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jdk/src/hotspot/share/opto/loopPredicate.cpp

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/*
* Copyright (c) 2011, 2023, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "memory/allocation.hpp"
#include "opto/loopnode.hpp"
#include "opto/addnode.hpp"
#include "opto/callnode.hpp"
#include "opto/castnode.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 hoist a check inside a loop body by inserting a Hoisted Predicate with an
* uncommon trap on the entry path to the loop. The old check inside the loop can be eliminated. If the condition of the
* Hoisted Predicate fails at runtime, we'll execute the uncommon trap to avoid entering the loop which misses the check.
* Loop Predication can currently remove array range checks and loop invariant checks (such as null checks).
*
* On top of these predicates added by Loop Predication, there are other kinds of predicates. The following list provides
* a complete description of all predicates used in the C2 compiler:
*
*
* There are different kinds of predicates throughout the code. We differentiate between the following predicates:
*
* - Regular Predicate: This term is used to refer to a Parse Predicate or a Runtime Predicate and can be used to
* distinguish from any Assertion Predicate.
* - Parse Predicate: Added during parsing to capture the current JVM state. This predicate represents a "placeholder"
* above which more Runtime Predicates can be created later after parsing.
*
* There are initially three Parse Predicates for each loop:
* - Loop Parse Predicate: The Parse Predicate added for Loop Predicates.
* - Profiled Loop Parse Predicate: The Parse Predicate added for Profiled Loop Predicates.
* - Loop Limit Check Parse Predicate: The Parse Predicate added for a Loop Limit Check Predicate.
* - Runtime Predicate: This term is used to refer to a Hoisted Predicate (either a Loop Predicate or a Profiled Loop
* Predicate) or a Loop Limit Check Predicate. These predicates will be checked at runtime while the
* Parse and Assertion Predicates are always removed before code generation (except for Initialized
* Assertion Predicates which are kept in debug builds while being removed in product builds).
* - Hoisted Predicate: Either a Loop Predicate or a Profiled Loop Predicate that was created during Loop Predication
* to hoist a check out of a loop. Each Hoisted Predicate is accompanied by additional
* Assertion Predicates.
* - Loop Predicate: A predicate that can either hoist a loop-invariant check out of a loop or a range check
* of the form "a[i*scale + offset]", where scale and offset are loop-invariant, out of a
* counted loop. A check must be executed in each loop iteration to hoist it. Otherwise, no
* Loop Predicate can be created. This predicate is created during Loop Predication and is
* inserted above the Loop Parse Predicate.
* - Profiled Loop: This predicate is very similar to a Loop Predicate but the hoisted check does not need
* Predicate to be executed in each loop iteration. By using profiling information, only checks with
* a high execution frequency are chosen to be replaced by a Profiled Loop Predicate. This
* predicate is created during Loop Predication and is inserted above the Profiled Loop
* Parse Predicate.
* - Loop Limit Check: This predicate is created when transforming a loop to a counted loop to protect against
* Predicate the case when adding the stride to the induction variable would cause an overflow which
* will not satisfy the loop limit exit condition. This overflow is unexpected for further
* counted loop optimizations and could lead to wrong results. Therefore, when this predicate
* fails at runtime, we must trap and recompile the method without turning the loop into a
* a counted loop to avoid these overflow problems.
* The predicate does not replace an actual check inside the loop. This predicate can only
* be added once above the Loop Limit Check Parse Predicate for a loop.
* - Assertion Predicate: An always true predicate which will never fail (its range is already covered by an earlier
* Hoisted Predicate or the main-loop entry guard) but is required in order to fold away a dead
* sub loop inside which some data could be proven to be dead (by the type system) and replaced
* by top. Without such Assertion Predicates, we could find that type ranges in Cast and ConvX2Y
* data nodes become impossible and are replaced by top. This is an indicator that the sub loop
* is never executed and must be dead. But there is no way for C2 to prove that the sub loop is
* actually dead. Assertion Predicates come to the rescue to fold such seemingly dead sub loops
* away to avoid a broken graph. Assertion Predicates are left in the graph as a sanity checks in
* debug builds (they must never fail at runtime) while they are being removed in product builds.
* We use special Opaque4 nodes to block some optimizations and replace the Assertion Predicates
* later in product builds.
*
* There are two kinds of Assertion Predicates:
* - Template Assertion Predicate: A template for an Assertion Predicate that uses OpaqueLoop*
* nodes as placeholders for the init and stride value of a loop.
* This predicate does not represent an actual check, yet, and
* just serves as a template to create an Initialized Assertion
* Predicate for a (sub) loop.
* - Initialized Assertion Predicate: An Assertion Predicate that represents an actual check for a
* (sub) loop that was initialized by cloning a Template
* Assertion Predicate. The check is always true and is covered
* by an earlier check (a Hoisted Predicate or the main-loop
* entry guard).
*
* Assertion Predicates are required when removing a range check from a loop. These are inserted
* either at Loop Predication or at Range Check Elimination:
* - Loop Predication: A range check inside a loop is replaced by a Hoisted Predicate before
* the loop. We add two additional Template Assertion Predicates from
* which we can later create Initialized Assertion Predicates. One
* would have been enough if the number of array accesses inside a sub
* loop does not change. But when unrolling the sub loop, we are
* doubling the number of array accesses - we need to cover them all.
* To do that, we only need to create an Initialized Assertion Predicate
* for the first, initial value and for the last value:
* Let a[i] be an array access in the original, not-yet unrolled loop
* with stride 1. When unrolling this loop, we double the stride
* (i.e. stride 2) and have now two accesses a[i] and a[i+1]. We need
* checks for both. When further unrolling this loop, we only need to
* keep the checks on the first and last access (e.g. a[i] and a[i+3]
* on the next unrolling step as they cover the checks in the middle
* for a[i+1] and a[i+2]).
* Therefore, we just need to cover:
* - Initial value: a[init]
* - Last value: a[init + new stride - original stride]
* (We could still only use one Template Assertion Predicate to create
* both Initialized Assertion Predicates from - might be worth doing
* at some point).
* When later splitting a loop (pre/main/post, peeling, unrolling),
* we create two Initialized Assertion Predicates from the Template
* Assertion Predicates by replacing the OpaqueLoop* nodes by actual
* values. Initially (before unrolling), both Assertion Predicates are
* equal. The Initialized Assertion Predicates are always true because
* their range is covered by a corresponding Hoisted Predicate.
* - Range Check Elimination: A range check is removed from the main-loop by changing the pre
* and main-loop iterations. We add two additional Template Assertion
* Predicates (see explanation in section above) and one Initialized
* Assertion Predicate for the just removed range check. When later
* unrolling the main-loop, we create two Initialized Assertion
* Predicates from the Template Assertion Predicates by replacing the
* OpaqueLoop* nodes by actual values for the unrolled loop.
* The Initialized Assertion Predicates are always true: They are true
* when entering the main-loop (because we adjusted the pre-loop exit
* condition), when executing the last iteration of the main-loop
* (because we adjusted the main-loop exit condition), and during all
* other iterations of the main-loop in-between by implication.
* Note that Range Check Elimination could remove additional range
* checks which we were not possible to remove with Loop Predication
* before (for example, because no Parse Predicates were available
* before the loop to create Hoisted Predicates with).
*
*
* In order to group predicates and refer to them throughout the code, we introduce the following additional terms:
* - Regular Predicate Block: A Regular Predicate Block groups all Runtime Predicates in a Runtime Predicate Block
* together with their dedicated Parse Predicate from which they were created (all predicates
* share the same uncommon trap). The Runtime Predicate Block could be empty (i.e. no
* Runtime Predicates created) and the Parse Predicate could be missing (after removing Parse
* Predicates). There are three such Regular Predicate Blocks:
* - Loop Predicate Block
* - Profiled Loop Predicate Block
* - Loop Limit Check Predicate Block
* - Runtime Predicate Block: A block containing all Runtime Predicates that share the same uncommon trap (i.e. belonging
* to a single Parse Predicate which is not included in this block). This block could be empty
* if there were no Runtime Predicates created with the Parse Predicate below this block.
* For the time being: We also count Assertion Predicates to this block but that will be
* changed with the redesign of Assertion Predicates where we remove them from this block
* (JDK-8288981).
*
* Initially, before applying any loop-splitting optimizations, we find the following structure after Loop Predication
* (predicates inside square brackets [] do not need to exist if there are no checks to hoist):
*
* [Loop Hoisted Predicate 1 + two Template Assertion Predicates] \ Runtime \
* [Loop Hoisted Predicate 2 + two Template Assertion Predicates] | Predicate |
* ... | Block | Loop Predicate Block
* [Loop Hoisted Predicate n + two Template Assertion Predicates] / |
* Loop Parse Predicate /
*
* [Profiled Loop Hoisted Predicate 1 + two Template Assertion Predicates] \ Runtime \
* [Profiled Loop Hoisted Predicate 2 + two Template Assertion Predicates] | Predicate | Profiled Loop
* ... | Block | Predicate Block
* [Profiled Loop Hoisted Predicate m + two Template Assertion Predicates] / |
* Profiled Loop Parse Predicate /
* \ Runtime
* [Loop Limit Check Predicate] (at most one) / Predicate \ Loop Limit Check
* Loop Limit Check Parse Predicate Block / Predicate Block
* Loop Head
*
* As an example, let's look at how the predicate structure looks for the main-loop after creating pre/main/post loops
* and applying Range Check Elimination (the order is insignificant):
*
* Main Loop entry (zero-trip) guard
* [For Loop Predicate 1: Two Template + two Initialized Assertion Predicates]
* [For Loop Predicate 2: Two Template + two Initialized Assertion Predicates]
* ...
* [For Loop Predicate n: Two Template + two Initialized Assertion Predicates]
*
* [For Profiled Loop Predicate 1: Two Template + two Initialized Assertion Predicates]
* [For Profiled Loop Predicate 2: Two Template + two Initialized Assertion Predicates]
* ...
* [For Profiled Loop Predicate m: Two Template + two Initialized Assertion Predicates]
*
* (after unrolling, we have two Initialized Assertion Predicates for the Assertion Predicates of Range Check Elimination)
* [For Range Check Elimination Check 1: Two Templates + one Initialized Assertion Predicate]
* [For Range Check Elimination Check 2: Two Templates + one Initialized Assertion Predicate]
* ...
* [For Range Check Elimination Check k: Two Templates + one Initialized Assertion Predicate]
* Main Loop Head
*/
//-------------------------------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 != nullptr) {
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 an IfTrue projection. This code is also used to clone predicates to cloned loops.
IfProjNode* PhaseIdealLoop::create_new_if_for_predicate(IfProjNode* cont_proj, Node* new_entry,
Deoptimization::DeoptReason reason,
const int opcode, const bool rewire_uncommon_proj_phi_inputs,
const 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 != nullptr) {
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 != nullptr) {
// Cloning the predicate to new location.
entry = new_entry;
}
// Create new_iff
IdealLoopTree* lp = get_loop(entry);
IfNode* new_iff = nullptr;
switch (opcode) {
case Op_If:
new_iff = new IfNode(entry, iff->in(1), iff->_prob, iff->_fcnt);
break;
case Op_RangeCheck:
new_iff = new RangeCheckNode(entry, iff->in(1), iff->_prob, iff->_fcnt);
break;
case Op_ParsePredicate:
new_iff = new ParsePredicateNode(entry, iff->in(1), reason);
break;
default:
fatal("no other If variant here");
}
register_control(new_iff, lp, entry);
IfProjNode* if_cont;
IfProjNode* 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
IfProjNode* 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);
_igvn.add_input_to(rgn, if_uct);
// 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);
Node* phi_input = use->in(proj_index);
if (uncommon_proj->outcnt() > 1 && !phi_input->is_CFG() && !phi_input->is_Phi() && get_ctrl(phi_input) == uncommon_proj) {
// There are some control dependent nodes on the uncommon projection. We cannot simply reuse these data nodes.
// We either need to rewire them from the old uncommon projection to the newly created uncommon proj (if the old
// If is dying) or clone them and update their control (if the old If is not dying).
if (rewire_uncommon_proj_phi_inputs) {
// Replace phi input for the old uncommon projection with TOP as the If is dying anyways. Reuse the old data
// nodes by simply updating control inputs and ctrl.
_igvn.replace_input_of(use, proj_index, C->top());
set_ctrl_of_nodes_with_same_ctrl(phi_input, uncommon_proj, if_uct);
} else {
phi_input = clone_nodes_with_same_ctrl(phi_input, uncommon_proj, if_uct);
}
}
use->add_req(phi_input);
has_phi = true;
}
}
assert(!has_phi || rgn->req() > 3, "no phis when region is created");
if (new_entry == nullptr) {
// Attach if_cont to iff
_igvn.replace_input_of(iff, 0, if_cont);
if (_idom != nullptr) {
set_idom(iff, if_cont, dom_depth(iff));
}
}
// When called from beautify_loops() idom is not constructed yet.
if (_idom != nullptr) {
Node* ridom = idom(rgn);
Node* nrdom = dom_lca_internal(ridom, new_iff);
set_idom(rgn, nrdom, dom_depth(rgn));
}
return if_cont->as_IfProj();
}
// Update ctrl and control inputs of all data nodes starting from 'node' to 'new_ctrl' which have 'old_ctrl' as
// current ctrl.
void PhaseIdealLoop::set_ctrl_of_nodes_with_same_ctrl(Node* node, ProjNode* old_ctrl, Node* new_ctrl) {
Unique_Node_List nodes_with_same_ctrl = find_nodes_with_same_ctrl(node, old_ctrl);
for (uint j = 0; j < nodes_with_same_ctrl.size(); j++) {
Node* next = nodes_with_same_ctrl[j];
if (next->in(0) == old_ctrl) {
_igvn.replace_input_of(next, 0, new_ctrl);
}
set_ctrl(next, new_ctrl);
}
}
// Recursively find all input nodes with the same ctrl.
Unique_Node_List PhaseIdealLoop::find_nodes_with_same_ctrl(Node* node, const ProjNode* ctrl) {
Unique_Node_List nodes_with_same_ctrl;
nodes_with_same_ctrl.push(node);
for (uint j = 0; j < nodes_with_same_ctrl.size(); j++) {
Node* next = nodes_with_same_ctrl[j];
for (uint k = 1; k < next->req(); k++) {
Node* in = next->in(k);
if (!in->is_Phi() && get_ctrl(in) == ctrl) {
nodes_with_same_ctrl.push(in);
}
}
}
return nodes_with_same_ctrl;
}
// Clone all nodes with the same ctrl as 'old_ctrl' starting from 'node' by following its inputs. Rewire the cloned nodes
// to 'new_ctrl'. Returns the clone of 'node'.
Node* PhaseIdealLoop::clone_nodes_with_same_ctrl(Node* node, ProjNode* old_ctrl, Node* new_ctrl) {
DEBUG_ONLY(uint last_idx = C->unique();)
Unique_Node_List nodes_with_same_ctrl = find_nodes_with_same_ctrl(node, old_ctrl);
Dict old_new_mapping = clone_nodes(nodes_with_same_ctrl); // Cloned but not rewired, yet
rewire_cloned_nodes_to_ctrl(old_ctrl, new_ctrl, nodes_with_same_ctrl, old_new_mapping);
Node* clone_phi_input = static_cast<Node*>(old_new_mapping[node]);
assert(clone_phi_input != nullptr && clone_phi_input->_idx >= last_idx, "must exist and be a proper clone");
return clone_phi_input;
}
// Clone all the nodes on 'list_to_clone' and return an old->new mapping.
Dict PhaseIdealLoop::clone_nodes(const Node_List& list_to_clone) {
Dict old_new_mapping(cmpkey, hashkey);
for (uint i = 0; i < list_to_clone.size(); i++) {
Node* next = list_to_clone[i];
Node* clone = next->clone();
_igvn.register_new_node_with_optimizer(clone);
old_new_mapping.Insert(next, clone);
}
return old_new_mapping;
}
// Rewire inputs of the unprocessed cloned nodes (inputs are not updated, yet, and still point to the old nodes) by
// using the old_new_mapping.
void PhaseIdealLoop::rewire_cloned_nodes_to_ctrl(const ProjNode* old_ctrl, Node* new_ctrl,
const Node_List& nodes_with_same_ctrl, const Dict& old_new_mapping) {
for (uint i = 0; i < nodes_with_same_ctrl.size(); i++) {
Node* next = nodes_with_same_ctrl[i];
Node* clone = static_cast<Node*>(old_new_mapping[next]);
if (next->in(0) == old_ctrl) {
// All data nodes with a control input to the uncommon projection in the chain need to be rewired to the new uncommon
// projection (could not only be the last data node in the chain but also, for example, a DivNode within the chain).
_igvn.replace_input_of(clone, 0, new_ctrl);
set_ctrl(clone, new_ctrl);
}
rewire_inputs_of_clones_to_clones(new_ctrl, clone, old_new_mapping, next);
}
}
// Rewire the inputs of the cloned nodes to the old nodes to the new clones.
void PhaseIdealLoop::rewire_inputs_of_clones_to_clones(Node* new_ctrl, Node* clone, const Dict& old_new_mapping,
const Node* next) {
for (uint i = 1; i < next->req(); i++) {
Node* in = next->in(i);
if (!in->is_Phi()) {
assert(!in->is_CFG(), "must be data node");
Node* in_clone = static_cast<Node*>(old_new_mapping[in]);
if (in_clone != nullptr) {
_igvn.replace_input_of(clone, i, in_clone);
set_ctrl(clone, new_ctrl);
}
}
}
}
IfProjNode* PhaseIdealLoop::clone_parse_predicate_to_unswitched_loop(ParsePredicateSuccessProj* predicate_proj,
Node* new_entry, Deoptimization::DeoptReason reason,
const bool slow_loop) {
IfProjNode* new_predicate_proj = create_new_if_for_predicate(predicate_proj, new_entry, reason, Op_ParsePredicate,
slow_loop);
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_parse_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);
return new_predicate_proj;
}
// Clones Assertion Predicates to both unswitched loops starting at 'old_predicate_proj' by following its control inputs.
// It also rewires the control edges of data nodes with dependencies in the loop from the old predicates to the new
// cloned predicates.
void PhaseIdealLoop::clone_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new,
Deoptimization::DeoptReason reason,
IfProjNode* old_predicate_proj, IfProjNode* iffast_pred,
IfProjNode* ifslow_pred) {
assert(iffast_pred->in(0)->is_If() && ifslow_pred->in(0)->is_If(), "sanity check");
// 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.
Unique_Node_List list;
get_assertion_predicates(old_predicate_proj, list);
Node_List to_process;
IfNode* iff = old_predicate_proj->in(0)->as_If();
IfProjNode* uncommon_proj = iff->proj_out(1 - old_predicate_proj->as_Proj()->_con)->as_IfProj();
// Process in reverse order such that 'create_new_if_for_predicate' can be used in
// 'clone_assertion_predicate_for_unswitched_loops' and the original order is maintained.
for (int i = list.size() - 1; i >= 0; i--) {
Node* 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(), "predicate must be a projection of an if node");
IfProjNode* predicate_proj = predicate->as_IfProj();
IfProjNode* fast_proj = clone_assertion_predicate_for_unswitched_loops(iff, predicate_proj, reason, iffast_pred);
assert(assertion_predicate_has_loop_opaque_node(fast_proj->in(0)->as_If()), "must find Assertion Predicate for fast loop");
IfProjNode* slow_proj = clone_assertion_predicate_for_unswitched_loops(iff, predicate_proj, reason, ifslow_pred);
assert(assertion_predicate_has_loop_opaque_node(slow_proj->in(0)->as_If()), "must find Assertion Predicate for slow loop");
// Update control dependent data nodes.
for (DUIterator j = predicate->outs(); predicate->has_out(j); j++) {
Node* fast_node = predicate->out(j);
if (loop->is_member(get_loop(ctrl_or_self(fast_node)))) {
assert(fast_node->in(0) == predicate, "only control edge");
Node* slow_node = old_new[fast_node->_idx];
assert(slow_node->in(0) == predicate, "only control edge");
_igvn.replace_input_of(fast_node, 0, fast_proj);
to_process.push(slow_node);
--j;
}
}
// Have to delay updates to the slow loop so uses of predicate are not modified while we iterate on them.
while (to_process.size() > 0) {
Node* slow_node = to_process.pop();
_igvn.replace_input_of(slow_node, 0, slow_proj);
}
}
}
// Put all Assertion Predicate projections on a list, starting at 'predicate' and going up in the tree. If 'get_opaque'
// is set, then the Opaque4 nodes of the Assertion Predicates are put on the list instead of the projections.
void PhaseIdealLoop::get_assertion_predicates(Node* predicate, Unique_Node_List& list, bool get_opaque) {
IfNode* iff = predicate->in(0)->as_If();
ProjNode* uncommon_proj = iff->proj_out(1 - predicate->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");
predicate = iff->in(0);
while (predicate != nullptr && 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->in(1)->Opcode() == Op_Opaque4 && assertion_predicate_has_loop_opaque_node(iff)) {
if (get_opaque) {
// Collect the predicate Opaque4 node.
list.push(iff->in(1));
} else {
// Collect the predicate projection.
list.push(predicate);
}
}
predicate = predicate->in(0)->in(0);
}
}
// Clone an Assertion Predicate for an unswitched loop. OpaqueLoopInit and OpaqueLoopStride nodes are cloned and uncommon
// traps are kept for the predicate (a Halt node is used later when creating pre/main/post loops and copying this cloned
// predicate again).
IfProjNode* PhaseIdealLoop::clone_assertion_predicate_for_unswitched_loops(Node* iff, IfProjNode* predicate,
Deoptimization::DeoptReason reason,
IfProjNode* output_proj) {
Node* bol = create_bool_from_template_assertion_predicate(iff, nullptr, nullptr, output_proj);
IfProjNode* if_proj = create_new_if_for_predicate(output_proj, nullptr, reason, iff->Opcode(),
false, predicate->is_IfTrue());
_igvn.replace_input_of(if_proj->in(0), 1, bol);
_igvn.replace_input_of(output_proj->in(0), 0, if_proj);
set_idom(output_proj->in(0), if_proj, dom_depth(if_proj));
return if_proj;
}
// Clone Parse Predicates to cloned loops when unswitching a loop.
void PhaseIdealLoop::clone_parse_and_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, Node_List& old_new,
IfProjNode*& iffast_pred, IfProjNode*& ifslow_pred) {
LoopNode* head = loop->_head->as_Loop();
Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl);
ParsePredicates parse_predicates(entry);
ParsePredicateSuccessProj* loop_predicate_proj = parse_predicates.loop_predicate_proj();
if (loop_predicate_proj != nullptr) {
// Clone Parse Predicate and Template Assertion Predicates of the Loop Predicate Block.
iffast_pred = clone_parse_predicate_to_unswitched_loop(loop_predicate_proj, iffast_pred,
Deoptimization::Reason_predicate, false);
check_cloned_parse_predicate_for_unswitching(iffast_pred, true);
ifslow_pred = clone_parse_predicate_to_unswitched_loop(loop_predicate_proj, ifslow_pred,
Deoptimization::Reason_predicate, true);
check_cloned_parse_predicate_for_unswitching(ifslow_pred, false);
clone_assertion_predicates_to_unswitched_loop(loop, old_new, Deoptimization::Reason_predicate, loop_predicate_proj,
iffast_pred, ifslow_pred);
}
ParsePredicateSuccessProj* profiled_loop_predicate_proj = parse_predicates.profiled_loop_predicate_proj();
if (profiled_loop_predicate_proj != nullptr) {
// Clone Parse Predicate and Template Assertion Predicates of the Profiled Loop Predicate Block.
iffast_pred = clone_parse_predicate_to_unswitched_loop(profiled_loop_predicate_proj, iffast_pred,
Deoptimization::Reason_profile_predicate, false);
check_cloned_parse_predicate_for_unswitching(iffast_pred, true);
ifslow_pred = clone_parse_predicate_to_unswitched_loop(profiled_loop_predicate_proj, ifslow_pred,
Deoptimization::Reason_profile_predicate, true);
check_cloned_parse_predicate_for_unswitching(ifslow_pred, false);
clone_assertion_predicates_to_unswitched_loop(loop, old_new, Deoptimization::Reason_profile_predicate,
profiled_loop_predicate_proj, iffast_pred, ifslow_pred);
}
ParsePredicateSuccessProj* loop_limit_check_predicate_proj = parse_predicates.loop_limit_check_predicate_proj();
if (loop_limit_check_predicate_proj != nullptr && !head->is_CountedLoop()) {
// Don't clone the Loop Limit Check Parse Predicate if we already have a counted loop (a Loop Limit Check Predicate
// is only created when converting a LoopNode to a CountedLoopNode).
iffast_pred = clone_parse_predicate_to_unswitched_loop(loop_limit_check_predicate_proj, iffast_pred,
Deoptimization::Reason_loop_limit_check, false);
check_cloned_parse_predicate_for_unswitching(iffast_pred, true);
ifslow_pred = clone_parse_predicate_to_unswitched_loop(loop_limit_check_predicate_proj, ifslow_pred,
Deoptimization::Reason_loop_limit_check, true);
check_cloned_parse_predicate_for_unswitching(ifslow_pred, false);
}
}
#ifndef PRODUCT
void PhaseIdealLoop::check_cloned_parse_predicate_for_unswitching(const Node* new_entry, const bool is_fast_loop) {
assert(new_entry != nullptr, "IfTrue or IfFalse after clone predicate");
if (TraceLoopPredicate) {
tty->print("Parse Predicate cloned to %s loop: ", is_fast_loop ? "fast" : "slow");
new_entry->in(0)->dump();
}
}
#endif
//------------------------------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;
Node* _data_dependency_on; // The projection into the loop on which data nodes are dependent or null otherwise
// 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) == nullptr ? 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 == nullptr) 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) == nullptr || !_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 != nullptr && !_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) == nullptr ? 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 == nullptr) 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 != nullptr && !_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),
_data_dependency_on(nullptr)
{
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-invariant.
// Loop predication could create new nodes for which the below
// invariant information is missing. Mark the 'entry' node to
// later check again if a node needs to be treated as non-loop-
// invariant as well.
_data_dependency_on = entry;
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);
}
}
}
}
}
}
// Did we explicitly mark some nodes non-loop-invariant? If so, return the entry node on which some data nodes
// are dependent that prevent loop predication. Otherwise, return null.
Node* data_dependency_on() {
return _data_dependency_on;
}
// 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(IfProjNode* if_success_proj, PhaseIdealLoop *phase, BasicType bt, Node *iv, Node *&range,
Node *&offset, jlong &scale) const {
IfNode* iff = if_success_proj->in(0)->as_If();
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 || if_success_proj->is_IfFalse()) {
// We don't have the required range check pattern:
// if (scale*iv + offset <u limit) {
//
// } else {
// trap();
// }
//
// Having the trap on the true projection:
// if (scale*iv + offset <u limit) {
// trap();
// }
//
// is not correct. We would need to flip the test to get the expected "trap on false path" pattern:
// if (scale*iv + offset >=u limit) {
//
// } else {
// trap();
// }
//
// If we create a Hoisted Range Check Predicate for this wrong pattern, it could succeed at runtime (i.e. true
// for the value of "scale*iv + offset" in the first loop iteration and true for the value of "scale*iv + offset"
// in the last loop iteration) while the check to be hoisted could fail in other loop iterations.
//
// Example:
// Loop: "for (int i = -1; i < 1000; i++)"
// init = "scale*iv + offset" in the first loop iteration = 1*-1 + 0 = -1
// last = "scale*iv + offset" in the last loop iteration = 1*999 + 0 = 999
// limit = 100
//
// Hoisted Range Check Predicate is always true:
// init >=u limit && last >=u limit <=>
// -1 >=u 100 && 999 >= u 100
//
// But for 0 <= x < 100: x >=u 100 is false.
// We would wrongly skip the branch with the trap() and possibly miss to execute some other statements inside that
// trap() branch.
return false;
}
if (!bol->in(1)->is_Cmp()) {
return false;
}
const CmpNode *cmp = bol->in(1)->as_Cmp();
if (cmp->Opcode() != Op_Cmp_unsigned(bt)) {
return false;
}
range = cmp->in(2);
if (range->Opcode() != Op_LoadRange) {
const TypeInteger* tinteger = phase->_igvn.type(range)->isa_integer(bt);
if (tinteger == nullptr || tinteger->empty() || tinteger->lo_as_long() < 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;
}
} else {
assert(bt == T_INT, "no LoadRange for longs");
}
scale = 0;
offset = nullptr;
if (!phase->is_scaled_iv_plus_offset(cmp->in(1), iv, bt, &scale, &offset)) {
return false;
}
return true;
}
bool IdealLoopTree::is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop *phase, Invariance& invar DEBUG_ONLY(COMMA ProjNode *predicate_proj)) const {
Node* range = nullptr;
Node* offset = nullptr;
jlong scale = 0;
Node* iv = _head->as_BaseCountedLoop()->phi();
Compile* C = Compile::current();
const uint old_unique_idx = C->unique();
if (!is_range_check_if(if_success_proj, phase, T_INT, iv, range, offset, scale)) {
return false;
}
if (!invar.is_invariant(range)) {
return false;
}
if (offset != nullptr) {
if (!invar.is_invariant(offset)) { // offset must be invariant
return false;
}
Node* data_dependency_on = invar.data_dependency_on();
if (data_dependency_on != nullptr && old_unique_idx < C->unique()) {
// 'offset' node was newly created in is_range_check_if(). Check that it does not depend on the entry projection
// into the loop. If it does, we cannot perform loop predication (see Invariant::Invariant()).
assert(!offset->is_CFG(), "offset must be a data node");
if (_phase->get_ctrl(offset) == data_dependency_on) {
return false;
}
}
}
#ifdef ASSERT
if (offset && phase->has_ctrl(offset)) {
Node* offset_ctrl = phase->get_ctrl(offset);
if (phase->get_loop(predicate_proj) == phase->get_loop(offset_ctrl) &&
phase->is_dominator(predicate_proj, offset_ctrl)) {
// If the control of offset is loop predication promoted by previous pass,
// then it will lead to cyclic dependency.
// Previously promoted loop predication is in the same loop of predication
// point.
// This situation can occur when pinning nodes too conservatively - can we do better?
assert(false, "cyclic dependency prevents range check elimination, idx: offset %d, offset_ctrl %d, predicate_proj %d",
offset->_idx, offset_ctrl->_idx, predicate_proj->_idx);
}
}
#endif
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 != nullptr && 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 = nullptr;
if (TraceLoopPredicate) {
predString = new (mtCompiler) stringStream();
predString->print("rc_predicate ");
}
overflow = false;
Node* max_idx_expr = nullptr;
const TypeInt* idx_type = TypeInt::INT;
if ((stride > 0) == (scale > 0) == upper) {
guarantee(limit != nullptr, "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(&_igvn);
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 = nullptr;
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());
delete predString;
}
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, IfProjNode* predicate_proj, float& loop_trip_cnt) {
if (!UseProfiledLoopPredicate) {
return false;
}
if (predicate_proj == nullptr) {
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 != nullptr && follow_branches) {
IdealLoopTree* child = l;
if (child->_child != nullptr &&
child->_head->is_OuterStripMinedLoop()) {
assert(child->_child->_next == nullptr, "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 != nullptr || 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() != nullptr) {
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;
}
float PathFrequency::to(Node* n) {
// post order walk on the CFG graph from n to _dom
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);
}
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;
}
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;
this_exit_f = check_and_truncate_frequency(this_exit_f);
f = f * this_exit_f;
f = check_and_truncate_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;
f = check_and_truncate_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;
f = check_and_truncate_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) {
return check_and_truncate_frequency(f);
}
} else if (c->is_Loop()) {
ShouldNotReachHere();
c = c->in(LoopNode::EntryControl);
} else if (c->is_Region()) {
_freqs_stack.push(0);
_stack.push(c, 2);
c = c->in(1);
} else {
if (c->is_IfProj()) {
IfNode* iff = c->in(0)->as_If();
if (iff->_prob == PROB_UNKNOWN) {
// assume never taken
_freqs.at_put_grow(c->_idx, 0, -1);
} else if (_phase->get_loop(c) != _phase->get_loop(iff)) {
if (iff->_fcnt == COUNT_UNKNOWN) {
// assume never taken
_freqs.at_put_grow(c->_idx, 0, -1);
} else {
// skip over loop
_stack.push(c, 1);
c = _phase->get_loop(c->in(0))->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
}
} else {
_stack.push(c, 1);
c = iff;
}
} else if (c->is_JumpProj()) {
JumpNode* jmp = c->in(0)->as_Jump();
if (_phase->get_loop(c) != _phase->get_loop(jmp)) {
if (jmp->_fcnt == COUNT_UNKNOWN) {
// assume never taken
_freqs.at_put_grow(c->_idx, 0, -1);
} else {
// skip over loop
_stack.push(c, 1);
c = _phase->get_loop(c->in(0))->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
}
} else {
_stack.push(c, 1);
c = jmp;
}
} else if (c->Opcode() == Op_CatchProj &&
c->in(0)->Opcode() == Op_Catch &&
c->in(0)->in(0)->is_Proj() &&
c->in(0)->in(0)->in(0)->is_Call()) {
// assume exceptions are never thrown
uint con = c->as_Proj()->_con;
if (con == CatchProjNode::fall_through_index) {
Node* call = c->in(0)->in(0)->in(0)->in(0);
if (_phase->get_loop(call) != _phase->get_loop(c)) {
_freqs.at_put_grow(c->_idx, 0, -1);
} else {
c = call;
}
} else {
assert(con >= CatchProjNode::catch_all_index, "what else?");
_freqs.at_put_grow(c->_idx, 0, -1);
}
} else if (c->unique_ctrl_out_or_null() == nullptr && !c->is_If() && !c->is_Jump()) {
ShouldNotReachHere();
} else {
c = c->in(0);
}
}
}
ShouldNotReachHere();
return -1;
}
void PhaseIdealLoop::loop_predication_follow_branches(Node *n, IdealLoopTree *loop, float loop_trip_cnt,
PathFrequency& pf, Node_Stack& stack, VectorSet& seen,
Node_List& if_proj_list) {
assert(n->is_Region(), "start from a region");
Node* tail = loop->tail();
stack.push(n, 1);
do {
Node* c = stack.node();
assert(c->is_Region() || c->is_IfProj(), "only region here");
uint i = stack.index();
if (i < c->req()) {
stack.set_index(i+1);
Node* in = c->in(i);
while (!is_dominator(in, tail) && !seen.test_set(in->_idx)) {
IdealLoopTree* in_loop = get_loop(in);
if (in_loop != loop) {
in = in_loop->_head->in(LoopNode::EntryControl);
} else if (in->is_Region()) {
stack.push(in, 1);
break;
} else if (in->is_IfProj() &&
in->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none) &&
(in->in(0)->Opcode() == Op_If ||
in->in(0)->Opcode() == Op_RangeCheck)) {
if (pf.to(in) * loop_trip_cnt >= 1) {
stack.push(in, 1);
}
in = in->in(0);
} else {
in = in->in(0);
}
}
} else {
if (c->is_IfProj()) {
if_proj_list.push(c);
}
stack.pop();
}
} while (stack.size() > 0);
}
bool PhaseIdealLoop::loop_predication_impl_helper(IdealLoopTree* loop, IfProjNode* if_success_proj,
ParsePredicateSuccessProj* parse_predicate_proj, CountedLoopNode* cl,
ConNode* zero, Invariance& invar, Deoptimization::DeoptReason reason) {
// Following are changed to nonnull when a predicate can be hoisted
IfProjNode* new_predicate_proj = nullptr;
IfNode* iff = if_success_proj->in(0)->as_If();
Node* test = iff->in(1);
if (!test->is_Bool()) { //Conv2B, ...
return false;
}
BoolNode* bol = test->as_Bool();
if (invar.is_invariant(bol)) {
// Invariant test
new_predicate_proj = create_new_if_for_predicate(parse_predicate_proj, nullptr,
reason,
iff->Opcode());
Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0);
BoolNode* new_predicate_bol = invar.clone(bol, ctrl)->as_Bool();
// Negate test if necessary (Parse Predicates always have IfTrue as success projection and IfFalse as uncommon trap)
bool negated = false;
if (if_success_proj->is_IfFalse()) {
new_predicate_bol = new BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate());
register_new_node(new_predicate_bol, ctrl);
negated = true;
}
IfNode* new_predicate_iff = new_predicate_proj->in(0)->as_If();
_igvn.hash_delete(new_predicate_iff);
new_predicate_iff->set_req(1, new_predicate_bol);
#ifndef PRODUCT
if (TraceLoopPredicate) {
tty->print("Predicate invariant if%s: %d ", negated ? " negated" : "", new_predicate_iff->_idx);
loop->dump_head();
} else if (TraceLoopOpts) {
tty->print("Predicate IC ");
loop->dump_head();
}
#endif
} else if (cl != nullptr && loop->is_range_check_if(if_success_proj, this, invar DEBUG_ONLY(COMMA parse_predicate_proj))) {
// Range check for counted loops
assert(if_success_proj->is_IfTrue(), "trap must be on false projection for a range check");
const Node* cmp = bol->in(1)->as_Cmp();
Node* idx = cmp->in(1);
assert(!invar.is_invariant(idx), "index is variant");
Node* rng = cmp->in(2);
assert(rng->Opcode() == Op_LoadRange || iff->is_RangeCheck() || _igvn.type(rng)->is_int()->_lo >= 0, "must be");
assert(invar.is_invariant(rng), "range must be invariant");
int scale = 1;
Node* offset = zero;
bool ok = is_scaled_iv_plus_offset(idx, cl->phi(), &scale, &offset);
assert(ok, "must be index expression");
Node* init = cl->init_trip();
// Limit is not exact.
// Calculate exact limit here.
// Note, counted loop's test is '<' or '>'.
loop->compute_trip_count(this);
Node* limit = exact_limit(loop);
int stride = cl->stride()->get_int();
// Build if's for the upper and lower bound tests. The
// lower_bound test will dominate the upper bound test and all
// cloned or created nodes will use the lower bound test as
// their declared control.
// Perform cloning to keep Invariance state correct since the
// late schedule will place invariant things in the loop.
Node* ctrl = parse_predicate_proj->in(0)->as_If()->in(0);
rng = invar.clone(rng, ctrl);
if (offset && offset != zero) {
assert(invar.is_invariant(offset), "offset must be loop invariant");
offset = invar.clone(offset, ctrl);
}
// If predicate expressions may overflow in the integer range, longs are used.
bool overflow = false;
// Test the lower bound
BoolNode* lower_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, false, overflow);
const int if_opcode = iff->Opcode();
IfProjNode* lower_bound_proj = create_new_if_for_predicate(parse_predicate_proj, nullptr, reason, overflow ? Op_If : if_opcode);
IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If();
_igvn.hash_delete(lower_bound_iff);
lower_bound_iff->set_req(1, lower_bound_bol);
if (TraceLoopPredicate) tty->print_cr("lower bound check if: %d", lower_bound_iff->_idx);
// Test the upper bound
BoolNode* upper_bound_bol = rc_predicate(loop, lower_bound_proj, scale, offset, init, limit, stride, rng, true,
overflow);
IfProjNode* upper_bound_proj = create_new_if_for_predicate(parse_predicate_proj, nullptr, reason, overflow ? Op_If : if_opcode);
assert(upper_bound_proj->in(0)->as_If()->in(0) == lower_bound_proj, "should dominate");
IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If();
_igvn.hash_delete(upper_bound_iff);
upper_bound_iff->set_req(1, upper_bound_bol);
if (TraceLoopPredicate) tty->print_cr("upper bound check if: %d", lower_bound_iff->_idx);
// Fall through into rest of the cleanup code which will move any dependent nodes to the skeleton predicates of the
// upper bound test. We always need to create skeleton predicates in order to properly remove dead loops when later
// splitting the predicated loop into (unreachable) sub-loops (i.e. done by unrolling, peeling, pre/main/post etc.).
new_predicate_proj = add_template_assertion_predicate(iff, loop, if_success_proj, parse_predicate_proj, upper_bound_proj, scale,
offset, init, limit, stride, rng, overflow, reason);
#ifndef PRODUCT
if (TraceLoopOpts && !TraceLoopPredicate) {
tty->print("Predicate RC ");
loop->dump_head();
}
#endif
} else {
// Loop variant check (for example, range check in non-counted loop)
// with uncommon trap.
return false;
}
assert(new_predicate_proj != nullptr, "sanity");
// Success - attach condition (new_predicate_bol) to predicate if
invar.map_ctrl(if_success_proj, new_predicate_proj); // so that invariance test can be appropriate
// Eliminate the old If in the loop body
dominated_by(new_predicate_proj, iff, if_success_proj->_con != new_predicate_proj->_con);
C->set_major_progress();
return true;
}
// Each newly created Hoisted Predicate is accompanied by two Template Assertion Predicates. Later, we initialize them
// by making a copy of them when splitting a loop into sub loops. The Assertion Predicates ensure that dead sub loops
// are removed properly.
IfProjNode* PhaseIdealLoop::add_template_assertion_predicate(IfNode* iff, IdealLoopTree* loop, IfProjNode* if_proj,
IfProjNode* predicate_proj, IfProjNode* upper_bound_proj,
int scale, Node* offset, Node* init, Node* limit, jint stride,
Node* rng, bool& overflow, Deoptimization::DeoptReason reason) {
// First predicate for the initial value on first loop iteration
Node* opaque_init = new OpaqueLoopInitNode(C, init);
register_new_node(opaque_init, upper_bound_proj);
bool negate = (if_proj->_con != predicate_proj->_con);
BoolNode* bol = rc_predicate(loop, upper_bound_proj, scale, offset, opaque_init, limit, stride, rng,
(stride > 0) != (scale > 0), overflow);
Node* opaque_bol = new Opaque4Node(C, bol, _igvn.intcon(1)); // This will go away once loop opts are over
C->add_template_assertion_predicate_opaq(opaque_bol);
register_new_node(opaque_bol, upper_bound_proj);
IfProjNode* new_proj = create_new_if_for_predicate(predicate_proj, nullptr, reason, overflow ? Op_If : iff->Opcode());
_igvn.replace_input_of(new_proj->in(0), 1, opaque_bol);
assert(opaque_init->outcnt() > 0, "should be used");
// Second predicate for init + (current stride - initial stride)
// This is identical to the previous predicate initially but as
// unrolling proceeds current stride is updated.
Node* init_stride = loop->_head->as_CountedLoop()->stride();
Node* opaque_stride = new OpaqueLoopStrideNode(C, init_stride);
register_new_node(opaque_stride, new_proj);
Node* max_value = new SubINode(opaque_stride, init_stride);
register_new_node(max_value, new_proj);
max_value = new AddINode(opaque_init, max_value);
register_new_node(max_value, new_proj);
// init + (current stride - initial stride) is within the loop so narrow its type by leveraging the type of the iv Phi
max_value = new CastIINode(max_value, loop->_head->as_CountedLoop()->phi()->bottom_type());
register_new_node(max_value, predicate_proj);
bol = rc_predicate(loop, new_proj, scale, offset, max_value, limit, stride, rng, (stride > 0) != (scale > 0),
overflow);
opaque_bol = new Opaque4Node(C, bol, _igvn.intcon(1));
C->add_template_assertion_predicate_opaq(opaque_bol);
register_new_node(opaque_bol, new_proj);
new_proj = create_new_if_for_predicate(predicate_proj, nullptr, reason, overflow ? Op_If : iff->Opcode());
_igvn.replace_input_of(new_proj->in(0), 1, opaque_bol);
assert(max_value->outcnt() > 0, "should be used");
assert(assertion_predicate_has_loop_opaque_node(new_proj->in(0)->as_If()), "unexpected");
return new_proj;
}
// Insert Hoisted Predicates for null checks and range checks and additional Template Assertion Predicates for range checks.
bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) {
if (!UseLoopPredicate) return false;
if (!loop->_head->is_Loop()) {
// Could be a simple region when irreducible loops are present.
return false;
}
LoopNode* head = loop->_head->as_Loop();
if (head->unique_ctrl_out()->is_NeverBranch()) {
// do nothing for infinite loops
return false;
}
if (head->is_OuterStripMinedLoop()) {
return false;
}
CountedLoopNode *cl = nullptr;
if (head->is_valid_counted_loop(T_INT)) {
cl = head->as_CountedLoop();
// do nothing for iteration-splitted loops
if (!cl->is_normal_loop()) return false;
// Avoid RCE if Counted loop's test is '!='.
BoolTest::mask bt = cl->loopexit()->test_trip();
if (bt != BoolTest::lt && bt != BoolTest::gt)
cl = nullptr;
}
Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl);
ParsePredicates parse_predicates(entry);
bool can_create_loop_predicates = true;
// We cannot add Loop Predicates if:
// - Already added Profiled Loop Predicates (Loop Predicates and Profiled Loop Predicates can be dependent
// through a data node, and thus we should only add new Profiled Loop Predicates which are below Loop Predicates
// in the graph).
// - There are currently no Profiled Loop Predicates, but we have a data node with a control dependency on the Loop
// Parse Predicate (could happen, for example, if we've removed an earlier created Profiled Loop Predicate with
// dominated_by()). We should not create a Loop Predicate for a check that is dependent on this data node because
// the Loop Predicate would end up above the data node with its dependency on the Loop Parse Predicate below. This
// would become unschedulable. However, we can still hoist the check as Profiled Loop Predicate which would end up
// below the Loop Parse Predicate.
if (Predicates::has_profiled_loop_predicates(parse_predicates)
|| (parse_predicates.loop_predicate_proj() != nullptr && parse_predicates.loop_predicate_proj()->outcnt() != 1)) {
can_create_loop_predicates = false;
}
ParsePredicateSuccessProj* loop_predicate_proj = parse_predicates.loop_predicate_proj();
ParsePredicateSuccessProj* profiled_loop_predicate_proj = parse_predicates.profiled_loop_predicate_proj();
float loop_trip_cnt = -1;
bool follow_branches = loop_predication_should_follow_branches(loop, profiled_loop_predicate_proj, loop_trip_cnt);
assert(!follow_branches || loop_trip_cnt >= 0, "negative trip count?");
if (loop_predicate_proj == nullptr && !follow_branches) {
#ifndef PRODUCT
if (TraceLoopPredicate) {
tty->print("missing predicate:");
loop->dump_head();
head->dump(1);
}
#endif
return false;
}
ConNode* zero = _igvn.intcon(0);
set_ctrl(zero, C->root());
ResourceArea* area = Thread::current()->resource_area();
Invariance invar(area, loop);
// Create list of if-projs such that a newer proj dominates all older
// projs in the list, and they all dominate loop->tail()
Node_List if_proj_list;
Node_List regions;
Node* current_proj = loop->tail(); // start from tail
Node_List controls;
while (current_proj != head) {
if (loop == get_loop(current_proj) && // still in the loop ?
current_proj->is_Proj() && // is a projection ?
(current_proj->in(0)->Opcode() == Op_If ||
current_proj->in(0)->Opcode() == Op_RangeCheck)) { // is a if projection ?
if_proj_list.push(current_proj);
}
if (follow_branches &&
current_proj->Opcode() == Op_Region &&
loop == get_loop(current_proj)) {
regions.push(current_proj);
}
current_proj = idom(current_proj);
}
bool hoisted = false; // true if at least one proj is promoted
if (can_create_loop_predicates) {
while (if_proj_list.size() > 0) {
Node* n = if_proj_list.pop();
IfProjNode* if_proj = n->as_IfProj();
IfNode* iff = if_proj->in(0)->as_If();
CallStaticJavaNode* call = if_proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
if (call == nullptr) {
if (loop->is_loop_exit(iff)) {
// stop processing the remaining projs in the list because the execution of them
// depends on the condition of "iff" (iff->in(1)).
break;
} else {
// Both arms are inside the loop. There are two cases:
// (1) there is one backward branch. In this case, any remaining proj
// in the if_proj list post-dominates "iff". So, the condition of "iff"
// does not determine the execution the remaining projs directly, and we
// can safely continue.
// (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj"
// does not dominate loop->tail(), so it can not be in the if_proj list.
continue;
}
}
Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(call->uncommon_trap_request());
if (reason == Deoptimization::Reason_predicate) {
break;
}
if (loop_predicate_proj != nullptr) {
hoisted = loop_predication_impl_helper(loop, if_proj, loop_predicate_proj, cl, zero, invar,
Deoptimization::Reason_predicate) | hoisted;
}
} // end while
}
if (follow_branches) {
assert(profiled_loop_predicate_proj != nullptr, "sanity check");
PathFrequency pf(loop->_head, this);
// Some projections were skipped by regular predicates because of
// an early loop exit. Try them with profile data.
while (if_proj_list.size() > 0) {
Node* if_proj = if_proj_list.pop();
float f = pf.to(if_proj);
if (if_proj->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none) &&
f * loop_trip_cnt >= 1) {
hoisted = loop_predication_impl_helper(loop, if_proj->as_IfProj(), profiled_loop_predicate_proj, cl, zero, invar,
Deoptimization::Reason_profile_predicate) | hoisted;
}
}
// And look into all branches
Node_Stack stack(0);
VectorSet seen;
Node_List if_proj_list_freq(area);
while (regions.size() > 0) {
Node* c = regions.pop();
loop_predication_follow_branches(c, loop, loop_trip_cnt, pf, stack, seen, if_proj_list_freq);
}
for (uint i = 0; i < if_proj_list_freq.size(); i++) {
IfProjNode* if_proj = if_proj_list_freq.at(i)->as_IfProj();
hoisted = loop_predication_impl_helper(loop, if_proj, profiled_loop_predicate_proj, cl, zero, invar, Deoptimization::Reason_profile_predicate) | hoisted;
}
}
#ifndef PRODUCT
// report that the loop predication has been actually performed
// for this loop
if (TraceLoopPredicate && hoisted) {
tty->print("Loop Predication Performed:");
loop->dump_head();
}
#endif
head->verify_strip_mined(1);
return hoisted;
}
//------------------------------loop_predication--------------------------------
// driver routine for loop predication optimization
bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) {
bool hoisted = false;
// Recursively promote predicates
if (_child) {
hoisted = _child->loop_predication( phase);
}
// self
if (!_irreducible && !tail()->is_top()) {
hoisted |= phase->loop_predication_impl(this);
}
if (_next) { //sibling
hoisted |= _next->loop_predication( phase);
}
return hoisted;
}
// Skip over all predicates (all Regular Predicate Blocks) starting at the Parse Predicate projection 'node'. Return the
// first node that is not a predicate If node anymore (i.e. entry into the first predicate If on top) or 'node' if 'node'
// is not a Parse Predicate projection.
Node* Predicates::skip_all_predicates(Node* node) {
ParsePredicates parse_predicates(node);
if (parse_predicates.has_any()) {
return skip_all_predicates(parse_predicates);
} else {
return node;
}
}
// Skip over all Runtime Predicates belonging to the given Parse Predicates. Return the first node that is not a predicate
// If node anymore (i.e. entry into the first predicate If on top).
Node* Predicates::skip_all_predicates(ParsePredicates& parse_predicates) {
assert(parse_predicates.has_any(), "must have at least one Parse Predicate");
return skip_predicates_in_block(parse_predicates.get_top_predicate_proj());
}
// Skip over all predicates in a Regular Predicate Block starting at the Parse Predicate projection
// 'parse_predicate_success_proj'. Return the first node not belonging this block anymore (i.e. entry
// into this Regular Predicate Block).
Node* Predicates::skip_predicates_in_block(ParsePredicateSuccessProj* parse_predicate_success_proj) {
IfProjNode* prev;
IfProjNode* next = parse_predicate_success_proj;
do {
prev = next;
next = next_predicate_proj_in_block(next);
} while (next != nullptr);
assert(prev->in(0)->is_If(), "must be predicate If");
return prev->in(0)->in(0);
}
// Find next Runtime Predicate projection in a Regular Predicate Block or return null if there is none.
IfProjNode* Predicates::next_predicate_proj_in_block(IfProjNode* proj) {
IfNode* iff = proj->in(0)->as_If();
ProjNode* uncommon_proj = iff->proj_out(1 - proj->_con);
Node* rgn = uncommon_proj->unique_ctrl_out();
assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
Node* next = iff->in(0);
if (next != nullptr && next->is_Proj() && next->in(0)->is_If()) {
uncommon_proj = next->in(0)->as_If()->proj_out(1 - next->as_Proj()->_con);
if (uncommon_proj->unique_ctrl_out() == rgn) {
// Same Runtime Predicate Block.
return next->as_IfProj();
}
}
return nullptr;
}
// Is there at least one Profiled Loop Predicate?
bool Predicates::has_profiled_loop_predicates(ParsePredicates& parse_predicates) {
ParsePredicateSuccessProj* profiled_loop_predicate = parse_predicates.profiled_loop_predicate_proj();
if (profiled_loop_predicate == nullptr) {
return false;
}
return Predicates::next_predicate_proj_in_block(profiled_loop_predicate) != nullptr;
}
// Given a node 'starting_proj', check if it is a Parse Predicate success projection.
// If so, find all Parse Predicates above the loop.
ParsePredicates::ParsePredicates(Node* starting_proj) : _top_predicate_proj(nullptr), _starting_proj(nullptr) {
if (starting_proj == nullptr || !starting_proj->is_IfTrue()) {
return; // Not a predicate.
}
_starting_proj = starting_proj->as_IfTrue();
find_parse_predicate_projections();
}
void ParsePredicates::find_parse_predicate_projections() {
Node* maybe_parse_predicate_proj = _starting_proj;
for (int i = 0; i < 3; i++) { // At most 3 Parse Predicates for a loop
if (!is_success_proj(maybe_parse_predicate_proj)) {
break;
}
ParsePredicateSuccessProj* parse_predicate_proj = maybe_parse_predicate_proj->as_IfTrue();
if (!assign_predicate_proj(parse_predicate_proj)) {
// Found a Parse Predicate of another (already removed) loop.
break;
}
_top_predicate_proj = parse_predicate_proj;
maybe_parse_predicate_proj = Predicates::skip_predicates_in_block(parse_predicate_proj);
}
}
// Is 'node' a success (non-UCT) projection of a Parse Predicate?
bool ParsePredicates::is_success_proj(Node* node) {
if (node == nullptr || !node->is_Proj()) {
return false;
}
ParsePredicateNode* parse_predicate = get_parse_predicate_or_null(node);
if (parse_predicate == nullptr) {
return false;
}
return !is_uct_proj(node, parse_predicate->deopt_reason());
}
// Is 'node' a UCT projection of a Parse Predicate of kind 'kind'?
bool ParsePredicates::is_uct_proj(Node* node, Deoptimization::DeoptReason deopt_reason) {
return node->as_Proj()->is_uncommon_trap_proj(deopt_reason);
}
// Check the parent of `parse_predicate_proj` is a ParsePredicateNode. If so return it. Otherwise, return null.
ParsePredicateNode* ParsePredicates::get_parse_predicate_or_null(Node* parse_predicate_proj) {
return parse_predicate_proj->in(0)->isa_ParsePredicate();
}
// Initialize the Parse Predicate projection field that matches the kind of the parent of `parse_predicate_proj`.
bool ParsePredicates::assign_predicate_proj(ParsePredicateSuccessProj* parse_predicate_proj) {
ParsePredicateNode* parse_predicate = get_parse_predicate_or_null(parse_predicate_proj);
assert(parse_predicate != nullptr, "must exist");
Deoptimization::DeoptReason deopt_reason = parse_predicate->deopt_reason();
switch (deopt_reason) {
case Deoptimization::DeoptReason::Reason_predicate:
if (_loop_predicate_proj != nullptr) {
return false;
}
_loop_predicate_proj = parse_predicate_proj;
break;
case Deoptimization::DeoptReason::Reason_profile_predicate:
if (_profiled_loop_predicate_proj != nullptr) {
return false;
}
_profiled_loop_predicate_proj = parse_predicate_proj;
break;
case Deoptimization::DeoptReason::Reason_loop_limit_check:
if (_loop_limit_check_predicate_proj != nullptr) {
return false;
}
_loop_limit_check_predicate_proj = parse_predicate_proj;
break;
default:
fatal("invalid case");
}
return true;
}
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