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/*
* Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "gc/shared/barrierSet.hpp"
#include "gc/shared/c2/barrierSetC2.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
#include "oops/objArrayKlass.hpp"
#include "opto/addnode.hpp"
#include "opto/castnode.hpp"
#include "opto/cfgnode.hpp"
#include "opto/connode.hpp"
#include "opto/convertnode.hpp"
#include "opto/loopnode.hpp"
#include "opto/machnode.hpp"
#include "opto/movenode.hpp"
#include "opto/narrowptrnode.hpp"
#include "opto/mulnode.hpp"
#include "opto/phaseX.hpp"
#include "opto/regalloc.hpp"
#include "opto/regmask.hpp"
#include "opto/runtime.hpp"
#include "opto/subnode.hpp"
#include "opto/vectornode.hpp"
#include "utilities/vmError.hpp"
// Portions of code courtesy of Clifford Click
// Optimization - Graph Style
//=============================================================================
//------------------------------Value------------------------------------------
// Compute the type of the RegionNode.
const Type* RegionNode::Value(PhaseGVN* phase) const {
for( uint i=1; i<req(); ++i ) { // For all paths in
Node *n = in(i); // Get Control source
if( !n ) continue; // Missing inputs are TOP
if( phase->type(n) == Type::CONTROL )
return Type::CONTROL;
}
return Type::TOP; // All paths dead? Then so are we
}
//------------------------------Identity---------------------------------------
// Check for Region being Identity.
Node* RegionNode::Identity(PhaseGVN* phase) {
// Cannot have Region be an identity, even if it has only 1 input.
// Phi users cannot have their Region input folded away for them,
// since they need to select the proper data input
return this;
}
//------------------------------merge_region-----------------------------------
// If a Region flows into a Region, merge into one big happy merge. This is
// hard to do if there is stuff that has to happen
static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
return NULL;
Node *progress = NULL; // Progress flag
PhaseIterGVN *igvn = phase->is_IterGVN();
uint rreq = region->req();
for( uint i = 1; i < rreq; i++ ) {
Node *r = region->in(i);
if( r && r->Opcode() == Op_Region && // Found a region?
r->in(0) == r && // Not already collapsed?
r != region && // Avoid stupid situations
r->outcnt() == 2 ) { // Self user and 'region' user only?
assert(!r->as_Region()->has_phi(), "no phi users");
if( !progress ) { // No progress
if (region->has_phi()) {
return NULL; // Only flatten if no Phi users
// igvn->hash_delete( phi );
}
igvn->hash_delete( region );
progress = region; // Making progress
}
igvn->hash_delete( r );
// Append inputs to 'r' onto 'region'
for( uint j = 1; j < r->req(); j++ ) {
// Move an input from 'r' to 'region'
region->add_req(r->in(j));
r->set_req(j, phase->C->top());
// Update phis of 'region'
//for( uint k = 0; k < max; k++ ) {
// Node *phi = region->out(k);
// if( phi->is_Phi() ) {
// phi->add_req(phi->in(i));
// }
//}
rreq++; // One more input to Region
} // Found a region to merge into Region
igvn->_worklist.push(r);
// Clobber pointer to the now dead 'r'
region->set_req(i, phase->C->top());
}
}
return progress;
}
//--------------------------------has_phi--------------------------------------
// Helper function: Return any PhiNode that uses this region or NULL
PhiNode* RegionNode::has_phi() const {
for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
Node* phi = fast_out(i);
if (phi->is_Phi()) { // Check for Phi users
assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
return phi->as_Phi(); // this one is good enough
}
}
return NULL;
}
//-----------------------------has_unique_phi----------------------------------
// Helper function: Return the only PhiNode that uses this region or NULL
PhiNode* RegionNode::has_unique_phi() const {
// Check that only one use is a Phi
PhiNode* only_phi = NULL;
for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
Node* phi = fast_out(i);
if (phi->is_Phi()) { // Check for Phi users
assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
if (only_phi == NULL) {
only_phi = phi->as_Phi();
} else {
return NULL; // multiple phis
}
}
}
return only_phi;
}
//------------------------------check_phi_clipping-----------------------------
// Helper function for RegionNode's identification of FP clipping
// Check inputs to the Phi
static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
min = NULL;
max = NULL;
val = NULL;
min_idx = 0;
max_idx = 0;
val_idx = 0;
uint phi_max = phi->req();
if( phi_max == 4 ) {
for( uint j = 1; j < phi_max; ++j ) {
Node *n = phi->in(j);
int opcode = n->Opcode();
switch( opcode ) {
case Op_ConI:
{
if( min == NULL ) {
min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
min_idx = j;
} else {
max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
max_idx = j;
if( min->get_int() > max->get_int() ) {
// Swap min and max
ConNode *temp;
uint temp_idx;
temp = min; min = max; max = temp;
temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
}
}
}
break;
default:
{
val = n;
val_idx = j;
}
break;
}
}
}
return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
}
//------------------------------check_if_clipping------------------------------
// Helper function for RegionNode's identification of FP clipping
// Check that inputs to Region come from two IfNodes,
//
// If
// False True
// If |
// False True |
// | | |
// RegionNode_inputs
//
static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
top_if = NULL;
bot_if = NULL;
// Check control structure above RegionNode for (if ( if ) )
Node *in1 = region->in(1);
Node *in2 = region->in(2);
Node *in3 = region->in(3);
// Check that all inputs are projections
if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
Node *in10 = in1->in(0);
Node *in20 = in2->in(0);
Node *in30 = in3->in(0);
// Check that #1 and #2 are ifTrue and ifFalse from same If
if( in10 != NULL && in10->is_If() &&
in20 != NULL && in20->is_If() &&
in30 != NULL && in30->is_If() && in10 == in20 &&
(in1->Opcode() != in2->Opcode()) ) {
Node *in100 = in10->in(0);
Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
// Check that control for in10 comes from other branch of IF from in3
if( in1000 != NULL && in1000->is_If() &&
in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
// Control pattern checks
top_if = (IfNode*)in1000;
bot_if = (IfNode*)in10;
}
}
}
return (top_if != NULL);
}
//------------------------------check_convf2i_clipping-------------------------
// Helper function for RegionNode's identification of FP clipping
// Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
convf2i = NULL;
// Check for the RShiftNode
Node *rshift = phi->in(idx);
assert( rshift, "Previous checks ensure phi input is present");
if( rshift->Opcode() != Op_RShiftI ) { return false; }
// Check for the LShiftNode
Node *lshift = rshift->in(1);
assert( lshift, "Previous checks ensure phi input is present");
if( lshift->Opcode() != Op_LShiftI ) { return false; }
// Check for the ConvF2INode
Node *conv = lshift->in(1);
if( conv->Opcode() != Op_ConvF2I ) { return false; }
// Check that shift amounts are only to get sign bits set after F2I
jint max_cutoff = max->get_int();
jint min_cutoff = min->get_int();
jint left_shift = lshift->in(2)->get_int();
jint right_shift = rshift->in(2)->get_int();
jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
if( left_shift != right_shift ||
0 > left_shift || left_shift >= BitsPerJavaInteger ||
max_post_shift < max_cutoff ||
max_post_shift < -min_cutoff ) {
// Shifts are necessary but current transformation eliminates them
return false;
}
// OK to return the result of ConvF2I without shifting
convf2i = (ConvF2INode*)conv;
return true;
}
//------------------------------check_compare_clipping-------------------------
// Helper function for RegionNode's identification of FP clipping
static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
Node *i1 = iff->in(1);
if ( !i1->is_Bool() ) { return false; }
BoolNode *bool1 = i1->as_Bool();
if( less_than && bool1->_test._test != BoolTest::le ) { return false; }
else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
const Node *cmpF = bool1->in(1);
if( cmpF->Opcode() != Op_CmpF ) { return false; }
// Test that the float value being compared against
// is equivalent to the int value used as a limit
Node *nodef = cmpF->in(2);
if( nodef->Opcode() != Op_ConF ) { return false; }
jfloat conf = nodef->getf();
jint coni = limit->get_int();
if( ((int)conf) != coni ) { return false; }
input = cmpF->in(1);
return true;
}
//------------------------------is_unreachable_region--------------------------
// Check if the RegionNode is part of an unsafe loop and unreachable from root.
bool RegionNode::is_unreachable_region(const PhaseGVN* phase) {
Node* top = phase->C->top();
assert(req() == 2 || (req() == 3 && in(1) != NULL && in(2) == top), "sanity check arguments");
if (_is_unreachable_region) {
// Return cached result from previous evaluation which should still be valid
assert(is_unreachable_from_root(phase), "walk the graph again and check if its indeed unreachable");
return true;
}
// First, cut the simple case of fallthrough region when NONE of
// region's phis references itself directly or through a data node.
if (is_possible_unsafe_loop(phase)) {
// If we have a possible unsafe loop, check if the region node is actually unreachable from root.
if (is_unreachable_from_root(phase)) {
_is_unreachable_region = true;
return true;
}
}
return false;
}
bool RegionNode::is_possible_unsafe_loop(const PhaseGVN* phase) const {
uint max = outcnt();
uint i;
for (i = 0; i < max; i++) {
Node* n = raw_out(i);
if (n != NULL && n->is_Phi()) {
PhiNode* phi = n->as_Phi();
assert(phi->in(0) == this, "sanity check phi");
if (phi->outcnt() == 0) {
continue; // Safe case - no loops
}
if (phi->outcnt() == 1) {
Node* u = phi->raw_out(0);
// Skip if only one use is an other Phi or Call or Uncommon trap.
// It is safe to consider this case as fallthrough.
if (u != NULL && (u->is_Phi() || u->is_CFG())) {
continue;
}
}
// Check when phi references itself directly or through an other node.
if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe) {
break; // Found possible unsafe data loop.
}
}
}
if (i >= max) {
return false; // An unsafe case was NOT found - don't need graph walk.
}
return true;
}
bool RegionNode::is_unreachable_from_root(const PhaseGVN* phase) const {
ResourceMark rm;
Node_List nstack;
VectorSet visited;
// Mark all control nodes reachable from root outputs
Node* n = (Node*)phase->C->root();
nstack.push(n);
visited.set(n->_idx);
while (nstack.size() != 0) {
n = nstack.pop();
uint max = n->outcnt();
for (uint i = 0; i < max; i++) {
Node* m = n->raw_out(i);
if (m != NULL && m->is_CFG()) {
if (m == this) {
return false; // We reached the Region node - it is not dead.
}
if (!visited.test_set(m->_idx))
nstack.push(m);
}
}
}
return true; // The Region node is unreachable - it is dead.
}
bool RegionNode::try_clean_mem_phi(PhaseGVN *phase) {
// Incremental inlining + PhaseStringOpts sometimes produce:
//
// cmpP with 1 top input
// |
// If
// / \
// IfFalse IfTrue /- Some Node
// \ / / /
// Region / /-MergeMem
// \---Phi
//
//
// It's expected by PhaseStringOpts that the Region goes away and is
// replaced by If's control input but because there's still a Phi,
// the Region stays in the graph. The top input from the cmpP is
// propagated forward and a subgraph that is useful goes away. The
// code below replaces the Phi with the MergeMem so that the Region
// is simplified.
PhiNode* phi = has_unique_phi();
if (phi && phi->type() == Type::MEMORY && req() == 3 && phi->is_diamond_phi(true)) {
MergeMemNode* m = NULL;
assert(phi->req() == 3, "same as region");
for (uint i = 1; i < 3; ++i) {
Node *mem = phi->in(i);
if (mem && mem->is_MergeMem() && in(i)->outcnt() == 1) {
// Nothing is control-dependent on path #i except the region itself.
m = mem->as_MergeMem();
uint j = 3 - i;
Node* other = phi->in(j);
if (other && other == m->base_memory()) {
// m is a successor memory to other, and is not pinned inside the diamond, so push it out.
// This will allow the diamond to collapse completely.
phase->is_IterGVN()->replace_node(phi, m);
return true;
}
}
}
}
return false;
}
//------------------------------Ideal------------------------------------------
// Return a node which is more "ideal" than the current node. Must preserve
// the CFG, but we can still strip out dead paths.
Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy
assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
// Check for RegionNode with no Phi users and both inputs come from either
// arm of the same IF. If found, then the control-flow split is useless.
bool has_phis = false;
if (can_reshape) { // Need DU info to check for Phi users
has_phis = (has_phi() != NULL); // Cache result
if (has_phis && try_clean_mem_phi(phase)) {
has_phis = false;
}
if (!has_phis) { // No Phi users? Nothing merging?
for (uint i = 1; i < req()-1; i++) {
Node *if1 = in(i);
if( !if1 ) continue;
Node *iff = if1->in(0);
if( !iff || !iff->is_If() ) continue;
for( uint j=i+1; j<req(); j++ ) {
if( in(j) && in(j)->in(0) == iff &&
if1->Opcode() != in(j)->Opcode() ) {
// Add the IF Projections to the worklist. They (and the IF itself)
// will be eliminated if dead.
phase->is_IterGVN()->add_users_to_worklist(iff);
set_req(i, iff->in(0));// Skip around the useless IF diamond
set_req(j, NULL);
return this; // Record progress
}
}
}
}
}
// Remove TOP or NULL input paths. If only 1 input path remains, this Region
// degrades to a copy.
bool add_to_worklist = true;
bool modified = false;
int cnt = 0; // Count of values merging
DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
int del_it = 0; // The last input path we delete
// For all inputs...
for( uint i=1; i<req(); ++i ){// For all paths in
Node *n = in(i); // Get the input
if( n != NULL ) {
// Remove useless control copy inputs
if( n->is_Region() && n->as_Region()->is_copy() ) {
set_req(i, n->nonnull_req());
modified = true;
i--;
continue;
}
if( n->is_Proj() ) { // Remove useless rethrows
Node *call = n->in(0);
if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
set_req(i, call->in(0));
modified = true;
i--;
continue;
}
}
if( phase->type(n) == Type::TOP ) {
set_req_X(i, NULL, phase); // Ignore TOP inputs
modified = true;
i--;
continue;
}
cnt++; // One more value merging
} else if (can_reshape) { // Else found dead path with DU info
PhaseIterGVN *igvn = phase->is_IterGVN();
del_req(i); // Yank path from self
del_it = i;
uint max = outcnt();
DUIterator j;
bool progress = true;
while(progress) { // Need to establish property over all users
progress = false;
for (j = outs(); has_out(j); j++) {
Node *n = out(j);
if( n->req() != req() && n->is_Phi() ) {
assert( n->in(0) == this, "" );
igvn->hash_delete(n); // Yank from hash before hacking edges
n->set_req_X(i,NULL,igvn);// Correct DU info
n->del_req(i); // Yank path from Phis
if( max != outcnt() ) {
progress = true;
j = refresh_out_pos(j);
max = outcnt();
}
}
}
}
add_to_worklist = false;
phase->is_IterGVN()->add_users_to_worklist(this);
i--;
}
}
if (can_reshape && cnt == 1) {
// Is it dead loop?
// If it is LoopNopde it had 2 (+1 itself) inputs and
// one of them was cut. The loop is dead if it was EntryContol.
// Loop node may have only one input because entry path
// is removed in PhaseIdealLoop::Dominators().
assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
if ((this->is_Loop() && (del_it == LoopNode::EntryControl ||
(del_it == 0 && is_unreachable_region(phase)))) ||
(!this->is_Loop() && has_phis && is_unreachable_region(phase))) {
// This region and therefore all nodes on the input control path(s) are unreachable
// from root. To avoid incomplete removal of unreachable subgraphs, walk up the CFG
// and aggressively replace all nodes by top.
PhaseIterGVN* igvn = phase->is_IterGVN();
Node* top = phase->C->top();
ResourceMark rm;
Node_List nstack;
VectorSet visited;
nstack.push(this);
visited.set(_idx);
while (nstack.size() != 0) {
Node* n = nstack.pop();
for (uint i = 0; i < n->req(); ++i) {
Node* m = n->in(i);
assert(m != (Node*)phase->C->root(), "Should be unreachable from root");
if (m != NULL && m->is_CFG() && !visited.test_set(m->_idx)) {
nstack.push(m);
}
}
if (n->is_Region()) {
// Eagerly replace phis with top to avoid regionless phis.
n->set_req(0, NULL);
bool progress = true;
uint max = n->outcnt();
DUIterator j;
while (progress) {
progress = false;
for (j = n->outs(); n->has_out(j); j++) {
Node* u = n->out(j);
if (u->is_Phi()) {
igvn->replace_node(u, top);
if (max != n->outcnt()) {
progress = true;
j = n->refresh_out_pos(j);
max = n->outcnt();
}
}
}
}
}
igvn->replace_node(n, top);
}
return NULL;
}
}
if( cnt <= 1 ) { // Only 1 path in?
set_req(0, NULL); // Null control input for region copy
if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
// No inputs or all inputs are NULL.
return NULL;
} else if (can_reshape) { // Optimization phase - remove the node
PhaseIterGVN *igvn = phase->is_IterGVN();
// Strip mined (inner) loop is going away, remove outer loop.
if (is_CountedLoop() &&
as_Loop()->is_strip_mined()) {
Node* outer_sfpt = as_CountedLoop()->outer_safepoint();
Node* outer_out = as_CountedLoop()->outer_loop_exit();
if (outer_sfpt != NULL && outer_out != NULL) {
Node* in = outer_sfpt->in(0);
igvn->replace_node(outer_out, in);
LoopNode* outer = as_CountedLoop()->outer_loop();
igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top());
}
}
if (is_CountedLoop()) {
Node* opaq = as_CountedLoop()->is_canonical_loop_entry();
if (opaq != NULL) {
// This is not a loop anymore. No need to keep the Opaque1 node on the test that guards the loop as it won't be
// subject to further loop opts.
assert(opaq->Opcode() == Op_OpaqueZeroTripGuard, "");
igvn->replace_node(opaq, opaq->in(1));
}
}
Node *parent_ctrl;
if( cnt == 0 ) {
assert( req() == 1, "no inputs expected" );
// During IGVN phase such region will be subsumed by TOP node
// so region's phis will have TOP as control node.
// Kill phis here to avoid it.
// Also set other user's input to top.
parent_ctrl = phase->C->top();
} else {
// The fallthrough case since we already checked dead loops above.
parent_ctrl = in(1);
assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
assert(parent_ctrl != this, "Close dead loop");
}
if (add_to_worklist) {
igvn->add_users_to_worklist(this); // Check for further allowed opts
}
for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
Node* n = last_out(i);
igvn->hash_delete(n); // Remove from worklist before modifying edges
if (n->outcnt() == 0) {
int uses_found = n->replace_edge(this, phase->C->top(), igvn);
if (uses_found > 1) { // (--i) done at the end of the loop.
i -= (uses_found - 1);
}
continue;
}
if( n->is_Phi() ) { // Collapse all Phis
// Eagerly replace phis to avoid regionless phis.
Node* in;
if( cnt == 0 ) {
assert( n->req() == 1, "No data inputs expected" );
in = parent_ctrl; // replaced by top
} else {
assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" );
in = n->in(1); // replaced by unique input
if( n->as_Phi()->is_unsafe_data_reference(in) )
in = phase->C->top(); // replaced by top
}
igvn->replace_node(n, in);
}
else if( n->is_Region() ) { // Update all incoming edges
assert(n != this, "Must be removed from DefUse edges");
int uses_found = n->replace_edge(this, parent_ctrl, igvn);
if (uses_found > 1) { // (--i) done at the end of the loop.
i -= (uses_found - 1);
}
}
else {
assert(n->in(0) == this, "Expect RegionNode to be control parent");
n->set_req(0, parent_ctrl);
}
#ifdef ASSERT
for( uint k=0; k < n->req(); k++ ) {
assert(n->in(k) != this, "All uses of RegionNode should be gone");
}
#endif
}
// Remove the RegionNode itself from DefUse info
igvn->remove_dead_node(this);
return NULL;
}
return this; // Record progress
}
// If a Region flows into a Region, merge into one big happy merge.
if (can_reshape) {
Node *m = merge_region(this, phase);
if (m != NULL) return m;
}
// Check if this region is the root of a clipping idiom on floats
if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
// Check that only one use is a Phi and that it simplifies to two constants +
PhiNode* phi = has_unique_phi();
if (phi != NULL) { // One Phi user
// Check inputs to the Phi
ConNode *min;
ConNode *max;
Node *val;
uint min_idx;
uint max_idx;
uint val_idx;
if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) {
IfNode *top_if;
IfNode *bot_if;
if( check_if_clipping( this, bot_if, top_if ) ) {
// Control pattern checks, now verify compares
Node *top_in = NULL; // value being compared against
Node *bot_in = NULL;
if( check_compare_clipping( true, bot_if, min, bot_in ) &&
check_compare_clipping( false, top_if, max, top_in ) ) {
if( bot_in == top_in ) {
PhaseIterGVN *gvn = phase->is_IterGVN();
assert( gvn != NULL, "Only had DefUse info in IterGVN");
// Only remaining check is that bot_in == top_in == (Phi's val + mods)
// Check for the ConvF2INode
ConvF2INode *convf2i;
if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
convf2i->in(1) == bot_in ) {
// Matched pattern, including LShiftI; RShiftI, replace with integer compares
// max test
Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
// min test
cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
// update input edges to region node
set_req_X( min_idx, if_min, gvn );
set_req_X( max_idx, if_max, gvn );
set_req_X( val_idx, ifF, gvn );
// remove unnecessary 'LShiftI; RShiftI' idiom
gvn->hash_delete(phi);
phi->set_req_X( val_idx, convf2i, gvn );
gvn->hash_find_insert(phi);
// Return transformed region node
return this;
}
}
}
}
}
}
}
if (can_reshape) {
modified |= optimize_trichotomy(phase->is_IterGVN());
}
return modified ? this : NULL;
}
//------------------------------optimize_trichotomy--------------------------
// Optimize nested comparisons of the following kind:
//
// int compare(int a, int b) {
// return (a < b) ? -1 : (a == b) ? 0 : 1;
// }
//
// Shape 1:
// if (compare(a, b) == 1) { ... } -> if (a > b) { ... }
//
// Shape 2:
// if (compare(a, b) == 0) { ... } -> if (a == b) { ... }
//
// Above code leads to the following IR shapes where both Ifs compare the
// same value and two out of three region inputs idx1 and idx2 map to
// the same value and control flow.
//
// (1) If (2) If
// / \ / \
// Proj Proj Proj Proj
// | \ | \
// | If | If If
// | / \ | / \ / \
// | Proj Proj | Proj Proj ==> Proj Proj
// | / / \ | / | /
// Region / \ | / | /
// \ / \ | / | /
// Region Region Region
//
// The method returns true if 'this' is modified and false otherwise.
bool RegionNode::optimize_trichotomy(PhaseIterGVN* igvn) {
int idx1 = 1, idx2 = 2;
Node* region = NULL;
if (req() == 3 && in(1) != NULL && in(2) != NULL) {
// Shape 1: Check if one of the inputs is a region that merges two control
// inputs and has no other users (especially no Phi users).
region = in(1)->isa_Region() ? in(1) : in(2)->isa_Region();
if (region == NULL || region->outcnt() != 2 || region->req() != 3) {
return false; // No suitable region input found
}
} else if (req() == 4) {
// Shape 2: Check if two control inputs map to the same value of the unique phi
// user and treat these as if they would come from another region (shape (1)).
PhiNode* phi = has_unique_phi();
if (phi == NULL) {
return false; // No unique phi user
}
if (phi->in(idx1) != phi->in(idx2)) {
idx2 = 3;
if (phi->in(idx1) != phi->in(idx2)) {
idx1 = 2;
if (phi->in(idx1) != phi->in(idx2)) {
return false; // No equal phi inputs found
}
}
}
assert(phi->in(idx1) == phi->in(idx2), "must be"); // Region is merging same value
region = this;
}
if (region == NULL || region->in(idx1) == NULL || region->in(idx2) == NULL) {
return false; // Region does not merge two control inputs
}
// At this point we know that region->in(idx1) and region->(idx2) map to the same
// value and control flow. Now search for ifs that feed into these region inputs.
ProjNode* proj1 = region->in(idx1)->isa_Proj();
ProjNode* proj2 = region->in(idx2)->isa_Proj();
if (proj1 == NULL || proj1->outcnt() != 1 ||
proj2 == NULL || proj2->outcnt() != 1) {
return false; // No projection inputs with region as unique user found
}
assert(proj1 != proj2, "should be different projections");
IfNode* iff1 = proj1->in(0)->isa_If();
IfNode* iff2 = proj2->in(0)->isa_If();
if (iff1 == NULL || iff1->outcnt() != 2 ||
iff2 == NULL || iff2->outcnt() != 2) {
return false; // No ifs found
}
if (iff1 == iff2) {
igvn->add_users_to_worklist(iff1); // Make sure dead if is eliminated
igvn->replace_input_of(region, idx1, iff1->in(0));
igvn->replace_input_of(region, idx2, igvn->C->top());
return (region == this); // Remove useless if (both projections map to the same control/value)
}
BoolNode* bol1 = iff1->in(1)->isa_Bool();
BoolNode* bol2 = iff2->in(1)->isa_Bool();
if (bol1 == NULL || bol2 == NULL) {
return false; // No bool inputs found
}
Node* cmp1 = bol1->in(1);
Node* cmp2 = bol2->in(1);
bool commute = false;
if (!cmp1->is_Cmp() || !cmp2->is_Cmp()) {
return false; // No comparison
} else if (cmp1->Opcode() == Op_CmpF || cmp1->Opcode() == Op_CmpD ||
cmp2->Opcode() == Op_CmpF || cmp2->Opcode() == Op_CmpD ||
cmp1->Opcode() == Op_CmpP || cmp1->Opcode() == Op_CmpN ||
cmp2->Opcode() == Op_CmpP || cmp2->Opcode() == Op_CmpN ||
cmp1->is_SubTypeCheck() || cmp2->is_SubTypeCheck()) {
// Floats and pointers don't exactly obey trichotomy. To be on the safe side, don't transform their tests.
// SubTypeCheck is not commutative
return false;
} else if (cmp1 != cmp2) {
if (cmp1->in(1) == cmp2->in(2) &&
cmp1->in(2) == cmp2->in(1)) {
commute = true; // Same but swapped inputs, commute the test
} else {
return false; // Ifs are not comparing the same values
}
}
proj1 = proj1->other_if_proj();
proj2 = proj2->other_if_proj();
if (!((proj1->unique_ctrl_out_or_null() == iff2 &&
proj2->unique_ctrl_out_or_null() == this) ||
(proj2->unique_ctrl_out_or_null() == iff1 &&
proj1->unique_ctrl_out_or_null() == this))) {
return false; // Ifs are not connected through other projs
}
// Found 'iff -> proj -> iff -> proj -> this' shape where all other projs are merged
// through 'region' and map to the same value. Merge the boolean tests and replace
// the ifs by a single comparison.
BoolTest test1 = (proj1->_con == 1) ? bol1->_test : bol1->_test.negate();
BoolTest test2 = (proj2->_con == 1) ? bol2->_test : bol2->_test.negate();
test1 = commute ? test1.commute() : test1;
// After possibly commuting test1, if we can merge test1 & test2, then proj2/iff2/bol2 are the nodes to refine.
BoolTest::mask res = test1.merge(test2);
if (res == BoolTest::illegal) {
return false; // Unable to merge tests
}
// Adjust iff1 to always pass (only iff2 will remain)
igvn->replace_input_of(iff1, 1, igvn->intcon(proj1->_con));
if (res == BoolTest::never) {
// Merged test is always false, adjust iff2 to always fail
igvn->replace_input_of(iff2, 1, igvn->intcon(1 - proj2->_con));
} else {
// Replace bool input of iff2 with merged test
BoolNode* new_bol = new BoolNode(bol2->in(1), res);
igvn->replace_input_of(iff2, 1, igvn->transform((proj2->_con == 1) ? new_bol : new_bol->negate(igvn)));
if (new_bol->outcnt() == 0) {
igvn->remove_dead_node(new_bol);
}
}
return false;
}
const RegMask &RegionNode::out_RegMask() const {
return RegMask::Empty;
}
// Find the one non-null required input. RegionNode only
Node *Node::nonnull_req() const {
assert( is_Region(), "" );
for( uint i = 1; i < _cnt; i++ )
if( in(i) )
return in(i);
ShouldNotReachHere();
return NULL;
}
//=============================================================================
// note that these functions assume that the _adr_type field is flattened
uint PhiNode::hash() const {
const Type* at = _adr_type;
return TypeNode::hash() + (at ? at->hash() : 0);
}
bool PhiNode::cmp( const Node &n ) const {
return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
}
static inline
const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
if (at == NULL || at == TypePtr::BOTTOM) return at;
return Compile::current()->alias_type(at)->adr_type();
}
//----------------------------make---------------------------------------------
// create a new phi with edges matching r and set (initially) to x
PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
uint preds = r->req(); // Number of predecessor paths
assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
PhiNode* p = new PhiNode(r, t, at);
for (uint j = 1; j < preds; j++) {
// Fill in all inputs, except those which the region does not yet have
if (r->in(j) != NULL)
p->init_req(j, x);
}
return p;
}
PhiNode* PhiNode::make(Node* r, Node* x) {
const Type* t = x->bottom_type();
const TypePtr* at = NULL;
if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
return make(r, x, t, at);
}
PhiNode* PhiNode::make_blank(Node* r, Node* x) {
const Type* t = x->bottom_type();
const TypePtr* at = NULL;
if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type());
return new PhiNode(r, t, at);
}
//------------------------slice_memory-----------------------------------------
// create a new phi with narrowed memory type
PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
PhiNode* mem = (PhiNode*) clone();
*(const TypePtr**)&mem->_adr_type = adr_type;
// convert self-loops, or else we get a bad graph
for (uint i = 1; i < req(); i++) {
if ((const Node*)in(i) == this) mem->set_req(i, mem);
}
mem->verify_adr_type();
return mem;
}
//------------------------split_out_instance-----------------------------------
// Split out an instance type from a bottom phi.
PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
const TypeOopPtr *t_oop = at->isa_oopptr();
assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
// Check if an appropriate node already exists.
Node *region = in(0);
for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
Node* use = region->fast_out(k);
if( use->is_Phi()) {
PhiNode *phi2 = use->as_Phi();
if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
return phi2;
}
}
}
Compile *C = igvn->C;
Arena *a = Thread::current()->resource_area();
Node_Array node_map = new Node_Array(a);
Node_Stack stack(a, C->live_nodes() >> 4);
PhiNode *nphi = slice_memory(at);
igvn->register_new_node_with_optimizer( nphi );
node_map.map(_idx, nphi);
stack.push((Node *)this, 1);
while(!stack.is_empty()) {
PhiNode *ophi = stack.node()->as_Phi();
uint i = stack.index();
assert(i >= 1, "not control edge");
stack.pop();
nphi = node_map[ophi->_idx]->as_Phi();
for (; i < ophi->req(); i++) {
Node *in = ophi->in(i);
if (in == NULL || igvn->type(in) == Type::TOP)
continue;
Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
opt = node_map[optphi->_idx];
if (opt == NULL) {
stack.push(ophi, i);
nphi = optphi->slice_memory(at);
igvn->register_new_node_with_optimizer( nphi );
node_map.map(optphi->_idx, nphi);
ophi = optphi;
i = 0; // will get incremented at top of loop
continue;
}
}
nphi->set_req(i, opt);
}
}
return nphi;
}
//------------------------verify_adr_type--------------------------------------
#ifdef ASSERT
void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
if (visited.test_set(_idx)) return; //already visited
// recheck constructor invariants:
verify_adr_type(false);
// recheck local phi/phi consistency:
assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
"adr_type must be consistent across phi nest");
// walk around
for (uint i = 1; i < req(); i++) {
Node* n = in(i);
if (n == NULL) continue;
const Node* np = in(i);
if (np->is_Phi()) {
np->as_Phi()->verify_adr_type(visited, at);
} else if (n->bottom_type() == Type::TOP
|| (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
// ignore top inputs
} else {
const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
// recheck phi/non-phi consistency at leaves:
assert((nat != NULL) == (at != NULL), "");
assert(nat == at || nat == TypePtr::BOTTOM,
"adr_type must be consistent at leaves of phi nest");
}
}
}
// Verify a whole nest of phis rooted at this one.
void PhiNode::verify_adr_type(bool recursive) const {
if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
if (Node::in_dump()) return; // muzzle asserts when printing
assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
if (!VerifyAliases) return; // verify thoroughly only if requested
assert(_adr_type == flatten_phi_adr_type(_adr_type),
"Phi::adr_type must be pre-normalized");
if (recursive) {
VectorSet visited;
verify_adr_type(visited, _adr_type);
}
}
#endif
//------------------------------Value------------------------------------------
// Compute the type of the PhiNode
const Type* PhiNode::Value(PhaseGVN* phase) const {
Node *r = in(0); // RegionNode
if( !r ) // Copy or dead
return in(1) ? phase->type(in(1)) : Type::TOP;
// Note: During parsing, phis are often transformed before their regions.
// This means we have to use type_or_null to defend against untyped regions.
if( phase->type_or_null(r) == Type::TOP ) // Dead code?
return Type::TOP;
// Check for trip-counted loop. If so, be smarter.
BaseCountedLoopNode* l = r->is_BaseCountedLoop() ? r->as_BaseCountedLoop() : NULL;
if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
// protect against init_trip() or limit() returning NULL
if (l->can_be_counted_loop(phase)) {
const Node* init = l->init_trip();
const Node* limit = l->limit();
const Node* stride = l->stride();
if (init != NULL && limit != NULL && stride != NULL) {
const TypeInteger* lo = phase->type(init)->isa_integer(l->bt());
const TypeInteger* hi = phase->type(limit)->isa_integer(l->bt());
const TypeInteger* stride_t = phase->type(stride)->isa_integer(l->bt());
if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here
assert(stride_t->is_con(), "bad stride type");
BoolTest::mask bt = l->loopexit()->test_trip();
// If the loop exit condition is "not equal", the condition
// would not trigger if init > limit (if stride > 0) or if
// init < limit if (stride > 0) so we can't deduce bounds
// for the iv from the exit condition.
if (bt != BoolTest::ne) {
jlong stride_con = stride_t->get_con_as_long(l->bt());
if (stride_con < 0) { // Down-counter loop
swap(lo, hi);
jlong iv_range_lower_limit = lo->lo_as_long();
// Prevent overflow when adding one below
if (iv_range_lower_limit < max_signed_integer(l->bt())) {
// The loop exit condition is: iv + stride > limit (iv is this Phi). So the loop iterates until
// iv + stride <= limit
// We know that: limit >= lo->lo_as_long() and stride <= -1
// So when the loop exits, iv has to be at most lo->lo_as_long() + 1
iv_range_lower_limit += 1; // lo is after decrement
// Exact bounds for the phi can be computed when ABS(stride) greater than 1 if bounds are constant.
if (lo->is_con() && hi->is_con() && hi->lo_as_long() > lo->hi_as_long() && stride_con != -1) {
julong uhi = static_cast<julong>(hi->lo_as_long());
julong ulo = static_cast<julong>(lo->hi_as_long());
julong diff = ((uhi - ulo - 1) / (-stride_con)) * (-stride_con);
julong ufirst = hi->lo_as_long() - diff;
iv_range_lower_limit = reinterpret_cast<jlong &>(ufirst);
assert(iv_range_lower_limit >= lo->lo_as_long() + 1, "should end up with narrower range");
}
}
return TypeInteger::make(MIN2(iv_range_lower_limit, hi->lo_as_long()), hi->hi_as_long(), 3, l->bt())->filter_speculative(_type);
} else if (stride_con >= 0) {
jlong iv_range_upper_limit = hi->hi_as_long();
// Prevent overflow when subtracting one below
if (iv_range_upper_limit > min_signed_integer(l->bt())) {
// The loop exit condition is: iv + stride < limit (iv is this Phi). So the loop iterates until
// iv + stride >= limit
// We know that: limit <= hi->hi_as_long() and stride >= 1
// So when the loop exits, iv has to be at most hi->hi_as_long() - 1
iv_range_upper_limit -= 1;
// Exact bounds for the phi can be computed when ABS(stride) greater than 1 if bounds are constant.
if (lo->is_con() && hi->is_con() && hi->lo_as_long() > lo->hi_as_long() && stride_con != 1) {
julong uhi = static_cast<julong>(hi->lo_as_long());
julong ulo = static_cast<julong>(lo->hi_as_long());
julong diff = ((uhi - ulo - 1) / stride_con) * stride_con;
julong ulast = lo->hi_as_long() + diff;
iv_range_upper_limit = reinterpret_cast<jlong &>(ulast);
assert(iv_range_upper_limit <= hi->hi_as_long() - 1, "should end up with narrower range");
}
}
return TypeInteger::make(lo->lo_as_long(), MAX2(lo->hi_as_long(), iv_range_upper_limit), 3, l->bt())->filter_speculative(_type);
}
}
}
}
} else if (l->in(LoopNode::LoopBackControl) != NULL &&
in(LoopNode::EntryControl) != NULL &&
phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
// During CCP, if we saturate the type of a counted loop's Phi
// before the special code for counted loop above has a chance
// to run (that is as long as the type of the backedge's control
// is top), we might end up with non monotonic types
return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type);
}
}
// Until we have harmony between classes and interfaces in the type
// lattice, we must tread carefully around phis which implicitly
// convert the one to the other.
const TypePtr* ttp = _type->make_ptr();
const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
const TypeInstKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_instklassptr() : NULL;
bool is_intf = false;
if (ttip != NULL) {
if (ttip->is_interface())
is_intf = true;
}
if (ttkp != NULL) {
if (ttkp->is_interface())
is_intf = true;
}
// Default case: merge all inputs
const Type *t = Type::TOP; // Merged type starting value
for (uint i = 1; i < req(); ++i) {// For all paths in
// Reachable control path?
if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
const Type* ti = phase->type(in(i));
// We assume that each input of an interface-valued Phi is a true
// subtype of that interface. This might not be true of the meet
// of all the input types. The lattice is not distributive in
// such cases. Ward off asserts in type.cpp by refusing to do
// meets between interfaces and proper classes.
const TypePtr* tip = ti->make_ptr();
const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
if (tiip) {
bool ti_is_intf = false;
if (tiip->is_interface())
ti_is_intf = true;
if (is_intf != ti_is_intf)
{ t = _type; break; }
}
t = t->meet_speculative(ti);
}
}
// The worst-case type (from ciTypeFlow) should be consistent with "t".
// That is, we expect that "t->higher_equal(_type)" holds true.
// There are various exceptions:
// - Inputs which are phis might in fact be widened unnecessarily.
// For example, an input might be a widened int while the phi is a short.
// - Inputs might be BotPtrs but this phi is dependent on a null check,
// and postCCP has removed the cast which encodes the result of the check.
// - The type of this phi is an interface, and the inputs are classes.
// - Value calls on inputs might produce fuzzy results.
// (Occurrences of this case suggest improvements to Value methods.)
//
// It is not possible to see Type::BOTTOM values as phi inputs,
// because the ciTypeFlow pre-pass produces verifier-quality types.
const Type* ft = t->filter_speculative(_type); // Worst case type
#ifdef ASSERT
// The following logic has been moved into TypeOopPtr::filter.
const Type* jt = t->join_speculative(_type);
if (jt->empty()) { // Emptied out???
// Check for evil case of 't' being a class and '_type' expecting an
// interface. This can happen because the bytecodes do not contain
// enough type info to distinguish a Java-level interface variable
// from a Java-level object variable. If we meet 2 classes which
// both implement interface I, but their meet is at 'j/l/O' which
// doesn't implement I, we have no way to tell if the result should
// be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows
// into a Phi which "knows" it's an Interface type we'll have to
// uplift the type.
if (!t->empty() && ttip && ttip->is_interface()) {
assert(ft == _type, ""); // Uplift to interface
} else if (!t->empty() && ttkp && ttkp->is_interface()) {
assert(ft == _type, ""); // Uplift to interface
} else {
// We also have to handle 'evil cases' of interface- vs. class-arrays
Type::get_arrays_base_elements(jt, _type, NULL, &ttip);
if (!t->empty() && ttip != NULL && ttip->is_interface()) {
assert(ft == _type, ""); // Uplift to array of interface
} else {
// Otherwise it's something stupid like non-overlapping int ranges
// found on dying counted loops.
assert(ft == Type::TOP, ""); // Canonical empty value
}
}
}
else {
// If we have an interface-typed Phi and we narrow to a class type, the join
// should report back the class. However, if we have a J/L/Object
// class-typed Phi and an interface flows in, it's possible that the meet &
// join report an interface back out. This isn't possible but happens
// because the type system doesn't interact well with interfaces.
const TypePtr *jtp = jt->make_ptr();
const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
const TypeInstKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_instklassptr() : NULL;
if (jtip && ttip) {
if (jtip->is_interface() &&
!ttip->is_interface()) {
assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
jt = ft;
}
}
if (jtkp && ttkp) {
if (jtkp->is_interface() &&
!jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
ttkp->is_loaded() && !ttkp->is_interface()) {
assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
jt = ft;
}
}
if (jt != ft && jt->base() == ft->base()) {
if (jt->isa_int() &&
jt->is_int()->_lo == ft->is_int()->_lo &&
jt->is_int()->_hi == ft->is_int()->_hi)
jt = ft;
if (jt->isa_long() &&
jt->is_long()->_lo == ft->is_long()->_lo &&
jt->is_long()->_hi == ft->is_long()->_hi)
jt = ft;
}
if (jt != ft) {
tty->print("merge type: "); t->dump(); tty->cr();
tty->print("kill type: "); _type->dump(); tty->cr();
tty->print("join type: "); jt->dump(); tty->cr();
tty->print("filter type: "); ft->dump(); tty->cr();
}
assert(jt == ft, "");
}
#endif //ASSERT
// Deal with conversion problems found in data loops.
ft = phase->saturate(ft, phase->type_or_null(this), _type);
return ft;
}
//------------------------------is_diamond_phi---------------------------------
// Does this Phi represent a simple well-shaped diamond merge? Return the
// index of the true path or 0 otherwise.
// If check_control_only is true, do not inspect the If node at the
// top, and return -1 (not an edge number) on success.
int PhiNode::is_diamond_phi(bool check_control_only) const {
// Check for a 2-path merge
Node *region = in(0);
if( !region ) return 0;
if( region->req() != 3 ) return 0;
if( req() != 3 ) return 0;
// Check that both paths come from the same If
Node *ifp1 = region->in(1);
Node *ifp2 = region->in(2);
if( !ifp1 || !ifp2 ) return 0;
Node *iff = ifp1->in(0);
if( !iff || !iff->is_If() ) return 0;
if( iff != ifp2->in(0) ) return 0;
if (check_control_only) return -1;
// Check for a proper bool/cmp
const Node *b = iff->in(1);
if( !b->is_Bool() ) return 0;
const Node *cmp = b->in(1);
if( !cmp->is_Cmp() ) return 0;
// Check for branching opposite expected
if( ifp2->Opcode() == Op_IfTrue ) {
assert( ifp1->Opcode() == Op_IfFalse, "" );
return 2;
} else {
assert( ifp1->Opcode() == Op_IfTrue, "" );
return 1;
}
}
//----------------------------check_cmove_id-----------------------------------
// Check for CMove'ing a constant after comparing against the constant.
// Happens all the time now, since if we compare equality vs a constant in
// the parser, we "know" the variable is constant on one path and we force
// it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
// conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more
// general in that we don't need constants. Since CMove's are only inserted
// in very special circumstances, we do it here on generic Phi's.
Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
assert(true_path !=0, "only diamond shape graph expected");
// is_diamond_phi() has guaranteed the correctness of the nodes sequence:
// phi->region->if_proj->ifnode->bool->cmp
Node* region = in(0);
Node* iff = region->in(1)->in(0);
BoolNode* b = iff->in(1)->as_Bool();
Node* cmp = b->in(1);
Node* tval = in(true_path);
Node* fval = in(3-true_path);
Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
if (id == NULL)
return NULL;
// Either value might be a cast that depends on a branch of 'iff'.
// Since the 'id' value will float free of the diamond, either
// decast or return failure.
Node* ctl = id->in(0);
if (ctl != NULL && ctl->in(0) == iff) {
if (id->is_ConstraintCast()) {
return id->in(1);
} else {
// Don't know how to disentangle this value.
return NULL;
}
}
return id;
}
//------------------------------Identity---------------------------------------
// Check for Region being Identity.
Node* PhiNode::Identity(PhaseGVN* phase) {
// Check for no merging going on
// (There used to be special-case code here when this->region->is_Loop.
// It would check for a tributary phi on the backedge that the main phi
// trivially, perhaps with a single cast. The unique_input method
// does all this and more, by reducing such tributaries to 'this'.)
Node* uin = unique_input(phase, false);
if (uin != NULL) {
return uin;
}
int true_path = is_diamond_phi();
// Delay CMove'ing identity if Ideal has not had the chance to handle unsafe cases, yet.
if (true_path != 0 && !(phase->is_IterGVN() && wait_for_region_igvn(phase))) {
Node* id = is_cmove_id(phase, true_path);
if (id != NULL) {
return id;
}
}
// Looking for phis with identical inputs. If we find one that has
// type TypePtr::BOTTOM, replace the current phi with the bottom phi.
if (phase->is_IterGVN() && type() == Type::MEMORY && adr_type() !=
TypePtr::BOTTOM && !adr_type()->is_known_instance()) {
uint phi_len = req();
Node* phi_reg = region();
for (DUIterator_Fast imax, i = phi_reg->fast_outs(imax); i < imax; i++) {
Node* u = phi_reg->fast_out(i);
if (u->is_Phi() && u->as_Phi()->type() == Type::MEMORY &&
u->adr_type() == TypePtr::BOTTOM && u->in(0) == phi_reg &&
u->req() == phi_len) {
for (uint j = 1; j < phi_len; j++) {
if (in(j) != u->in(j)) {
u = NULL;
break;
}
}
if (u != NULL) {
return u;
}
}
}
}
return this; // No identity
}
//-----------------------------unique_input------------------------------------
// Find the unique value, discounting top, self-loops, and casts.
// Return top if there are no inputs, and self if there are multiple.
Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) {
// 1) One unique direct input,
// or if uncast is true:
// 2) some of the inputs have an intervening ConstraintCast
// 3) an input is a self loop
//
// 1) input or 2) input or 3) input __
// / \ / \ \ / \
// \ / | cast phi cast
// phi \ / / \ /
// phi / --
Node* r = in(0); // RegionNode
Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed)
for (uint i = 1, cnt = req(); i < cnt; ++i) {
Node* rc = r->in(i);
if (rc == NULL || phase->type(rc) == Type::TOP)
continue; // ignore unreachable control path
Node* n = in(i);
if (n == NULL)
continue;
Node* un = n;
if (uncast) {
#ifdef ASSERT
Node* m = un->uncast();
#endif
while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) {
Node* next = un->in(1);
if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
// risk exposing raw ptr at safepoint
break;
}
un = next;
}
assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
}
if (un == NULL || un == this || phase->type(un) == Type::TOP) {
continue; // ignore if top, or in(i) and "this" are in a data cycle
}
// Check for a unique input (maybe uncasted)
if (input == NULL) {
input = un;
} else if (input != un) {
input = NodeSentinel; // no unique input
}
}
if (input == NULL) {
return phase->C->top(); // no inputs
}
if (input != NodeSentinel) {
return input; // one unique direct input
}
// Nothing.
return NULL;
}
//------------------------------is_x2logic-------------------------------------
// Check for simple convert-to-boolean pattern
// If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
// Convert Phi to an ConvIB.
static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
assert(true_path !=0, "only diamond shape graph expected");
// Convert the true/false index into an expected 0/1 return.
// Map 2->0 and 1->1.
int flipped = 2-true_path;
// is_diamond_phi() has guaranteed the correctness of the nodes sequence:
// phi->region->if_proj->ifnode->bool->cmp
Node *region = phi->in(0);
Node *iff = region->in(1)->in(0);
BoolNode *b = (BoolNode*)iff->in(1);
const CmpNode *cmp = (CmpNode*)b->in(1);
Node *zero = phi->in(1);
Node *one = phi->in(2);
const Type *tzero = phase->type( zero );
const Type *tone = phase->type( one );
// Check for compare vs 0
const Type *tcmp = phase->type(cmp->in(2));
if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
// Allow cmp-vs-1 if the other input is bounded by 0-1
if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
return NULL;
flipped = 1-flipped; // Test is vs 1 instead of 0!
}
// Check for setting zero/one opposite expected
if( tzero == TypeInt::ZERO ) {
if( tone == TypeInt::ONE ) {
} else return NULL;
} else if( tzero == TypeInt::ONE ) {
if( tone == TypeInt::ZERO ) {
flipped = 1-flipped;
} else return NULL;
} else return NULL;
// Check for boolean test backwards
if( b->_test._test == BoolTest::ne ) {
} else if( b->_test._test == BoolTest::eq ) {
flipped = 1-flipped;
} else return NULL;
// Build int->bool conversion
Node *n = new Conv2BNode(cmp->in(1));
if( flipped )
n = new XorINode( phase->transform(n), phase->intcon(1) );
return n;
}
//------------------------------is_cond_add------------------------------------
// Check for simple conditional add pattern: "(P < Q) ? X+Y : X;"
// To be profitable the control flow has to disappear; there can be no other
// values merging here. We replace the test-and-branch with:
// "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by
// moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
// Then convert Y to 0-or-Y and finally add.
// This is a key transform for SpecJava _201_compress.
static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
assert(true_path !=0, "only diamond shape graph expected");
// is_diamond_phi() has guaranteed the correctness of the nodes sequence:
// phi->region->if_proj->ifnode->bool->cmp
RegionNode *region = (RegionNode*)phi->in(0);
Node *iff = region->in(1)->in(0);
BoolNode* b = iff->in(1)->as_Bool();
const CmpNode *cmp = (CmpNode*)b->in(1);
// Make sure only merging this one phi here
if (region->has_unique_phi() != phi) return NULL;
// Make sure each arm of the diamond has exactly one output, which we assume
// is the region. Otherwise, the control flow won't disappear.
if (region->in(1)->outcnt() != 1) return NULL;
if (region->in(2)->outcnt() != 1) return NULL;
// Check for "(P < Q)" of type signed int
if (b->_test._test != BoolTest::lt) return NULL;
if (cmp->Opcode() != Op_CmpI) return NULL;
Node *p = cmp->in(1);
Node *q = cmp->in(2);
Node *n1 = phi->in( true_path);
Node *n2 = phi->in(3-true_path);
int op = n1->Opcode();
if( op != Op_AddI // Need zero as additive identity
/*&&op != Op_SubI &&
op != Op_AddP &&
op != Op_XorI &&
op != Op_OrI*/
return NULL;
Node *x = n2;
Node *y = NULL;
if( x == n1->in(1) ) {
y = n1->in(2);
} else if( x == n1->in(2) ) {
y = n1->in(1);
} else return NULL;
// Not so profitable if compare and add are constants
if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
return NULL;
Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
Node *j_and = phase->transform( new AndINode(cmplt,y) );
return new AddINode(j_and,x);
}
//------------------------------is_absolute------------------------------------
// Check for absolute value.
static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
assert(true_path !=0, "only diamond shape graph expected");
int cmp_zero_idx = 0; // Index of compare input where to look for zero
int phi_x_idx = 0; // Index of phi input where to find naked x
// ABS ends with the merge of 2 control flow paths.
// Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
int false_path = 3 - true_path;
// is_diamond_phi() has guaranteed the correctness of the nodes sequence:
// phi->region->if_proj->ifnode->bool->cmp
BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
Node *cmp = bol->in(1);
// Check bool sense
if (cmp->Opcode() == Op_CmpF || cmp->Opcode() == Op_CmpD) {
switch (bol->_test._test) {
case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break;
case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break;
case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
default: return NULL; break;
}
} else if (cmp->Opcode() == Op_CmpI || cmp->Opcode() == Op_CmpL) {
switch (bol->_test._test) {
case BoolTest::lt:
case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
case BoolTest::gt:
case BoolTest::ge: cmp_zero_idx = 2; phi_x_idx = true_path; break;
default: return NULL; break;
}
}
// Test is next
const Type *tzero = NULL;
switch (cmp->Opcode()) {
case Op_CmpI: tzero = TypeInt::ZERO; break; // Integer ABS
case Op_CmpL: tzero = TypeLong::ZERO; break; // Long ABS
case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS
case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS
default: return NULL;
}
// Find zero input of compare; the other input is being abs'd
Node *x = NULL;
bool flip = false;
if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
x = cmp->in(3 - cmp_zero_idx);
} else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
// The test is inverted, we should invert the result...
--> --------------------
--> maximum size reached
--> --------------------
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