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8055816: Remove dead code in g1BlockOffsetTable

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Reviewed-by: tschatzl, mgerdin
This commit is contained in:
Bengt Rutisson 2014-08-27 10:51:08 +02:00
parent 9086b5795f
commit bbe82cb85b
5 changed files with 13 additions and 374 deletions
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182
hotspot/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp
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@ -32,13 +32,6 @@
void G1BlockOffsetSharedArrayMappingChangedListener::on_commit(uint start_idx, size_t num_regions) {
// Nothing to do. The BOT is hard-wired to be part of the HeapRegion, and we cannot
// retrieve it here since this would cause firing of several asserts. The code
// executed after commit of a region already needs to do some re-initialization of
// the HeapRegion, so we combine that.
}
//////////////////////////////////////////////////////////////////////
// G1BlockOffsetSharedArray
//////////////////////////////////////////////////////////////////////
@ -72,26 +65,16 @@ bool G1BlockOffsetSharedArray::is_card_boundary(HeapWord* p) const {
return (delta & right_n_bits(LogN_words)) == (size_t)NoBits;
}
void G1BlockOffsetSharedArray::set_offset_array(HeapWord* left, HeapWord* right, u_char offset) {
set_offset_array(index_for(left), index_for(right -1), offset);
}
//////////////////////////////////////////////////////////////////////
// G1BlockOffsetArray
//////////////////////////////////////////////////////////////////////
G1BlockOffsetArray::G1BlockOffsetArray(G1BlockOffsetSharedArray* array,
MemRegion mr, bool init_to_zero) :
MemRegion mr) :
G1BlockOffsetTable(mr.start(), mr.end()),
_unallocated_block(_bottom),
_array(array), _gsp(NULL),
_init_to_zero(init_to_zero) {
_array(array), _gsp(NULL) {
assert(_bottom <= _end, "arguments out of order");
if (!_init_to_zero) {
// initialize cards to point back to mr.start()
set_remainder_to_point_to_start(mr.start() + N_words, mr.end());
_array->set_offset_array(0, 0); // set first card to 0
}
}
void G1BlockOffsetArray::set_space(G1OffsetTableContigSpace* sp) {
@ -181,93 +164,6 @@ G1BlockOffsetArray::set_remainder_to_point_to_start_incl(size_t start_card, size
DEBUG_ONLY(check_all_cards(start_card, end_card);)
}
// The block [blk_start, blk_end) has been allocated;
// adjust the block offset table to represent this information;
// right-open interval: [blk_start, blk_end)
void
G1BlockOffsetArray::alloc_block(HeapWord* blk_start, HeapWord* blk_end) {
mark_block(blk_start, blk_end);
allocated(blk_start, blk_end);
}
// Adjust BOT to show that a previously whole block has been split
// into two.
void G1BlockOffsetArray::split_block(HeapWord* blk, size_t blk_size,
size_t left_blk_size) {
// Verify that the BOT shows [blk, blk + blk_size) to be one block.
verify_single_block(blk, blk_size);
// Update the BOT to indicate that [blk + left_blk_size, blk + blk_size)
// is one single block.
mark_block(blk + left_blk_size, blk + blk_size);
}
// Action_mark - update the BOT for the block [blk_start, blk_end).
// Current typical use is for splitting a block.
// Action_single - update the BOT for an allocation.
// Action_verify - BOT verification.
void G1BlockOffsetArray::do_block_internal(HeapWord* blk_start,
HeapWord* blk_end,
Action action) {
assert(Universe::heap()->is_in_reserved(blk_start),
"reference must be into the heap");
assert(Universe::heap()->is_in_reserved(blk_end-1),
"limit must be within the heap");
// This is optimized to make the test fast, assuming we only rarely
// cross boundaries.
uintptr_t end_ui = (uintptr_t)(blk_end - 1);
uintptr_t start_ui = (uintptr_t)blk_start;
// Calculate the last card boundary preceding end of blk
intptr_t boundary_before_end = (intptr_t)end_ui;
clear_bits(boundary_before_end, right_n_bits(LogN));
if (start_ui <= (uintptr_t)boundary_before_end) {
// blk starts at or crosses a boundary
// Calculate index of card on which blk begins
size_t start_index = _array->index_for(blk_start);
// Index of card on which blk ends
size_t end_index = _array->index_for(blk_end - 1);
// Start address of card on which blk begins
HeapWord* boundary = _array->address_for_index(start_index);
assert(boundary <= blk_start, "blk should start at or after boundary");
if (blk_start != boundary) {
// blk starts strictly after boundary
// adjust card boundary and start_index forward to next card
boundary += N_words;
start_index++;
}
assert(start_index <= end_index, "monotonicity of index_for()");
assert(boundary <= (HeapWord*)boundary_before_end, "tautology");
switch (action) {
case Action_mark: {
if (init_to_zero()) {
_array->set_offset_array(start_index, boundary, blk_start);
break;
} // Else fall through to the next case
}
case Action_single: {
_array->set_offset_array(start_index, boundary, blk_start);
// We have finished marking the "offset card". We need to now
// mark the subsequent cards that this blk spans.
if (start_index < end_index) {
HeapWord* rem_st = _array->address_for_index(start_index) + N_words;
HeapWord* rem_end = _array->address_for_index(end_index) + N_words;
set_remainder_to_point_to_start(rem_st, rem_end);
}
break;
}
case Action_check: {
_array->check_offset_array(start_index, boundary, blk_start);
// We have finished checking the "offset card". We need to now
// check the subsequent cards that this blk spans.
check_all_cards(start_index + 1, end_index);
break;
}
default:
ShouldNotReachHere();
}
}
}
// The card-interval [start_card, end_card] is a closed interval; this
// is an expensive check -- use with care and only under protection of
// suitable flag.
@ -306,25 +202,6 @@ void G1BlockOffsetArray::check_all_cards(size_t start_card, size_t end_card) con
}
}
// The range [blk_start, blk_end) represents a single contiguous block
// of storage; modify the block offset table to represent this
// information; Right-open interval: [blk_start, blk_end)
// NOTE: this method does _not_ adjust _unallocated_block.
void
G1BlockOffsetArray::single_block(HeapWord* blk_start, HeapWord* blk_end) {
do_block_internal(blk_start, blk_end, Action_single);
}
// Mark the BOT such that if [blk_start, blk_end) straddles a card
// boundary, the card following the first such boundary is marked
// with the appropriate offset.
// NOTE: this method does _not_ adjust _unallocated_block or
// any cards subsequent to the first one.
void
G1BlockOffsetArray::mark_block(HeapWord* blk_start, HeapWord* blk_end) {
do_block_internal(blk_start, blk_end, Action_mark);
}
HeapWord* G1BlockOffsetArray::block_start_unsafe(const void* addr) {
assert(_bottom <= addr && addr < _end,
"addr must be covered by this Array");
@ -397,57 +274,13 @@ G1BlockOffsetArray::forward_to_block_containing_addr_slow(HeapWord* q,
return forward_to_block_containing_addr_const(q, n, addr);
}
HeapWord* G1BlockOffsetArray::block_start_careful(const void* addr) const {
assert(_array->offset_array(0) == 0, "objects can't cross covered areas");
assert(_bottom <= addr && addr < _end,
"addr must be covered by this Array");
// Must read this exactly once because it can be modified by parallel
// allocation.
HeapWord* ub = _unallocated_block;
if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) {
assert(ub < _end, "tautology (see above)");
return ub;
}
// Otherwise, find the block start using the table, but taking
// care (cf block_start_unsafe() above) not to parse any objects/blocks
// on the cards themselves.
size_t index = _array->index_for(addr);
assert(_array->address_for_index(index) == addr,
"arg should be start of card");
HeapWord* q = (HeapWord*)addr;
uint offset;
do {
offset = _array->offset_array(index--);
q -= offset;
} while (offset == N_words);
assert(q <= addr, "block start should be to left of arg");
return q;
}
// Note that the committed size of the covered space may have changed,
// so the table size might also wish to change.
void G1BlockOffsetArray::resize(size_t new_word_size) {
HeapWord* new_end = _bottom + new_word_size;
if (_end < new_end && !init_to_zero()) {
// verify that the old and new boundaries are also card boundaries
assert(_array->is_card_boundary(_end),
"_end not a card boundary");
assert(_array->is_card_boundary(new_end),
"new _end would not be a card boundary");
// set all the newly added cards
_array->set_offset_array(_end, new_end, N_words);
}
_end = new_end; // update _end
}
void G1BlockOffsetArray::set_region(MemRegion mr) {
_bottom = mr.start();
_end = mr.end();
}
//
// threshold_
// | _index_
@ -606,7 +439,7 @@ block_start_unsafe_const(const void* addr) const {
G1BlockOffsetArrayContigSpace::
G1BlockOffsetArrayContigSpace(G1BlockOffsetSharedArray* array,
MemRegion mr) :
G1BlockOffsetArray(array, mr, true)
G1BlockOffsetArray(array, mr)
{
_next_offset_threshold = NULL;
_next_offset_index = 0;
@ -641,15 +474,6 @@ HeapWord* G1BlockOffsetArrayContigSpace::initialize_threshold() {
return _next_offset_threshold;
}
void G1BlockOffsetArrayContigSpace::zero_bottom_entry() {
assert(!Universe::heap()->is_in_reserved(_array->_offset_array),
"just checking");
size_t bottom_index = _array->index_for(_bottom);
assert(_array->address_for_index(bottom_index) == _bottom,
"Precondition of call");
_array->set_offset_array(bottom_index, 0);
}
void
G1BlockOffsetArrayContigSpace::set_for_starts_humongous(HeapWord* new_top) {
assert(new_top <= _end, "_end should have already been updated");