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jdk/src/hotspot/share/opto/phaseX.cpp
Roland Westrelin e0f1c3a746 8351889: C2 crash: assertion failed: Base pointers must match (addp 344) 
Reviewed-by: rcastanedalo, thartmann
Backport-of: ad29642d8f4e8e0fb1223b14b85ab7841d7b1b51
2026-01-09 08:39:46 +00:00

3521 lines
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/*
* Copyright (c) 1997, 2025, 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 "gc/shared/barrierSet.hpp"
#include "gc/shared/c2/barrierSetC2.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
#include "opto/addnode.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) {
C->print_method(PHASE_BEFORE_REMOVEUSELESS, 3);
// 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) {
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");
}
#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, nullptr, ""); }
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 from scratch
PhaseIterGVN::PhaseIterGVN() : _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) {
const Type* newtype = type_or_null(n);
if (nn != n || oldtype != newtype) {
C->print_method(PHASE_AFTER_ITER_GVN_STEP, 5, n);
}
if (TraceIterativeGVN) {
uint wlsize = _worklist.size();
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();)
NOT_PRODUCT(C->reset_igv_phase_iter(PHASE_AFTER_ITER_GVN_STEP);)
C->print_method(PHASE_BEFORE_ITER_GVN, 3);
if (StressIGVN) {
shuffle_worklist();
}
// The node count check in the loop below (check_node_count) assumes that we
// increase the live node count with at most
// max_live_nodes_increase_per_iteration in between checks. If this
// assumption does not hold, there is a risk that we exceed the max node
// limit in between checks and trigger an assert during node creation.
const int max_live_nodes_increase_per_iteration = NodeLimitFudgeFactor * 3;
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() > 0) {
if (C->check_node_count(max_live_nodes_increase_per_iteration, "Out of nodes")) {
C->print_method(PHASE_AFTER_ITER_GVN, 3);
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");
C->print_method(PHASE_AFTER_ITER_GVN, 3);
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
DEBUG_ONLY(int live_nodes_before = C->live_nodes();)
Node* nn = transform_old(n);
DEBUG_ONLY(int live_nodes_after = C->live_nodes();)
// Ensure we did not increase the live node count with more than
// max_live_nodes_increase_per_iteration during the call to transform_old
DEBUG_ONLY(int increase = live_nodes_after - live_nodes_before;)
assert(increase < max_live_nodes_increase_per_iteration,
"excessive live node increase in single iteration of IGVN: %d "
"(should be at most %d)",
increase, max_live_nodes_increase_per_iteration);
NOT_PRODUCT(trace_PhaseIterGVN(n, nn, oldtype);)
} else if (!n->is_top()) {
remove_dead_node(n);
}
loop_count++;
}
NOT_PRODUCT(verify_PhaseIterGVN();)
C->print_method(PHASE_AFTER_ITER_GVN, 3);
}
#ifdef ASSERT
void PhaseIterGVN::verify_optimize() {
assert(_worklist.size() == 0, "igvn worklist must be empty before verify");
if (is_verify_Value() ||
is_verify_Ideal() ||
is_verify_Identity() ||
is_verify_invariants()) {
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);
if (is_verify_Value()) { failure |= verify_Value_for(n); }
if (is_verify_Ideal()) { failure |= verify_Ideal_for(n, false); }
if (is_verify_Ideal()) { failure |= verify_Ideal_for(n, true); }
if (is_verify_Identity()) { failure |= verify_Identity_for(n); }
if (is_verify_invariants()) { failure |= verify_node_invariants_for(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/broken graph in PhaseIterGVN");
}
verify_empty_worklist(nullptr);
}
void PhaseIterGVN::verify_empty_worklist(Node* node) {
// Verify that the igvn worklist is empty. If no optimization happened, then
// nothing needs to be on the worklist.
if (_worklist.size() == 0) { return; }
stringStream ss; // Print as a block without tty lock.
for (uint j = 0; j < _worklist.size(); j++) {
Node* n = _worklist.at(j);
ss.print("igvn.worklist[%d] ", j);
n->dump("\n", false, &ss);
}
if (_worklist.size() != 0 && node != nullptr) {
ss.print_cr("Previously optimized:");
node->dump("\n", false, &ss);
}
tty->print_cr("%s", ss.as_string());
assert(false, "igvn worklist must still be empty after verify");
}
// 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_Value_for(Node* n, bool strict) {
// 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 (!strict && 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 (!strict && 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;
}
stringStream ss; // Print as a block without tty lock.
ss.cr();
ss.print_cr("Missed Value optimization:");
n->dump_bfs(1, nullptr, "", &ss);
ss.print_cr("Current type:");
told->dump_on(&ss);
ss.cr();
ss.print_cr("Optimized type:");
tnew->dump_on(&ss);
ss.cr();
tty->print_cr("%s", ss.as_string());
return true;
}
// Check that all Ideal optimizations that could be done were done.
// Returns true if it found missed optimization opportunities and
// false otherwise (no missed optimization, or skipped verification).
bool PhaseIterGVN::verify_Ideal_for(Node* n, bool can_reshape) {
// First, we check a list of exceptions, where we skip verification,
// because there are known cases where Ideal can optimize after IGVN.
// Some may be expected and cannot be fixed, and others should be fixed.
switch (n->Opcode()) {
// RangeCheckNode::Ideal looks up the chain for about 999 nodes
// (see "Range-Check scan limit"). So, it is possible that something
// is optimized in that input subgraph, and the RangeCheck was not
// added to the worklist because it would be too expensive to walk
// down the graph for 1000 nodes and put all on the worklist.
//
// Found with:
// java -XX:VerifyIterativeGVN=0100 -Xbatch --version
case Op_RangeCheck:
return false;
// IfNode::Ideal does:
// Node* prev_dom = search_identical(dist, igvn);
// which means we seach up the CFG, traversing at most up to a distance.
// If anything happens rather far away from the If, we may not put the If
// back on the worklist.
//
// Found with:
// java -XX:VerifyIterativeGVN=0100 -Xcomp --version
case Op_If:
return false;
// IfNode::simple_subsuming
// Looks for dominating test that subsumes the current test.
// Notification could be difficult because of larger distance.
//
// Found with:
// runtime/exceptionMsgs/ArrayIndexOutOfBoundsException/ArrayIndexOutOfBoundsExceptionTest.java#id1
// -XX:VerifyIterativeGVN=1110
case Op_CountedLoopEnd:
return false;
// LongCountedLoopEndNode::Ideal
// Probably same issue as above.
//
// Found with:
// compiler/predicates/assertion/TestAssertionPredicates.java#NoLoopPredicationXbatch
// -XX:StressLongCountedLoop=2000000 -XX:+IgnoreUnrecognizedVMOptions -XX:VerifyIterativeGVN=1110
case Op_LongCountedLoopEnd:
return false;
// RegionNode::Ideal does "Skip around the useless IF diamond".
// 245 IfTrue === 244
// 258 If === 245 257
// 259 IfTrue === 258 [[ 263 ]]
// 260 IfFalse === 258 [[ 263 ]]
// 263 Region === 263 260 259 [[ 263 268 ]]
// to
// 245 IfTrue === 244
// 263 Region === 263 245 _ [[ 263 268 ]]
//
// "Useless" means that there is no code in either branch of the If.
// I found a case where this was not done yet during IGVN.
// Why does the Region not get added to IGVN worklist when the If diamond becomes useless?
//
// Found with:
// java -XX:VerifyIterativeGVN=0100 -Xcomp --version
case Op_Region:
return false;
// In AddNode::Ideal, we call "commute", which swaps the inputs so
// that smaller idx are first. Tracking it back, it led me to
// PhaseIdealLoop::remix_address_expressions which swapped the edges.
//
// Example:
// Before PhaseIdealLoop::remix_address_expressions
// 154 AddI === _ 12 144
// After PhaseIdealLoop::remix_address_expressions
// 154 AddI === _ 144 12
// After AddNode::Ideal
// 154 AddI === _ 12 144
//
// I suspect that the node should be added to the IGVN worklist after
// PhaseIdealLoop::remix_address_expressions
//
// This is the only case I looked at, there may be others. Found like this:
// java -XX:VerifyIterativeGVN=0100 -Xbatch --version
//
// The following hit the same logic in PhaseIdealLoop::remix_address_expressions.
//
// Note: currently all of these fail also for other reasons, for example
// because of "commute" doing the reordering with the phi below. Once
// that is resolved, we can come back to this issue here.
//
// case Op_AddD:
// case Op_AddI:
// case Op_AddL:
// case Op_AddF:
// case Op_MulI:
// case Op_MulL:
// case Op_MulF:
// case Op_MulD:
// if (n->in(1)->_idx > n->in(2)->_idx) {
// // Expect "commute" to revert this case.
// return false;
// }
// break; // keep verifying
// AddFNode::Ideal calls "commute", which can reorder the inputs for this:
// Check for tight loop increments: Loop-phi of Add of loop-phi
// It wants to take the phi into in(1):
// 471 Phi === 435 38 390
// 390 AddF === _ 471 391
//
// Other Associative operators are also affected equally.
//
// Investigate why this does not happen earlier during IGVN.
//
// Found with:
// test/hotspot/jtreg/compiler/loopopts/superword/ReductionPerf.java
// -XX:VerifyIterativeGVN=1110
case Op_AddD:
//case Op_AddI: // Also affected for other reasons, see case further down.
//case Op_AddL: // Also affected for other reasons, see case further down.
case Op_AddF:
case Op_MulI:
case Op_MulL:
case Op_MulF:
case Op_MulD:
case Op_MinF:
case Op_MinD:
case Op_MaxF:
case Op_MaxD:
// XorINode::Ideal
// Found with:
// compiler/intrinsics/chacha/TestChaCha20.java
// -XX:VerifyIterativeGVN=1110
case Op_XorI:
case Op_XorL:
// It seems we may have similar issues with the HF cases.
// Found with aarch64:
// compiler/vectorization/TestFloat16VectorOperations.java
// -XX:VerifyIterativeGVN=1110
case Op_AddHF:
case Op_MulHF:
case Op_MaxHF:
case Op_MinHF:
return false;
// In MulNode::Ideal the edges can be swapped to help value numbering:
//
// // We are OK if right is a constant, or right is a load and
// // left is a non-constant.
// if( !(t2->singleton() ||
// (in(2)->is_Load() && !(t1->singleton() || in(1)->is_Load())) ) ) {
// if( t1->singleton() || // Left input is a constant?
// // Otherwise, sort inputs (commutativity) to help value numbering.
// (in(1)->_idx > in(2)->_idx) ) {
// swap_edges(1, 2);
//
// Why was this not done earlier during IGVN?
//
// Found with:
// test/hotspot/jtreg/gc/stress/gcbasher/TestGCBasherWithG1.java
// -XX:VerifyIterativeGVN=1110
case Op_AndI:
// Same for AndL.
// Found with:
// compiler/intrinsics/bigInteger/MontgomeryMultiplyTest.java
// -XX:VerifyIterativeGVN=1110
case Op_AndL:
return false;
// SubLNode::Ideal does transform like:
// Convert "c1 - (y+c0)" into "(c1-c0) - y"
//
// In IGVN before verification:
// 8423 ConvI2L === _ 3519 [[ 8424 ]] #long:-2
// 8422 ConvI2L === _ 8399 [[ 8424 ]] #long:3..256:www
// 8424 AddL === _ 8422 8423 [[ 8383 ]] !orig=[8382]
// 8016 ConL === 0 [[ 8383 ]] #long:0
// 8383 SubL === _ 8016 8424 [[ 8156 ]] !orig=[8154]
//
// And then in verification:
// 8338 ConL === 0 [[ 8339 8424 ]] #long:-2 <----- Was constant folded.
// 8422 ConvI2L === _ 8399 [[ 8424 ]] #long:3..256:www
// 8424 AddL === _ 8422 8338 [[ 8383 ]] !orig=[8382]
// 8016 ConL === 0 [[ 8383 ]] #long:0
// 8383 SubL === _ 8016 8424 [[ 8156 ]] !orig=[8154]
//
// So the form changed from:
// c1 - (y + [8423 ConvI2L])
// to
// c1 - (y + -2)
// but the SubL was not added to the IGVN worklist. Investigate why.
// There could be other issues too.
//
// There seems to be a related AddL IGVN optimization that triggers
// the same SubL optimization, so investigate that too.
//
// Found with:
// java -XX:VerifyIterativeGVN=0100 -Xcomp --version
case Op_SubL:
return false;
// SubINode::Ideal does
// Convert "x - (y+c0)" into "(x-y) - c0" AND
// Convert "c1 - (y+c0)" into "(c1-c0) - y"
//
// Investigate why this does not yet happen during IGVN.
//
// Found with:
// test/hotspot/jtreg/compiler/c2/IVTest.java
// -XX:VerifyIterativeGVN=1110
case Op_SubI:
return false;
// AddNode::IdealIL does transform like:
// Convert x + (con - y) into "(x - y) + con"
//
// In IGVN before verification:
// 8382 ConvI2L
// 8381 ConvI2L === _ 791 [[ 8383 ]] #long:0
// 8383 SubL === _ 8381 8382
// 8168 ConvI2L
// 8156 AddL === _ 8168 8383 [[ 8158 ]]
//
// And then in verification:
// 8424 AddL
// 8016 ConL === 0 [[ 8383 ]] #long:0 <--- Was constant folded.
// 8383 SubL === _ 8016 8424
// 8168 ConvI2L
// 8156 AddL === _ 8168 8383 [[ 8158 ]]
//
// So the form changed from:
// x + (ConvI2L(0) - [8382 ConvI2L])
// to
// x + (0 - [8424 AddL])
// but the AddL was not added to the IGVN worklist. Investigate why.
// There could be other issues, too. For example with "commute", see above.
//
// Found with:
// java -XX:VerifyIterativeGVN=0100 -Xcomp --version
case Op_AddL:
return false;
// SubTypeCheckNode::Ideal calls SubTypeCheckNode::verify_helper, which does
// Node* cmp = phase->transform(new CmpPNode(subklass, in(SuperKlass)));
// record_for_cleanup(cmp, phase);
// This verification code in the Ideal code creates new nodes, and checks
// if they fold in unexpected ways. This means some nodes are created and
// added to the worklist, even if the SubTypeCheck is not optimized. This
// goes agains the assumption of the verification here, which assumes that
// if the node is not optimized, then no new nodes should be created, and
// also no nodes should be added to the worklist.
// I see two options:
// 1) forbid what verify_helper does, because for each Ideal call it
// uses memory and that is suboptimal. But it is not clear how that
// verification can be done otherwise.
// 2) Special case the verification here. Probably the new nodes that
// were just created are dead, i.e. they are not connected down to
// root. We could verify that, and remove those nodes from the graph
// by setting all their inputs to nullptr. And of course we would
// have to remove those nodes from the worklist.
// Maybe there are other options too, I did not dig much deeper yet.
//
// Found with:
// java -XX:VerifyIterativeGVN=0100 -Xbatch --version
case Op_SubTypeCheck:
return false;
// LoopLimitNode::Ideal when stride is constant power-of-2, we can do a lowering
// to other nodes: Conv, Add, Sub, Mul, And ...
//
// 107 ConI === 0 [[ ... ]] #int:2
// 84 LoadRange === _ 7 83
// 50 ConI === 0 [[ ... ]] #int:0
// 549 LoopLimit === _ 50 84 107
//
// I stepped backward, to see how the node was generated, and I found that it was
// created in PhaseIdealLoop::exact_limit and not changed since. It is added to the
// IGVN worklist. I quickly checked when it goes into LoopLimitNode::Ideal after
// that, and it seems we want to skip lowering it until after loop-opts, but never
// add call record_for_post_loop_opts_igvn. This would be an easy fix, but there
// could be other issues too.
//
// Fond with:
// java -XX:VerifyIterativeGVN=0100 -Xcomp --version
case Op_LoopLimit:
return false;
// PhiNode::Ideal calls split_flow_path, which tries to do this:
// "This optimization tries to find two or more inputs of phi with the same constant
// value. It then splits them into a separate Phi, and according Region."
//
// Example:
// 130 DecodeN === _ 129
// 50 ConP === 0 [[ 18 91 99 18 ]] #null
// 18 Phi === 14 50 130 50 [[ 133 ]] #java/lang/Object * Oop:java/lang/Object *
//
// turns into:
//
// 50 ConP === 0 [[ 99 91 18 ]] #null
// 130 DecodeN === _ 129 [[ 18 ]]
// 18 Phi === 14 130 50 [[ 133 ]] #java/lang/Object * Oop:java/lang/Object *
//
// We would have to investigate why this optimization does not happen during IGVN.
// There could also be other issues - I did not investigate further yet.
//
// Found with:
// java -XX:VerifyIterativeGVN=0100 -Xcomp --version
case Op_Phi:
return false;
// MemBarNode::Ideal does "Eliminate volatile MemBars for scalar replaced objects".
// For examle "The allocated object does not escape".
//
// It seems the difference to earlier calls to MemBarNode::Ideal, is that there
// alloc->as_Allocate()->does_not_escape_thread() returned false, but in verification
// it returned true. Why does the MemBarStoreStore not get added to the IGVN
// worklist when this change happens?
//
// Found with:
// java -XX:VerifyIterativeGVN=0100 -Xcomp --version
case Op_MemBarStoreStore:
return false;
// ConvI2LNode::Ideal converts
// 648 AddI === _ 583 645 [[ 661 ]]
// 661 ConvI2L === _ 648 [[ 664 ]] #long:0..maxint-1:www
// into
// 772 ConvI2L === _ 645 [[ 773 ]] #long:-120..maxint-61:www
// 771 ConvI2L === _ 583 [[ 773 ]] #long:60..120:www
// 773 AddL === _ 771 772 [[ ]]
//
// We have to investigate why this does not happen during IGVN in this case.
// There could also be other issues - I did not investigate further yet.
//
// Found with:
// java -XX:VerifyIterativeGVN=0100 -Xcomp --version
case Op_ConvI2L:
return false;
// AddNode::IdealIL can do this transform (and similar other ones):
// Convert "a*b+a*c into a*(b+c)
// The example had AddI(MulI(a, b), MulI(a, c)). Why did this not happen
// during IGVN? There was a mutation for one of the MulI, and only
// after that the pattern was as needed for the optimization. The MulI
// was added to the IGVN worklist, but not the AddI. This probably
// can be fixed by adding the correct pattern in add_users_of_use_to_worklist.
//
// Found with:
// test/hotspot/jtreg/compiler/loopopts/superword/ReductionPerf.java
// -XX:VerifyIterativeGVN=1110
case Op_AddI:
return false;
// ArrayCopyNode::Ideal
// calls ArrayCopyNode::prepare_array_copy
// calls Compile::conv_I2X_index -> is called with sizetype = intcon(0), I think that
// is not expected, and we create a range int:0..-1
// calls Compile::constrained_convI2L -> creates ConvI2L(intcon(1), int:0..-1)
// note: the type is already empty!
// calls PhaseIterGVN::transform
// calls PhaseIterGVN::transform_old
// calls PhaseIterGVN::subsume_node -> subsume ConvI2L with TOP
// calls Unique_Node_List::push -> pushes TOP to worklist
//
// Once we get back to ArrayCopyNode::prepare_array_copy, we get back TOP, and
// return false. This means we eventually return nullptr from ArrayCopyNode::Ideal.
//
// Question: is it ok to push anything to the worklist during ::Ideal, if we will
// return nullptr, indicating nothing happened?
// Is it smart to do transform in Compile::constrained_convI2L, and then
// check for TOP in calls ArrayCopyNode::prepare_array_copy?
// Should we just allow TOP to land on the worklist, as an exception?
//
// Found with:
// compiler/arraycopy/TestArrayCopyAsLoadsStores.java
// -XX:VerifyIterativeGVN=1110
case Op_ArrayCopy:
return false;
// CastLLNode::Ideal
// calls ConstraintCastNode::optimize_integer_cast -> pushes CastLL through SubL
//
// Could be a notification issue, where updates inputs of CastLL do not notify
// down through SubL to CastLL.
//
// Found With:
// compiler/c2/TestMergeStoresMemorySegment.java#byte-array
// -XX:VerifyIterativeGVN=1110
case Op_CastLL:
return false;
// Similar case happens to CastII
//
// Found With:
// compiler/c2/TestScalarReplacementMaxLiveNodes.java
// -XX:VerifyIterativeGVN=1110
case Op_CastII:
return false;
// MaxLNode::Ideal
// calls AddNode::Ideal
// calls commute -> decides to swap edges
//
// Another notification issue, because we check inputs of inputs?
// MaxL -> Phi -> Loop
// MaxL -> Phi -> MaxL
//
// Found with:
// compiler/c2/irTests/TestIfMinMax.java
// -XX:VerifyIterativeGVN=1110
case Op_MaxL:
case Op_MinL:
return false;
// OrINode::Ideal
// calls AddNode::Ideal
// calls commute -> left is Load, right not -> commute.
//
// Not sure why notification does not work here, seems like
// the depth is only 1, so it should work. Needs investigation.
//
// Found with:
// compiler/codegen/TestCharVect2.java#id0
// -XX:VerifyIterativeGVN=1110
case Op_OrI:
case Op_OrL:
return false;
// Bool -> constant folded to 1.
// Issue with notification?
//
// Found with:
// compiler/c2/irTests/TestVectorizationMismatchedAccess.java
// -XX:VerifyIterativeGVN=1110
case Op_Bool:
return false;
// LShiftLNode::Ideal
// Looks at pattern: "(x + x) << c0", converts it to "x << (c0 + 1)"
// Probably a notification issue.
//
// Found with:
// compiler/conversions/TestMoveConvI2LOrCastIIThruAddIs.java
// -ea -esa -XX:CompileThreshold=100 -XX:+UnlockExperimentalVMOptions -server -XX:-TieredCompilation -XX:+IgnoreUnrecognizedVMOptions -XX:VerifyIterativeGVN=1110
case Op_LShiftL:
return false;
// LShiftINode::Ideal
// pattern: ((x + con1) << con2) -> x << con2 + con1 << con2
// Could be issue with notification of inputs of inputs
//
// Side-note: should cases like these not be shared between
// LShiftI and LShiftL?
//
// Found with:
// compiler/escapeAnalysis/Test6689060.java
// -XX:+IgnoreUnrecognizedVMOptions -XX:VerifyIterativeGVN=1110 -ea -esa -XX:CompileThreshold=100 -XX:+UnlockExperimentalVMOptions -server -XX:-TieredCompilation -XX:+IgnoreUnrecognizedVMOptions -XX:VerifyIterativeGVN=1110
case Op_LShiftI:
return false;
// AddPNode::Ideal seems to do set_req without removing lock first.
// Found with various vector tests tier1-tier3.
case Op_AddP:
return false;
// StrIndexOfNode::Ideal
// Found in tier1-3.
case Op_StrIndexOf:
case Op_StrIndexOfChar:
return false;
// StrEqualsNode::Identity
//
// Found (linux x64 only?) with:
// serviceability/sa/ClhsdbThreadContext.java
// -XX:+UnlockExperimentalVMOptions -XX:LockingMode=1 -XX:+IgnoreUnrecognizedVMOptions -XX:VerifyIterativeGVN=1110
// Note: The -XX:LockingMode option is not available anymore.
case Op_StrEquals:
return false;
// AryEqNode::Ideal
// Not investigated. Reshapes itself and adds lots of nodes to the worklist.
//
// Found with:
// vmTestbase/vm/mlvm/meth/stress/compiler/i2c_c2i/Test.java
// -XX:+UnlockDiagnosticVMOptions -XX:-TieredCompilation -XX:+StressUnstableIfTraps -XX:+IgnoreUnrecognizedVMOptions -XX:VerifyIterativeGVN=1110
case Op_AryEq:
return false;
// MergeMemNode::Ideal
// Found in tier1-3. Did not investigate further yet.
case Op_MergeMem:
return false;
// URShiftINode::Ideal
// Found in tier1-3. Did not investigate further yet.
case Op_URShiftI:
return false;
// CMoveINode::Ideal
// Found in tier1-3. Did not investigate further yet.
case Op_CMoveI:
return false;
// CmpPNode::Ideal calls isa_const_java_mirror
// and generates new constant nodes, even if no progress is made.
// We can probably rewrite this so that only types are generated.
// It seems that object types are not hashed, we could investigate
// if that is an option as well.
//
// Found with:
// java -XX:VerifyIterativeGVN=1110 -Xcomp --version
case Op_CmpP:
return false;
// MinINode::Ideal
// Did not investigate, but there are some patterns that might
// need more notification.
case Op_MinI:
case Op_MaxI: // preemptively removed it as well.
return false;
}
if (n->is_Load()) {
// LoadNode::Ideal uses tries to find an earlier memory state, and
// checks can_see_stored_value for it.
//
// Investigate why this was not already done during IGVN.
// A similar issue happens with Identity.
//
// There seem to be other cases where loads go up some steps, like
// LoadNode::Ideal going up 10x steps to find dominating load.
//
// Found with:
// test/hotspot/jtreg/compiler/arraycopy/TestCloneAccess.java
// -XX:VerifyIterativeGVN=1110
return false;
}
if (n->is_Store()) {
// StoreNode::Ideal can do this:
// // Capture an unaliased, unconditional, simple store into an initializer.
// // Or, if it is independent of the allocation, hoist it above the allocation.
// That replaces the Store with a MergeMem.
//
// We have to investigate why this does not happen during IGVN in this case.
// There could also be other issues - I did not investigate further yet.
//
// Found with:
// java -XX:VerifyIterativeGVN=0100 -Xcomp --version
return false;
}
if (n->is_Vector()) {
// VectorNode::Ideal swaps edges, but only for ops
// that are deemed commutable. But swap_edges
// requires the hash to be invariant when the edges
// are swapped, which is not implemented for these
// vector nodes. This seems not to create any trouble
// usually, but we can also get graphs where in the
// end the nodes are not all commuted, so there is
// definitively an issue here.
//
// Probably we have two options: kill the hash, or
// properly make the hash commutation friendly.
//
// Found with:
// compiler/vectorapi/TestMaskedMacroLogicVector.java
// -XX:+IgnoreUnrecognizedVMOptions -XX:VerifyIterativeGVN=1110 -XX:+UseParallelGC -XX:+UseNUMA
return false;
}
if (n->is_Region()) {
// LoopNode::Ideal calls RegionNode::Ideal.
// CountedLoopNode::Ideal calls RegionNode::Ideal too.
// But I got an issue because RegionNode::optimize_trichotomy
// then modifies another node, and pushes nodes to the worklist
// Not sure if this is ok, modifying another node like that.
// Maybe it is, then we need to look into what to do with
// the nodes that are now on the worklist, maybe just clear
// them out again. But maybe modifying other nodes like that
// is also bad design. In the end, we return nullptr for
// the current CountedLoop. But the extra nodes on the worklist
// trip the asserts later on.
//
// Found with:
// compiler/eliminateAutobox/TestShortBoxing.java
// -ea -esa -XX:CompileThreshold=100 -XX:+UnlockExperimentalVMOptions -server -XX:-TieredCompilation -XX:+IgnoreUnrecognizedVMOptions -XX:VerifyIterativeGVN=1110
return false;
}
if (n->is_CallJava()) {
// CallStaticJavaNode::Ideal
// Led to a crash:
// assert((is_CallStaticJava() && cg->is_mh_late_inline()) || (is_CallDynamicJava() && cg->is_virtual_late_inline())) failed: mismatch
//
// Did not investigate yet, could be a bug.
// Or maybe it does not expect to be called during verification.
//
// Found with:
// test/jdk/jdk/incubator/vector/VectorRuns.java
// -XX:VerifyIterativeGVN=1110
// CallDynamicJavaNode::Ideal, and I think also for CallStaticJavaNode::Ideal
// and possibly their subclasses.
// During late inlining it can call CallJavaNode::register_for_late_inline
// That means we do more rounds of late inlining, but might fail.
// Then we do IGVN again, and register the node again for late inlining.
// This creates an endless cycle. Everytime we try late inlining, we
// are also creating more nodes, especially SafePoint and MergeMem.
// These nodes are immediately rejected when the inlining fails in the
// do_late_inline_check, but they still grow the memory, until we hit
// the MemLimit and crash.
// The assumption here seems that CallDynamicJavaNode::Ideal does not get
// called repeatedly, and eventually we terminate. I fear this is not
// a great assumption to make. We should investigate more.
//
// Found with:
// compiler/loopopts/superword/TestDependencyOffsets.java#vanilla-U
// -XX:+IgnoreUnrecognizedVMOptions -XX:VerifyIterativeGVN=1110
return false;
}
// The number of nodes shoud not increase.
uint old_unique = C->unique();
// The hash of a node should not change, this would indicate different inputs
uint old_hash = n->hash();
Node* i = n->Ideal(this, can_reshape);
// If there was no new Idealization, we are probably happy.
if (i == nullptr) {
if (old_unique < C->unique()) {
stringStream ss; // Print as a block without tty lock.
ss.cr();
ss.print_cr("Ideal optimization did not make progress but created new unused nodes.");
ss.print_cr(" old_unique = %d, unique = %d", old_unique, C->unique());
n->dump_bfs(1, nullptr, "", &ss);
tty->print_cr("%s", ss.as_string());
return true;
}
if (old_hash != n->hash()) {
stringStream ss; // Print as a block without tty lock.
ss.cr();
ss.print_cr("Ideal optimization did not make progress but node hash changed.");
ss.print_cr(" old_hash = %d, hash = %d", old_hash, n->hash());
n->dump_bfs(1, nullptr, "", &ss);
tty->print_cr("%s", ss.as_string());
return true;
}
verify_empty_worklist(n);
// Everything is good.
return false;
}
// We just saw a new Idealization which was not done during IGVN.
stringStream ss; // Print as a block without tty lock.
ss.cr();
ss.print_cr("Missed Ideal optimization (can_reshape=%s):", can_reshape ? "true": "false");
if (i == n) {
ss.print_cr("The node was reshaped by Ideal.");
} else {
ss.print_cr("The node was replaced by Ideal.");
ss.print_cr("Old node:");
n->dump_bfs(1, nullptr, "", &ss);
}
ss.print_cr("The result after Ideal:");
i->dump_bfs(1, nullptr, "", &ss);
tty->print_cr("%s", ss.as_string());
return true;
}
// Check that all Identity optimizations that could be done were done.
// Returns true if it found missed optimization opportunities and
// false otherwise (no missed optimization, or skipped verification).
bool PhaseIterGVN::verify_Identity_for(Node* n) {
// First, we check a list of exceptions, where we skip verification,
// because there are known cases where Ideal can optimize after IGVN.
// Some may be expected and cannot be fixed, and others should be fixed.
switch (n->Opcode()) {
// SafePointNode::Identity can remove SafePoints, but wants to wait until
// after loopopts:
// // Transforming long counted loops requires a safepoint node. Do not
// // eliminate a safepoint until loop opts are over.
// if (in(0)->is_Proj() && !phase->C->major_progress()) {
//
// I think the check for major_progress does delay it until after loopopts
// but it does not ensure that the node is on the IGVN worklist after
// loopopts. I think we should try to instead check for
// phase->C->post_loop_opts_phase() and call record_for_post_loop_opts_igvn.
//
// Found with:
// java -XX:VerifyIterativeGVN=1000 -Xcomp --version
case Op_SafePoint:
return false;
// MergeMemNode::Identity replaces the MergeMem with its base_memory if it
// does not record any other memory splits.
//
// I did not deeply investigate, but it looks like MergeMemNode::Identity
// never got called during IGVN for this node, investigate why.
//
// Found with:
// java -XX:VerifyIterativeGVN=1000 -Xcomp --version
case Op_MergeMem:
return false;
// ConstraintCastNode::Identity finds casts that are the same, except that
// the control is "higher up", i.e. dominates. The call goes via
// ConstraintCastNode::dominating_cast to PhaseGVN::is_dominator_helper,
// which traverses up to 100 idom steps. If anything gets optimized somewhere
// away from the cast, but within 100 idom steps, the cast may not be
// put on the IGVN worklist any more.
//
// Found with:
// java -XX:VerifyIterativeGVN=1000 -Xcomp --version
case Op_CastPP:
case Op_CastII:
case Op_CastLL:
return false;
// Same issue for CheckCastPP, uses ConstraintCastNode::Identity and
// checks dominator, which may be changed, but too far up for notification
// to work.
//
// Found with:
// compiler/c2/irTests/TestSkeletonPredicates.java
// -XX:VerifyIterativeGVN=1110
case Op_CheckCastPP:
return false;
// In SubNode::Identity, we do:
// Convert "(X+Y) - Y" into X and "(X+Y) - X" into Y
// In the example, the AddI had an input replaced, the AddI is
// added to the IGVN worklist, but the SubI is one link further
// down and is not added. I checked add_users_of_use_to_worklist
// where I would expect the SubI would be added, and I cannot
// find the pattern, only this one:
// If changed AddI/SubI inputs, check CmpU for range check optimization.
//
// Fix this "notification" issue and check if there are any other
// issues.
//
// Found with:
// java -XX:VerifyIterativeGVN=1000 -Xcomp --version
case Op_SubI:
case Op_SubL:
return false;
// PhiNode::Identity checks for patterns like:
// r = (x != con) ? x : con;
// that can be constant folded to "x".
//
// Call goes through PhiNode::is_cmove_id and CMoveNode::is_cmove_id.
// I suspect there was some earlier change to one of the inputs, but
// not all relevant outputs were put on the IGVN worklist.
//
// Found with:
// test/hotspot/jtreg/gc/stress/gcbasher/TestGCBasherWithG1.java
// -XX:VerifyIterativeGVN=1110
case Op_Phi:
return false;
// ConvI2LNode::Identity does
// convert I2L(L2I(x)) => x
//
// Investigate why this did not already happen during IGVN.
//
// Found with:
// compiler/loopopts/superword/TestDependencyOffsets.java#vanilla-A
// -XX:VerifyIterativeGVN=1110
case Op_ConvI2L:
return false;
// MaxNode::find_identity_operation
// Finds patterns like Max(A, Max(A, B)) -> Max(A, B)
// This can be a 2-hop search, so maybe notification is not
// good enough.
//
// Found with:
// compiler/codegen/TestBooleanVect.java
// -XX:VerifyIterativeGVN=1110
case Op_MaxL:
case Op_MinL:
case Op_MaxI:
case Op_MinI:
case Op_MaxF:
case Op_MinF:
case Op_MaxHF:
case Op_MinHF:
case Op_MaxD:
case Op_MinD:
return false;
// AddINode::Identity
// Converts (x-y)+y to x
// Could be issue with notification
//
// Turns out AddL does the same.
//
// Found with:
// compiler/c2/Test6792161.java
// -ea -esa -XX:CompileThreshold=100 -XX:+UnlockExperimentalVMOptions -server -XX:-TieredCompilation -XX:+IgnoreUnrecognizedVMOptions -XX:VerifyIterativeGVN=1110
case Op_AddI:
case Op_AddL:
return false;
// AbsINode::Identity
// Not investigated yet.
case Op_AbsI:
return false;
}
if (n->is_Load()) {
// LoadNode::Identity tries to look for an earlier store value via
// can_see_stored_value. I found an example where this led to
// an Allocation, where we could assume the value was still zero.
// So the LoadN can be replaced with a zerocon.
//
// Investigate why this was not already done during IGVN.
// A similar issue happens with Ideal.
//
// Found with:
// java -XX:VerifyIterativeGVN=1000 -Xcomp --version
return false;
}
if (n->is_Store()) {
// StoreNode::Identity
// Not investigated, but found missing optimization for StoreI.
// Looks like a StoreI is replaced with an InitializeNode.
//
// Found with:
// applications/ctw/modules/java_base_2.java
// -ea -esa -XX:CompileThreshold=100 -XX:+UnlockExperimentalVMOptions -server -XX:-TieredCompilation -Djava.awt.headless=true -XX:+IgnoreUnrecognizedVMOptions -XX:VerifyIterativeGVN=1110
return false;
}
if (n->is_Vector()) {
// Found with tier1-3. Not investigated yet.
// The observed issue was with AndVNode::Identity
return false;
}
Node* i = n->Identity(this);
// If we cannot find any other Identity, we are happy.
if (i == n) {
verify_empty_worklist(n);
return false;
}
// The verification just found a new Identity that was not found during IGVN.
stringStream ss; // Print as a block without tty lock.
ss.cr();
ss.print_cr("Missed Identity optimization:");
ss.print_cr("Old node:");
n->dump_bfs(1, nullptr, "", &ss);
ss.print_cr("New node:");
i->dump_bfs(1, nullptr, "", &ss);
tty->print_cr("%s", ss.as_string());
return true;
}
// Some other verifications that are not specific to a particular transformation.
bool PhaseIterGVN::verify_node_invariants_for(const Node* n) {
if (n->is_AddP()) {
if (!n->as_AddP()->address_input_has_same_base()) {
stringStream ss; // Print as a block without tty lock.
ss.cr();
ss.print_cr("Base pointers must match for AddP chain:");
n->dump_bfs(2, nullptr, "", &ss);
tty->print_cr("%s", ss.as_string());
return true;
}
}
return false;
}
#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 if (dead->is_data_proj_of_pure_function(in)) {
_worklist.push(in);
} 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, Unique_Node_List& worklist) {
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, _worklist);
Unique_Node_List& worklist = _worklist;
// 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
add_users_of_use_to_worklist(n, use, worklist);
}
}
void PhaseIterGVN::add_users_of_use_to_worklist(Node* n, Node* use, Unique_Node_List& worklist) {
if(use->is_Multi() || // Multi-definer? Push projs on worklist
use->is_Store() ) // Enable store/load same address
add_users_to_worklist0(use, worklist);
// 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, worklist);
}
}
uint use_op = use->Opcode();
if(use->is_Cmp()) { // Enable CMP/BOOL optimization
add_users_to_worklist0(use, worklist); // 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, worklist);
}
}
}
}
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, Sub, and Xor - all do "uncast"
// Patterns:
// ConstraintCast+ -> Sub
// ConstraintCast+ -> Phi
// ConstraintCast+ -> Xor
if (use->is_ConstraintCast()) {
auto push_the_uses_to_worklist = [&](Node* n){
if (n->is_Phi() || n->is_Sub() || n->Opcode() == Op_XorI || n->Opcode() == Op_XorL) {
worklist.push(n);
}
};
auto is_boundary = [](Node* n){ return !n->is_ConstraintCast(); };
use->visit_uses(push_the_uses_to_worklist, is_boundary);
}
// If changed LShift inputs, check RShift users for useless sign-ext
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_RShiftI || u->Opcode() == Op_RShiftL)
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 AndI/AndL inputs, check RShift/URShift users for "(x & mask) >> shift" optimization opportunity
if (use_op == Op_AndI || use_op == Op_AndL) {
for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
Node* u = use->fast_out(i2);
if (u->Opcode() == Op_RShiftI || u->Opcode() == Op_RShiftL ||
u->Opcode() == Op_URShiftI || u->Opcode() == Op_URShiftL) {
worklist.push(u);
}
}
}
// Check for redundant conversion patterns:
// ConvD2L->ConvL2D->ConvD2L
// ConvF2I->ConvI2F->ConvF2I
// ConvF2L->ConvL2F->ConvF2L
// ConvI2F->ConvF2I->ConvI2F
// Note: there may be other 3-nodes conversion chains that would require to be added here, but these
// are the only ones that are known to trigger missed optimizations otherwise
if (use_op == Op_ConvL2D ||
use_op == Op_ConvI2F ||
use_op == Op_ConvL2F ||
use_op == Op_ConvF2I) {
for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
Node* u = use->fast_out(i2);
if ((use_op == Op_ConvL2D && u->Opcode() == Op_ConvD2L) ||
(use_op == Op_ConvI2F && u->Opcode() == Op_ConvF2I) ||
(use_op == Op_ConvL2F && u->Opcode() == Op_ConvF2L) ||
(use_op == Op_ConvF2I && u->Opcode() == Op_ConvI2F)) {
worklist.push(u);
}
}
}
// If changed AddP inputs:
// - check Stores for loop invariant, and
// - if the changed input is the offset, check constant-offset AddP users for
// address expression flattening.
if (use_op == Op_AddP) {
bool offset_changed = n == use->in(AddPNode::Offset);
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);
} else if (offset_changed && u->is_AddP() && u->in(AddPNode::Offset)->is_Con()) {
worklist.push(u);
}
}
}
// Check for "abs(0-x)" into "abs(x)" conversion
if (use->is_Sub()) {
for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
Node* u = use->fast_out(i2);
if (u->Opcode() == Op_AbsD || u->Opcode() == Op_AbsF ||
u->Opcode() == Op_AbsL || u->Opcode() == Op_AbsI) {
worklist.push(u);
}
}
}
auto enqueue_init_mem_projs = [&](ProjNode* proj) {
add_users_to_worklist0(proj, worklist);
};
// 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) {
init->for_each_proj(enqueue_init_mem_projs, TypeFunc::Memory);
}
}
// 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, worklist);
}
}
if (use_op == Op_Initialize) {
InitializeNode* init = use->as_Initialize();
init->for_each_proj(enqueue_init_mem_projs, TypeFunc::Memory);
}
// 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);
}
}
// From CastX2PNode::Ideal
// CastX2P(AddX(x, y))
// CastX2P(SubX(x, y))
if (use->Opcode() == Op_AddX || use->Opcode() == Op_SubX) {
for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
Node* u = use->fast_out(i2);
if (u->Opcode() == Op_CastX2P) {
worklist.push(u);
}
}
}
/* AndNode has a special handling when one of the operands is a LShiftNode:
* (LHS << s) & RHS
* if RHS fits in less than s bits, the value of this expression is 0.
* The difficulty is that there might be a conversion node (ConvI2L) between
* the LShiftINode and the AndLNode, like so:
* AndLNode(ConvI2L(LShiftI(LHS, s)), RHS)
* This case is handled by And[IL]Node::Value(PhaseGVN*)
* (see `AndIL_min_trailing_zeros`).
*
* But, when the shift is updated during IGVN, pushing the user (ConvI2L)
* is not enough: there might be no update happening there. We need to
* directly push the And[IL]Node on the worklist, jumping over ConvI2L.
*
* Moreover we can have ConstraintCasts in between. It may look like
* ConstraintCast+ -> ConvI2L -> ConstraintCast+ -> And
* and And[IL]Node::Value(PhaseGVN*) still handles that by looking through casts.
* So we must deal with that as well.
*/
if (use->is_ConstraintCast() || use_op == Op_ConvI2L) {
auto is_boundary = [](Node* n){ return !n->is_ConstraintCast() && n->Opcode() != Op_ConvI2L; };
auto push_and_to_worklist = [&worklist](Node* n){
if (n->Opcode() == Op_AndL || n->Opcode() == Op_AndI) {
worklist.push(n);
}
};
use->visit_uses(push_and_to_worklist, is_boundary);
}
}
/**
* 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:
case Op_UDivI:
case Op_UModI: {
// 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:
case Op_UDivL:
case Op_UModL: {
// 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);
Unique_Node_List worklist_revisit(&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());
// This is the meat of CCP: pull from worklist; compute new value; push changes out.
// Do the first round. Since all initial types are TOP, this will visit all alive nodes.
while (worklist.size() != 0) {
Node* n = fetch_next_node(worklist);
DEBUG_ONLY(worklist_verify.push(n);)
if (needs_revisit(n)) {
worklist_revisit.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);
}
analyze_step(worklist, n);
}
// More rounds to catch updates far in the graph.
// Revisit nodes that might be able to refine their types at the end of the round.
// If so, process these nodes. If there is remaining work, start another round.
do {
while (worklist.size() != 0) {
Node* n = fetch_next_node(worklist);
analyze_step(worklist, n);
}
for (uint t = 0; t < worklist_revisit.size(); t++) {
Node* n = worklist_revisit.at(t);
analyze_step(worklist, n);
}
} while (worklist.size() != 0);
DEBUG_ONLY(verify_analyze(worklist_verify);)
}
void PhaseCCP::analyze_step(Unique_Node_List& worklist, Node* 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);
}
if (KillPathsReachableByDeadTypeNode && n->is_Type() && new_type == Type::TOP) {
// Keep track of Type nodes to kill CFG paths that use Type
// nodes that become dead.
_maybe_top_type_nodes.push(n);
}
}
// Some nodes can refine their types due to type change somewhere deep
// in the graph. We will need to revisit them before claiming convergence.
// Add nodes here if particular *Node::Value is doing deep graph traversals
// not handled by PhaseCCP::push_more_uses().
bool PhaseCCP::needs_revisit(Node* n) const {
// LoadNode performs deep traversals. Load is not notified for changes far away.
if (n->is_Load()) {
return true;
}
// 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()) {
return true;
}
return false;
}
#ifdef ASSERT
// For every node n on verify list, check if type(n) == n->Value()
// Note for CCP the non-convergence can lead to unsound analysis and mis-compilation.
// Therefore, we are verifying Value convergence strictly.
void PhaseCCP::verify_analyze(Unique_Node_List& worklist_verify) {
bool failure = false;
while (worklist_verify.size()) {
Node* n = worklist_verify.pop();
failure |= verify_Value_for(n, /* strict = */ true);
}
// 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 in the same round,
// or that they are added in PhaseCCP::needs_revisit() so that analysis revisits
// them at the end of the round.
assert(!failure, "PhaseCCP not at fixpoint: analysis result may be unsound.");
}
#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);
push_bool_with_cmpu_and_mask(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);
const uint cmpu_opcode = cmpu->Opcode();
if (cmpu_opcode == Op_CmpU || cmpu_opcode == Op_CmpU3) {
// Got a CmpU or CmpU3 which might need the new type information from node n.
push_if_not_bottom_type(worklist, cmpu);
}
}
}
}
// Look for the following shape, which can be optimized by BoolNode::Value_cmpu_and_mask() (i.e. corresponds to case
// (1b): "(m & x) <u (m + 1))".
// If any of the inputs on the level (%%) change, we need to revisit Bool because we could have prematurely found that
// the Bool is constant (i.e. case (1b) can be applied) which could become invalid with new type information during CCP.
//
// m x m 1 (%%)
// \ / \ /
// AndI AddI
// \ /
// CmpU
// |
// Bool
//
void PhaseCCP::push_bool_with_cmpu_and_mask(Unique_Node_List& worklist, const Node* use) const {
uint use_op = use->Opcode();
if (use_op != Op_AndI && (use_op != Op_AddI || use->in(2)->find_int_con(0) != 1)) {
// Not "m & x" or "m + 1"
return;
}
for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
Node* cmpu = use->fast_out(i);
if (cmpu->Opcode() == Op_CmpU) {
push_bool_matching_case1b(worklist, cmpu);
}
}
}
// Push any Bool below 'cmpu' that matches case (1b) of BoolNode::Value_cmpu_and_mask().
void PhaseCCP::push_bool_matching_case1b(Unique_Node_List& worklist, const Node* cmpu) const {
assert(cmpu->Opcode() == Op_CmpU, "must be");
for (DUIterator_Fast imax, i = cmpu->fast_outs(imax); i < imax; i++) {
Node* bol = cmpu->fast_out(i);
if (!bol->is_Bool() || bol->as_Bool()->_test._test != BoolTest::lt) {
// Not a Bool with "<u"
continue;
}
Node* andI = cmpu->in(1);
Node* addI = cmpu->in(2);
if (andI->Opcode() != Op_AndI || addI->Opcode() != Op_AddI || addI->in(2)->find_int_con(0) != 1) {
// Not "m & x" and "m + 1"
continue;
}
Node* m = addI->in(1);
if (m == andI->in(1) || m == andI->in(2)) {
// Is "m" shared? Matched (1b) and thus we revisit Bool.
push_if_not_bottom_type(worklist, bol);
}
}
}
// 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, or CON & 3 to zero if they are bitwise disjoint.
// Add the AndI/L nodes back to the worklist to re-apply Value() in case the value is now a constant or shift
// value changed.
void PhaseCCP::push_and(Unique_Node_List& worklist, const Node* parent, const Node* use) const {
const TypeInteger* parent_type = type(parent)->isa_integer(type(parent)->basic_type());
uint use_op = use->Opcode();
if (
// Pattern: parent (now constant) -> (ConstraintCast | ConvI2L)* -> And
(parent_type != nullptr && parent_type->is_con()) ||
// Pattern: parent -> LShift (use) -> (ConstraintCast | ConvI2L)* -> And
((use_op == Op_LShiftI || use_op == Op_LShiftL) && use->in(2) == parent)) {
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);
}
};
auto is_boundary = [](Node* n) {
return !(n->is_ConstraintCast() || n->Opcode() == Op_ConvI2L);
};
use->visit_uses(push_and_uses_to_worklist, is_boundary);
}
}
// 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;
if (KillPathsReachableByDeadTypeNode) {
for (uint i = 0; i < _maybe_top_type_nodes.size(); ++i) {
Node* type_node = _maybe_top_type_nodes.at(i);
if (type(type_node) == Type::TOP) {
ResourceMark rm;
type_node->as_Type()->make_paths_from_here_dead(this, nullptr, "ccp");
}
}
} else {
assert(_maybe_top_type_nodes.size() == 0, "we don't need type nodes");
}
// 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, &_root_and_safepoints);
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
add_users_to_worklist(n); // if ideal or identity optimizations depend on the input type, users need to be notified
}
// 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");
#ifdef ASSERT
if (igvn->hash_find(this) == this) {
tty->print_cr("Need to remove from hash before changing edges");
this->dump(1);
tty->print_cr("Set at i = %d", i);
n->dump();
assert(false, "Need to remove from hash before changing edges");
}
#endif
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 ) {
assert(_a == Compile::current()->comp_arena(), "Should be allocated in comp_arena");
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
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