;
for (; i < end; i++) {
// Elided until CR 6977974 is fixed properly.
// assert(!reducing || _offset_array[i] >= offset, "Not reducing");
_offset_array[i] = offset;
}
}
fill_range(index_for(left), num_cards, offset);
}
void set_offset_array(size_t left, size_t right, u_char offset, bool reducing = false) {
@ -182,20 +185,7 @@ class BlockOffsetSharedArray: public CHeapObj<mtGC> {
assert(left <= right, "indexes out of order");
size_t num_cards = right - left + 1;
// Below, we may use an explicit loop instead of memset
// because on certain platforms memset() can give concurrent
// readers "out-of-thin-air," phantom zeros; see 6948537.
if (UseMemSetInBOT) {
memset(&_offset_array[left], offset, num_cards);
} else {
size_t i = left;
const size_t end = i + num_cards;
for (; i < end; i++) {
// Elided until CR 6977974 is fixed properly.
// assert(!reducing || _offset_array[i] >= offset, "Not reducing");
_offset_array[i] = offset;
}
}
fill_range(left, num_cards, offset);
}
void check_offset_array(size_t index, HeapWord* high, HeapWord* low) const {