/*
* Copyright (c) 1998, 2011, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "memory/allocation.inline.hpp"
#include "opto/chaitin.hpp"
#include "opto/compile.hpp"
#include "opto/indexSet.hpp"
#include "opto/regmask.hpp"
// This file defines the IndexSet class, a set of sparse integer indices.
// This data structure is used by the compiler in its liveness analysis and
// during register allocation. It also defines an iterator for this class.
//-------------------------------- Initializations ------------------------------
IndexSet::BitBlock IndexSet::_empty_block = IndexSet::BitBlock();
#ifdef ASSERT
// Initialize statistics counters
julong IndexSet::_alloc_new = 0;
julong IndexSet::_alloc_total = 0;
julong IndexSet::_total_bits = 0;
julong IndexSet::_total_used_blocks = 0;
julong IndexSet::_total_unused_blocks = 0;
// Per set, or all sets operation tracing
int IndexSet::_serial_count = 1;
#endif
// What is the first set bit in a 5 bit integer?
const byte IndexSetIterator::_first_bit[32] = {
0, 0, 1, 0,
2, 0, 1, 0,
3, 0, 1, 0,
2, 0, 1, 0,
4, 0, 1, 0,
2, 0, 1, 0,
3, 0, 1, 0,
2, 0, 1, 0
};
// What is the second set bit in a 5 bit integer?
const byte IndexSetIterator::_second_bit[32] = {
5, 5, 5, 1,
5, 2, 2, 1,
5, 3, 3, 1,
3, 2, 2, 1,
5, 4, 4, 1,
4, 2, 2, 1,
4, 3, 3, 1,
3, 2, 2, 1
};
// I tried implementing the IndexSetIterator with a window_size of 8 and
// didn't seem to get a noticeable speedup. I am leaving in the tables
// in case we want to switch back.
/*const byte IndexSetIterator::_first_bit[256] = {
8, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0
};
const byte IndexSetIterator::_second_bit[256] = {
8, 8, 8, 1, 8, 2, 2, 1, 8, 3, 3, 1, 3, 2, 2, 1,
8, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
8, 5, 5, 1, 5, 2, 2, 1, 5, 3, 3, 1, 3, 2, 2, 1,
5, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
8, 6, 6, 1, 6, 2, 2, 1, 6, 3, 3, 1, 3, 2, 2, 1,
6, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
6, 5, 5, 1, 5, 2, 2, 1, 5, 3, 3, 1, 3, 2, 2, 1,
5, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
8, 7, 7, 1, 7, 2, 2, 1, 7, 3, 3, 1, 3, 2, 2, 1,
7, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
7, 5, 5, 1, 5, 2, 2, 1, 5, 3, 3, 1, 3, 2, 2, 1,
5, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
7, 6, 6, 1, 6, 2, 2, 1, 6, 3, 3, 1, 3, 2, 2, 1,
6, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1,
6, 5, 5, 1, 5, 2, 2, 1, 5, 3, 3, 1, 3, 2, 2, 1,
5, 4, 4, 1, 4, 2, 2, 1, 4, 3, 3, 1, 3, 2, 2, 1
};*/
//---------------------------- IndexSet::populate_free_list() -----------------------------
// Populate the free BitBlock list with a batch of BitBlocks. The BitBlocks
// are 32 bit aligned.
void IndexSet::populate_free_list() {
Compile *compile = Compile::current();
BitBlock *free = (BitBlock*)compile->indexSet_free_block_list();
char *mem = (char*)arena()->Amalloc_4(sizeof(BitBlock) *
bitblock_alloc_chunk_size + 32);
// Align the pointer to a 32 bit boundary.
BitBlock *new_blocks = (BitBlock*)(((uintptr_t)mem + 32) & ~0x001F);
// Add the new blocks to the free list.
for (int i = 0; i < bitblock_alloc_chunk_size; i++) {
new_blocks->set_next(free);
free = new_blocks;
new_blocks++;
}
compile->set_indexSet_free_block_list(free);
#ifdef ASSERT
if (CollectIndexSetStatistics) {
inc_stat_counter(&_alloc_new, bitblock_alloc_chunk_size);
}
#endif
}
//---------------------------- IndexSet::alloc_block() ------------------------
// Allocate a BitBlock from the free list. If the free list is empty,
// prime it.
IndexSet::BitBlock *IndexSet::alloc_block() {
#ifdef ASSERT
if (CollectIndexSetStatistics) {
inc_stat_counter(&_alloc_total, 1);
}
#endif
Compile *compile = Compile::current();
BitBlock* free_list = (BitBlock*)compile->indexSet_free_block_list();
if (free_list == NULL) {
populate_free_list();
free_list = (BitBlock*)compile->indexSet_free_block_list();
}
BitBlock *block = free_list;
compile->set_indexSet_free_block_list(block->next());
block->clear();
return block;
}
//---------------------------- IndexSet::alloc_block_containing() -------------
// Allocate a new BitBlock and put it into the position in the _blocks array
// corresponding to element.
IndexSet::BitBlock *IndexSet::alloc_block_containing(uint element) {
BitBlock *block = alloc_block();
uint bi = get_block_index(element);
_blocks[bi] = block;
return block;
}
//---------------------------- IndexSet::free_block() -------------------------
// Add a BitBlock to the free list.
void IndexSet::free_block(uint i) {
debug_only(check_watch("free block", i));
assert(i < _max_blocks, "block index too large");
BitBlock *block = _blocks[i];
assert(block != &_empty_block, "cannot free the empty block");
block->set_next((IndexSet::BitBlock*)Compile::current()->indexSet_free_block_list());
Compile::current()->set_indexSet_free_block_list(block);
set_block(i,&_empty_block);
}
//------------------------------lrg_union--------------------------------------
// Compute the union of all elements of one and two which interfere with
// the RegMask mask. If the degree of the union becomes exceeds
// fail_degree, the union bails out. The underlying set is cleared before
// the union is performed.
uint IndexSet::lrg_union(uint lr1, uint lr2,
const uint fail_degree,
const PhaseIFG *ifg,
const RegMask &mask ) {
IndexSet *one = ifg->neighbors(lr1);
IndexSet *two = ifg->neighbors(lr2);
LRG &lrg1 = ifg->lrgs(lr1);
LRG &lrg2 = ifg->lrgs(lr2);
#ifdef ASSERT
assert(_max_elements == one->_max_elements, "max element mismatch");
check_watch("union destination");
one->check_watch("union source");
two->check_watch("union source");
#endif
// Compute the degree of the combined live-range. The combined
// live-range has the union of the original live-ranges' neighbors set as
// well as the neighbors of all intermediate copies, minus those neighbors
// that can not use the intersected allowed-register-set.
// Copy the larger set. Insert the smaller set into the larger.
if (two->count() > one->count()) {
IndexSet *temp = one;
one = two;
two = temp;
}
clear();
// Used to compute degree of register-only interferences. Infinite-stack
// neighbors do not alter colorability, as they can always color to some
// other color. (A variant of the Briggs assertion)
uint reg_degree = 0;
uint element;
// Load up the combined interference set with the neighbors of one
IndexSetIterator elements(one);
while ((element = elements.next()) != 0) {
LRG &lrg = ifg->lrgs(element);
if (mask.overlap(lrg.mask())) {
insert(element);
if( !lrg.mask().is_AllStack() ) {
reg_degree += lrg1.compute_degree(lrg);
if( reg_degree >= fail_degree ) return reg_degree;
} else {
// !!!!! Danger! No update to reg_degree despite having a neighbor.
// A variant of the Briggs assertion.
// Not needed if I simplify during coalesce, ala George/Appel.
assert( lrg.lo_degree(), "" );
}
}
}
// Add neighbors of two as well
IndexSetIterator elements2(two);
while ((element = elements2.next()) != 0) {
LRG &lrg = ifg->lrgs(element);
if (mask.overlap(lrg.mask())) {
if (insert(element)) {
if( !lrg.mask().is_AllStack() ) {
reg_degree += lrg2.compute_degree(lrg);
if( reg_degree >= fail_degree ) return reg_degree;
} else {
// !!!!! Danger! No update to reg_degree despite having a neighbor.
// A variant of the Briggs assertion.
// Not needed if I simplify during coalesce, ala George/Appel.
assert( lrg.lo_degree(), "" );
}
}
}
}
return reg_degree;
}
//---------------------------- IndexSet() -----------------------------
// A deep copy constructor. This is used when you need a scratch copy of this set.
IndexSet::IndexSet (IndexSet *set) {
#ifdef ASSERT
_serial_number = _serial_count++;
set->check_watch("copied", _serial_number);
check_watch("initialized by copy", set->_serial_number);
_max_elements = set->_max_elements;
#endif
_count = set->_count;
_max_blocks = set->_max_blocks;
if (_max_blocks <= preallocated_block_list_size) {
_blocks = _preallocated_block_list;
} else {
_blocks =
(IndexSet::BitBlock**) arena()->Amalloc_4(sizeof(IndexSet::BitBlock**) * _max_blocks);
}
for (uint i = 0; i < _max_blocks; i++) {
BitBlock *block = set->_blocks[i];
if (block == &_empty_block) {
set_block(i, &_empty_block);
} else {
BitBlock *new_block = alloc_block();
memcpy(new_block->words(), block->words(), sizeof(uint32) * words_per_block);
set_block(i, new_block);
}
}
}
//---------------------------- IndexSet::initialize() -----------------------------
// Prepare an IndexSet for use.
void IndexSet::initialize(uint max_elements) {
#ifdef ASSERT
_serial_number = _serial_count++;
check_watch("initialized", max_elements);
_max_elements = max_elements;
#endif
_count = 0;
_max_blocks = (max_elements + bits_per_block - 1) / bits_per_block;
if (_max_blocks <= preallocated_block_list_size) {
_blocks = _preallocated_block_list;
} else {
_blocks = (IndexSet::BitBlock**) arena()->Amalloc_4(sizeof(IndexSet::BitBlock**) * _max_blocks);
}
for (uint i = 0; i < _max_blocks; i++) {
set_block(i, &_empty_block);
}
}
//---------------------------- IndexSet::initialize()------------------------------
// Prepare an IndexSet for use. If it needs to allocate its _blocks array, it does
// so from the Arena passed as a parameter. BitBlock allocation is still done from
// the static Arena which was set with reset_memory().
void IndexSet::initialize(uint max_elements, Arena *arena) {
#ifdef ASSERT
_serial_number = _serial_count++;
check_watch("initialized2", max_elements);
_max_elements = max_elements;
#endif // ASSERT
_count = 0;
_max_blocks = (max_elements + bits_per_block - 1) / bits_per_block;
if (_max_blocks <= preallocated_block_list_size) {
_blocks = _preallocated_block_list;
} else {
_blocks = (IndexSet::BitBlock**) arena->Amalloc_4(sizeof(IndexSet::BitBlock**) * _max_blocks);
}
for (uint i = 0; i < _max_blocks; i++) {
set_block(i, &_empty_block);
}
}
//---------------------------- IndexSet::swap() -----------------------------
// Exchange two IndexSets.
void IndexSet::swap(IndexSet *set) {
#ifdef ASSERT
assert(_max_elements == set->_max_elements, "must have same universe size to swap");
check_watch("swap", set->_serial_number);
set->check_watch("swap", _serial_number);
#endif
for (uint i = 0; i < _max_blocks; i++) {
BitBlock *temp = _blocks[i];
set_block(i, set->_blocks[i]);
set->set_block(i, temp);
}
uint temp = _count;
_count = set->_count;
set->_count = temp;
}
//---------------------------- IndexSet::dump() -----------------------------
// Print this set. Used for debugging.
#ifndef PRODUCT
void IndexSet::dump() const {
IndexSetIterator elements(this);
tty->print("{");
uint i;
while ((i = elements.next()) != 0) {
tty->print("L%d ", i);
}
tty->print_cr("}");
}
#endif
#ifdef ASSERT
//---------------------------- IndexSet::tally_iteration_statistics() -----------------------------
// Update block/bit counts to reflect that this set has been iterated over.
void IndexSet::tally_iteration_statistics() const {
inc_stat_counter(&_total_bits, count());
for (uint i = 0; i < _max_blocks; i++) {
if (_blocks[i] != &_empty_block) {
inc_stat_counter(&_total_used_blocks, 1);
} else {
inc_stat_counter(&_total_unused_blocks, 1);
}
}
}
//---------------------------- IndexSet::print_statistics() -----------------------------
// Print statistics about IndexSet usage.
void IndexSet::print_statistics() {
julong total_blocks = _total_used_blocks + _total_unused_blocks;
tty->print_cr ("Accumulated IndexSet usage statistics:");
tty->print_cr ("--------------------------------------");
tty->print_cr (" Iteration:");
tty->print_cr (" blocks visited: " UINT64_FORMAT, total_blocks);
tty->print_cr (" blocks empty: %4.2f%%", 100.0*(double)_total_unused_blocks/total_blocks);
tty->print_cr (" bit density (bits/used blocks): %4.2f", (double)_total_bits/_total_used_blocks);
tty->print_cr (" bit density (bits/all blocks): %4.2f", (double)_total_bits/total_blocks);
tty->print_cr (" Allocation:");
tty->print_cr (" blocks allocated: " UINT64_FORMAT, _alloc_new);
tty->print_cr (" blocks used/reused: " UINT64_FORMAT, _alloc_total);
}
//---------------------------- IndexSet::verify() -----------------------------
// Expensive test of IndexSet sanity. Ensure that the count agrees with the
// number of bits in the blocks. Make sure the iterator is seeing all elements
// of the set. Meant for use during development.
void IndexSet::verify() const {
assert(!member(0), "zero cannot be a member");
uint count = 0;
uint i;
for (i = 1; i < _max_elements; i++) {
if (member(i)) {
count++;
assert(count <= _count, "_count is messed up");
}
}
IndexSetIterator elements(this);
count = 0;
while ((i = elements.next()) != 0) {
count++;
assert(member(i), "returned a non member");
assert(count <= _count, "iterator returned wrong number of elements");
}
}
#endif
//---------------------------- IndexSetIterator() -----------------------------
// Create an iterator for a set. If empty blocks are detected when iterating
// over the set, these blocks are replaced.
IndexSetIterator::IndexSetIterator(IndexSet *set) {
#ifdef ASSERT
if (CollectIndexSetStatistics) {
set->tally_iteration_statistics();
}
set->check_watch("traversed", set->count());
#endif
if (set->is_empty()) {
_current = 0;
_next_word = IndexSet::words_per_block;
_next_block = 1;
_max_blocks = 1;
// We don't need the following values when we iterate over an empty set.
// The commented out code is left here to document that the omission
// is intentional.
//
//_value = 0;
//_words = NULL;
//_blocks = NULL;
//_set = NULL;
} else {
_current = 0;
_value = 0;
_next_block = 0;
_next_word = IndexSet::words_per_block;
_max_blocks = set->_max_blocks;
_words = NULL;
_blocks = set->_blocks;
_set = set;
}
}
//---------------------------- IndexSetIterator(const) -----------------------------
// Iterate over a constant IndexSet.
IndexSetIterator::IndexSetIterator(const IndexSet *set) {
#ifdef ASSERT
if (CollectIndexSetStatistics) {
set->tally_iteration_statistics();
}
// We don't call check_watch from here to avoid bad recursion.
// set->check_watch("traversed const", set->count());
#endif
if (set->is_empty()) {
_current = 0;
_next_word = IndexSet::words_per_block;
_next_block = 1;
_max_blocks = 1;
// We don't need the following values when we iterate over an empty set.
// The commented out code is left here to document that the omission
// is intentional.
//
//_value = 0;
//_words = NULL;
//_blocks = NULL;
//_set = NULL;
} else {
_current = 0;
_value = 0;
_next_block = 0;
_next_word = IndexSet::words_per_block;
_max_blocks = set->_max_blocks;
_words = NULL;
_blocks = set->_blocks;
_set = NULL;
}
}
//---------------------------- List16Iterator::advance_and_next() -----------------------------
// Advance to the next non-empty word in the set being iterated over. Return the next element
// if there is one. If we are done, return 0. This method is called from the next() method
// when it gets done with a word.
uint IndexSetIterator::advance_and_next() {
// See if there is another non-empty word in the current block.
for (uint wi = _next_word; wi < (unsigned)IndexSet::words_per_block; wi++) {
if (_words[wi] != 0) {
// Found a non-empty word.
_value = ((_next_block - 1) * IndexSet::bits_per_block) + (wi * IndexSet::bits_per_word);
_current = _words[wi];
_next_word = wi+1;
return next();
}
}
// We ran out of words in the current block. Advance to next non-empty block.
for (uint bi = _next_block; bi < _max_blocks; bi++) {
if (_blocks[bi] != &IndexSet::_empty_block) {
// Found a non-empty block.
_words = _blocks[bi]->words();
for (uint wi = 0; wi < (unsigned)IndexSet::words_per_block; wi++) {
if (_words[wi] != 0) {
// Found a non-empty word.
_value = (bi * IndexSet::bits_per_block) + (wi * IndexSet::bits_per_word);
_current = _words[wi];
_next_block = bi+1;
_next_word = wi+1;
return next();
}
}
// All of the words in the block were empty. Replace
// the block with the empty block.
if (_set) {
_set->free_block(bi);
}
}
}
// These assignments make redundant calls to next on a finished iterator
// faster. Probably not necessary.
_next_block = _max_blocks;
_next_word = IndexSet::words_per_block;
// No more words.
return 0;
}