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android / toolchain / jdk / jdk21 / HEAD / . / src / hotspot / share / opto / phaseX.cpp
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/*
* Copyright (c) 1997, 2023, 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 "gc/shared/barrierSet.hpp"
#include "gc/shared/c2/barrierSetC2.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
#include "opto/block.hpp"
#include "opto/callnode.hpp"
#include "opto/castnode.hpp"
#include "opto/cfgnode.hpp"
#include "opto/idealGraphPrinter.hpp"
#include "opto/loopnode.hpp"
#include "opto/machnode.hpp"
#include "opto/opcodes.hpp"
#include "opto/phaseX.hpp"
#include "opto/regalloc.hpp"
#include "opto/rootnode.hpp"
#include "utilities/macros.hpp"
#include "utilities/powerOfTwo.hpp"
//=============================================================================
#define NODE_HASH_MINIMUM_SIZE 255
//------------------------------NodeHash---------------------------------------
NodeHash::NodeHash(Arena *arena, uint est_max_size) :
_a(arena),
_max( round_up(est_max_size < NODE_HASH_MINIMUM_SIZE ? NODE_HASH_MINIMUM_SIZE : est_max_size) ),
_inserts(0), _insert_limit( insert_limit() ),
_table( NEW_ARENA_ARRAY( _a , Node* , _max ) )
#ifndef PRODUCT
, _grows(0),_look_probes(0), _lookup_hits(0), _lookup_misses(0),
_insert_probes(0), _delete_probes(0), _delete_hits(0), _delete_misses(0),
_total_inserts(0), _total_insert_probes(0)
#endif
{
// _sentinel must be in the current node space
_sentinel = new ProjNode(nullptr, TypeFunc::Control);
memset(_table,0,sizeof(Node*)*_max);
}
//------------------------------hash_find--------------------------------------
// Find in hash table
Node *NodeHash::hash_find( const Node *n ) {
// ((Node*)n)->set_hash( n->hash() );
uint hash = n->hash();
if (hash == Node::NO_HASH) {
NOT_PRODUCT( _lookup_misses++ );
return nullptr;
}
uint key = hash & (_max-1);
uint stride = key | 0x01;
NOT_PRODUCT( _look_probes++ );
Node *k = _table[key]; // Get hashed value
if( !k ) { // ?Miss?
NOT_PRODUCT( _lookup_misses++ );
return nullptr; // Miss!
}
int op = n->Opcode();
uint req = n->req();
while( 1 ) { // While probing hash table
if( k->req() == req && // Same count of inputs
k->Opcode() == op ) { // Same Opcode
for( uint i=0; i<req; i++ )
if( n->in(i)!=k->in(i)) // Different inputs?
goto collision; // "goto" is a speed hack...
if( n->cmp(*k) ) { // Check for any special bits
NOT_PRODUCT( _lookup_hits++ );
return k; // Hit!
}
}
collision:
NOT_PRODUCT( _look_probes++ );
key = (key + stride/*7*/) & (_max-1); // Stride through table with relative prime
k = _table[key]; // Get hashed value
if( !k ) { // ?Miss?
NOT_PRODUCT( _lookup_misses++ );
return nullptr; // Miss!
}
}
ShouldNotReachHere();
return nullptr;
}
//------------------------------hash_find_insert-------------------------------
// Find in hash table, insert if not already present
// Used to preserve unique entries in hash table
Node *NodeHash::hash_find_insert( Node *n ) {
// n->set_hash( );
uint hash = n->hash();
if (hash == Node::NO_HASH) {
NOT_PRODUCT( _lookup_misses++ );
return nullptr;
}
uint key = hash & (_max-1);
uint stride = key | 0x01; // stride must be relatively prime to table siz
uint first_sentinel = 0; // replace a sentinel if seen.
NOT_PRODUCT( _look_probes++ );
Node *k = _table[key]; // Get hashed value
if( !k ) { // ?Miss?
NOT_PRODUCT( _lookup_misses++ );
_table[key] = n; // Insert into table!
debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
check_grow(); // Grow table if insert hit limit
return nullptr; // Miss!
}
else if( k == _sentinel ) {
first_sentinel = key; // Can insert here
}
int op = n->Opcode();
uint req = n->req();
while( 1 ) { // While probing hash table
if( k->req() == req && // Same count of inputs
k->Opcode() == op ) { // Same Opcode
for( uint i=0; i<req; i++ )
if( n->in(i)!=k->in(i)) // Different inputs?
goto collision; // "goto" is a speed hack...
if( n->cmp(*k) ) { // Check for any special bits
NOT_PRODUCT( _lookup_hits++ );
return k; // Hit!
}
}
collision:
NOT_PRODUCT( _look_probes++ );
key = (key + stride) & (_max-1); // Stride through table w/ relative prime
k = _table[key]; // Get hashed value
if( !k ) { // ?Miss?
NOT_PRODUCT( _lookup_misses++ );
key = (first_sentinel == 0) ? key : first_sentinel; // ?saw sentinel?
_table[key] = n; // Insert into table!
debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
check_grow(); // Grow table if insert hit limit
return nullptr; // Miss!
}
else if( first_sentinel == 0 && k == _sentinel ) {
first_sentinel = key; // Can insert here
}
}
ShouldNotReachHere();
return nullptr;
}
//------------------------------hash_insert------------------------------------
// Insert into hash table
void NodeHash::hash_insert( Node *n ) {
// // "conflict" comments -- print nodes that conflict
// bool conflict = false;
// n->set_hash();
uint hash = n->hash();
if (hash == Node::NO_HASH) {
return;
}
check_grow();
uint key = hash & (_max-1);
uint stride = key | 0x01;
while( 1 ) { // While probing hash table
NOT_PRODUCT( _insert_probes++ );
Node *k = _table[key]; // Get hashed value
if( !k || (k == _sentinel) ) break; // Found a slot
assert( k != n, "already inserted" );
// if( PrintCompilation && PrintOptoStatistics && Verbose ) { tty->print(" conflict: "); k->dump(); conflict = true; }
key = (key + stride) & (_max-1); // Stride through table w/ relative prime
}
_table[key] = n; // Insert into table!
debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
// if( conflict ) { n->dump(); }
}
//------------------------------hash_delete------------------------------------
// Replace in hash table with sentinel
bool NodeHash::hash_delete( const Node *n ) {
Node *k;
uint hash = n->hash();
if (hash == Node::NO_HASH) {
NOT_PRODUCT( _delete_misses++ );
return false;
}
uint key = hash & (_max-1);
uint stride = key | 0x01;
debug_only( uint counter = 0; );
for( ; /* (k != nullptr) && (k != _sentinel) */; ) {
debug_only( counter++ );
NOT_PRODUCT( _delete_probes++ );
k = _table[key]; // Get hashed value
if( !k ) { // Miss?
NOT_PRODUCT( _delete_misses++ );
return false; // Miss! Not in chain
}
else if( n == k ) {
NOT_PRODUCT( _delete_hits++ );
_table[key] = _sentinel; // Hit! Label as deleted entry
debug_only(((Node*)n)->exit_hash_lock()); // Unlock the node upon removal from table.
return true;
}
else {
// collision: move through table with prime offset
key = (key + stride/*7*/) & (_max-1);
assert( counter <= _insert_limit, "Cycle in hash-table");
}
}
ShouldNotReachHere();
return false;
}
//------------------------------round_up---------------------------------------
// Round up to nearest power of 2
uint NodeHash::round_up(uint x) {
x += (x >> 2); // Add 25% slop
return MAX2(16U, round_up_power_of_2(x));
}
//------------------------------grow-------------------------------------------
// Grow _table to next power of 2 and insert old entries
void NodeHash::grow() {
// Record old state
uint old_max = _max;
Node **old_table = _table;
// Construct new table with twice the space
#ifndef PRODUCT
_grows++;
_total_inserts += _inserts;
_total_insert_probes += _insert_probes;
_insert_probes = 0;
#endif
_inserts = 0;
_max = _max << 1;
_table = NEW_ARENA_ARRAY( _a , Node* , _max ); // (Node**)_a->Amalloc( _max * sizeof(Node*) );
memset(_table,0,sizeof(Node*)*_max);
_insert_limit = insert_limit();
// Insert old entries into the new table
for( uint i = 0; i < old_max; i++ ) {
Node *m = *old_table++;
if( !m || m == _sentinel ) continue;
debug_only(m->exit_hash_lock()); // Unlock the node upon removal from old table.
hash_insert(m);
}
}
//------------------------------clear------------------------------------------
// Clear all entries in _table to null but keep storage
void NodeHash::clear() {
#ifdef ASSERT
// Unlock all nodes upon removal from table.
for (uint i = 0; i < _max; i++) {
Node* n = _table[i];
if (!n || n == _sentinel) continue;
n->exit_hash_lock();
}
#endif
memset( _table, 0, _max * sizeof(Node*) );
}
//-----------------------remove_useless_nodes----------------------------------
// Remove useless nodes from value table,
// implementation does not depend on hash function
void NodeHash::remove_useless_nodes(VectorSet &useful) {
// Dead nodes in the hash table inherited from GVN should not replace
// existing nodes, remove dead nodes.
uint max = size();
Node *sentinel_node = sentinel();
for( uint i = 0; i < max; ++i ) {
Node *n = at(i);
if(n != nullptr && n != sentinel_node && !useful.test(n->_idx)) {
debug_only(n->exit_hash_lock()); // Unlock the node when removed
_table[i] = sentinel_node; // Replace with placeholder
}
}
}
void NodeHash::check_no_speculative_types() {
#ifdef ASSERT
uint max = size();
Unique_Node_List live_nodes;
Compile::current()->identify_useful_nodes(live_nodes);
Node *sentinel_node = sentinel();
for (uint i = 0; i < max; ++i) {
Node *n = at(i);
if (n != nullptr &&
n != sentinel_node &&
n->is_Type() &&
live_nodes.member(n)) {
TypeNode* tn = n->as_Type();
const Type* t = tn->type();
const Type* t_no_spec = t->remove_speculative();
assert(t == t_no_spec, "dead node in hash table or missed node during speculative cleanup");
}
}
#endif
}
#ifndef PRODUCT
//------------------------------dump-------------------------------------------
// Dump statistics for the hash table
void NodeHash::dump() {
_total_inserts += _inserts;
_total_insert_probes += _insert_probes;
if (PrintCompilation && PrintOptoStatistics && Verbose && (_inserts > 0)) {
if (WizardMode) {
for (uint i=0; i<_max; i++) {
if (_table[i])
tty->print("%d/%d/%d ",i,_table[i]->hash()&(_max-1),_table[i]->_idx);
}
}
tty->print("\nGVN Hash stats: %d grows to %d max_size\n", _grows, _max);
tty->print(" %d/%d (%8.1f%% full)\n", _inserts, _max, (double)_inserts/_max*100.0);
tty->print(" %dp/(%dh+%dm) (%8.2f probes/lookup)\n", _look_probes, _lookup_hits, _lookup_misses, (double)_look_probes/(_lookup_hits+_lookup_misses));
tty->print(" %dp/%di (%8.2f probes/insert)\n", _total_insert_probes, _total_inserts, (double)_total_insert_probes/_total_inserts);
// sentinels increase lookup cost, but not insert cost
assert((_lookup_misses+_lookup_hits)*4+100 >= _look_probes, "bad hash function");
assert( _inserts+(_inserts>>3) < _max, "table too full" );
assert( _inserts*3+100 >= _insert_probes, "bad hash function" );
}
}
Node *NodeHash::find_index(uint idx) { // For debugging
// Find an entry by its index value
for( uint i = 0; i < _max; i++ ) {
Node *m = _table[i];
if( !m || m == _sentinel ) continue;
if( m->_idx == (uint)idx ) return m;
}
return nullptr;
}
#endif
#ifdef ASSERT
NodeHash::~NodeHash() {
// Unlock all nodes upon destruction of table.
if (_table != (Node**)badAddress) clear();
}
#endif
//=============================================================================
//------------------------------PhaseRemoveUseless-----------------------------
// 1) Use a breadthfirst walk to collect useful nodes reachable from root.
PhaseRemoveUseless::PhaseRemoveUseless(PhaseGVN* gvn, Unique_Node_List& worklist, PhaseNumber phase_num) : Phase(phase_num) {
// Implementation requires an edge from root to each SafePointNode
// at a backward branch. Inserted in add_safepoint().
// Identify nodes that are reachable from below, useful.
C->identify_useful_nodes(_useful);
// Update dead node list
C->update_dead_node_list(_useful);
// Remove all useless nodes from PhaseValues' recorded types
// Must be done before disconnecting nodes to preserve hash-table-invariant
gvn->remove_useless_nodes(_useful.member_set());
// Remove all useless nodes from future worklist
worklist.remove_useless_nodes(_useful.member_set());
// Disconnect 'useless' nodes that are adjacent to useful nodes
C->disconnect_useless_nodes(_useful, worklist);
}
//=============================================================================
//------------------------------PhaseRenumberLive------------------------------
// First, remove useless nodes (equivalent to identifying live nodes).
// Then, renumber live nodes.
//
// The set of live nodes is returned by PhaseRemoveUseless in the _useful structure.
// If the number of live nodes is 'x' (where 'x' == _useful.size()), then the
// PhaseRenumberLive updates the node ID of each node (the _idx field) with a unique
// value in the range [0, x).
//
// At the end of the PhaseRenumberLive phase, the compiler's count of unique nodes is
// updated to 'x' and the list of dead nodes is reset (as there are no dead nodes).
//
// The PhaseRenumberLive phase updates two data structures with the new node IDs.
// (1) The "worklist" is "C->igvn_worklist()", which is to collect which nodes need to
// be processed by IGVN after removal of the useless nodes.
// (2) Type information "gvn->types()" (same as "C->types()") maps every node ID to
// the node's type. The mapping is updated to use the new node IDs as well. We
// create a new map, and swap it with the old one.
//
// Other data structures used by the compiler are not updated. The hash table for value
// numbering ("C->node_hash()", referenced by PhaseValue::_table) is not updated because
// computing the hash values is not based on node IDs.
PhaseRenumberLive::PhaseRenumberLive(PhaseGVN* gvn,
Unique_Node_List& worklist,
PhaseNumber phase_num) :
PhaseRemoveUseless(gvn, worklist, Remove_Useless_And_Renumber_Live),
_new_type_array(C->comp_arena()),
_old2new_map(C->unique(), C->unique(), -1),
_is_pass_finished(false),
_live_node_count(C->live_nodes())
{
assert(RenumberLiveNodes, "RenumberLiveNodes must be set to true for node renumbering to take place");
assert(C->live_nodes() == _useful.size(), "the number of live nodes must match the number of useful nodes");
assert(_delayed.size() == 0, "should be empty");
assert(&worklist == C->igvn_worklist(), "reference still same as the one from Compile");
assert(&gvn->types() == C->types(), "reference still same as that from Compile");
GrowableArray<Node_Notes*>* old_node_note_array = C->node_note_array();
if (old_node_note_array != nullptr) {
int new_size = (_useful.size() >> 8) + 1; // The node note array uses blocks, see C->_log2_node_notes_block_size
new_size = MAX2(8, new_size);
C->set_node_note_array(new (C->comp_arena()) GrowableArray<Node_Notes*> (C->comp_arena(), new_size, 0, nullptr));
C->grow_node_notes(C->node_note_array(), new_size);
}
assert(worklist.is_subset_of(_useful), "only useful nodes should still be in the worklist");
// Iterate over the set of live nodes.
for (uint current_idx = 0; current_idx < _useful.size(); current_idx++) {
Node* n = _useful.at(current_idx);
const Type* type = gvn->type_or_null(n);
_new_type_array.map(current_idx, type);
assert(_old2new_map.at(n->_idx) == -1, "already seen");
_old2new_map.at_put(n->_idx, current_idx);
if (old_node_note_array != nullptr) {
Node_Notes* nn = C->locate_node_notes(old_node_note_array, n->_idx);
C->set_node_notes_at(current_idx, nn);
}
n->set_idx(current_idx); // Update node ID.
if (update_embedded_ids(n) < 0) {
_delayed.push(n); // has embedded IDs; handle later
}
}
// VectorSet in Unique_Node_Set must be recomputed, since IDs have changed.
worklist.recompute_idx_set();
assert(_live_node_count == _useful.size(), "all live nodes must be processed");
_is_pass_finished = true; // pass finished; safe to process delayed updates
while (_delayed.size() > 0) {
Node* n = _delayed.pop();
int no_of_updates = update_embedded_ids(n);
assert(no_of_updates > 0, "should be updated");
}
// Replace the compiler's type information with the updated type information.
gvn->types().swap(_new_type_array);
// Update the unique node count of the compilation to the number of currently live nodes.
C->set_unique(_live_node_count);
// Set the dead node count to 0 and reset dead node list.
C->reset_dead_node_list();
}
int PhaseRenumberLive::new_index(int old_idx) {
assert(_is_pass_finished, "not finished");
if (_old2new_map.at(old_idx) == -1) { // absent
// Allocate a placeholder to preserve uniqueness
_old2new_map.at_put(old_idx, _live_node_count);
_live_node_count++;
}
return _old2new_map.at(old_idx);
}
int PhaseRenumberLive::update_embedded_ids(Node* n) {
int no_of_updates = 0;
if (n->is_Phi()) {
PhiNode* phi = n->as_Phi();
if (phi->_inst_id != -1) {
if (!_is_pass_finished) {
return -1; // delay
}
int new_idx = new_index(phi->_inst_id);
assert(new_idx != -1, "");
phi->_inst_id = new_idx;
no_of_updates++;
}
if (phi->_inst_mem_id != -1) {
if (!_is_pass_finished) {
return -1; // delay
}
int new_idx = new_index(phi->_inst_mem_id);
assert(new_idx != -1, "");
phi->_inst_mem_id = new_idx;
no_of_updates++;
}
}
const Type* type = _new_type_array.fast_lookup(n->_idx);
if (type != nullptr && type->isa_oopptr() && type->is_oopptr()->is_known_instance()) {
if (!_is_pass_finished) {
return -1; // delay
}
int old_idx = type->is_oopptr()->instance_id();
int new_idx = new_index(old_idx);
const Type* new_type = type->is_oopptr()->with_instance_id(new_idx);
_new_type_array.map(n->_idx, new_type);
no_of_updates++;
}
return no_of_updates;
}
void PhaseValues::init_con_caches() {
memset(_icons,0,sizeof(_icons));
memset(_lcons,0,sizeof(_lcons));
memset(_zcons,0,sizeof(_zcons));
}
//--------------------------------find_int_type--------------------------------
const TypeInt* PhaseValues::find_int_type(Node* n) {
if (n == nullptr) return nullptr;
// Call type_or_null(n) to determine node's type since we might be in
// parse phase and call n->Value() may return wrong type.
// (For example, a phi node at the beginning of loop parsing is not ready.)
const Type* t = type_or_null(n);
if (t == nullptr) return nullptr;
return t->isa_int();
}
//-------------------------------find_long_type--------------------------------
const TypeLong* PhaseValues::find_long_type(Node* n) {
if (n == nullptr) return nullptr;
// (See comment above on type_or_null.)
const Type* t = type_or_null(n);
if (t == nullptr) return nullptr;
return t->isa_long();
}
//------------------------------~PhaseValues-----------------------------------
#ifndef PRODUCT
PhaseValues::~PhaseValues() {
// Statistics for NodeHash
_table.dump();
// Statistics for value progress and efficiency
if( PrintCompilation && Verbose && WizardMode ) {
tty->print("\n%sValues: %d nodes ---> %d/%d (%d)",
is_IterGVN() ? "Iter" : " ", C->unique(), made_progress(), made_transforms(), made_new_values());
if( made_transforms() != 0 ) {
tty->print_cr(" ratio %f", made_progress()/(float)made_transforms() );
} else {
tty->cr();
}
}
}
#endif
//------------------------------makecon----------------------------------------
ConNode* PhaseValues::makecon(const Type* t) {
assert(t->singleton(), "must be a constant");
assert(!t->empty() || t == Type::TOP, "must not be vacuous range");
switch (t->base()) { // fast paths
case Type::Half:
case Type::Top: return (ConNode*) C->top();
case Type::Int: return intcon( t->is_int()->get_con() );
case Type::Long: return longcon( t->is_long()->get_con() );
default: break;
}
if (t->is_zero_type())
return zerocon(t->basic_type());
return uncached_makecon(t);
}
//--------------------------uncached_makecon-----------------------------------
// Make an idealized constant - one of ConINode, ConPNode, etc.
ConNode* PhaseValues::uncached_makecon(const Type *t) {
assert(t->singleton(), "must be a constant");
ConNode* x = ConNode::make(t);
ConNode* k = (ConNode*)hash_find_insert(x); // Value numbering
if (k == nullptr) {
set_type(x, t); // Missed, provide type mapping
GrowableArray<Node_Notes*>* nna = C->node_note_array();
if (nna != nullptr) {
Node_Notes* loc = C->locate_node_notes(nna, x->_idx, true);
loc->clear(); // do not put debug info on constants
}
} else {
x->destruct(this); // Hit, destroy duplicate constant
x = k; // use existing constant
}
return x;
}
//------------------------------intcon-----------------------------------------
// Fast integer constant. Same as "transform(new ConINode(TypeInt::make(i)))"
ConINode* PhaseValues::intcon(jint i) {
// Small integer? Check cache! Check that cached node is not dead
if (i >= _icon_min && i <= _icon_max) {
ConINode* icon = _icons[i-_icon_min];
if (icon != nullptr && icon->in(TypeFunc::Control) != nullptr)
return icon;
}
ConINode* icon = (ConINode*) uncached_makecon(TypeInt::make(i));
assert(icon->is_Con(), "");
if (i >= _icon_min && i <= _icon_max)
_icons[i-_icon_min] = icon; // Cache small integers
return icon;
}
//------------------------------longcon----------------------------------------
// Fast long constant.
ConLNode* PhaseValues::longcon(jlong l) {
// Small integer? Check cache! Check that cached node is not dead
if (l >= _lcon_min && l <= _lcon_max) {
ConLNode* lcon = _lcons[l-_lcon_min];
if (lcon != nullptr && lcon->in(TypeFunc::Control) != nullptr)
return lcon;
}
ConLNode* lcon = (ConLNode*) uncached_makecon(TypeLong::make(l));
assert(lcon->is_Con(), "");
if (l >= _lcon_min && l <= _lcon_max)
_lcons[l-_lcon_min] = lcon; // Cache small integers
return lcon;
}
ConNode* PhaseValues::integercon(jlong l, BasicType bt) {
if (bt == T_INT) {
return intcon(checked_cast<jint>(l));
}
assert(bt == T_LONG, "not an integer");
return longcon(l);
}
//------------------------------zerocon-----------------------------------------
// Fast zero or null constant. Same as "transform(ConNode::make(Type::get_zero_type(bt)))"
ConNode* PhaseValues::zerocon(BasicType bt) {
assert((uint)bt <= _zcon_max, "domain check");
ConNode* zcon = _zcons[bt];
if (zcon != nullptr && zcon->in(TypeFunc::Control) != nullptr)
return zcon;
zcon = (ConNode*) uncached_makecon(Type::get_zero_type(bt));
_zcons[bt] = zcon;
return zcon;
}
//=============================================================================
Node* PhaseGVN::apply_ideal(Node* k, bool can_reshape) {
Node* i = BarrierSet::barrier_set()->barrier_set_c2()->ideal_node(this, k, can_reshape);
if (i == nullptr) {
i = k->Ideal(this, can_reshape);
}
return i;
}
//------------------------------transform--------------------------------------
// Return a node which computes the same function as this node, but in a
// faster or cheaper fashion.
Node *PhaseGVN::transform( Node *n ) {
return transform_no_reclaim(n);
}
//------------------------------transform--------------------------------------
// Return a node which computes the same function as this node, but
// in a faster or cheaper fashion.
Node *PhaseGVN::transform_no_reclaim(Node *n) {
NOT_PRODUCT( set_transforms(); )
// Apply the Ideal call in a loop until it no longer applies
Node* k = n;
Node* i = apply_ideal(k, /*can_reshape=*/false);
NOT_PRODUCT(uint loop_count = 1;)
while (i != nullptr) {
assert(i->_idx >= k->_idx, "Idealize should return new nodes, use Identity to return old nodes" );
k = i;
#ifdef ASSERT
if (loop_count >= K + C->live_nodes()) {
dump_infinite_loop_info(i, "PhaseGVN::transform_no_reclaim");
}
#endif
i = apply_ideal(k, /*can_reshape=*/false);
NOT_PRODUCT(loop_count++;)
}
NOT_PRODUCT(if (loop_count != 0) { set_progress(); })
// If brand new node, make space in type array.
ensure_type_or_null(k);
// Since I just called 'Value' to compute the set of run-time values
// for this Node, and 'Value' is non-local (and therefore expensive) I'll
// cache Value. Later requests for the local phase->type of this Node can
// use the cached Value instead of suffering with 'bottom_type'.
const Type* t = k->Value(this); // Get runtime Value set
assert(t != nullptr, "value sanity");
if (type_or_null(k) != t) {
#ifndef PRODUCT
// Do not count initial visit to node as a transformation
if (type_or_null(k) == nullptr) {
inc_new_values();
set_progress();
}
#endif
set_type(k, t);
// If k is a TypeNode, capture any more-precise type permanently into Node
k->raise_bottom_type(t);
}
if (t->singleton() && !k->is_Con()) {
NOT_PRODUCT(set_progress();)
return makecon(t); // Turn into a constant
}
// Now check for Identities
i = k->Identity(this); // Look for a nearby replacement
if (i != k) { // Found? Return replacement!
NOT_PRODUCT(set_progress();)
return i;
}
// Global Value Numbering
i = hash_find_insert(k); // Insert if new
if (i && (i != k)) {
// Return the pre-existing node
NOT_PRODUCT(set_progress();)
return i;
}
// Return Idealized original
return k;
}
bool PhaseGVN::is_dominator_helper(Node *d, Node *n, bool linear_only) {
if (d->is_top() || (d->is_Proj() && d->in(0)->is_top())) {
return false;
}
if (n->is_top() || (n->is_Proj() && n->in(0)->is_top())) {
return false;
}
assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
int i = 0;
while (d != n) {
n = IfNode::up_one_dom(n, linear_only);
i++;
if (n == nullptr || i >= 100) {
return false;
}
}
return true;
}
#ifdef ASSERT
//------------------------------dead_loop_check--------------------------------
// Check for a simple dead loop when a data node references itself directly
// or through an other data node excluding cons and phis.
void PhaseGVN::dead_loop_check( Node *n ) {
// Phi may reference itself in a loop
if (n != nullptr && !n->is_dead_loop_safe() && !n->is_CFG()) {
// Do 2 levels check and only data inputs.
bool no_dead_loop = true;
uint cnt = n->req();
for (uint i = 1; i < cnt && no_dead_loop; i++) {
Node *in = n->in(i);
if (in == n) {
no_dead_loop = false;
} else if (in != nullptr && !in->is_dead_loop_safe()) {
uint icnt = in->req();
for (uint j = 1; j < icnt && no_dead_loop; j++) {
if (in->in(j) == n || in->in(j) == in)
no_dead_loop = false;
}
}
}
if (!no_dead_loop) n->dump_bfs(100,0,"#");
assert(no_dead_loop, "dead loop detected");
}
}
/**
* Dumps information that can help to debug the problem. A debug
* build fails with an assert.
*/
void PhaseGVN::dump_infinite_loop_info(Node* n, const char* where) {
n->dump(4);
assert(false, "infinite loop in %s", where);
}
#endif
//=============================================================================
//------------------------------PhaseIterGVN-----------------------------------
// Initialize with previous PhaseIterGVN info; used by PhaseCCP
PhaseIterGVN::PhaseIterGVN(PhaseIterGVN* igvn) : _delay_transform(igvn->_delay_transform),
_worklist(*C->igvn_worklist())
{
_iterGVN = true;
assert(&_worklist == &igvn->_worklist, "sanity");
}
//------------------------------PhaseIterGVN-----------------------------------
// Initialize with previous PhaseGVN info from Parser
PhaseIterGVN::PhaseIterGVN(PhaseGVN* gvn) : _delay_transform(false),
_worklist(*C->igvn_worklist())
{
_iterGVN = true;
uint max;
// Dead nodes in the hash table inherited from GVN were not treated as
// roots during def-use info creation; hence they represent an invisible
// use. Clear them out.
max = _table.size();
for( uint i = 0; i < max; ++i ) {
Node *n = _table.at(i);
if(n != nullptr && n != _table.sentinel() && n->outcnt() == 0) {
if( n->is_top() ) continue;
// If remove_useless_nodes() has run, we expect no such nodes left.
assert(false, "remove_useless_nodes missed this node");
hash_delete(n);
}
}
// Any Phis or Regions on the worklist probably had uses that could not
// make more progress because the uses were made while the Phis and Regions
// were in half-built states. Put all uses of Phis and Regions on worklist.
max = _worklist.size();
for( uint j = 0; j < max; j++ ) {
Node *n = _worklist.at(j);
uint uop = n->Opcode();
if( uop == Op_Phi || uop == Op_Region ||
n->is_Type() ||
n->is_Mem() )
add_users_to_worklist(n);
}
}
void PhaseIterGVN::shuffle_worklist() {
if (_worklist.size() < 2) return;
for (uint i = _worklist.size() - 1; i >= 1; i--) {
uint j = C->random() % (i + 1);
swap(_worklist.adr()[i], _worklist.adr()[j]);
}
}
#ifndef PRODUCT
void PhaseIterGVN::verify_step(Node* n) {
if (is_verify_def_use()) {
ResourceMark rm;
VectorSet visited;
Node_List worklist;
_verify_window[_verify_counter % _verify_window_size] = n;
++_verify_counter;
if (C->unique() < 1000 || 0 == _verify_counter % (C->unique() < 10000 ? 10 : 100)) {
++_verify_full_passes;
worklist.push(C->root());
Node::verify(-1, visited, worklist);
return;
}
for (int i = 0; i < _verify_window_size; i++) {
Node* n = _verify_window[i];
if (n == nullptr) {
continue;
}
if (n->in(0) == NodeSentinel) { // xform_idom
_verify_window[i] = n->in(1);
--i;
continue;
}
// Typical fanout is 1-2, so this call visits about 6 nodes.
if (!visited.test_set(n->_idx)) {
worklist.push(n);
}
}
Node::verify(4, visited, worklist);
}
}
void PhaseIterGVN::trace_PhaseIterGVN(Node* n, Node* nn, const Type* oldtype) {
if (TraceIterativeGVN) {
uint wlsize = _worklist.size();
const Type* newtype = type_or_null(n);
if (nn != n) {
// print old node
tty->print("< ");
if (oldtype != newtype && oldtype != nullptr) {
oldtype->dump();
}
do { tty->print("\t"); } while (tty->position() < 16);
tty->print("<");
n->dump();
}
if (oldtype != newtype || nn != n) {
// print new node and/or new type
if (oldtype == nullptr) {
tty->print("* ");
} else if (nn != n) {
tty->print("> ");
} else {
tty->print("= ");
}
if (newtype == nullptr) {
tty->print("null");
} else {
newtype->dump();
}
do { tty->print("\t"); } while (tty->position() < 16);
nn->dump();
}
if (Verbose && wlsize < _worklist.size()) {
tty->print(" Push {");
while (wlsize != _worklist.size()) {
Node* pushed = _worklist.at(wlsize++);
tty->print(" %d", pushed->_idx);
}
tty->print_cr(" }");
}
if (nn != n) {
// ignore n, it might be subsumed
verify_step((Node*) nullptr);
}
}
}
void PhaseIterGVN::init_verifyPhaseIterGVN() {
_verify_counter = 0;
_verify_full_passes = 0;
for (int i = 0; i < _verify_window_size; i++) {
_verify_window[i] = nullptr;
}
#ifdef ASSERT
// Verify that all modified nodes are on _worklist
Unique_Node_List* modified_list = C->modified_nodes();
while (modified_list != nullptr && modified_list->size()) {
Node* n = modified_list->pop();
if (!n->is_Con() && !_worklist.member(n)) {
n->dump();
fatal("modified node is not on IGVN._worklist");
}
}
#endif
}
void PhaseIterGVN::verify_PhaseIterGVN() {
#ifdef ASSERT
// Verify nodes with changed inputs.
Unique_Node_List* modified_list = C->modified_nodes();
while (modified_list != nullptr && modified_list->size()) {
Node* n = modified_list->pop();
if (!n->is_Con()) { // skip Con nodes
n->dump();
fatal("modified node was not processed by IGVN.transform_old()");
}
}
#endif
C->verify_graph_edges();
if (is_verify_def_use() && PrintOpto) {
if (_verify_counter == _verify_full_passes) {
tty->print_cr("VerifyIterativeGVN: %d transforms and verify passes",
(int) _verify_full_passes);
} else {
tty->print_cr("VerifyIterativeGVN: %d transforms, %d full verify passes",
(int) _verify_counter, (int) _verify_full_passes);
}
}
#ifdef ASSERT
if (modified_list != nullptr) {
while (modified_list->size() > 0) {
Node* n = modified_list->pop();
n->dump();
assert(false, "VerifyIterativeGVN: new modified node was added");
}
}
verify_optimize();
#endif
}
#endif /* PRODUCT */
#ifdef ASSERT
/**
* Dumps information that can help to debug the problem. A debug
* build fails with an assert.
*/
void PhaseIterGVN::dump_infinite_loop_info(Node* n, const char* where) {
n->dump(4);
_worklist.dump();
assert(false, "infinite loop in %s", where);
}
/**
* Prints out information about IGVN if the 'verbose' option is used.
*/
void PhaseIterGVN::trace_PhaseIterGVN_verbose(Node* n, int num_processed) {
if (TraceIterativeGVN && Verbose) {
tty->print(" Pop ");
n->dump();
if ((num_processed % 100) == 0) {
_worklist.print_set();
}
}
}
#endif /* ASSERT */
void PhaseIterGVN::optimize() {
DEBUG_ONLY(uint num_processed = 0;)
NOT_PRODUCT(init_verifyPhaseIterGVN();)
if (StressIGVN) {
shuffle_worklist();
}
uint loop_count = 0;
// Pull from worklist and transform the node. If the node has changed,
// update edge info and put uses on worklist.
while(_worklist.size()) {
if (C->check_node_count(NodeLimitFudgeFactor * 2, "Out of nodes")) {
return;
}
Node* n = _worklist.pop();
if (loop_count >= K * C->live_nodes()) {
DEBUG_ONLY(dump_infinite_loop_info(n, "PhaseIterGVN::optimize");)
C->record_method_not_compilable("infinite loop in PhaseIterGVN::optimize");
return;
}
DEBUG_ONLY(trace_PhaseIterGVN_verbose(n, num_processed++);)
if (n->outcnt() != 0) {
NOT_PRODUCT(const Type* oldtype = type_or_null(n));
// Do the transformation
Node* nn = transform_old(n);
NOT_PRODUCT(trace_PhaseIterGVN(n, nn, oldtype);)
} else if (!n->is_top()) {
remove_dead_node(n);
}
loop_count++;
}
NOT_PRODUCT(verify_PhaseIterGVN();)
}
#ifdef ASSERT
void PhaseIterGVN::verify_optimize() {
if (is_verify_Value()) {
ResourceMark rm;
Unique_Node_List worklist;
bool failure = false;
// BFS all nodes, starting at root
worklist.push(C->root());
for (uint j = 0; j < worklist.size(); ++j) {
Node* n = worklist.at(j);
failure |= verify_node_value(n);
// traverse all inputs and outputs
for (uint i = 0; i < n->req(); i++) {
if (n->in(i) != nullptr) {
worklist.push(n->in(i));
}
}
for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
worklist.push(n->fast_out(i));
}
}
// If we get this assert, check why the reported nodes were not processed again in IGVN.
// We should either make sure that these nodes are properly added back to the IGVN worklist
// in PhaseIterGVN::add_users_to_worklist to update them again or add an exception
// in the verification code above if that is not possible for some reason (like Load nodes).
assert(!failure, "Missed optimization opportunity in PhaseIterGVN");
}
}
// Check that type(n) == n->Value(), return true if we have a failure.
// We have a list of exceptions, see detailed comments in code.
// (1) Integer "widen" changes, but the range is the same.
// (2) LoadNode performs deep traversals. Load is not notified for changes far away.
// (3) CmpPNode performs deep traversals if it compares oopptr. CmpP is not notified for changes far away.
bool PhaseIterGVN::verify_node_value(Node* n) {
// If we assert inside type(n), because the type is still a null, then maybe
// the node never went through gvn.transform, which would be a bug.
const Type* told = type(n);
const Type* tnew = n->Value(this);
if (told == tnew) {
return false;
}
// Exception (1)
// Integer "widen" changes, but range is the same.
if (told->isa_integer(tnew->basic_type()) != nullptr) { // both either int or long
const TypeInteger* t0 = told->is_integer(tnew->basic_type());
const TypeInteger* t1 = tnew->is_integer(tnew->basic_type());
if (t0->lo_as_long() == t1->lo_as_long() &&
t0->hi_as_long() == t1->hi_as_long()) {
return false; // ignore integer widen
}
}
// Exception (2)
// LoadNode performs deep traversals. Load is not notified for changes far away.
if (n->is_Load() && !told->singleton()) {
// MemNode::can_see_stored_value looks up through many memory nodes,
// which means we would need to notify modifications from far up in
// the inputs all the way down to the LoadNode. We don't do that.
return false;
}
// Exception (3)
// CmpPNode performs deep traversals if it compares oopptr. CmpP is not notified for changes far away.
if (n->Opcode() == Op_CmpP && type(n->in(1))->isa_oopptr() && type(n->in(2))->isa_oopptr()) {
// SubNode::Value
// CmpPNode::sub
// MemNode::detect_ptr_independence
// MemNode::all_controls_dominate
// We find all controls of a pointer load, and see if they dominate the control of
// an allocation. If they all dominate, we know the allocation is after (independent)
// of the pointer load, and we can say the pointers are different. For this we call
// n->dominates(sub, nlist) to check if controls n of the pointer load dominate the
// control sub of the allocation. The problems is that sometimes dominates answers
// false conservatively, and later it can determine that it is indeed true. Loops with
// Region heads can lead to giving up, whereas LoopNodes can be skipped easier, and
// so the traversal becomes more powerful. This is difficult to remidy, we would have
// to notify the CmpP of CFG updates. Luckily, we recompute CmpP::Value during CCP
// after loop-opts, so that should take care of many of these cases.
return false;
}
tty->cr();
tty->print_cr("Missed Value optimization:");
n->dump_bfs(1, 0, "");
tty->print_cr("Current type:");
told->dump_on(tty);
tty->cr();
tty->print_cr("Optimized type:");
tnew->dump_on(tty);
tty->cr();
return true;
}
#endif
/**
* Register a new node with the optimizer. Update the types array, the def-use
* info. Put on worklist.
*/
Node* PhaseIterGVN::register_new_node_with_optimizer(Node* n, Node* orig) {
set_type_bottom(n);
_worklist.push(n);
if (orig != nullptr) C->copy_node_notes_to(n, orig);
return n;
}
//------------------------------transform--------------------------------------
// Non-recursive: idealize Node 'n' with respect to its inputs and its value
Node *PhaseIterGVN::transform( Node *n ) {
if (_delay_transform) {
// Register the node but don't optimize for now
register_new_node_with_optimizer(n);
return n;
}
// If brand new node, make space in type array, and give it a type.
ensure_type_or_null(n);
if (type_or_null(n) == nullptr) {
set_type_bottom(n);
}
return transform_old(n);
}
Node *PhaseIterGVN::transform_old(Node* n) {
NOT_PRODUCT(set_transforms());
// Remove 'n' from hash table in case it gets modified
_table.hash_delete(n);
#ifdef ASSERT
if (is_verify_def_use()) {
assert(!_table.find_index(n->_idx), "found duplicate entry in table");
}
#endif
// Allow Bool -> Cmp idealisation in late inlining intrinsics that return a bool
if (n->is_Cmp()) {
add_users_to_worklist(n);
}
// Apply the Ideal call in a loop until it no longer applies
Node* k = n;
DEBUG_ONLY(dead_loop_check(k);)
DEBUG_ONLY(bool is_new = (k->outcnt() == 0);)
C->remove_modified_node(k);
Node* i = apply_ideal(k, /*can_reshape=*/true);
assert(i != k || is_new || i->outcnt() > 0, "don't return dead nodes");
#ifndef PRODUCT
verify_step(k);
#endif
DEBUG_ONLY(uint loop_count = 1;)
while (i != nullptr) {
#ifdef ASSERT
if (loop_count >= K + C->live_nodes()) {
dump_infinite_loop_info(i, "PhaseIterGVN::transform_old");
}
#endif
assert((i->_idx >= k->_idx) || i->is_top(), "Idealize should return new nodes, use Identity to return old nodes");
// Made a change; put users of original Node on worklist
add_users_to_worklist(k);
// Replacing root of transform tree?
if (k != i) {
// Make users of old Node now use new.
subsume_node(k, i);
k = i;
}
DEBUG_ONLY(dead_loop_check(k);)
// Try idealizing again
DEBUG_ONLY(is_new = (k->outcnt() == 0);)
C->remove_modified_node(k);
i = apply_ideal(k, /*can_reshape=*/true);
assert(i != k || is_new || (i->outcnt() > 0), "don't return dead nodes");
#ifndef PRODUCT
verify_step(k);
#endif
DEBUG_ONLY(loop_count++;)
}
// If brand new node, make space in type array.
ensure_type_or_null(k);
// See what kind of values 'k' takes on at runtime
const Type* t = k->Value(this);
assert(t != nullptr, "value sanity");
// Since I just called 'Value' to compute the set of run-time values
// for this Node, and 'Value' is non-local (and therefore expensive) I'll
// cache Value. Later requests for the local phase->type of this Node can
// use the cached Value instead of suffering with 'bottom_type'.
if (type_or_null(k) != t) {
#ifndef PRODUCT
inc_new_values();
set_progress();
#endif
set_type(k, t);
// If k is a TypeNode, capture any more-precise type permanently into Node
k->raise_bottom_type(t);
// Move users of node to worklist
add_users_to_worklist(k);
}
// If 'k' computes a constant, replace it with a constant
if (t->singleton() && !k->is_Con()) {
NOT_PRODUCT(set_progress();)
Node* con = makecon(t); // Make a constant
add_users_to_worklist(k);
subsume_node(k, con); // Everybody using k now uses con
return con;
}
// Now check for Identities
i = k->Identity(this); // Look for a nearby replacement
if (i != k) { // Found? Return replacement!
NOT_PRODUCT(set_progress();)
add_users_to_worklist(k);
subsume_node(k, i); // Everybody using k now uses i
return i;
}
// Global Value Numbering
i = hash_find_insert(k); // Check for pre-existing node
if (i && (i != k)) {
// Return the pre-existing node if it isn't dead
NOT_PRODUCT(set_progress();)
add_users_to_worklist(k);
subsume_node(k, i); // Everybody using k now uses i
return i;
}
// Return Idealized original
return k;
}
//---------------------------------saturate------------------------------------
const Type* PhaseIterGVN::saturate(const Type* new_type, const Type* old_type,
const Type* limit_type) const {
return new_type->narrow(old_type);
}
//------------------------------remove_globally_dead_node----------------------
// Kill a globally dead Node. All uses are also globally dead and are
// aggressively trimmed.
void PhaseIterGVN::remove_globally_dead_node( Node *dead ) {
enum DeleteProgress {
PROCESS_INPUTS,
PROCESS_OUTPUTS
};
ResourceMark rm;
Node_Stack stack(32);
stack.push(dead, PROCESS_INPUTS);
while (stack.is_nonempty()) {
dead = stack.node();
if (dead->Opcode() == Op_SafePoint) {
dead->as_SafePoint()->disconnect_from_root(this);
}
uint progress_state = stack.index();
assert(dead != C->root(), "killing root, eh?");
assert(!dead->is_top(), "add check for top when pushing");
NOT_PRODUCT( set_progress(); )
if (progress_state == PROCESS_INPUTS) {
// After following inputs, continue to outputs
stack.set_index(PROCESS_OUTPUTS);
if (!dead->is_Con()) { // Don't kill cons but uses
bool recurse = false;
// Remove from hash table
_table.hash_delete( dead );
// Smash all inputs to 'dead', isolating him completely
for (uint i = 0; i < dead->req(); i++) {
Node *in = dead->in(i);
if (in != nullptr && in != C->top()) { // Points to something?
int nrep = dead->replace_edge(in, nullptr, this); // Kill edges
assert((nrep > 0), "sanity");
if (in->outcnt() == 0) { // Made input go dead?
stack.push(in, PROCESS_INPUTS); // Recursively remove
recurse = true;
} else if (in->outcnt() == 1 &&
in->has_special_unique_user()) {
_worklist.push(in->unique_out());
} else if (in->outcnt() <= 2 && dead->is_Phi()) {
if (in->Opcode() == Op_Region) {
_worklist.push(in);
} else if (in->is_Store()) {
DUIterator_Fast imax, i = in->fast_outs(imax);
_worklist.push(in->fast_out(i));
i++;
if (in->outcnt() == 2) {
_worklist.push(in->fast_out(i));
i++;
}
assert(!(i < imax), "sanity");
}
} else {
BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(this, in);
}
if (ReduceFieldZeroing && dead->is_Load() && i == MemNode::Memory &&
in->is_Proj() && in->in(0) != nullptr && in->in(0)->is_Initialize()) {
// A Load that directly follows an InitializeNode is
// going away. The Stores that follow are candidates
// again to be captured by the InitializeNode.
for (DUIterator_Fast jmax, j = in->fast_outs(jmax); j < jmax; j++) {
Node *n = in->fast_out(j);
if (n->is_Store()) {
_worklist.push(n);
}
}
}
} // if (in != nullptr && in != C->top())
} // for (uint i = 0; i < dead->req(); i++)
if (recurse) {
continue;
}
} // if (!dead->is_Con())
} // if (progress_state == PROCESS_INPUTS)
// Aggressively kill globally dead uses
// (Rather than pushing all the outs at once, we push one at a time,
// plus the parent to resume later, because of the indefinite number
// of edge deletions per loop trip.)
if (dead->outcnt() > 0) {
// Recursively remove output edges
stack.push(dead->raw_out(0), PROCESS_INPUTS);
} else {
// Finished disconnecting all input and output edges.
stack.pop();
// Remove dead node from iterative worklist
_worklist.remove(dead);
C->remove_useless_node(dead);
}
} // while (stack.is_nonempty())
}
//------------------------------subsume_node-----------------------------------
// Remove users from node 'old' and add them to node 'nn'.
void PhaseIterGVN::subsume_node( Node *old, Node *nn ) {
if (old->Opcode() == Op_SafePoint) {
old->as_SafePoint()->disconnect_from_root(this);
}
assert( old != hash_find(old), "should already been removed" );
assert( old != C->top(), "cannot subsume top node");
// Copy debug or profile information to the new version:
C->copy_node_notes_to(nn, old);
// Move users of node 'old' to node 'nn'
for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin; ) {
Node* use = old->last_out(i); // for each use...
// use might need re-hashing (but it won't if it's a new node)
rehash_node_delayed(use);
// Update use-def info as well
// We remove all occurrences of old within use->in,
// so as to avoid rehashing any node more than once.
// The hash table probe swamps any outer loop overhead.
uint num_edges = 0;
for (uint jmax = use->len(), j = 0; j < jmax; j++) {
if (use->in(j) == old) {
use->set_req(j, nn);
++num_edges;
}
}
i -= num_edges; // we deleted 1 or more copies of this edge
}
// Search for instance field data PhiNodes in the same region pointing to the old
// memory PhiNode and update their instance memory ids to point to the new node.
if (old->is_Phi() && old->as_Phi()->type()->has_memory() && old->in(0) != nullptr) {
Node* region = old->in(0);
for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
PhiNode* phi = region->fast_out(i)->isa_Phi();
if (phi != nullptr && phi->inst_mem_id() == (int)old->_idx) {
phi->set_inst_mem_id((int)nn->_idx);
}
}
}
// Smash all inputs to 'old', isolating him completely
Node *temp = new Node(1);
temp->init_req(0,nn); // Add a use to nn to prevent him from dying
remove_dead_node( old );
temp->del_req(0); // Yank bogus edge
if (nn != nullptr && nn->outcnt() == 0) {
_worklist.push(nn);
}
#ifndef PRODUCT
if (is_verify_def_use()) {
for ( int i = 0; i < _verify_window_size; i++ ) {
if ( _verify_window[i] == old )
_verify_window[i] = nn;
}
}
#endif
temp->destruct(this); // reuse the _idx of this little guy
}
//------------------------------add_users_to_worklist--------------------------
void PhaseIterGVN::add_users_to_worklist0( Node *n ) {
for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
_worklist.push(n->fast_out(i)); // Push on worklist
}
}
// Return counted loop Phi if as a counted loop exit condition, cmp
// compares the induction variable with n
static PhiNode* countedloop_phi_from_cmp(CmpNode* cmp, Node* n) {
for (DUIterator_Fast imax, i = cmp->fast_outs(imax); i < imax; i++) {
Node* bol = cmp->fast_out(i);
for (DUIterator_Fast i2max, i2 = bol->fast_outs(i2max); i2 < i2max; i2++) {
Node* iff = bol->fast_out(i2);
if (iff->is_BaseCountedLoopEnd()) {
BaseCountedLoopEndNode* cle = iff->as_BaseCountedLoopEnd();
if (cle->limit() == n) {
PhiNode* phi = cle->phi();
if (phi != nullptr) {
return phi;
}
}
}
}
}
return nullptr;
}
void PhaseIterGVN::add_users_to_worklist( Node *n ) {
add_users_to_worklist0(n);
// Move users of node to worklist
for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
Node* use = n->fast_out(i); // Get use
if( use->is_Multi() || // Multi-definer? Push projs on worklist
use->is_Store() ) // Enable store/load same address
add_users_to_worklist0(use);
// If we changed the receiver type to a call, we need to revisit
// the Catch following the call. It's looking for a non-null
// receiver to know when to enable the regular fall-through path
// in addition to the NullPtrException path.
if (use->is_CallDynamicJava() && n == use->in(TypeFunc::Parms)) {
Node* p = use->as_CallDynamicJava()->proj_out_or_null(TypeFunc::Control);
if (p != nullptr) {
add_users_to_worklist0(p);
}
}
uint use_op = use->Opcode();
if(use->is_Cmp()) { // Enable CMP/BOOL optimization
add_users_to_worklist(use); // Put Bool on worklist
if (use->outcnt() > 0) {
Node* bol = use->raw_out(0);
if (bol->outcnt() > 0) {
Node* iff = bol->raw_out(0);
if (iff->outcnt() == 2) {
// Look for the 'is_x2logic' pattern: "x ? : 0 : 1" and put the
// phi merging either 0 or 1 onto the worklist
Node* ifproj0 = iff->raw_out(0);
Node* ifproj1 = iff->raw_out(1);
if (ifproj0->outcnt() > 0 && ifproj1->outcnt() > 0) {
Node* region0 = ifproj0->raw_out(0);
Node* region1 = ifproj1->raw_out(0);
if( region0 == region1 )
add_users_to_worklist0(region0);
}
}
}
}
if (use_op == Op_CmpI || use_op == Op_CmpL) {
Node* phi = countedloop_phi_from_cmp(use->as_Cmp(), n);
if (phi != nullptr) {
// Input to the cmp of a loop exit check has changed, thus
// the loop limit may have changed, which can then change the
// range values of the trip-count Phi.
_worklist.push(phi);
}
}
if (use_op == Op_CmpI) {
Node* cmp = use;
Node* in1 = cmp->in(1);
Node* in2 = cmp->in(2);
// Notify CmpI / If pattern from CastIINode::Value (left pattern).
// Must also notify if in1 is modified and possibly turns into X (right pattern).
//
// in1 in2 in1 in2
// | | | |
// +--- | --+ | |
// | | | | |
// CmpINode | CmpINode
// | | |
// BoolNode | BoolNode
// | | OR |
// IfNode | IfNode
// | | |
// IfProj | IfProj X
// | | | |
// CastIINode CastIINode
//
if (in1 != in2) { // if they are equal, the CmpI can fold them away
if (in1 == n) {
// in1 modified -> could turn into X -> do traversal based on right pattern.
for (DUIterator_Fast i2max, i2 = cmp->fast_outs(i2max); i2 < i2max; i2++) {
Node* bol = cmp->fast_out(i2); // For each Bool
if (bol->is_Bool()) {
for (DUIterator_Fast i3max, i3 = bol->fast_outs(i3max); i3 < i3max; i3++) {
Node* iff = bol->fast_out(i3); // For each If
if (iff->is_If()) {
for (DUIterator_Fast i4max, i4 = iff->fast_outs(i4max); i4 < i4max; i4++) {
Node* if_proj = iff->fast_out(i4); // For each IfProj
assert(if_proj->is_IfProj(), "If only has IfTrue and IfFalse as outputs");
for (DUIterator_Fast i5max, i5 = if_proj->fast_outs(i5max); i5 < i5max; i5++) {
Node* castii = if_proj->fast_out(i5); // For each CastII
if (castii->is_CastII() &&
castii->as_CastII()->carry_dependency()) {
_worklist.push(castii);
}
}
}
}
}
}
}
} else {
// Only in2 modified -> can assume X == in2 (left pattern).
assert(n == in2, "only in2 modified");
// Find all CastII with input in1.
for (DUIterator_Fast jmax, j = in1->fast_outs(jmax); j < jmax; j++) {
Node* castii = in1->fast_out(j);
if (castii->is_CastII() && castii->as_CastII()->carry_dependency()) {
// Find If.
if (castii->in(0) != nullptr && castii->in(0)->in(0) != nullptr && castii->in(0)->in(0)->is_If()) {
Node* ifnode = castii->in(0)->in(0);
// Check that if connects to the cmp
if (ifnode->in(1) != nullptr && ifnode->in(1)->is_Bool() && ifnode->in(1)->in(1) == cmp) {
_worklist.push(castii);
}
}
}
}
}
}
}
}
// If changed Cast input, notify down for Phi and Sub - both do "uncast"
// Patterns:
// ConstraintCast+ -> Sub
// ConstraintCast+ -> Phi
if (use->is_ConstraintCast()) {
auto push_phi_or_sub_uses_to_worklist = [&](Node* n){
if (n->is_Phi() || n->is_Sub()) {
_worklist.push(n);
}
};
ConstraintCastNode::visit_uncasted_uses(use, push_phi_or_sub_uses_to_worklist);
}
// If changed LShift inputs, check RShift users for useless sign-ext
if( use_op == Op_LShiftI ) {
for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
Node* u = use->fast_out(i2);
if (u->Opcode() == Op_RShiftI)
_worklist.push(u);
}
}
// If changed LShift inputs, check And users for shift and mask (And) operation
if (use_op == Op_LShiftI || use_op == Op_LShiftL) {
for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
Node* u = use->fast_out(i2);
if (u->Opcode() == Op_AndI || u->Opcode() == Op_AndL) {
_worklist.push(u);
}
}
}
// If changed AddI/SubI inputs, check CmpU for range check optimization.
if (use_op == Op_AddI || use_op == Op_SubI) {
for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
Node* u = use->fast_out(i2);
if (u->is_Cmp() && (u->Opcode() == Op_CmpU)) {
_worklist.push(u);
}
}
}
// If changed AddP inputs, check Stores for loop invariant
if( use_op == Op_AddP ) {
for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
Node* u = use->fast_out(i2);
if (u->is_Mem())
_worklist.push(u);
}
}
// If changed initialization activity, check dependent Stores
if (use_op == Op_Allocate || use_op == Op_AllocateArray) {
InitializeNode* init = use->as_Allocate()->initialization();
if (init != nullptr) {
Node* imem = init->proj_out_or_null(TypeFunc::Memory);
if (imem != nullptr) add_users_to_worklist0(imem);
}
}
// If the ValidLengthTest input changes then the fallthrough path out of the AllocateArray may have become dead.
// CatchNode::Value() is responsible for killing that path. The CatchNode has to be explicitly enqueued for igvn
// to guarantee the change is not missed.
if (use_op == Op_AllocateArray && n == use->in(AllocateNode::ValidLengthTest)) {
Node* p = use->as_AllocateArray()->proj_out_or_null(TypeFunc::Control);
if (p != nullptr) {
add_users_to_worklist0(p);
}
}
if (use_op == Op_Initialize) {
Node* imem = use->as_Initialize()->proj_out_or_null(TypeFunc::Memory);
if (imem != nullptr) add_users_to_worklist0(imem);
}
// Loading the java mirror from a Klass requires two loads and the type
// of the mirror load depends on the type of 'n'. See LoadNode::Value().
// LoadBarrier?(LoadP(LoadP(AddP(foo:Klass, #java_mirror))))
BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
bool has_load_barrier_nodes = bs->has_load_barrier_nodes();
if (use_op == Op_LoadP && use->bottom_type()->isa_rawptr()) {
for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
Node* u = use->fast_out(i2);
const Type* ut = u->bottom_type();
if (u->Opcode() == Op_LoadP && ut->isa_instptr()) {
if (has_load_barrier_nodes) {
// Search for load barriers behind the load
for (DUIterator_Fast i3max, i3 = u->fast_outs(i3max); i3 < i3max; i3++) {
Node* b = u->fast_out(i3);
if (bs->is_gc_barrier_node(b)) {
_worklist.push(b);
}
}
}
_worklist.push(u);
}
}
}
if (use->Opcode() == Op_OpaqueZeroTripGuard) {
assert(use->outcnt() <= 1, "OpaqueZeroTripGuard can't be shared");
if (use->outcnt() == 1) {
Node* cmp = use->unique_out();
_worklist.push(cmp);
}
}
}
}
/**
* Remove the speculative part of all types that we know of
*/
void PhaseIterGVN::remove_speculative_types() {
assert(UseTypeSpeculation, "speculation is off");
for (uint i = 0; i < _types.Size(); i++) {
const Type* t = _types.fast_lookup(i);
if (t != nullptr) {
_types.map(i, t->remove_speculative());
}
}
_table.check_no_speculative_types();
}
// Check if the type of a divisor of a Div or Mod node includes zero.
bool PhaseIterGVN::no_dependent_zero_check(Node* n) const {
switch (n->Opcode()) {
case Op_DivI:
case Op_ModI: {
// Type of divisor includes 0?
if (type(n->in(2)) == Type::TOP) {
// 'n' is dead. Treat as if zero check is still there to avoid any further optimizations.
return false;
}
const TypeInt* type_divisor = type(n->in(2))->is_int();
return (type_divisor->_hi < 0 || type_divisor->_lo > 0);
}
case Op_DivL:
case Op_ModL: {
// Type of divisor includes 0?
if (type(n->in(2)) == Type::TOP) {
// 'n' is dead. Treat as if zero check is still there to avoid any further optimizations.
return false;
}
const TypeLong* type_divisor = type(n->in(2))->is_long();
return (type_divisor->_hi < 0 || type_divisor->_lo > 0);
}
}
return true;
}
//=============================================================================
#ifndef PRODUCT
uint PhaseCCP::_total_invokes = 0;
uint PhaseCCP::_total_constants = 0;
#endif
//------------------------------PhaseCCP---------------------------------------
// Conditional Constant Propagation, ala Wegman & Zadeck
PhaseCCP::PhaseCCP( PhaseIterGVN *igvn ) : PhaseIterGVN(igvn) {
NOT_PRODUCT( clear_constants(); )
assert( _worklist.size() == 0, "" );
analyze();
}
#ifndef PRODUCT
//------------------------------~PhaseCCP--------------------------------------
PhaseCCP::~PhaseCCP() {
inc_invokes();
_total_constants += count_constants();
}
#endif
#ifdef ASSERT
void PhaseCCP::verify_type(Node* n, const Type* tnew, const Type* told) {
if (tnew->meet(told) != tnew->remove_speculative()) {
n->dump(1);
tty->print("told = "); told->dump(); tty->cr();
tty->print("tnew = "); tnew->dump(); tty->cr();
fatal("Not monotonic");
}
assert(!told->isa_int() || !tnew->isa_int() || told->is_int()->_widen <= tnew->is_int()->_widen, "widen increases");
assert(!told->isa_long() || !tnew->isa_long() || told->is_long()->_widen <= tnew->is_long()->_widen, "widen increases");
}
#endif //ASSERT
// In this analysis, all types are initially set to TOP. We iteratively call Value() on all nodes of the graph until
// we reach a fixed-point (i.e. no types change anymore). We start with a list that only contains the root node. Each time
// a new type is set, we push all uses of that node back to the worklist (in some cases, we also push grandchildren
// or nodes even further down back to the worklist because their type could change as a result of the current type
// change).
void PhaseCCP::analyze() {
// Initialize all types to TOP, optimistic analysis
for (uint i = 0; i < C->unique(); i++) {
_types.map(i, Type::TOP);
}
// CCP worklist is placed on a local arena, so that we can allow ResourceMarks on "Compile::current()->resource_arena()".
// We also do not want to put the worklist on "Compile::current()->comp_arena()", as that one only gets de-allocated after
// Compile is over. The local arena gets de-allocated at the end of its scope.
ResourceArea local_arena(mtCompiler);
Unique_Node_List worklist(&local_arena);
DEBUG_ONLY(Unique_Node_List worklist_verify(&local_arena);)
// Push root onto worklist
worklist.push(C->root());
assert(_root_and_safepoints.size() == 0, "must be empty (unused)");
_root_and_safepoints.push(C->root());
// Pull from worklist; compute new value; push changes out.
// This loop is the meat of CCP.
while (worklist.size() != 0) {
Node* n = fetch_next_node(worklist);
DEBUG_ONLY(worklist_verify.push(n);)
if (n->is_SafePoint()) {
// Make sure safepoints are processed by PhaseCCP::transform even if they are
// not reachable from the bottom. Otherwise, infinite loops would be removed.
_root_and_safepoints.push(n);
}
const Type* new_type = n->Value(this);
if (new_type != type(n)) {
DEBUG_ONLY(verify_type(n, new_type, type(n));)
dump_type_and_node(n, new_type);
set_type(n, new_type);
push_child_nodes_to_worklist(worklist, n);
}
}
DEBUG_ONLY(verify_analyze(worklist_verify);)
}
#ifdef ASSERT
// For every node n on verify list, check if type(n) == n->Value()
// We have a list of exceptions, see comments in verify_node_value.
void PhaseCCP::verify_analyze(Unique_Node_List& worklist_verify) {
bool failure = false;
while (worklist_verify.size()) {
Node* n = worklist_verify.pop();
failure |= verify_node_value(n);
}
// If we get this assert, check why the reported nodes were not processed again in CCP.
// We should either make sure that these nodes are properly added back to the CCP worklist
// in PhaseCCP::push_child_nodes_to_worklist() to update their type or add an exception
// in the verification code above if that is not possible for some reason (like Load nodes).
assert(!failure, "Missed optimization opportunity in PhaseCCP");
}
#endif
// Fetch next node from worklist to be examined in this iteration.
Node* PhaseCCP::fetch_next_node(Unique_Node_List& worklist) {
if (StressCCP) {
return worklist.remove(C->random() % worklist.size());
} else {
return worklist.pop();
}
}
#ifndef PRODUCT
void PhaseCCP::dump_type_and_node(const Node* n, const Type* t) {
if (TracePhaseCCP) {
t->dump();
do {
tty->print("\t");
} while (tty->position() < 16);
n->dump();
}
}
#endif
// We need to propagate the type change of 'n' to all its uses. Depending on the kind of node, additional nodes
// (grandchildren or even further down) need to be revisited as their types could also be improved as a result
// of the new type of 'n'. Push these nodes to the worklist.
void PhaseCCP::push_child_nodes_to_worklist(Unique_Node_List& worklist, Node* n) const {
for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
Node* use = n->fast_out(i);
push_if_not_bottom_type(worklist, use);
push_more_uses(worklist, n, use);
}
}
void PhaseCCP::push_if_not_bottom_type(Unique_Node_List& worklist, Node* n) const {
if (n->bottom_type() != type(n)) {
worklist.push(n);
}
}
// For some nodes, we need to propagate the type change to grandchildren or even further down.
// Add them back to the worklist.
void PhaseCCP::push_more_uses(Unique_Node_List& worklist, Node* parent, const Node* use) const {
push_phis(worklist, use);
push_catch(worklist, use);
push_cmpu(worklist, use);
push_counted_loop_phi(worklist, parent, use);
push_loadp(worklist, use);
push_and(worklist, parent, use);
push_cast_ii(worklist, parent, use);
push_opaque_zero_trip_guard(worklist, use);
}
// We must recheck Phis too if use is a Region.
void PhaseCCP::push_phis(Unique_Node_List& worklist, const Node* use) const {
if (use->is_Region()) {
for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
push_if_not_bottom_type(worklist, use->fast_out(i));
}
}
}
// If we changed the receiver type to a call, we need to revisit the Catch node following the call. It's looking for a
// non-null receiver to know when to enable the regular fall-through path in addition to the NullPtrException path.
// Same is true if the type of a ValidLengthTest input to an AllocateArrayNode changes.
void PhaseCCP::push_catch(Unique_Node_List& worklist, const Node* use) {
if (use->is_Call()) {
for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
Node* proj = use->fast_out(i);
if (proj->is_Proj() && proj->as_Proj()->_con == TypeFunc::Control) {
Node* catch_node = proj->find_out_with(Op_Catch);
if (catch_node != nullptr) {
worklist.push(catch_node);
}
}
}
}
}
// CmpU nodes can get their type information from two nodes up in the graph (instead of from the nodes immediately
// above). Make sure they are added to the worklist if nodes they depend on are updated since they could be missed
// and get wrong types otherwise.
void PhaseCCP::push_cmpu(Unique_Node_List& worklist, const Node* use) const {
uint use_op = use->Opcode();
if (use_op == Op_AddI || use_op == Op_SubI) {
for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
Node* cmpu = use->fast_out(i);
if (cmpu->Opcode() == Op_CmpU) {
// Got a CmpU which might need the new type information from node n.
push_if_not_bottom_type(worklist, cmpu);
}
}
}
}
// If n is used in a counted loop exit condition, then the type of the counted loop's Phi depends on the type of 'n'.
// Seem PhiNode::Value().
void PhaseCCP::push_counted_loop_phi(Unique_Node_List& worklist, Node* parent, const Node* use) {
uint use_op = use->Opcode();
if (use_op == Op_CmpI || use_op == Op_CmpL) {
PhiNode* phi = countedloop_phi_from_cmp(use->as_Cmp(), parent);
if (phi != nullptr) {
worklist.push(phi);
}
}
}
// Loading the java mirror from a Klass requires two loads and the type of the mirror load depends on the type of 'n'.
// See LoadNode::Value().
void PhaseCCP::push_loadp(Unique_Node_List& worklist, const Node* use) const {
BarrierSetC2* barrier_set = BarrierSet::barrier_set()->barrier_set_c2();
bool has_load_barrier_nodes = barrier_set->has_load_barrier_nodes();
if (use->Opcode() == Op_LoadP && use->bottom_type()->isa_rawptr()) {
for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
Node* loadp = use->fast_out(i);
const Type* ut = loadp->bottom_type();
if (loadp->Opcode() == Op_LoadP && ut->isa_instptr() && ut != type(loadp)) {
if (has_load_barrier_nodes) {
// Search for load barriers behind the load
push_load_barrier(worklist, barrier_set, loadp);
}
worklist.push(loadp);
}
}
}
}
void PhaseCCP::push_load_barrier(Unique_Node_List& worklist, const BarrierSetC2* barrier_set, const Node* use) {
for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
Node* barrier_node = use->fast_out(i);
if (barrier_set->is_gc_barrier_node(barrier_node)) {
worklist.push(barrier_node);
}
}
}
// AndI/L::Value() optimizes patterns similar to (v << 2) & 3 to zero if they are bitwise disjoint.
// Add the AndI/L nodes back to the worklist to re-apply Value() in case the shift value changed.
// Pattern: parent -> LShift (use) -> ConstraintCast* -> And
void PhaseCCP::push_and(Unique_Node_List& worklist, const Node* parent, const Node* use) const {
uint use_op = use->Opcode();
if ((use_op == Op_LShiftI || use_op == Op_LShiftL)
&& use->in(2) == parent) { // is shift value (right-hand side of LShift)
auto push_and_uses_to_worklist = [&](Node* n){
uint opc = n->Opcode();
if (opc == Op_AndI || opc == Op_AndL) {
push_if_not_bottom_type(worklist, n);
}
};
ConstraintCastNode::visit_uncasted_uses(use, push_and_uses_to_worklist);
}
}
// CastII::Value() optimizes CmpI/If patterns if the right input of the CmpI has a constant type. If the CastII input is
// the same node as the left input into the CmpI node, the type of the CastII node can be improved accordingly. Add the
// CastII node back to the worklist to re-apply Value() to either not miss this optimization or to undo it because it
// cannot be applied anymore. We could have optimized the type of the CastII before but now the type of the right input
// of the CmpI (i.e. 'parent') is no longer constant. The type of the CastII must be widened in this case.
void PhaseCCP::push_cast_ii(Unique_Node_List& worklist, const Node* parent, const Node* use) const {
if (use->Opcode() == Op_CmpI && use->in(2) == parent) {
Node* other_cmp_input = use->in(1);
for (DUIterator_Fast imax, i = other_cmp_input->fast_outs(imax); i < imax; i++) {
Node* cast_ii = other_cmp_input->fast_out(i);
if (cast_ii->is_CastII()) {
push_if_not_bottom_type(worklist, cast_ii);
}
}
}
}
void PhaseCCP::push_opaque_zero_trip_guard(Unique_Node_List& worklist, const Node* use) const {
if (use->Opcode() == Op_OpaqueZeroTripGuard) {
push_if_not_bottom_type(worklist, use->unique_out());
}
}
//------------------------------do_transform-----------------------------------
// Top level driver for the recursive transformer
void PhaseCCP::do_transform() {
// Correct leaves of new-space Nodes; they point to old-space.
C->set_root( transform(C->root())->as_Root() );
assert( C->top(), "missing TOP node" );
assert( C->root(), "missing root" );
}
//------------------------------transform--------------------------------------
// Given a Node in old-space, clone him into new-space.
// Convert any of his old-space children into new-space children.
Node *PhaseCCP::transform( Node *n ) {
assert(n->is_Root(), "traversal must start at root");
assert(_root_and_safepoints.member(n), "root (n) must be in list");
ResourceMark rm;
// Map: old node idx -> node after CCP (or nullptr if not yet transformed or useless).
Node_List node_map;
// Pre-allocate to avoid frequent realloc
GrowableArray <Node *> transform_stack(C->live_nodes() >> 1);
// track all visited nodes, so that we can remove the complement
Unique_Node_List useful;
// Initialize the traversal.
// This CCP pass may prove that no exit test for a loop ever succeeds (i.e. the loop is infinite). In that case,
// the logic below doesn't follow any path from Root to the loop body: there's at least one such path but it's proven
// never taken (its type is TOP). As a consequence the node on the exit path that's input to Root (let's call it n) is
// replaced by the top node and the inputs of that node n are not enqueued for further processing. If CCP only works
// through the graph from Root, this causes the loop body to never be processed here even when it's not dead (that
// is reachable from Root following its uses). To prevent that issue, transform() starts walking the graph from Root
// and all safepoints.
for (uint i = 0; i < _root_and_safepoints.size(); ++i) {
Node* nn = _root_and_safepoints.at(i);
Node* new_node = node_map[nn->_idx];
assert(new_node == nullptr, "");
new_node = transform_once(nn); // Check for constant
node_map.map(nn->_idx, new_node); // Flag as having been cloned
transform_stack.push(new_node); // Process children of cloned node
useful.push(new_node);
}
while (transform_stack.is_nonempty()) {
Node* clone = transform_stack.pop();
uint cnt = clone->req();
for( uint i = 0; i < cnt; i++ ) { // For all inputs do
Node *input = clone->in(i);
if( input != nullptr ) { // Ignore nulls
Node *new_input = node_map[input->_idx]; // Check for cloned input node
if( new_input == nullptr ) {
new_input = transform_once(input); // Check for constant
node_map.map( input->_idx, new_input );// Flag as having been cloned
transform_stack.push(new_input); // Process children of cloned node
useful.push(new_input);
}
assert( new_input == clone->in(i), "insanity check");
}
}
}
// The above transformation might lead to subgraphs becoming unreachable from the
// bottom while still being reachable from the top. As a result, nodes in that
// subgraph are not transformed and their bottom types are not updated, leading to
// an inconsistency between bottom_type() and type(). In rare cases, LoadNodes in
// such a subgraph, might be re-enqueued for IGVN indefinitely by MemNode::Ideal_common
// because their address type is inconsistent. Therefore, we aggressively remove
// all useless nodes here even before PhaseIdealLoop::build_loop_late gets a chance
// to remove them anyway.
if (C->cached_top_node()) {
useful.push(C->cached_top_node());
}
C->update_dead_node_list(useful);
remove_useless_nodes(useful.member_set());
_worklist.remove_useless_nodes(useful.member_set());
C->disconnect_useless_nodes(useful, _worklist);
Node* new_root = node_map[n->_idx];
assert(new_root->is_Root(), "transformed root node must be a root node");
return new_root;
}
//------------------------------transform_once---------------------------------
// For PhaseCCP, transformation is IDENTITY unless Node computed a constant.
Node *PhaseCCP::transform_once( Node *n ) {
const Type *t = type(n);
// Constant? Use constant Node instead
if( t->singleton() ) {
Node *nn = n; // Default is to return the original constant
if( t == Type::TOP ) {
// cache my top node on the Compile instance
if( C->cached_top_node() == nullptr || C->cached_top_node()->in(0) == nullptr ) {
C->set_cached_top_node(ConNode::make(Type::TOP));
set_type(C->top(), Type::TOP);
}
nn = C->top();
}
if( !n->is_Con() ) {
if( t != Type::TOP ) {
nn = makecon(t); // ConNode::make(t);
NOT_PRODUCT( inc_constants(); )
} else if( n->is_Region() ) { // Unreachable region
// Note: nn == C->top()
n->set_req(0, nullptr); // Cut selfreference
bool progress = true;
uint max = n->outcnt();
DUIterator i;
while (progress) {
progress = false;
// Eagerly remove dead phis to avoid phis copies creation.
for (i = n->outs(); n->has_out(i); i++) {
Node* m = n->out(i);
if (m->is_Phi()) {
assert(type(m) == Type::TOP, "Unreachable region should not have live phis.");
replace_node(m, nn);
if (max != n->outcnt()) {
progress = true;
i = n->refresh_out_pos(i);
max = n->outcnt();
}
}
}
}
}
replace_node(n,nn); // Update DefUse edges for new constant
}
return nn;
}
// If x is a TypeNode, capture any more-precise type permanently into Node
if (t != n->bottom_type()) {
hash_delete(n); // changing bottom type may force a rehash
n->raise_bottom_type(t);
_worklist.push(n); // n re-enters the hash table via the worklist
}
// TEMPORARY fix to ensure that 2nd GVN pass eliminates null checks
switch( n->Opcode() ) {
case Op_CallStaticJava: // Give post-parse call devirtualization a chance
case Op_CallDynamicJava:
case Op_FastLock: // Revisit FastLocks for lock coarsening
case Op_If:
case Op_CountedLoopEnd:
case Op_Region:
case Op_Loop:
case Op_CountedLoop:
case Op_Conv2B:
case Op_Opaque1:
_worklist.push(n);
break;
default:
break;
}
return n;
}
//---------------------------------saturate------------------------------------
const Type* PhaseCCP::saturate(const Type* new_type, const Type* old_type,
const Type* limit_type) const {
const Type* wide_type = new_type->widen(old_type, limit_type);
if (wide_type != new_type) { // did we widen?
// If so, we may have widened beyond the limit type. Clip it back down.
new_type = wide_type->filter(limit_type);
}
return new_type;
}
//------------------------------print_statistics-------------------------------
#ifndef PRODUCT
void PhaseCCP::print_statistics() {
tty->print_cr("CCP: %d constants found: %d", _total_invokes, _total_constants);
}
#endif
//=============================================================================
#ifndef PRODUCT
uint PhasePeephole::_total_peepholes = 0;
#endif
//------------------------------PhasePeephole----------------------------------
// Conditional Constant Propagation, ala Wegman & Zadeck
PhasePeephole::PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg )
: PhaseTransform(Peephole), _regalloc(regalloc), _cfg(cfg) {
NOT_PRODUCT( clear_peepholes(); )
}
#ifndef PRODUCT
//------------------------------~PhasePeephole---------------------------------
PhasePeephole::~PhasePeephole() {
_total_peepholes += count_peepholes();
}
#endif
//------------------------------transform--------------------------------------
Node *PhasePeephole::transform( Node *n ) {
ShouldNotCallThis();
return nullptr;
}
//------------------------------do_transform-----------------------------------
void PhasePeephole::do_transform() {
bool method_name_not_printed = true;
// Examine each basic block
for (uint block_number = 1; block_number < _cfg.number_of_blocks(); ++block_number) {
Block* block = _cfg.get_block(block_number);
bool block_not_printed = true;
for (bool progress = true; progress;) {
progress = false;
// block->end_idx() not valid after PhaseRegAlloc
uint end_index = block->number_of_nodes();
for( uint instruction_index = end_index - 1; instruction_index > 0; --instruction_index ) {
Node *n = block->get_node(instruction_index);
if( n->is_Mach() ) {
MachNode *m = n->as_Mach();
// check for peephole opportunities
int result = m->peephole(block, instruction_index, &_cfg, _regalloc);
if( result != -1 ) {
#ifndef PRODUCT
if( PrintOptoPeephole ) {
// Print method, first time only
if( C->method() && method_name_not_printed ) {
C->method()->print_short_name(); tty->cr();
method_name_not_printed = false;
}
// Print this block
if( Verbose && block_not_printed) {
tty->print_cr("in block");
block->dump();
block_not_printed = false;
}
// Print the peephole number
tty->print_cr("peephole number: %d", result);
}
inc_peepholes();
#endif
// Set progress, start again
progress = true;
break;
}
}
}
}
}
}
//------------------------------print_statistics-------------------------------
#ifndef PRODUCT
void PhasePeephole::print_statistics() {
tty->print_cr("Peephole: peephole rules applied: %d", _total_peepholes);
}
#endif
//=============================================================================
//------------------------------set_req_X--------------------------------------
void Node::set_req_X( uint i, Node *n, PhaseIterGVN *igvn ) {
assert( is_not_dead(n), "can not use dead node");
assert( igvn->hash_find(this) != this, "Need to remove from hash before changing edges" );
Node *old = in(i);
set_req(i, n);
// old goes dead?
if( old ) {
switch (old->outcnt()) {
case 0:
// Put into the worklist to kill later. We do not kill it now because the
// recursive kill will delete the current node (this) if dead-loop exists
if (!old->is_top())
igvn->_worklist.push( old );
break;
case 1:
if( old->is_Store() || old->has_special_unique_user() )
igvn->add_users_to_worklist( old );
break;
case 2:
if( old->is_Store() )
igvn->add_users_to_worklist( old );
if( old->Opcode() == Op_Region )
igvn->_worklist.push(old);
break;
case 3:
if( old->Opcode() == Op_Region ) {
igvn->_worklist.push(old);
igvn->add_users_to_worklist( old );
}
break;
default:
break;
}
BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn, old);
}
}
void Node::set_req_X(uint i, Node *n, PhaseGVN *gvn) {
PhaseIterGVN* igvn = gvn->is_IterGVN();
if (igvn == nullptr) {
set_req(i, n);
return;
}
set_req_X(i, n, igvn);
}
//-------------------------------replace_by-----------------------------------
// Using def-use info, replace one node for another. Follow the def-use info
// to all users of the OLD node. Then make all uses point to the NEW node.
void Node::replace_by(Node *new_node) {
assert(!is_top(), "top node has no DU info");
for (DUIterator_Last imin, i = last_outs(imin); i >= imin; ) {
Node* use = last_out(i);
uint uses_found = 0;
for (uint j = 0; j < use->len(); j++) {
if (use->in(j) == this) {
if (j < use->req())
use->set_req(j, new_node);
else use->set_prec(j, new_node);
uses_found++;
}
}
i -= uses_found; // we deleted 1 or more copies of this edge
}
}
//=============================================================================
//-----------------------------------------------------------------------------
void Type_Array::grow( uint i ) {
if( !_max ) {
_max = 1;
_types = (const Type**)_a->Amalloc( _max * sizeof(Type*) );
_types[0] = nullptr;
}
uint old = _max;
_max = next_power_of_2(i);
_types = (const Type**)_a->Arealloc( _types, old*sizeof(Type*),_max*sizeof(Type*));
memset( &_types[old], 0, (_max-old)*sizeof(Type*) );
}
//------------------------------dump-------------------------------------------
#ifndef PRODUCT
void Type_Array::dump() const {
uint max = Size();
for( uint i = 0; i < max; i++ ) {
if( _types[i] != nullptr ) {
tty->print(" %d\t== ", i); _types[i]->dump(); tty->cr();
}
}
}
#endif