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jdk-24/hotspot/src/share/vm/c1/c1_ValueMap.cpp

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/*
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* Copyright (c) 1999, 2012, Oracle and/or its affiliates. All rights reserved.
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* 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.
*
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* 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.
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*
*/
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#include "precompiled.hpp"
#include "c1/c1_Canonicalizer.hpp"
#include "c1/c1_IR.hpp"
#include "c1/c1_ValueMap.hpp"
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#include "c1/c1_ValueStack.hpp"
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#include "utilities/bitMap.inline.hpp"
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#ifndef PRODUCT
int ValueMap::_number_of_finds = 0;
int ValueMap::_number_of_hits = 0;
int ValueMap::_number_of_kills = 0;
#define TRACE_VALUE_NUMBERING(code) if (PrintValueNumbering) { code; }
#else
#define TRACE_VALUE_NUMBERING(code)
#endif
ValueMap::ValueMap()
: _nesting(0)
, _entries(ValueMapInitialSize, NULL)
, _killed_values()
, _entry_count(0)
{
NOT_PRODUCT(reset_statistics());
}
ValueMap::ValueMap(ValueMap* old)
: _nesting(old->_nesting + 1)
, _entries(old->_entries.length())
, _killed_values()
, _entry_count(old->_entry_count)
{
for (int i = size() - 1; i >= 0; i--) {
_entries.at_put(i, old->entry_at(i));
}
_killed_values.set_from(&old->_killed_values);
}
void ValueMap::increase_table_size() {
int old_size = size();
int new_size = old_size * 2 + 1;
ValueMapEntryList worklist(8);
ValueMapEntryArray new_entries(new_size, NULL);
int new_entry_count = 0;
TRACE_VALUE_NUMBERING(tty->print_cr("increasing table size from %d to %d", old_size, new_size));
for (int i = old_size - 1; i >= 0; i--) {
ValueMapEntry* entry;
for (entry = entry_at(i); entry != NULL; entry = entry->next()) {
if (!is_killed(entry->value())) {
worklist.push(entry);
}
}
while (!worklist.is_empty()) {
entry = worklist.pop();
int new_index = entry_index(entry->hash(), new_size);
if (entry->nesting() != nesting() && new_entries.at(new_index) != entry->next()) {
// changing entries with a lower nesting than the current nesting of the table
// is not allowed because then the same entry is contained in multiple value maps.
// clone entry when next-pointer must be changed
entry = new ValueMapEntry(entry->hash(), entry->value(), entry->nesting(), NULL);
}
entry->set_next(new_entries.at(new_index));
new_entries.at_put(new_index, entry);
new_entry_count++;
}
}
_entries = new_entries;
_entry_count = new_entry_count;
}
Value ValueMap::find_insert(Value x) {
const intx hash = x->hash();
if (hash != 0) {
// 0 hash means: exclude from value numbering
NOT_PRODUCT(_number_of_finds++);
for (ValueMapEntry* entry = entry_at(entry_index(hash, size())); entry != NULL; entry = entry->next()) {
if (entry->hash() == hash) {
Value f = entry->value();
if (!is_killed(f) && f->is_equal(x)) {
NOT_PRODUCT(_number_of_hits++);
TRACE_VALUE_NUMBERING(tty->print_cr("Value Numbering: %s %c%d equal to %c%d (size %d, entries %d, nesting-diff %d)", x->name(), x->type()->tchar(), x->id(), f->type()->tchar(), f->id(), size(), entry_count(), nesting() - entry->nesting()));
if (entry->nesting() != nesting() && f->as_Constant() == NULL) {
// non-constant values of of another block must be pinned,
// otherwise it is possible that they are not evaluated
f->pin(Instruction::PinGlobalValueNumbering);
}
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assert(x->type()->tag() == f->type()->tag(), "should have same type");
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return f;
}
}
}
// x not found, so insert it
if (entry_count() >= size_threshold()) {
increase_table_size();
}
int idx = entry_index(hash, size());
_entries.at_put(idx, new ValueMapEntry(hash, x, nesting(), entry_at(idx)));
_entry_count++;
TRACE_VALUE_NUMBERING(tty->print_cr("Value Numbering: insert %s %c%d (size %d, entries %d, nesting %d)", x->name(), x->type()->tchar(), x->id(), size(), entry_count(), nesting()));
}
return x;
}
#define GENERIC_KILL_VALUE(must_kill_implementation) \
NOT_PRODUCT(_number_of_kills++); \
\
for (int i = size() - 1; i >= 0; i--) { \
ValueMapEntry* prev_entry = NULL; \
for (ValueMapEntry* entry = entry_at(i); entry != NULL; entry = entry->next()) { \
Value value = entry->value(); \
\
must_kill_implementation(must_kill, entry, value) \
\
if (must_kill) { \
kill_value(value); \
\
if (prev_entry == NULL) { \
_entries.at_put(i, entry->next()); \
_entry_count--; \
} else if (prev_entry->nesting() == nesting()) { \
prev_entry->set_next(entry->next()); \
_entry_count--; \
} else { \
prev_entry = entry; \
} \
\
TRACE_VALUE_NUMBERING(tty->print_cr("Value Numbering: killed %s %c%d (size %d, entries %d, nesting-diff %d)", value->name(), value->type()->tchar(), value->id(), size(), entry_count(), nesting() - entry->nesting())); \
} else { \
prev_entry = entry; \
} \
} \
} \
#define MUST_KILL_MEMORY(must_kill, entry, value) \
bool must_kill = value->as_LoadField() != NULL || value->as_LoadIndexed() != NULL;
#define MUST_KILL_ARRAY(must_kill, entry, value) \
bool must_kill = value->as_LoadIndexed() != NULL \
&& value->type()->tag() == type->tag();
#define MUST_KILL_FIELD(must_kill, entry, value) \
/* ciField's are not unique; must compare their contents */ \
LoadField* lf = value->as_LoadField(); \
bool must_kill = lf != NULL \
&& lf->field()->holder() == field->holder() \
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&& (all_offsets || lf->field()->offset() == field->offset());
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void ValueMap::kill_memory() {
GENERIC_KILL_VALUE(MUST_KILL_MEMORY);
}
void ValueMap::kill_array(ValueType* type) {
GENERIC_KILL_VALUE(MUST_KILL_ARRAY);
}
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void ValueMap::kill_field(ciField* field, bool all_offsets) {
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GENERIC_KILL_VALUE(MUST_KILL_FIELD);
}
void ValueMap::kill_map(ValueMap* map) {
assert(is_global_value_numbering(), "only for global value numbering");
_killed_values.set_union(&map->_killed_values);
}
void ValueMap::kill_all() {
assert(is_local_value_numbering(), "only for local value numbering");
for (int i = size() - 1; i >= 0; i--) {
_entries.at_put(i, NULL);
}
_entry_count = 0;
}
#ifndef PRODUCT
void ValueMap::print() {
tty->print_cr("(size %d, entries %d, nesting %d)", size(), entry_count(), nesting());
int entries = 0;
for (int i = 0; i < size(); i++) {
if (entry_at(i) != NULL) {
tty->print(" %2d: ", i);
for (ValueMapEntry* entry = entry_at(i); entry != NULL; entry = entry->next()) {
Value value = entry->value();
tty->print("%s %c%d (%s%d) -> ", value->name(), value->type()->tchar(), value->id(), is_killed(value) ? "x" : "", entry->nesting());
entries++;
}
tty->print_cr("NULL");
}
}
_killed_values.print();
assert(entry_count() == entries, "entry_count incorrect");
}
void ValueMap::reset_statistics() {
_number_of_finds = 0;
_number_of_hits = 0;
_number_of_kills = 0;
}
void ValueMap::print_statistics() {
float hit_rate = 0;
if (_number_of_finds != 0) {
hit_rate = (float)_number_of_hits / _number_of_finds;
}
tty->print_cr("finds:%3d hits:%3d kills:%3d hit rate: %1.4f", _number_of_finds, _number_of_hits, _number_of_kills, hit_rate);
}
#endif
class ShortLoopOptimizer : public ValueNumberingVisitor {
private:
GlobalValueNumbering* _gvn;
BlockList _loop_blocks;
bool _too_complicated_loop;
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bool _has_field_store[T_ARRAY + 1];
bool _has_indexed_store[T_ARRAY + 1];
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// simplified access to methods of GlobalValueNumbering
ValueMap* current_map() { return _gvn->current_map(); }
ValueMap* value_map_of(BlockBegin* block) { return _gvn->value_map_of(block); }
// implementation for abstract methods of ValueNumberingVisitor
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void kill_memory() { _too_complicated_loop = true; }
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void kill_field(ciField* field, bool all_offsets) {
current_map()->kill_field(field, all_offsets);
assert(field->type()->basic_type() >= 0 && field->type()->basic_type() <= T_ARRAY, "Invalid type");
_has_field_store[field->type()->basic_type()] = true;
}
void kill_array(ValueType* type) {
current_map()->kill_array(type);
BasicType basic_type = as_BasicType(type); assert(basic_type >= 0 && basic_type <= T_ARRAY, "Invalid type");
_has_indexed_store[basic_type] = true;
}
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public:
ShortLoopOptimizer(GlobalValueNumbering* gvn)
: _gvn(gvn)
, _loop_blocks(ValueMapMaxLoopSize)
, _too_complicated_loop(false)
{
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for (int i=0; i<= T_ARRAY; i++){
_has_field_store[i] = false;
_has_indexed_store[i] = false;
}
}
bool has_field_store(BasicType type) {
assert(type >= 0 && type <= T_ARRAY, "Invalid type");
return _has_field_store[type];
}
bool has_indexed_store(BasicType type) {
assert(type >= 0 && type <= T_ARRAY, "Invalid type");
return _has_indexed_store[type];
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}
bool process(BlockBegin* loop_header);
};
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class LoopInvariantCodeMotion : public StackObj {
private:
GlobalValueNumbering* _gvn;
ShortLoopOptimizer* _short_loop_optimizer;
Instruction* _insertion_point;
ValueStack * _state;
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bool _insert_is_pred;
7153771: array bound check elimination for c1 When possible optimize out array bound checks, inserting predicates when needed. Reviewed-by: never, kvn, twisti
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void set_invariant(Value v) const { _gvn->set_processed(v); }
bool is_invariant(Value v) const { return _gvn->is_processed(v); }
void process_block(BlockBegin* block);
public:
LoopInvariantCodeMotion(ShortLoopOptimizer *slo, GlobalValueNumbering* gvn, BlockBegin* loop_header, BlockList* loop_blocks);
};
LoopInvariantCodeMotion::LoopInvariantCodeMotion(ShortLoopOptimizer *slo, GlobalValueNumbering* gvn, BlockBegin* loop_header, BlockList* loop_blocks)
: _gvn(gvn), _short_loop_optimizer(slo) {
TRACE_VALUE_NUMBERING(tty->print_cr("using loop invariant code motion loop_header = %d", loop_header->block_id()));
TRACE_VALUE_NUMBERING(tty->print_cr("** loop invariant code motion for short loop B%d", loop_header->block_id()));
BlockBegin* insertion_block = loop_header->dominator();
if (insertion_block->number_of_preds() == 0) {
return; // only the entry block does not have a predecessor
}
assert(insertion_block->end()->as_Base() == NULL, "cannot insert into entry block");
_insertion_point = insertion_block->end()->prev();
8011706: specjvm2008 test xml.transform gets array bound exception with c1 Loop invariant code motion may move load before store to the same field Reviewed-by: kvn
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_insert_is_pred = loop_header->is_predecessor(insertion_block);
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BlockEnd *block_end = insertion_block->end();
_state = block_end->state_before();
if (!_state) {
// If, TableSwitch and LookupSwitch always have state_before when
// loop invariant code motion happens..
assert(block_end->as_Goto(), "Block has to be goto");
_state = block_end->state();
}
// the loop_blocks are filled by going backward from the loop header, so this processing order is best
assert(loop_blocks->at(0) == loop_header, "loop header must be first loop block");
process_block(loop_header);
for (int i = loop_blocks->length() - 1; i >= 1; i--) {
process_block(loop_blocks->at(i));
}
}
void LoopInvariantCodeMotion::process_block(BlockBegin* block) {
TRACE_VALUE_NUMBERING(tty->print_cr("processing block B%d", block->block_id()));
Instruction* prev = block;
Instruction* cur = block->next();
while (cur != NULL) {
// determine if cur instruction is loop invariant
// only selected instruction types are processed here
bool cur_invariant = false;
if (cur->as_Constant() != NULL) {
cur_invariant = !cur->can_trap();
} else if (cur->as_ArithmeticOp() != NULL || cur->as_LogicOp() != NULL || cur->as_ShiftOp() != NULL) {
assert(cur->as_Op2() != NULL, "must be Op2");
Op2* op2 = (Op2*)cur;
cur_invariant = !op2->can_trap() && is_invariant(op2->x()) && is_invariant(op2->y());
} else if (cur->as_LoadField() != NULL) {
LoadField* lf = (LoadField*)cur;
// deoptimizes on NullPointerException
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cur_invariant = !lf->needs_patching() && !lf->field()->is_volatile() && !_short_loop_optimizer->has_field_store(lf->field()->type()->basic_type()) && is_invariant(lf->obj()) && _insert_is_pred;
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} else if (cur->as_ArrayLength() != NULL) {
ArrayLength *length = cur->as_ArrayLength();
cur_invariant = is_invariant(length->array());
} else if (cur->as_LoadIndexed() != NULL) {
LoadIndexed *li = (LoadIndexed *)cur->as_LoadIndexed();
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cur_invariant = !_short_loop_optimizer->has_indexed_store(as_BasicType(cur->type())) && is_invariant(li->array()) && is_invariant(li->index()) && _insert_is_pred;
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}
if (cur_invariant) {
// perform value numbering and mark instruction as loop-invariant
_gvn->substitute(cur);
if (cur->as_Constant() == NULL) {
// ensure that code for non-constant instructions is always generated
cur->pin();
}
// remove cur instruction from loop block and append it to block before loop
Instruction* next = cur->next();
Instruction* in = _insertion_point->next();
_insertion_point = _insertion_point->set_next(cur);
cur->set_next(in);
// Deoptimize on exception
cur->set_flag(Instruction::DeoptimizeOnException, true);
// Clear exception handlers
cur->set_exception_handlers(NULL);
TRACE_VALUE_NUMBERING(tty->print_cr("Instruction %c%d is loop invariant", cur->type()->tchar(), cur->id()));
if (cur->state_before() != NULL) {
cur->set_state_before(_state->copy());
}
if (cur->exception_state() != NULL) {
cur->set_exception_state(_state->copy());
}
cur = prev->set_next(next);
} else {
prev = cur;
cur = cur->next();
}
}
}
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bool ShortLoopOptimizer::process(BlockBegin* loop_header) {
TRACE_VALUE_NUMBERING(tty->print_cr("** loop header block"));
_too_complicated_loop = false;
_loop_blocks.clear();
_loop_blocks.append(loop_header);
for (int i = 0; i < _loop_blocks.length(); i++) {
BlockBegin* block = _loop_blocks.at(i);
TRACE_VALUE_NUMBERING(tty->print_cr("processing loop block B%d", block->block_id()));
if (block->is_set(BlockBegin::exception_entry_flag)) {
// this would be too complicated
return false;
}
// add predecessors to worklist
for (int j = block->number_of_preds() - 1; j >= 0; j--) {
BlockBegin* pred = block->pred_at(j);
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if (pred->is_set(BlockBegin::osr_entry_flag)) {
return false;
}
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ValueMap* pred_map = value_map_of(pred);
if (pred_map != NULL) {
current_map()->kill_map(pred_map);
} else if (!_loop_blocks.contains(pred)) {
if (_loop_blocks.length() >= ValueMapMaxLoopSize) {
return false;
}
_loop_blocks.append(pred);
}
}
// use the instruction visitor for killing values
for (Value instr = block->next(); instr != NULL; instr = instr->next()) {
instr->visit(this);
if (_too_complicated_loop) {
return false;
}
}
}
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bool optimistic = this->_gvn->compilation()->is_optimistic();
if (UseLoopInvariantCodeMotion && optimistic) {
LoopInvariantCodeMotion code_motion(this, _gvn, loop_header, &_loop_blocks);
}
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TRACE_VALUE_NUMBERING(tty->print_cr("** loop successfully optimized"));
return true;
}
GlobalValueNumbering::GlobalValueNumbering(IR* ir)
: _current_map(NULL)
, _value_maps(ir->linear_scan_order()->length(), NULL)
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, _compilation(ir->compilation())
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{
TRACE_VALUE_NUMBERING(tty->print_cr("****** start of global value numbering"));
ShortLoopOptimizer short_loop_optimizer(this);
BlockList* blocks = ir->linear_scan_order();
int num_blocks = blocks->length();
BlockBegin* start_block = blocks->at(0);
assert(start_block == ir->start() && start_block->number_of_preds() == 0 && start_block->dominator() == NULL, "must be start block");
assert(start_block->next()->as_Base() != NULL && start_block->next()->next() == NULL, "start block must not have instructions");
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// method parameters are not linked in instructions list, so process them separateley
for_each_state_value(start_block->state(), value,
assert(value->as_Local() != NULL, "only method parameters allowed");
set_processed(value);
);
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// initial, empty value map with nesting 0
set_value_map_of(start_block, new ValueMap());
for (int i = 1; i < num_blocks; i++) {
BlockBegin* block = blocks->at(i);
TRACE_VALUE_NUMBERING(tty->print_cr("**** processing block B%d", block->block_id()));
int num_preds = block->number_of_preds();
assert(num_preds > 0, "block must have predecessors");
BlockBegin* dominator = block->dominator();
assert(dominator != NULL, "dominator must exist");
assert(value_map_of(dominator) != NULL, "value map of dominator must exist");
// create new value map with increased nesting
_current_map = new ValueMap(value_map_of(dominator));
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if (num_preds == 1 && !block->is_set(BlockBegin::exception_entry_flag)) {
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assert(dominator == block->pred_at(0), "dominator must be equal to predecessor");
// nothing to do here
} else if (block->is_set(BlockBegin::linear_scan_loop_header_flag)) {
// block has incoming backward branches -> try to optimize short loops
if (!short_loop_optimizer.process(block)) {
// loop is too complicated, so kill all memory loads because there might be
// stores to them in the loop
current_map()->kill_memory();
}
} else {
// only incoming forward branches that are already processed
for (int j = 0; j < num_preds; j++) {
BlockBegin* pred = block->pred_at(j);
ValueMap* pred_map = value_map_of(pred);
if (pred_map != NULL) {
// propagate killed values of the predecessor to this block
current_map()->kill_map(value_map_of(pred));
} else {
// kill all memory loads because predecessor not yet processed
// (this can happen with non-natural loops and OSR-compiles)
current_map()->kill_memory();
}
}
}
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// phi functions are not linked in instructions list, so process them separateley
for_each_phi_fun(block, phi,
set_processed(phi);
);
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TRACE_VALUE_NUMBERING(tty->print("value map before processing block: "); current_map()->print());
// visit all instructions of this block
for (Value instr = block->next(); instr != NULL; instr = instr->next()) {
// check if instruction kills any values
instr->visit(this);
7153771: array bound check elimination for c1 When possible optimize out array bound checks, inserting predicates when needed. Reviewed-by: never, kvn, twisti
2013-03-21 09:27:54 +01:00
// perform actual value numbering
substitute(instr);
Initial load
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}
// remember value map for successors
set_value_map_of(block, current_map());
}
7153771: array bound check elimination for c1 When possible optimize out array bound checks, inserting predicates when needed. Reviewed-by: never, kvn, twisti
2013-03-21 09:27:54 +01:00
if (_has_substitutions) {
Initial load
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SubstitutionResolver resolver(ir);
}
TRACE_VALUE_NUMBERING(tty->print("****** end of global value numbering. "); ValueMap::print_statistics());
}
7153771: array bound check elimination for c1 When possible optimize out array bound checks, inserting predicates when needed. Reviewed-by: never, kvn, twisti
2013-03-21 09:27:54 +01:00
void GlobalValueNumbering::substitute(Instruction* instr) {
assert(!instr->has_subst(), "substitution already set");
Value subst = current_map()->find_insert(instr);
if (subst != instr) {
assert(!subst->has_subst(), "can't have a substitution");
TRACE_VALUE_NUMBERING(tty->print_cr("substitution for %d set to %d", instr->id(), subst->id()));
instr->set_subst(subst);
_has_substitutions = true;
}
set_processed(instr);
}
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