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loopPredicate.cpp
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loopPredicate.cpp
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/*
* Copyright (c) 2011, 2018, 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 "opto/loopnode.hpp"
#include "opto/addnode.hpp"
#include "opto/callnode.hpp"
#include "opto/connode.hpp"
#include "opto/convertnode.hpp"
#include "opto/loopnode.hpp"
#include "opto/matcher.hpp"
#include "opto/mulnode.hpp"
#include "opto/opaquenode.hpp"
#include "opto/rootnode.hpp"
#include "opto/subnode.hpp"
#include <fenv.h>
#include <math.h>
/*
* The general idea of Loop Predication is to insert a predicate on the entry
* path to a loop, and raise a uncommon trap if the check of the condition fails.
* The condition checks are promoted from inside the loop body, and thus
* the checks inside the loop could be eliminated. Currently, loop predication
* optimization has been applied to remove array range check and loop invariant
* checks (such as null checks).
*
* There are at least 3 kinds of predicates: a place holder inserted
* at parse time, the tests added by predication above the place
* holder (referred to as concrete predicates), skeleton predicates
* that are added between main loop and pre loop to protect C2 from
* inconsistencies in some rare cases of over unrolling. Skeleton
* predicates themselves are expanded and updated as unrolling
* proceeds. They don't compile to any code.
*
*/
//-------------------------------register_control-------------------------
void PhaseIdealLoop::register_control(Node* n, IdealLoopTree *loop, Node* pred, bool update_body) {
assert(n->is_CFG(), "msust be control node");
_igvn.register_new_node_with_optimizer(n);
if (update_body) {
loop->_body.push(n);
}
set_loop(n, loop);
// When called from beautify_loops() idom is not constructed yet.
if (_idom != NULL) {
set_idom(n, pred, dom_depth(pred));
}
}
//------------------------------create_new_if_for_predicate------------------------
// create a new if above the uct_if_pattern for the predicate to be promoted.
//
// before after
// ---------- ----------
// ctrl ctrl
// | |
// | |
// v v
// iff new_iff
// / \ / \
// / \ / \
// v v v v
// uncommon_proj cont_proj if_uct if_cont
// \ | | | |
// \ | | | |
// v v v | v
// rgn loop | iff
// | | / \
// | | / \
// v | v v
// uncommon_trap | uncommon_proj cont_proj
// \ \ | |
// \ \ | |
// v v v v
// rgn loop
// |
// |
// v
// uncommon_trap
//
//
// We will create a region to guard the uct call if there is no one there.
// The continuation projection (if_cont) of the new_iff is returned which
// is by default a true projection if 'if_cont_is_true_proj' is true.
// Otherwise, the continuation projection is set up to be the false
// projection. This code is also used to clone predicates to cloned loops.
ProjNode* PhaseIdealLoop::create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
Deoptimization::DeoptReason reason,
int opcode, bool if_cont_is_true_proj) {
assert(cont_proj->is_uncommon_trap_if_pattern(reason), "must be a uct if pattern!");
IfNode* iff = cont_proj->in(0)->as_If();
ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con);
Node *rgn = uncommon_proj->unique_ctrl_out();
assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
uint proj_index = 1; // region's edge corresponding to uncommon_proj
if (!rgn->is_Region()) { // create a region to guard the call
assert(rgn->is_Call(), "must be call uct");
CallNode* call = rgn->as_Call();
IdealLoopTree* loop = get_loop(call);
rgn = new RegionNode(1);
Node* uncommon_proj_orig = uncommon_proj;
uncommon_proj = uncommon_proj->clone()->as_Proj();
register_control(uncommon_proj, loop, iff);
rgn->add_req(uncommon_proj);
register_control(rgn, loop, uncommon_proj);
_igvn.replace_input_of(call, 0, rgn);
// When called from beautify_loops() idom is not constructed yet.
if (_idom != NULL) {
set_idom(call, rgn, dom_depth(rgn));
}
// Move nodes pinned on the projection or whose control is set to
// the projection to the region.
lazy_replace(uncommon_proj_orig, rgn);
} else {
// Find region's edge corresponding to uncommon_proj
for (; proj_index < rgn->req(); proj_index++)
if (rgn->in(proj_index) == uncommon_proj) break;
assert(proj_index < rgn->req(), "sanity");
}
Node* entry = iff->in(0);
if (new_entry != NULL) {
// Clonning the predicate to new location.
entry = new_entry;
}
// Create new_iff
IdealLoopTree* lp = get_loop(entry);
IfNode* new_iff = NULL;
if (opcode == Op_If) {
new_iff = new IfNode(entry, iff->in(1), iff->_prob, iff->_fcnt);
} else {
assert(opcode == Op_RangeCheck, "no other if variant here");
new_iff = new RangeCheckNode(entry, iff->in(1), iff->_prob, iff->_fcnt);
}
register_control(new_iff, lp, entry);
Node* if_cont;
Node* if_uct;
if (if_cont_is_true_proj) {
if_cont = new IfTrueNode(new_iff);
if_uct = new IfFalseNode(new_iff);
} else {
if_uct = new IfTrueNode(new_iff);
if_cont = new IfFalseNode(new_iff);
}
if (cont_proj->is_IfFalse()) {
// Swap
Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp;
}
register_control(if_cont, lp, new_iff);
register_control(if_uct, get_loop(rgn), new_iff);
// if_uct to rgn
_igvn.hash_delete(rgn);
rgn->add_req(if_uct);
// When called from beautify_loops() idom is not constructed yet.
if (_idom != NULL) {
Node* ridom = idom(rgn);
Node* nrdom = dom_lca_internal(ridom, new_iff);
set_idom(rgn, nrdom, dom_depth(rgn));
}
// If rgn has phis add new edges which has the same
// value as on original uncommon_proj pass.
assert(rgn->in(rgn->req() -1) == if_uct, "new edge should be last");
bool has_phi = false;
for (DUIterator_Fast imax, i = rgn->fast_outs(imax); i < imax; i++) {
Node* use = rgn->fast_out(i);
if (use->is_Phi() && use->outcnt() > 0) {
assert(use->in(0) == rgn, "");
_igvn.rehash_node_delayed(use);
use->add_req(use->in(proj_index));
has_phi = true;
}
}
assert(!has_phi || rgn->req() > 3, "no phis when region is created");
if (new_entry == NULL) {
// Attach if_cont to iff
_igvn.replace_input_of(iff, 0, if_cont);
if (_idom != NULL) {
set_idom(iff, if_cont, dom_depth(iff));
}
}
return if_cont->as_Proj();
}
//--------------------------clone_predicate-----------------------
ProjNode* PhaseIdealLoop::clone_loop_predicate(ProjNode* predicate_proj, Node* new_entry, Deoptimization::DeoptReason reason,
bool is_slow_loop, uint idx_before_clone, Node_List &old_new) {
ProjNode* new_predicate_proj = create_new_if_for_predicate(predicate_proj, new_entry, reason, Op_If);
IfNode* iff = new_predicate_proj->in(0)->as_If();
Node* ctrl = iff->in(0);
// Match original condition since predicate's projections could be swapped.
assert(predicate_proj->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be");
Node* opq = new Opaque1Node(C, predicate_proj->in(0)->in(1)->in(1)->in(1));
C->add_predicate_opaq(opq);
Node* bol = new Conv2BNode(opq);
register_new_node(opq, ctrl);
register_new_node(bol, ctrl);
_igvn.hash_delete(iff);
iff->set_req(1, bol);
clone_concrete_loop_predicates(reason, predicate_proj, new_predicate_proj, is_slow_loop, idx_before_clone, old_new);
return new_predicate_proj;
}
// Clones all non-empty loop predicates (including skeleton predicates) starting at 'old_predicate_proj' to 'new_predicate_proj'
// and rewires the control edges of data nodes in the loop to the old predicates to the new cloned predicates.
void PhaseIdealLoop::clone_concrete_loop_predicates(Deoptimization::DeoptReason reason, ProjNode* old_predicate_proj,
ProjNode* new_predicate_proj, bool is_slow_loop, uint idx_before_clone,
Node_List &old_new) {
assert(old_predicate_proj->is_Proj(), "must be projection");
IfNode* iff = old_predicate_proj->in(0)->as_If();
ProjNode* uncommon_proj = iff->proj_out(1 - old_predicate_proj->as_Proj()->_con);
Node* rgn = uncommon_proj->unique_ctrl_out();
assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
assert(iff->in(1)->in(1)->Opcode() == Op_Opaque1, "unexpected predicate shape");
Node* predicate = iff->in(0);
Node* current_proj = old_predicate_proj;
Node* prev_proj = current_proj;
Unique_Node_List list;
while (predicate != NULL && predicate->is_Proj() && predicate->in(0)->is_If()) {
iff = predicate->in(0)->as_If();
uncommon_proj = iff->proj_out(1 - predicate->as_Proj()->_con);
if (uncommon_proj->unique_ctrl_out() != rgn)
break;
if (iff->is_RangeCheck()) {
// Only need to clone range check predicates as those can be changed and duplicated by inserting pre/main/post loops
// and doing loop unrolling. Push the original predicates on a list to later process them in reverse order to keep the
// original predicate order.
list.push(predicate);
#ifdef ASSERT
} else {
// All other If predicates should not have a control input to nodes belonging to the original loop
for (DUIterator i = predicate->outs(); predicate->has_out(i); i++) {
Node* old_node = predicate->out(i);
Node* new_node = old_new[old_node->_idx];
if (!old_node->is_CFG() && new_node != NULL && old_node->_idx >= idx_before_clone) {
assert(false, "should not be part of the original loop");
}
}
#endif
}
predicate = predicate->in(0)->in(0);
}
// Process in reverse order such that 'create_new_if_for_predicate' can be used and the original order is maintained
for (int i = list.size()-1; i >= 0; i--) {
predicate = list.at(i);
assert(predicate->in(0)->is_If(), "must be If node");
iff = predicate->in(0)->as_If();
assert(predicate->is_Proj() && predicate->as_Proj()->is_IfProj() && iff->is_RangeCheck(), "predicate must be a projection of a range check");
IfProjNode* predicate_proj = predicate->as_IfProj();
// cloned_proj is the same type of projection as the original predicate projection (IfTrue or IfFalse)
ProjNode* cloned_proj = create_new_if_for_predicate(new_predicate_proj, NULL, reason, Op_RangeCheck, predicate_proj->is_IfTrue());
// Replace bool input by input from original predicate
_igvn.replace_input_of(cloned_proj->in(0), 1, iff->in(1));
if (is_slow_loop) {
for (DUIterator i = predicate->outs(); predicate->has_out(i); i++) {
Node* slow_node = predicate->out(i);
Node* fast_node = old_new[slow_node->_idx];
if (!slow_node->is_CFG() && fast_node != NULL && slow_node->_idx > idx_before_clone) {
// 'slow_node' is a data node and part of the slow loop. This is a clone of the fast loop node
// which was temporarily added below in order to verify that 'slow_node' is a clone of 'fast_node'.
// Update the control input and reset the mapping for 'slow_node' back to NULL.
_igvn.replace_input_of(slow_node, 0, cloned_proj);
old_new.map(slow_node->_idx, NULL);
--i;
}
assert(slow_node->_idx <= idx_before_clone || old_new[slow_node->_idx] == NULL, "mapping of cloned nodes must be null");
}
// Let old predicates before unswitched loops which were cloned die if all their control edges were rewired
// to the cloned predicates in the unswitched loops.
if (predicate->outcnt() == 1) {
_igvn.replace_input_of(iff, 1, _igvn.intcon(predicate_proj->_con));
}
} else {
// Fast loop
for (DUIterator i = predicate->outs(); predicate->has_out(i); i++) {
Node* fast_node = predicate->out(i);
Node* slow_node = old_new[fast_node->_idx];
if (!fast_node->is_CFG() && slow_node != NULL && slow_node->_idx > idx_before_clone) {
// 'fast_node' is a data node and part of the fast loop. Add the clone of the fast loop node
// to the 'old_new' mapping in order to verify later when cloning the predicates for the slow loop
// that 'slow_node' is a clone of 'fast_node'. Update the control input for 'fast_node'.
_igvn.replace_input_of(fast_node, 0, cloned_proj);
assert(old_new[slow_node->_idx] == NULL, "mapping must be null for cloned nodes");
old_new.map(slow_node->_idx, fast_node);
--i;
}
}
}
}
}
//--------------------------clone_loop_predicates-----------------------
// Clone loop predicates to cloned loops when unswitching a loop.
Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check,
bool is_slow_loop, uint idx_before_clone, Node_List &old_new) {
#ifdef ASSERT
assert(LoopUnswitching, "sanity - only called when unswitching a loop");
if (new_entry == NULL || !(new_entry->is_Proj() || new_entry->is_Region() || new_entry->is_SafePoint())) {
if (new_entry != NULL)
new_entry->dump();
assert(false, "not IfTrue, IfFalse, Region or SafePoint");
}
#endif
// Search original predicates
Node* entry = old_entry;
ProjNode* limit_check_proj = NULL;
limit_check_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
if (limit_check_proj != NULL) {
entry = skip_loop_predicates(entry);
}
ProjNode* profile_predicate_proj = NULL;
ProjNode* predicate_proj = NULL;
if (UseProfiledLoopPredicate) {
profile_predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
if (profile_predicate_proj != NULL) {
entry = skip_loop_predicates(entry);
}
}
if (UseLoopPredicate) {
predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
}
if (predicate_proj != NULL) { // right pattern that can be used by loop predication
// clone predicate
new_entry = clone_loop_predicate(predicate_proj, new_entry, Deoptimization::Reason_predicate, is_slow_loop,
idx_before_clone, old_new);
assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone predicate");
if (TraceLoopPredicate) {
tty->print("Loop Predicate cloned: ");
debug_only( new_entry->in(0)->dump(); );
}
}
if (profile_predicate_proj != NULL) { // right pattern that can be used by loop predication
// clone predicate
new_entry = clone_loop_predicate(profile_predicate_proj, new_entry,Deoptimization::Reason_profile_predicate,
is_slow_loop, idx_before_clone, old_new);
assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone predicate");
if (TraceLoopPredicate) {
tty->print("Loop Predicate cloned: ");
debug_only( new_entry->in(0)->dump(); );
}
}
if (limit_check_proj != NULL && clone_limit_check) {
// Clone loop limit check last to insert it before loop.
// Don't clone a limit check which was already finalized
// for this counted loop (only one limit check is needed).
new_entry = clone_loop_predicate(limit_check_proj, new_entry, Deoptimization::Reason_loop_limit_check,
is_slow_loop, idx_before_clone, old_new);
assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone limit check");
if (TraceLoopLimitCheck) {
tty->print("Loop Limit Check cloned: ");
debug_only( new_entry->in(0)->dump(); )
}
}
return new_entry;
}
//--------------------------skip_loop_predicates------------------------------
// Skip related predicates.
Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) {
IfNode* iff = entry->in(0)->as_If();
ProjNode* uncommon_proj = iff->proj_out(1 - entry->as_Proj()->_con);
Node* rgn = uncommon_proj->unique_ctrl_out();
assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
entry = entry->in(0)->in(0);
while (entry != NULL && entry->is_Proj() && entry->in(0)->is_If()) {
uncommon_proj = entry->in(0)->as_If()->proj_out(1 - entry->as_Proj()->_con);
if (uncommon_proj->unique_ctrl_out() != rgn)
break;
entry = entry->in(0)->in(0);
}
return entry;
}
Node* PhaseIdealLoop::skip_all_loop_predicates(Node* entry) {
Node* predicate = NULL;
predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
if (predicate != NULL) {
entry = skip_loop_predicates(entry);
}
if (UseProfiledLoopPredicate) {
predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
if (predicate != NULL) { // right pattern that can be used by loop predication
entry = skip_loop_predicates(entry);
}
}
if (UseLoopPredicate) {
predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
if (predicate != NULL) { // right pattern that can be used by loop predication
entry = skip_loop_predicates(entry);
}
}
return entry;
}
//--------------------------find_predicate_insertion_point-------------------
// Find a good location to insert a predicate
ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason) {
if (start_c == NULL || !start_c->is_Proj())
return NULL;
if (start_c->as_Proj()->is_uncommon_trap_if_pattern(reason)) {
return start_c->as_Proj();
}
return NULL;
}
//--------------------------find_predicate------------------------------------
// Find a predicate
Node* PhaseIdealLoop::find_predicate(Node* entry) {
Node* predicate = NULL;
predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
if (predicate != NULL) { // right pattern that can be used by loop predication
return entry;
}
if (UseLoopPredicate) {
predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
if (predicate != NULL) { // right pattern that can be used by loop predication
return entry;
}
}
if (UseProfiledLoopPredicate) {
predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
if (predicate != NULL) { // right pattern that can be used by loop predication
return entry;
}
}
return NULL;
}
//------------------------------Invariance-----------------------------------
// Helper class for loop_predication_impl to compute invariance on the fly and
// clone invariants.
class Invariance : public StackObj {
VectorSet _visited, _invariant;
Node_Stack _stack;
VectorSet _clone_visited;
Node_List _old_new; // map of old to new (clone)
IdealLoopTree* _lpt;
PhaseIdealLoop* _phase;
// Helper function to set up the invariance for invariance computation
// If n is a known invariant, set up directly. Otherwise, look up the
// the possibility to push n onto the stack for further processing.
void visit(Node* use, Node* n) {
if (_lpt->is_invariant(n)) { // known invariant
_invariant.set(n->_idx);
} else if (!n->is_CFG()) {
Node *n_ctrl = _phase->ctrl_or_self(n);
Node *u_ctrl = _phase->ctrl_or_self(use); // self if use is a CFG
if (_phase->is_dominator(n_ctrl, u_ctrl)) {
_stack.push(n, n->in(0) == NULL ? 1 : 0);
}
}
}
// Compute invariance for "the_node" and (possibly) all its inputs recursively
// on the fly
void compute_invariance(Node* n) {
assert(_visited.test(n->_idx), "must be");
visit(n, n);
while (_stack.is_nonempty()) {
Node* n = _stack.node();
uint idx = _stack.index();
if (idx == n->req()) { // all inputs are processed
_stack.pop();
// n is invariant if it's inputs are all invariant
bool all_inputs_invariant = true;
for (uint i = 0; i < n->req(); i++) {
Node* in = n->in(i);
if (in == NULL) continue;
assert(_visited.test(in->_idx), "must have visited input");
if (!_invariant.test(in->_idx)) { // bad guy
all_inputs_invariant = false;
break;
}
}
if (all_inputs_invariant) {
// If n's control is a predicate that was moved out of the
// loop, it was marked invariant but n is only invariant if
// it depends only on that test. Otherwise, unless that test
// is out of the loop, it's not invariant.
if (n->is_CFG() || n->depends_only_on_test() || n->in(0) == NULL || !_phase->is_member(_lpt, n->in(0))) {
_invariant.set(n->_idx); // I am a invariant too
}
}
} else { // process next input
_stack.set_index(idx + 1);
Node* m = n->in(idx);
if (m != NULL && !_visited.test_set(m->_idx)) {
visit(n, m);
}
}
}
}
// Helper function to set up _old_new map for clone_nodes.
// If n is a known invariant, set up directly ("clone" of n == n).
// Otherwise, push n onto the stack for real cloning.
void clone_visit(Node* n) {
assert(_invariant.test(n->_idx), "must be invariant");
if (_lpt->is_invariant(n)) { // known invariant
_old_new.map(n->_idx, n);
} else { // to be cloned
assert(!n->is_CFG(), "should not see CFG here");
_stack.push(n, n->in(0) == NULL ? 1 : 0);
}
}
// Clone "n" and (possibly) all its inputs recursively
void clone_nodes(Node* n, Node* ctrl) {
clone_visit(n);
while (_stack.is_nonempty()) {
Node* n = _stack.node();
uint idx = _stack.index();
if (idx == n->req()) { // all inputs processed, clone n!
_stack.pop();
// clone invariant node
Node* n_cl = n->clone();
_old_new.map(n->_idx, n_cl);
_phase->register_new_node(n_cl, ctrl);
for (uint i = 0; i < n->req(); i++) {
Node* in = n_cl->in(i);
if (in == NULL) continue;
n_cl->set_req(i, _old_new[in->_idx]);
}
} else { // process next input
_stack.set_index(idx + 1);
Node* m = n->in(idx);
if (m != NULL && !_clone_visited.test_set(m->_idx)) {
clone_visit(m); // visit the input
}
}
}
}
public:
Invariance(Arena* area, IdealLoopTree* lpt) :
_visited(area), _invariant(area),
_stack(area, 10 /* guess */),
_clone_visited(area), _old_new(area),
_lpt(lpt), _phase(lpt->_phase)
{
LoopNode* head = _lpt->_head->as_Loop();
Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl);
if (entry->outcnt() != 1) {
// If a node is pinned between the predicates and the loop
// entry, we won't be able to move any node in the loop that
// depends on it above it in a predicate. Mark all those nodes
// as non loop invariatnt.
Unique_Node_List wq;
wq.push(entry);
for (uint next = 0; next < wq.size(); ++next) {
Node *n = wq.at(next);
for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
Node* u = n->fast_out(i);
if (!u->is_CFG()) {
Node* c = _phase->get_ctrl(u);
if (_lpt->is_member(_phase->get_loop(c)) || _phase->is_dominator(c, head)) {
_visited.set(u->_idx);
wq.push(u);
}
}
}
}
}
}
// Map old to n for invariance computation and clone
void map_ctrl(Node* old, Node* n) {
assert(old->is_CFG() && n->is_CFG(), "must be");
_old_new.map(old->_idx, n); // "clone" of old is n
_invariant.set(old->_idx); // old is invariant
_clone_visited.set(old->_idx);
}
// Driver function to compute invariance
bool is_invariant(Node* n) {
if (!_visited.test_set(n->_idx))
compute_invariance(n);
return (_invariant.test(n->_idx) != 0);
}
// Driver function to clone invariant
Node* clone(Node* n, Node* ctrl) {
assert(ctrl->is_CFG(), "must be");
assert(_invariant.test(n->_idx), "must be an invariant");
if (!_clone_visited.test(n->_idx))
clone_nodes(n, ctrl);
return _old_new[n->_idx];
}
};
//------------------------------is_range_check_if -----------------------------------
// Returns true if the predicate of iff is in "scale*iv + offset u< load_range(ptr)" format
// Note: this function is particularly designed for loop predication. We require load_range
// and offset to be loop invariant computed on the fly by "invar"
bool IdealLoopTree::is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const {
if (!is_loop_exit(iff)) {
return false;
}
if (!iff->in(1)->is_Bool()) {
return false;
}
const BoolNode *bol = iff->in(1)->as_Bool();
if (bol->_test._test != BoolTest::lt) {
return false;
}
if (!bol->in(1)->is_Cmp()) {
return false;
}
const CmpNode *cmp = bol->in(1)->as_Cmp();
if (cmp->Opcode() != Op_CmpU) {
return false;
}
Node* range = cmp->in(2);
if (range->Opcode() != Op_LoadRange && !iff->is_RangeCheck()) {
const TypeInt* tint = phase->_igvn.type(range)->isa_int();
if (tint == NULL || tint->empty() || tint->_lo < 0) {
// Allow predication on positive values that aren't LoadRanges.
// This allows optimization of loops where the length of the
// array is a known value and doesn't need to be loaded back
// from the array.
return false;
}
}
if (!invar.is_invariant(range)) {
return false;
}
Node *iv = _head->as_CountedLoop()->phi();
int scale = 0;
Node *offset = NULL;
if (!phase->is_scaled_iv_plus_offset(cmp->in(1), iv, &scale, &offset)) {
return false;
}
if (offset && !invar.is_invariant(offset)) { // offset must be invariant
return false;
}
return true;
}
//------------------------------rc_predicate-----------------------------------
// Create a range check predicate
//
// for (i = init; i < limit; i += stride) {
// a[scale*i+offset]
// }
//
// Compute max(scale*i + offset) for init <= i < limit and build the predicate
// as "max(scale*i + offset) u< a.length".
//
// There are two cases for max(scale*i + offset):
// (1) stride*scale > 0
// max(scale*i + offset) = scale*(limit-stride) + offset
// (2) stride*scale < 0
// max(scale*i + offset) = scale*init + offset
BoolNode* PhaseIdealLoop::rc_predicate(IdealLoopTree *loop, Node* ctrl,
int scale, Node* offset,
Node* init, Node* limit, jint stride,
Node* range, bool upper, bool &overflow) {
jint con_limit = (limit != NULL && limit->is_Con()) ? limit->get_int() : 0;
jint con_init = init->is_Con() ? init->get_int() : 0;
jint con_offset = offset->is_Con() ? offset->get_int() : 0;
stringStream* predString = NULL;
if (TraceLoopPredicate) {
predString = new stringStream();
predString->print("rc_predicate ");
}
overflow = false;
Node* max_idx_expr = NULL;
const TypeInt* idx_type = TypeInt::INT;
if ((stride > 0) == (scale > 0) == upper) {
guarantee(limit != NULL, "sanity");
if (TraceLoopPredicate) {
if (limit->is_Con()) {
predString->print("(%d ", con_limit);
} else {
predString->print("(limit ");
}
predString->print("- %d) ", stride);
}
// Check if (limit - stride) may overflow
const TypeInt* limit_type = _igvn.type(limit)->isa_int();
jint limit_lo = limit_type->_lo;
jint limit_hi = limit_type->_hi;
if ((stride > 0 && (java_subtract(limit_lo, stride) < limit_lo)) ||
(stride < 0 && (java_subtract(limit_hi, stride) > limit_hi))) {
// No overflow possible
ConINode* con_stride = _igvn.intcon(stride);
set_ctrl(con_stride, C->root());
max_idx_expr = new SubINode(limit, con_stride);
idx_type = TypeInt::make(limit_lo - stride, limit_hi - stride, limit_type->_widen);
} else {
// May overflow
overflow = true;
limit = new ConvI2LNode(limit);
register_new_node(limit, ctrl);
ConLNode* con_stride = _igvn.longcon(stride);
set_ctrl(con_stride, C->root());
max_idx_expr = new SubLNode(limit, con_stride);
}
register_new_node(max_idx_expr, ctrl);
} else {
if (TraceLoopPredicate) {
if (init->is_Con()) {
predString->print("%d ", con_init);
} else {
predString->print("init ");
}
}
idx_type = _igvn.type(init)->isa_int();
max_idx_expr = init;
}
if (scale != 1) {
ConNode* con_scale = _igvn.intcon(scale);
set_ctrl(con_scale, C->root());
if (TraceLoopPredicate) {
predString->print("* %d ", scale);
}
// Check if (scale * max_idx_expr) may overflow
const TypeInt* scale_type = TypeInt::make(scale);
MulINode* mul = new MulINode(max_idx_expr, con_scale);
idx_type = (TypeInt*)mul->mul_ring(idx_type, scale_type);
if (overflow || TypeInt::INT->higher_equal(idx_type)) {
// May overflow
mul->destruct();
if (!overflow) {
max_idx_expr = new ConvI2LNode(max_idx_expr);
register_new_node(max_idx_expr, ctrl);
}
overflow = true;
con_scale = _igvn.longcon(scale);
set_ctrl(con_scale, C->root());
max_idx_expr = new MulLNode(max_idx_expr, con_scale);
} else {
// No overflow possible
max_idx_expr = mul;
}
register_new_node(max_idx_expr, ctrl);
}
if (offset && (!offset->is_Con() || con_offset != 0)){
if (TraceLoopPredicate) {
if (offset->is_Con()) {
predString->print("+ %d ", con_offset);
} else {
predString->print("+ offset");
}
}
// Check if (max_idx_expr + offset) may overflow
const TypeInt* offset_type = _igvn.type(offset)->isa_int();
jint lo = java_add(idx_type->_lo, offset_type->_lo);
jint hi = java_add(idx_type->_hi, offset_type->_hi);
if (overflow || (lo > hi) ||
((idx_type->_lo & offset_type->_lo) < 0 && lo >= 0) ||
((~(idx_type->_hi | offset_type->_hi)) < 0 && hi < 0)) {
// May overflow
if (!overflow) {
max_idx_expr = new ConvI2LNode(max_idx_expr);
register_new_node(max_idx_expr, ctrl);
}
overflow = true;
offset = new ConvI2LNode(offset);
register_new_node(offset, ctrl);
max_idx_expr = new AddLNode(max_idx_expr, offset);
} else {
// No overflow possible
max_idx_expr = new AddINode(max_idx_expr, offset);
}
register_new_node(max_idx_expr, ctrl);
}
CmpNode* cmp = NULL;
if (overflow) {
// Integer expressions may overflow, do long comparison
range = new ConvI2LNode(range);
register_new_node(range, ctrl);
cmp = new CmpULNode(max_idx_expr, range);
} else {
cmp = new CmpUNode(max_idx_expr, range);
}
register_new_node(cmp, ctrl);
BoolNode* bol = new BoolNode(cmp, BoolTest::lt);
register_new_node(bol, ctrl);
if (TraceLoopPredicate) {
predString->print_cr("<u range");
tty->print("%s", predString->base());
predString->~stringStream();
}
return bol;
}
// Should loop predication look not only in the path from tail to head
// but also in branches of the loop body?
bool PhaseIdealLoop::loop_predication_should_follow_branches(IdealLoopTree *loop, ProjNode *predicate_proj, float& loop_trip_cnt) {
if (!UseProfiledLoopPredicate) {
return false;
}
if (predicate_proj == NULL) {
return false;
}
LoopNode* head = loop->_head->as_Loop();
bool follow_branches = true;
IdealLoopTree* l = loop->_child;
// For leaf loops and loops with a single inner loop
while (l != NULL && follow_branches) {
IdealLoopTree* child = l;
if (child->_child != NULL &&
child->_head->is_OuterStripMinedLoop()) {
assert(child->_child->_next == NULL, "only one inner loop for strip mined loop");
assert(child->_child->_head->is_CountedLoop() && child->_child->_head->as_CountedLoop()->is_strip_mined(), "inner loop should be strip mined");
child = child->_child;
}
if (child->_child != NULL || child->_irreducible) {
follow_branches = false;
}
l = l->_next;
}
if (follow_branches) {
loop->compute_profile_trip_cnt(this);
if (head->is_profile_trip_failed()) {
follow_branches = false;
} else {
loop_trip_cnt = head->profile_trip_cnt();
if (head->is_CountedLoop()) {
CountedLoopNode* cl = head->as_CountedLoop();
if (cl->phi() != NULL) {
const TypeInt* t = _igvn.type(cl->phi())->is_int();
float worst_case_trip_cnt = ((float)t->_hi - t->_lo) / ABS(cl->stride_con());
if (worst_case_trip_cnt < loop_trip_cnt) {
loop_trip_cnt = worst_case_trip_cnt;
}
}
}
}
}
return follow_branches;
}
// Compute probability of reaching some CFG node from a fixed
// dominating CFG node
class PathFrequency {
private:
Node* _dom; // frequencies are computed relative to this node
Node_Stack _stack;
GrowableArray<float> _freqs_stack; // keep track of intermediate result at regions
GrowableArray<float> _freqs; // cache frequencies
PhaseIdealLoop* _phase;
void set_rounding(int mode) {
// fesetround is broken on windows
NOT_WINDOWS(fesetround(mode);)
}
void check_frequency(float f) {
NOT_WINDOWS(assert(f <= 1 && f >= 0, "Incorrect frequency");)
}
public:
PathFrequency(Node* dom, PhaseIdealLoop* phase)
: _dom(dom), _stack(0), _phase(phase) {
}
float to(Node* n) {
// post order walk on the CFG graph from n to _dom
set_rounding(FE_TOWARDZERO); // make sure rounding doesn't push frequency above 1
IdealLoopTree* loop = _phase->get_loop(_dom);
Node* c = n;
for (;;) {
assert(_phase->get_loop(c) == loop, "have to be in the same loop");
if (c == _dom || _freqs.at_grow(c->_idx, -1) >= 0) {
float f = c == _dom ? 1 : _freqs.at(c->_idx);
Node* prev = c;
while (_stack.size() > 0 && prev == c) {
Node* n = _stack.node();
if (!n->is_Region()) {
if (_phase->get_loop(n) != _phase->get_loop(n->in(0))) {
// Found an inner loop: compute frequency of reaching this
// exit from the loop head by looking at the number of
// times each loop exit was taken
IdealLoopTree* inner_loop = _phase->get_loop(n->in(0));
LoopNode* inner_head = inner_loop->_head->as_Loop();
assert(_phase->get_loop(n) == loop, "only 1 inner loop");
if (inner_head->is_OuterStripMinedLoop()) {
inner_head->verify_strip_mined(1);
if (n->in(0) == inner_head->in(LoopNode::LoopBackControl)->in(0)) {
n = n->in(0)->in(0)->in(0);
}
inner_loop = inner_loop->_child;
inner_head = inner_loop->_head->as_Loop();
inner_head->verify_strip_mined(1);
}
set_rounding(FE_UPWARD); // make sure rounding doesn't push frequency above 1
float loop_exit_cnt = 0.0f;
for (uint i = 0; i < inner_loop->_body.size(); i++) {
Node *n = inner_loop->_body[i];
float c = inner_loop->compute_profile_trip_cnt_helper(n);
loop_exit_cnt += c;
}
set_rounding(FE_TOWARDZERO);
float cnt = -1;
if (n->in(0)->is_If()) {
IfNode* iff = n->in(0)->as_If();
float p = n->in(0)->as_If()->_prob;
if (n->Opcode() == Op_IfFalse) {
p = 1 - p;
}
if (p > PROB_MIN) {
cnt = p * iff->_fcnt;
} else {
cnt = 0;
}
} else {
assert(n->in(0)->is_Jump(), "unsupported node kind");
JumpNode* jmp = n->in(0)->as_Jump();
float p = n->in(0)->as_Jump()->_probs[n->as_JumpProj()->_con];
cnt = p * jmp->_fcnt;
}
float this_exit_f = cnt > 0 ? cnt / loop_exit_cnt : 0;
check_frequency(this_exit_f);
f = f * this_exit_f;
check_frequency(f);
} else {
float p = -1;
if (n->in(0)->is_If()) {
p = n->in(0)->as_If()->_prob;
if (n->Opcode() == Op_IfFalse) {
p = 1 - p;
}
} else {
assert(n->in(0)->is_Jump(), "unsupported node kind");
p = n->in(0)->as_Jump()->_probs[n->as_JumpProj()->_con];
}
f = f * p;
check_frequency(f);
}
_freqs.at_put_grow(n->_idx, (float)f, -1);
_stack.pop();
} else {
float prev_f = _freqs_stack.pop();
float new_f = f;
f = new_f + prev_f;
check_frequency(f);
uint i = _stack.index();
if (i < n->req()) {
c = n->in(i);
_stack.set_index(i+1);
_freqs_stack.push(f);
} else {
_freqs.at_put_grow(n->_idx, f, -1);
_stack.pop();
}
}
}
if (_stack.size() == 0) {
set_rounding(FE_TONEAREST);
check_frequency(f);
return f;
}
} else if (c->is_Loop()) {
ShouldNotReachHere();
c = c->in(LoopNode::EntryControl);
} else if (c->is_Region()) {