JDK14/Java14源码在线阅读
/*
* Copyright (c) 1998, 2019, 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
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*/
#include "precompiled.hpp"
#include "ci/ciMethodData.hpp"
#include "compiler/compileLog.hpp"
#include "gc/shared/barrierSet.hpp"
#include "gc/shared/c2/barrierSetC2.hpp"
#include "libadt/vectset.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
#include "opto/addnode.hpp"
#include "opto/callnode.hpp"
#include "opto/connode.hpp"
#include "opto/convertnode.hpp"
#include "opto/divnode.hpp"
#include "opto/idealGraphPrinter.hpp"
#include "opto/loopnode.hpp"
#include "opto/mulnode.hpp"
#include "opto/rootnode.hpp"
#include "opto/superword.hpp"
//=============================================================================
//--------------------------is_cloop_ind_var-----------------------------------
// Determine if a node is a counted loop induction variable.
// NOTE: The method is declared in "node.hpp".
bool Node::is_cloop_ind_var() const {
return (is_Phi() && !as_Phi()->is_copy() &&
as_Phi()->region()->is_CountedLoop() &&
as_Phi()->region()->as_CountedLoop()->phi() == this);
}
//=============================================================================
//------------------------------dump_spec--------------------------------------
// Dump special per-node info
#ifndef PRODUCT
void LoopNode::dump_spec(outputStream *st) const {
if (is_inner_loop()) st->print( "inner " );
if (is_partial_peel_loop()) st->print( "partial_peel " );
if (partial_peel_has_failed()) st->print( "partial_peel_failed " );
}
#endif
//------------------------------is_valid_counted_loop-------------------------
bool LoopNode::is_valid_counted_loop() const {
if (is_CountedLoop()) {
CountedLoopNode* l = as_CountedLoop();
CountedLoopEndNode* le = l->loopexit_or_null();
if (le != NULL &&
le->proj_out_or_null(1 /* true */) == l->in(LoopNode::LoopBackControl)) {
Node* phi = l->phi();
Node* exit = le->proj_out_or_null(0 /* false */);
if (exit != NULL && exit->Opcode() == Op_IfFalse &&
phi != NULL && phi->is_Phi() &&
phi->in(LoopNode::LoopBackControl) == l->incr() &&
le->loopnode() == l && le->stride_is_con()) {
return true;
}
}
}
return false;
}
//------------------------------get_early_ctrl---------------------------------
// Compute earliest legal control
Node *PhaseIdealLoop::get_early_ctrl( Node *n ) {
assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" );
uint i;
Node *early;
if (n->in(0) && !n->is_expensive()) {
early = n->in(0);
if (!early->is_CFG()) // Might be a non-CFG multi-def
early = get_ctrl(early); // So treat input as a straight data input
i = 1;
} else {
early = get_ctrl(n->in(1));
i = 2;
}
uint e_d = dom_depth(early);
assert( early, "" );
for (; i < n->req(); i++) {
Node *cin = get_ctrl(n->in(i));
assert( cin, "" );
// Keep deepest dominator depth
uint c_d = dom_depth(cin);
if (c_d > e_d) { // Deeper guy?
early = cin; // Keep deepest found so far
e_d = c_d;
} else if (c_d == e_d && // Same depth?
early != cin) { // If not equal, must use slower algorithm
// If same depth but not equal, one _must_ dominate the other
// and we want the deeper (i.e., dominated) guy.
Node *n1 = early;
Node *n2 = cin;
while (1) {
n1 = idom(n1); // Walk up until break cycle
n2 = idom(n2);
if (n1 == cin || // Walked early up to cin
dom_depth(n2) < c_d)
break; // early is deeper; keep him
if (n2 == early || // Walked cin up to early
dom_depth(n1) < c_d) {
early = cin; // cin is deeper; keep him
break;
}
}
e_d = dom_depth(early); // Reset depth register cache
}
}
// Return earliest legal location
assert(early == find_non_split_ctrl(early), "unexpected early control");
if (n->is_expensive() && !_verify_only && !_verify_me) {
assert(n->in(0), "should have control input");
early = get_early_ctrl_for_expensive(n, early);
}
return early;
}
//------------------------------get_early_ctrl_for_expensive---------------------------------
// Move node up the dominator tree as high as legal while still beneficial
Node *PhaseIdealLoop::get_early_ctrl_for_expensive(Node *n, Node* earliest) {
assert(n->in(0) && n->is_expensive(), "expensive node with control input here");
assert(OptimizeExpensiveOps, "optimization off?");
Node* ctl = n->in(0);
assert(ctl->is_CFG(), "expensive input 0 must be cfg");
uint min_dom_depth = dom_depth(earliest);
#ifdef ASSERT
if (!is_dominator(ctl, earliest) && !is_dominator(earliest, ctl)) {
dump_bad_graph("Bad graph detected in get_early_ctrl_for_expensive", n, earliest, ctl);
assert(false, "Bad graph detected in get_early_ctrl_for_expensive");
}
#endif
if (dom_depth(ctl) < min_dom_depth) {
return earliest;
}
while (1) {
Node *next = ctl;
// Moving the node out of a loop on the projection of a If
// confuses loop predication. So once we hit a Loop in a If branch
// that doesn't branch to an UNC, we stop. The code that process
// expensive nodes will notice the loop and skip over it to try to
// move the node further up.
if (ctl->is_CountedLoop() && ctl->in(1) != NULL && ctl->in(1)->in(0) != NULL && ctl->in(1)->in(0)->is_If()) {
if (!ctl->in(1)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
break;
}
next = idom(ctl->in(1)->in(0));
} else if (ctl->is_Proj()) {
// We only move it up along a projection if the projection is
// the single control projection for its parent: same code path,
// if it's a If with UNC or fallthrough of a call.
Node* parent_ctl = ctl->in(0);
if (parent_ctl == NULL) {
break;
} else if (parent_ctl->is_CountedLoopEnd() && parent_ctl->as_CountedLoopEnd()->loopnode() != NULL) {
next = parent_ctl->as_CountedLoopEnd()->loopnode()->init_control();
} else if (parent_ctl->is_If()) {
if (!ctl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
break;
}
assert(idom(ctl) == parent_ctl, "strange");
next = idom(parent_ctl);
} else if (ctl->is_CatchProj()) {
if (ctl->as_Proj()->_con != CatchProjNode::fall_through_index) {
break;
}
assert(parent_ctl->in(0)->in(0)->is_Call(), "strange graph");
next = parent_ctl->in(0)->in(0)->in(0);
} else {
// Check if parent control has a single projection (this
// control is the only possible successor of the parent
// control). If so, we can try to move the node above the
// parent control.
int nb_ctl_proj = 0;
for (DUIterator_Fast imax, i = parent_ctl->fast_outs(imax); i < imax; i++) {
Node *p = parent_ctl->fast_out(i);
if (p->is_Proj() && p->is_CFG()) {
nb_ctl_proj++;
if (nb_ctl_proj > 1) {
break;
}
}
}
if (nb_ctl_proj > 1) {
break;
}
assert(parent_ctl->is_Start() || parent_ctl->is_MemBar() || parent_ctl->is_Call() ||
BarrierSet::barrier_set()->barrier_set_c2()->is_gc_barrier_node(parent_ctl), "unexpected node");
assert(idom(ctl) == parent_ctl, "strange");
next = idom(parent_ctl);
}
} else {
next = idom(ctl);
}
if (next->is_Root() || next->is_Start() || dom_depth(next) < min_dom_depth) {
break;
}
ctl = next;
}
if (ctl != n->in(0)) {
_igvn.replace_input_of(n, 0, ctl);
_igvn.hash_insert(n);
}
return ctl;
}
//------------------------------set_early_ctrl---------------------------------
// Set earliest legal control
void PhaseIdealLoop::set_early_ctrl( Node *n ) {
Node *early = get_early_ctrl(n);
// Record earliest legal location
set_ctrl(n, early);
}
//------------------------------set_subtree_ctrl-------------------------------
// set missing _ctrl entries on new nodes
void PhaseIdealLoop::set_subtree_ctrl( Node *n ) {
// Already set? Get out.
if( _nodes[n->_idx] ) return;
// Recursively set _nodes array to indicate where the Node goes
uint i;
for( i = 0; i < n->req(); ++i ) {
Node *m = n->in(i);
if( m && m != C->root() )
set_subtree_ctrl( m );
}
// Fixup self
set_early_ctrl( n );
}
// Create a skeleton strip mined outer loop: a Loop head before the
// inner strip mined loop, a safepoint and an exit condition guarded
// by an opaque node after the inner strip mined loop with a backedge
// to the loop head. The inner strip mined loop is left as it is. Only
// once loop optimizations are over, do we adjust the inner loop exit
// condition to limit its number of iterations, set the outer loop
// exit condition and add Phis to the outer loop head. Some loop
// optimizations that operate on the inner strip mined loop need to be
// aware of the outer strip mined loop: loop unswitching needs to
// clone the outer loop as well as the inner, unrolling needs to only
// clone the inner loop etc. No optimizations need to change the outer
// strip mined loop as it is only a skeleton.
IdealLoopTree* PhaseIdealLoop::create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
IdealLoopTree* loop, float cl_prob, float le_fcnt,
Node*& entry_control, Node*& iffalse) {
Node* outer_test = _igvn.intcon(0);
set_ctrl(outer_test, C->root());
Node *orig = iffalse;
iffalse = iffalse->clone();
_igvn.register_new_node_with_optimizer(iffalse);
set_idom(iffalse, idom(orig), dom_depth(orig));
IfNode *outer_le = new OuterStripMinedLoopEndNode(iffalse, outer_test, cl_prob, le_fcnt);
Node *outer_ift = new IfTrueNode (outer_le);
Node* outer_iff = orig;
_igvn.replace_input_of(outer_iff, 0, outer_le);
LoopNode *outer_l = new OuterStripMinedLoopNode(C, init_control, outer_ift);
entry_control = outer_l;
IdealLoopTree* outer_ilt = new IdealLoopTree(this, outer_l, outer_ift);
IdealLoopTree* parent = loop->_parent;
IdealLoopTree* sibling = parent->_child;
if (sibling == loop) {
parent->_child = outer_ilt;
} else {
while (sibling->_next != loop) {
sibling = sibling->_next;
}
sibling->_next = outer_ilt;
}
outer_ilt->_next = loop->_next;
outer_ilt->_parent = parent;
outer_ilt->_child = loop;
outer_ilt->_nest = loop->_nest;
loop->_parent = outer_ilt;
loop->_next = NULL;
loop->_nest++;
set_loop(iffalse, outer_ilt);
register_control(outer_le, outer_ilt, iffalse);
register_control(outer_ift, outer_ilt, outer_le);
set_idom(outer_iff, outer_le, dom_depth(outer_le));
_igvn.register_new_node_with_optimizer(outer_l);
set_loop(outer_l, outer_ilt);
set_idom(outer_l, init_control, dom_depth(init_control)+1);
return outer_ilt;
}
void PhaseIdealLoop::insert_loop_limit_check(ProjNode* limit_check_proj, Node* cmp_limit, Node* bol) {
Node* new_predicate_proj = create_new_if_for_predicate(limit_check_proj, NULL,
Deoptimization::Reason_loop_limit_check,
Op_If);
Node* iff = new_predicate_proj->in(0);
assert(iff->Opcode() == Op_If, "bad graph shape");
Node* conv = iff->in(1);
assert(conv->Opcode() == Op_Conv2B, "bad graph shape");
Node* opaq = conv->in(1);
assert(opaq->Opcode() == Op_Opaque1, "bad graph shape");
cmp_limit = _igvn.register_new_node_with_optimizer(cmp_limit);
bol = _igvn.register_new_node_with_optimizer(bol);
set_subtree_ctrl(bol);
_igvn.replace_input_of(iff, 1, bol);
#ifndef PRODUCT
// report that the loop predication has been actually performed
// for this loop
if (TraceLoopLimitCheck) {
tty->print_cr("Counted Loop Limit Check generated:");
debug_only( bol->dump(2); )
}
#endif
}
//------------------------------is_counted_loop--------------------------------
bool PhaseIdealLoop::is_counted_loop(Node* x, IdealLoopTree*& loop) {
PhaseGVN *gvn = &_igvn;
// Counted loop head must be a good RegionNode with only 3 not NULL
// control input edges: Self, Entry, LoopBack.
if (x->in(LoopNode::Self) == NULL || x->req() != 3 || loop->_irreducible) {
return false;
}
Node *init_control = x->in(LoopNode::EntryControl);
Node *back_control = x->in(LoopNode::LoopBackControl);
if (init_control == NULL || back_control == NULL) // Partially dead
return false;
// Must also check for TOP when looking for a dead loop
if (init_control->is_top() || back_control->is_top())
return false;
// Allow funny placement of Safepoint
if (back_control->Opcode() == Op_SafePoint) {
if (LoopStripMiningIter != 0) {
// Leaving the safepoint on the backedge and creating a
// CountedLoop will confuse optimizations. We can't move the
// safepoint around because its jvm state wouldn't match a new
// location. Give up on that loop.
return false;
}
back_control = back_control->in(TypeFunc::Control);
}
// Controlling test for loop
Node *iftrue = back_control;
uint iftrue_op = iftrue->Opcode();
if (iftrue_op != Op_IfTrue &&
iftrue_op != Op_IfFalse)
// I have a weird back-control. Probably the loop-exit test is in
// the middle of the loop and I am looking at some trailing control-flow
// merge point. To fix this I would have to partially peel the loop.
return false; // Obscure back-control
// Get boolean guarding loop-back test
Node *iff = iftrue->in(0);
if (get_loop(iff) != loop || !iff->in(1)->is_Bool())
return false;
BoolNode *test = iff->in(1)->as_Bool();
BoolTest::mask bt = test->_test._test;
float cl_prob = iff->as_If()->_prob;
if (iftrue_op == Op_IfFalse) {
bt = BoolTest(bt).negate();
cl_prob = 1.0 - cl_prob;
}
// Get backedge compare
Node *cmp = test->in(1);
int cmp_op = cmp->Opcode();
if (cmp_op != Op_CmpI)
return false; // Avoid pointer & float compares
// Find the trip-counter increment & limit. Limit must be loop invariant.
Node *incr = cmp->in(1);
Node *limit = cmp->in(2);
// ---------
// need 'loop()' test to tell if limit is loop invariant
// ---------
if (!is_member(loop, get_ctrl(incr))) { // Swapped trip counter and limit?
Node *tmp = incr; // Then reverse order into the CmpI
incr = limit;
limit = tmp;
bt = BoolTest(bt).commute(); // And commute the exit test
}
if (is_member(loop, get_ctrl(limit))) // Limit must be loop-invariant
return false;
if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
return false;
Node* phi_incr = NULL;
// Trip-counter increment must be commutative & associative.
if (incr->Opcode() == Op_CastII) {
incr = incr->in(1);
}
if (incr->is_Phi()) {
if (incr->as_Phi()->region() != x || incr->req() != 3)
return false; // Not simple trip counter expression
phi_incr = incr;
incr = phi_incr->in(LoopNode::LoopBackControl); // Assume incr is on backedge of Phi
if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
return false;
}
Node* trunc1 = NULL;
Node* trunc2 = NULL;
const TypeInt* iv_trunc_t = NULL;
Node* orig_incr = incr;
if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t))) {
return false; // Funny increment opcode
}
assert(incr->Opcode() == Op_AddI, "wrong increment code");
const TypeInt* limit_t = gvn->type(limit)->is_int();
if (trunc1 != NULL) {
// When there is a truncation, we must be sure that after the truncation
// the trip counter will end up higher than the limit, otherwise we are looking
// at an endless loop. Can happen with range checks.
// Example:
// int i = 0;
// while (true)
// sum + = array[i];
// i++;
// i = i && 0x7fff;
// }
//
// If the array is shorter than 0x8000 this exits through a AIOOB
// - Counted loop transformation is ok
// If the array is longer then this is an endless loop
// - No transformation can be done.
const TypeInt* incr_t = gvn->type(orig_incr)->is_int();
if (limit_t->_hi > incr_t->_hi) {
// if the limit can have a higher value than the increment (before the phi)
return false;
}
}
// Get merge point
Node *xphi = incr->in(1);
Node *stride = incr->in(2);
if (!stride->is_Con()) { // Oops, swap these
if (!xphi->is_Con()) // Is the other guy a constant?
return false; // Nope, unknown stride, bail out
Node *tmp = xphi; // 'incr' is commutative, so ok to swap
xphi = stride;
stride = tmp;
}
if (xphi->Opcode() == Op_CastII) {
xphi = xphi->in(1);
}
// Stride must be constant
int stride_con = stride->get_int();
if (stride_con == 0)
return false; // missed some peephole opt
if (!xphi->is_Phi())
return false; // Too much math on the trip counter
if (phi_incr != NULL && phi_incr != xphi)
return false;
PhiNode *phi = xphi->as_Phi();
// Phi must be of loop header; backedge must wrap to increment
if (phi->region() != x)
return false;
if ((trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr) ||
(trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1)) {
return false;
}
Node *init_trip = phi->in(LoopNode::EntryControl);
// If iv trunc type is smaller than int, check for possible wrap.
if (!TypeInt::INT->higher_equal(iv_trunc_t)) {
assert(trunc1 != NULL, "must have found some truncation");
// Get a better type for the phi (filtered thru if's)
const TypeInt* phi_ft = filtered_type(phi);
// Can iv take on a value that will wrap?
//
// Ensure iv's limit is not within "stride" of the wrap value.
//
// Example for "short" type
// Truncation ensures value is in the range -32768..32767 (iv_trunc_t)
// If the stride is +10, then the last value of the induction
// variable before the increment (phi_ft->_hi) must be
// <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to
// ensure no truncation occurs after the increment.
if (stride_con > 0) {
if (iv_trunc_t->_hi - phi_ft->_hi < stride_con ||
iv_trunc_t->_lo > phi_ft->_lo) {
return false; // truncation may occur
}
} else if (stride_con < 0) {
if (iv_trunc_t->_lo - phi_ft->_lo > stride_con ||
iv_trunc_t->_hi < phi_ft->_hi) {
return false; // truncation may occur
}
}
// No possibility of wrap so truncation can be discarded
// Promote iv type to Int
} else {
assert(trunc1 == NULL && trunc2 == NULL, "no truncation for int");
}
// If the condition is inverted and we will be rolling
// through MININT to MAXINT, then bail out.
if (bt == BoolTest::eq || // Bail out, but this loop trips at most twice!
// Odd stride
(bt == BoolTest::ne && stride_con != 1 && stride_con != -1) ||
// Count down loop rolls through MAXINT
((bt == BoolTest::le || bt == BoolTest::lt) && stride_con < 0) ||
// Count up loop rolls through MININT
((bt == BoolTest::ge || bt == BoolTest::gt) && stride_con > 0)) {
return false; // Bail out
}
const TypeInt* init_t = gvn->type(init_trip)->is_int();
if (stride_con > 0) {
jlong init_p = (jlong)init_t->_lo + stride_con;
if (init_p > (jlong)max_jint || init_p > (jlong)limit_t->_hi)
return false; // cyclic loop or this loop trips only once
} else {
jlong init_p = (jlong)init_t->_hi + stride_con;
if (init_p < (jlong)min_jint || init_p < (jlong)limit_t->_lo)
return false; // cyclic loop or this loop trips only once
}
if (phi_incr != NULL && bt != BoolTest::ne) {
// check if there is a possiblity of IV overflowing after the first increment
if (stride_con > 0) {
if (init_t->_hi > max_jint - stride_con) {
return false;
}
} else {
if (init_t->_lo < min_jint - stride_con) {
return false;
}
}
}
// =================================================
// ---- SUCCESS! Found A Trip-Counted Loop! -----
//
assert(x->Opcode() == Op_Loop, "regular loops only");
C->print_method(PHASE_BEFORE_CLOOPS, 3);
Node *hook = new Node(6);
// ===================================================
// Generate loop limit check to avoid integer overflow
// in cases like next (cyclic loops):
//
// for (i=0; i <= max_jint; i++) {}
// for (i=0; i < max_jint; i+=2) {}
//
//
// Limit check predicate depends on the loop test:
//
// for(;i != limit; i++) --> limit <= (max_jint)
// for(;i < limit; i+=stride) --> limit <= (max_jint - stride + 1)
// for(;i <= limit; i+=stride) --> limit <= (max_jint - stride )
//
// Check if limit is excluded to do more precise int overflow check.
bool incl_limit = (bt == BoolTest::le || bt == BoolTest::ge);
int stride_m = stride_con - (incl_limit ? 0 : (stride_con > 0 ? 1 : -1));
// If compare points directly to the phi we need to adjust
// the compare so that it points to the incr. Limit have
// to be adjusted to keep trip count the same and the
// adjusted limit should be checked for int overflow.
if (phi_incr != NULL) {
stride_m += stride_con;
}
if (limit->is_Con()) {
int limit_con = limit->get_int();
if ((stride_con > 0 && limit_con > (max_jint - stride_m)) ||
(stride_con < 0 && limit_con < (min_jint - stride_m))) {
// Bailout: it could be integer overflow.
return false;
}
} else if ((stride_con > 0 && limit_t->_hi <= (max_jint - stride_m)) ||
(stride_con < 0 && limit_t->_lo >= (min_jint - stride_m))) {
// Limit's type may satisfy the condition, for example,
// when it is an array length.
} else {
// Generate loop's limit check.
// Loop limit check predicate should be near the loop.
ProjNode *limit_check_proj = find_predicate_insertion_point(init_control, Deoptimization::Reason_loop_limit_check);
if (!limit_check_proj) {
// The limit check predicate is not generated if this method trapped here before.
#ifdef ASSERT
if (TraceLoopLimitCheck) {
tty->print("missing loop limit check:");
loop->dump_head();
x->dump(1);
}
#endif
return false;
}
IfNode* check_iff = limit_check_proj->in(0)->as_If();
if (!is_dominator(get_ctrl(limit), check_iff->in(0))) {
return false;
}
Node* cmp_limit;
Node* bol;
if (stride_con > 0) {
cmp_limit = new CmpINode(limit, _igvn.intcon(max_jint - stride_m));
bol = new BoolNode(cmp_limit, BoolTest::le);
} else {
cmp_limit = new CmpINode(limit, _igvn.intcon(min_jint - stride_m));
bol = new BoolNode(cmp_limit, BoolTest::ge);
}
insert_loop_limit_check(limit_check_proj, cmp_limit, bol);
}
// Now we need to canonicalize loop condition.
if (bt == BoolTest::ne) {
assert(stride_con == 1 || stride_con == -1, "simple increment only");
if (stride_con > 0 && init_t->_hi < limit_t->_lo) {
// 'ne' can be replaced with 'lt' only when init < limit.
bt = BoolTest::lt;
} else if (stride_con < 0 && init_t->_lo > limit_t->_hi) {
// 'ne' can be replaced with 'gt' only when init > limit.
bt = BoolTest::gt;
} else {
ProjNode *limit_check_proj = find_predicate_insertion_point(init_control, Deoptimization::Reason_loop_limit_check);
if (!limit_check_proj) {
// The limit check predicate is not generated if this method trapped here before.
#ifdef ASSERT
if (TraceLoopLimitCheck) {
tty->print("missing loop limit check:");
loop->dump_head();
x->dump(1);
}
#endif
return false;
}
IfNode* check_iff = limit_check_proj->in(0)->as_If();
if (!is_dominator(get_ctrl(limit), check_iff->in(0)) ||
!is_dominator(get_ctrl(init_trip), check_iff->in(0))) {
return false;
}
Node* cmp_limit;
Node* bol;
if (stride_con > 0) {
cmp_limit = new CmpINode(init_trip, limit);
bol = new BoolNode(cmp_limit, BoolTest::lt);
} else {
cmp_limit = new CmpINode(init_trip, limit);
bol = new BoolNode(cmp_limit, BoolTest::gt);
}
insert_loop_limit_check(limit_check_proj, cmp_limit, bol);
if (stride_con > 0) {
// 'ne' can be replaced with 'lt' only when init < limit.
bt = BoolTest::lt;
} else if (stride_con < 0) {
// 'ne' can be replaced with 'gt' only when init > limit.
bt = BoolTest::gt;
}
}
}
if (phi_incr != NULL) {
// If compare points directly to the phi we need to adjust
// the compare so that it points to the incr. Limit have
// to be adjusted to keep trip count the same and we
// should avoid int overflow.
//
// i = init; do {} while(i++ < limit);
// is converted to
// i = init; do {} while(++i < limit+1);
//
limit = gvn->transform(new AddINode(limit, stride));
}
if (incl_limit) {
// The limit check guaranties that 'limit <= (max_jint - stride)' so
// we can convert 'i <= limit' to 'i < limit+1' since stride != 0.
//
Node* one = (stride_con > 0) ? gvn->intcon( 1) : gvn->intcon(-1);
limit = gvn->transform(new AddINode(limit, one));
if (bt == BoolTest::le)
bt = BoolTest::lt;
else if (bt == BoolTest::ge)
bt = BoolTest::gt;
else
ShouldNotReachHere();
}
set_subtree_ctrl( limit );
if (LoopStripMiningIter == 0) {
// Check for SafePoint on backedge and remove
Node *sfpt = x->in(LoopNode::LoopBackControl);
if (sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) {
lazy_replace( sfpt, iftrue );
if (loop->_safepts != NULL) {
loop->_safepts->yank(sfpt);
}
loop->_tail = iftrue;
}
}
// Build a canonical trip test.
// Clone code, as old values may be in use.
incr = incr->clone();
incr->set_req(1,phi);
incr->set_req(2,stride);
incr = _igvn.register_new_node_with_optimizer(incr);
set_early_ctrl( incr );
_igvn.rehash_node_delayed(phi);
phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn );
// If phi type is more restrictive than Int, raise to
// Int to prevent (almost) infinite recursion in igvn
// which can only handle integer types for constants or minint..maxint.
if (!TypeInt::INT->higher_equal(phi->bottom_type())) {
Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInt::INT);
nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl));
nphi = _igvn.register_new_node_with_optimizer(nphi);
set_ctrl(nphi, get_ctrl(phi));
_igvn.replace_node(phi, nphi);
phi = nphi->as_Phi();
}
cmp = cmp->clone();
cmp->set_req(1,incr);
cmp->set_req(2,limit);
cmp = _igvn.register_new_node_with_optimizer(cmp);
set_ctrl(cmp, iff->in(0));
test = test->clone()->as_Bool();
(*(BoolTest*)&test->_test)._test = bt;
test->set_req(1,cmp);
_igvn.register_new_node_with_optimizer(test);
set_ctrl(test, iff->in(0));
// Replace the old IfNode with a new LoopEndNode
Node *lex = _igvn.register_new_node_with_optimizer(new CountedLoopEndNode( iff->in(0), test, cl_prob, iff->as_If()->_fcnt ));
IfNode *le = lex->as_If();
uint dd = dom_depth(iff);
set_idom(le, le->in(0), dd); // Update dominance for loop exit
set_loop(le, loop);
// Get the loop-exit control
Node *iffalse = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue));
// Need to swap loop-exit and loop-back control?
if (iftrue_op == Op_IfFalse) {
Node *ift2=_igvn.register_new_node_with_optimizer(new IfTrueNode (le));
Node *iff2=_igvn.register_new_node_with_optimizer(new IfFalseNode(le));
loop->_tail = back_control = ift2;
set_loop(ift2, loop);
set_loop(iff2, get_loop(iffalse));
// Lazy update of 'get_ctrl' mechanism.
lazy_replace(iffalse, iff2);
lazy_replace(iftrue, ift2);
// Swap names
iffalse = iff2;
iftrue = ift2;
} else {
_igvn.rehash_node_delayed(iffalse);
_igvn.rehash_node_delayed(iftrue);
iffalse->set_req_X( 0, le, &_igvn );
iftrue ->set_req_X( 0, le, &_igvn );
}
set_idom(iftrue, le, dd+1);
set_idom(iffalse, le, dd+1);
assert(iff->outcnt() == 0, "should be dead now");
lazy_replace( iff, le ); // fix 'get_ctrl'
Node *sfpt2 = le->in(0);
Node* entry_control = init_control;
bool strip_mine_loop = LoopStripMiningIter > 1 && loop->_child == NULL &&
sfpt2->Opcode() == Op_SafePoint && !loop->_has_call;
IdealLoopTree* outer_ilt = NULL;
if (strip_mine_loop) {
outer_ilt = create_outer_strip_mined_loop(test, cmp, init_control, loop,
cl_prob, le->_fcnt, entry_control,
iffalse);
}
// Now setup a new CountedLoopNode to replace the existing LoopNode
CountedLoopNode *l = new CountedLoopNode(entry_control, back_control);
l->set_unswitch_count(x->as_Loop()->unswitch_count()); // Preserve
// The following assert is approximately true, and defines the intention
// of can_be_counted_loop. It fails, however, because phase->type
// is not yet initialized for this loop and its parts.
//assert(l->can_be_counted_loop(this), "sanity");
_igvn.register_new_node_with_optimizer(l);
set_loop(l, loop);
loop->_head = l;
// Fix all data nodes placed at the old loop head.
// Uses the lazy-update mechanism of 'get_ctrl'.
lazy_replace( x, l );
set_idom(l, entry_control, dom_depth(entry_control) + 1);
if (LoopStripMiningIter == 0 || strip_mine_loop) {
// Check for immediately preceding SafePoint and remove
if (sfpt2->Opcode() == Op_SafePoint && (LoopStripMiningIter != 0 || is_deleteable_safept(sfpt2))) {
if (strip_mine_loop) {
Node* outer_le = outer_ilt->_tail->in(0);
Node* sfpt = sfpt2->clone();
sfpt->set_req(0, iffalse);
outer_le->set_req(0, sfpt);
register_control(sfpt, outer_ilt, iffalse);
set_idom(outer_le, sfpt, dom_depth(sfpt));
}
lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control));
if (loop->_safepts != NULL) {
loop->_safepts->yank(sfpt2);
}
}
}
// Free up intermediate goo
_igvn.remove_dead_node(hook);
#ifdef ASSERT
assert(l->is_valid_counted_loop(), "counted loop shape is messed up");
assert(l == loop->_head && l->phi() == phi && l->loopexit_or_null() == lex, "" );
#endif
#ifndef PRODUCT
if (TraceLoopOpts) {
tty->print("Counted ");
loop->dump_head();
}
#endif
C->print_method(PHASE_AFTER_CLOOPS, 3);
// Capture bounds of the loop in the induction variable Phi before
// subsequent transformation (iteration splitting) obscures the
// bounds
l->phi()->as_Phi()->set_type(l->phi()->Value(&_igvn));
if (strip_mine_loop) {
l->mark_strip_mined();
l->verify_strip_mined(1);
outer_ilt->_head->as_Loop()->verify_strip_mined(1);
loop = outer_ilt;
}
return true;
}
//----------------------exact_limit-------------------------------------------
Node* PhaseIdealLoop::exact_limit( IdealLoopTree *loop ) {
assert(loop->_head->is_CountedLoop(), "");
CountedLoopNode *cl = loop->_head->as_CountedLoop();
assert(cl->is_valid_counted_loop(), "");
if (ABS(cl->stride_con()) == 1 ||
cl->limit()->Opcode() == Op_LoopLimit) {
// Old code has exact limit (it could be incorrect in case of int overflow).
// Loop limit is exact with stride == 1. And loop may already have exact limit.
return cl->limit();
}
Node *limit = NULL;
#ifdef ASSERT
BoolTest::mask bt = cl->loopexit()->test_trip();
assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
#endif
if (cl->has_exact_trip_count()) {
// Simple case: loop has constant boundaries.
// Use jlongs to avoid integer overflow.
int stride_con = cl->stride_con();
jlong init_con = cl->init_trip()->get_int();
jlong limit_con = cl->limit()->get_int();
julong trip_cnt = cl->trip_count();
jlong final_con = init_con + trip_cnt*stride_con;
int final_int = (int)final_con;
// The final value should be in integer range since the loop
// is counted and the limit was checked for overflow.
assert(final_con == (jlong)final_int, "final value should be integer");
limit = _igvn.intcon(final_int);
} else {
// Create new LoopLimit node to get exact limit (final iv value).
limit = new LoopLimitNode(C, cl->init_trip(), cl->limit(), cl->stride());
register_new_node(limit, cl->in(LoopNode::EntryControl));
}
assert(limit != NULL, "sanity");
return limit;
}
//------------------------------Ideal------------------------------------------
// Return a node which is more "ideal" than the current node.
// Attempt to convert into a counted-loop.
Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
if (!can_be_counted_loop(phase) && !is_OuterStripMinedLoop()) {
phase->C->set_major_progress();
}
return RegionNode::Ideal(phase, can_reshape);
}
#ifdef ASSERT
void LoopNode::verify_strip_mined(int expect_skeleton) const {
const OuterStripMinedLoopNode* outer = NULL;
const CountedLoopNode* inner = NULL;
if (is_strip_mined()) {
if (!is_valid_counted_loop()) {
return; // Skip malformed counted loop
}
assert(is_CountedLoop(), "no Loop should be marked strip mined");
inner = as_CountedLoop();
outer = inner->in(LoopNode::EntryControl)->as_OuterStripMinedLoop();
} else if (is_OuterStripMinedLoop()) {
outer = this->as_OuterStripMinedLoop();
inner = outer->unique_ctrl_out()->as_CountedLoop();
assert(inner->is_valid_counted_loop() && inner->is_strip_mined(), "OuterStripMinedLoop should have been removed");
assert(!is_strip_mined(), "outer loop shouldn't be marked strip mined");
}
if (inner != NULL || outer != NULL) {
assert(inner != NULL && outer != NULL, "missing loop in strip mined nest");
Node* outer_tail = outer->in(LoopNode::LoopBackControl);
Node* outer_le = outer_tail->in(0);
assert(outer_le->Opcode() == Op_OuterStripMinedLoopEnd, "tail of outer loop should be an If");
Node* sfpt = outer_le->in(0);
assert(sfpt->Opcode() == Op_SafePoint, "where's the safepoint?");
Node* inner_out = sfpt->in(0);
if (inner_out->outcnt() != 1) {
ResourceMark rm;
Unique_Node_List wq;
for (DUIterator_Fast imax, i = inner_out->fast_outs(imax); i < imax; i++) {
Node* u = inner_out->fast_out(i);
if (u == sfpt) {
continue;
}
wq.clear();
wq.push(u);
bool found_sfpt = false;
for (uint next = 0; next < wq.size() && !found_sfpt; next++) {
Node* n = wq.at(next);
for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && !found_sfpt; i++) {
Node* u = n->fast_out(i);
if (u == sfpt) {
found_sfpt = true;
}
if (!u->is_CFG()) {
wq.push(u);
}
}
}
assert(found_sfpt, "no node in loop that's not input to safepoint");
}
}
CountedLoopEndNode* cle = inner_out->in(0)->as_CountedLoopEnd();
assert(cle == inner->loopexit_or_null(), "mismatch");
bool has_skeleton = outer_le->in(1)->bottom_type()->singleton() && outer_le->in(1)->bottom_type()->is_int()->get_con() == 0;
if (has_skeleton) {
assert(expect_skeleton == 1 || expect_skeleton == -1, "unexpected skeleton node");
assert(outer->outcnt() == 2, "only phis");
} else {
assert(expect_skeleton == 0 || expect_skeleton == -1, "no skeleton node?");
uint phis = 0;
for (DUIterator_Fast imax, i = inner->fast_outs(imax); i < imax; i++) {
Node* u = inner->fast_out(i);
if (u->is_Phi()) {
phis++;
}
}
for (DUIterator_Fast imax, i = outer->fast_outs(imax); i < imax; i++) {
Node* u = outer->fast_out(i);
assert(u == outer || u == inner || u->is_Phi(), "nothing between inner and outer loop");
}
uint stores = 0;
for (DUIterator_Fast imax, i = inner_out->fast_outs(imax); i < imax; i++) {
Node* u = inner_out->fast_out(i);
if (u->is_Store()) {
stores++;
}
}
assert(outer->outcnt() >= phis + 2 && outer->outcnt() <= phis + 2 + stores + 1, "only phis");
}
assert(sfpt->outcnt() == 1, "no data node");
assert(outer_tail->outcnt() == 1 || !has_skeleton, "no data node");
}
}
#endif
//=============================================================================
//------------------------------Ideal------------------------------------------
// Return a node which is more "ideal" than the current node.
// Attempt to convert into a counted-loop.
Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
return RegionNode::Ideal(phase, can_reshape);
}
//------------------------------dump_spec--------------------------------------
// Dump special per-node info
#ifndef PRODUCT
void CountedLoopNode::dump_spec(outputStream *st) const {
LoopNode::dump_spec(st);
if (stride_is_con()) {
st->print("stride: %d ",stride_con());
}
if (is_pre_loop ()) st->print("pre of N%d" , _main_idx);
if (is_main_loop()) st->print("main of N%d", _idx);
if (is_post_loop()) st->print("post of N%d", _main_idx);
if (is_strip_mined()) st->print(" strip mined");
}
#endif
//=============================================================================
int CountedLoopEndNode::stride_con() const {
return stride()->bottom_type()->is_int()->get_con();
}
//=============================================================================
//------------------------------Value-----------------------------------------
const Type* LoopLimitNode::Value(PhaseGVN* phase) const {
const Type* init_t = phase->type(in(Init));
const Type* limit_t = phase->type(in(Limit));
const Type* stride_t = phase->type(in(Stride));
// Either input is TOP ==> the result is TOP
if (init_t == Type::TOP) return Type::TOP;
if (limit_t == Type::TOP) return Type::TOP;
if (stride_t == Type::TOP) return Type::TOP;
int stride_con = stride_t->is_int()->get_con();
if (stride_con == 1)
return NULL; // Identity
if (init_t->is_int()->is_con() && limit_t->is_int()->is_con()) {
// Use jlongs to avoid integer overflow.
jlong init_con = init_t->is_int()->get_con();
jlong limit_con = limit_t->is_int()->get_con();
int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
jlong trip_count = (limit_con - init_con + stride_m)/stride_con;
jlong final_con = init_con + stride_con*trip_count;
int final_int = (int)final_con;
// The final value should be in integer range since the loop
// is counted and the limit was checked for overflow.
assert(final_con == (jlong)final_int, "final value should be integer");
return TypeInt::make(final_int);
}
return bottom_type(); // TypeInt::INT
}
//------------------------------Ideal------------------------------------------
// Return a node which is more "ideal" than the current node.
Node *LoopLimitNode::Ideal(PhaseGVN *phase, bool can_reshape) {
if (phase->type(in(Init)) == Type::TOP ||
phase->type(in(Limit)) == Type::TOP ||
phase->type(in(Stride)) == Type::TOP)
return NULL; // Dead
int stride_con = phase->type(in(Stride))->is_int()->get_con();
if (stride_con == 1)
return NULL; // Identity
if (in(Init)->is_Con() && in(Limit)->is_Con())
return NULL; // Value
// Delay following optimizations until all loop optimizations
// done to keep Ideal graph simple.
if (!can_reshape || phase->C->major_progress())
return NULL;
const TypeInt* init_t = phase->type(in(Init) )->is_int();
const TypeInt* limit_t = phase->type(in(Limit))->is_int();
int stride_p;
jlong lim, ini;
julong max;
if (stride_con > 0) {
stride_p = stride_con;
lim = limit_t->_hi;
ini = init_t->_lo;
max = (julong)max_jint;
} else {
stride_p = -stride_con;
lim = init_t->_hi;
ini = limit_t->_lo;
max = (julong)min_jint;
}
julong range = lim - ini + stride_p;
if (range <= max) {
// Convert to integer expression if it is not overflow.
Node* stride_m = phase->intcon(stride_con - (stride_con > 0 ? 1 : -1));
Node *range = phase->transform(new SubINode(in(Limit), in(Init)));
Node *bias = phase->transform(new AddINode(range, stride_m));
Node *trip = phase->transform(new DivINode(0, bias, in(Stride)));
Node *span = phase->transform(new MulINode(trip, in(Stride)));
return new AddINode(span, in(Init)); // exact limit
}
if (is_power_of_2(stride_p) || // divisor is 2^n
!Matcher::has_match_rule(Op_LoopLimit)) { // or no specialized Mach node?
// Convert to long expression to avoid integer overflow
// and let igvn optimizer convert this division.
//
Node* init = phase->transform( new ConvI2LNode(in(Init)));
Node* limit = phase->transform( new ConvI2LNode(in(Limit)));
Node* stride = phase->longcon(stride_con);
Node* stride_m = phase->longcon(stride_con - (stride_con > 0 ? 1 : -1));
Node *range = phase->transform(new SubLNode(limit, init));
Node *bias = phase->transform(new AddLNode(range, stride_m));
Node *span;
if (stride_con > 0 && is_power_of_2(stride_p)) {
// bias >= 0 if stride >0, so if stride is 2^n we can use &(-stride)
// and avoid generating rounding for division. Zero trip guard should
// guarantee that init < limit but sometimes the guard is missing and
// we can get situation when init > limit. Note, for the empty loop
// optimization zero trip guard is generated explicitly which leaves
// only RCE predicate where exact limit is used and the predicate
// will simply fail forcing recompilation.
Node* neg_stride = phase->longcon(-stride_con);
span = phase->transform(new AndLNode(bias, neg_stride));
} else {
Node *trip = phase->transform(new DivLNode(0, bias, stride));
span = phase->transform(new MulLNode(trip, stride));
}
// Convert back to int
Node *span_int = phase->transform(new ConvL2INode(span));
return new AddINode(span_int, in(Init)); // exact limit
}
return NULL; // No progress
}
//------------------------------Identity---------------------------------------
// If stride == 1 return limit node.
Node* LoopLimitNode::Identity(PhaseGVN* phase) {
int stride_con = phase->type(in(Stride))->is_int()->get_con();
if (stride_con == 1 || stride_con == -1)
return in(Limit);
return this;
}
//=============================================================================
//----------------------match_incr_with_optional_truncation--------------------
// Match increment with optional truncation:
// CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16
// Return NULL for failure. Success returns the increment node.
Node* CountedLoopNode::match_incr_with_optional_truncation(
Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type) {
// Quick cutouts:
if (expr == NULL || expr->req() != 3) return NULL;
Node *t1 = NULL;
Node *t2 = NULL;
const TypeInt* trunc_t = TypeInt::INT;
Node* n1 = expr;
int n1op = n1->Opcode();
// Try to strip (n1 & M) or (n1 << N >> N) from n1.
if (n1op == Op_AndI &&
n1->in(2)->is_Con() &&
n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) {
// %%% This check should match any mask of 2**K-1.
t1 = n1;
n1 = t1->in(1);
n1op = n1->Opcode();
trunc_t = TypeInt::CHAR;
} else if (n1op == Op_RShiftI &&
n1->in(1) != NULL &&
n1->in(1)->Opcode() == Op_LShiftI &&
n1->in(2) == n1->in(1)->in(2) &&
n1->in(2)->is_Con()) {
jint shift = n1->in(2)->bottom_type()->is_int()->get_con();
// %%% This check should match any shift in [1..31].
if (shift == 16 || shift == 8) {
t1 = n1;
t2 = t1->in(1);
n1 = t2->in(1);
n1op = n1->Opcode();
if (shift == 16) {
trunc_t = TypeInt::SHORT;
} else if (shift == 8) {
trunc_t = TypeInt::BYTE;
}
}
}
// If (maybe after stripping) it is an AddI, we won:
if (n1op == Op_AddI) {
*trunc1 = t1;
*trunc2 = t2;
*trunc_type = trunc_t;
return n1;
}
// failed
return NULL;
}
LoopNode* CountedLoopNode::skip_strip_mined(int expect_skeleton) {
if (is_strip_mined() && is_valid_counted_loop()) {
verify_strip_mined(expect_skeleton);
return in(EntryControl)->as_Loop();
}
return this;
}
OuterStripMinedLoopNode* CountedLoopNode::outer_loop() const {
assert(is_strip_mined(), "not a strip mined loop");
Node* c = in(EntryControl);
if (c == NULL || c->is_top() || !c->is_OuterStripMinedLoop()) {
return NULL;
}
return c->as_OuterStripMinedLoop();
}
IfTrueNode* OuterStripMinedLoopNode::outer_loop_tail() const {
Node* c = in(LoopBackControl);
if (c == NULL || c->is_top()) {
return NULL;
}
return c->as_IfTrue();
}
IfTrueNode* CountedLoopNode::outer_loop_tail() const {
LoopNode* l = outer_loop();
if (l == NULL) {
return NULL;
}
return l->outer_loop_tail();
}
OuterStripMinedLoopEndNode* OuterStripMinedLoopNode::outer_loop_end() const {
IfTrueNode* proj = outer_loop_tail();
if (proj == NULL) {
return NULL;
}
Node* c = proj->in(0);
if (c == NULL || c->is_top() || c->outcnt() != 2) {
return NULL;
}
return c->as_OuterStripMinedLoopEnd();
}
OuterStripMinedLoopEndNode* CountedLoopNode::outer_loop_end() const {
LoopNode* l = outer_loop();
if (l == NULL) {
return NULL;
}
return l->outer_loop_end();
}
IfFalseNode* OuterStripMinedLoopNode::outer_loop_exit() const {
IfNode* le = outer_loop_end();
if (le == NULL) {
return NULL;
}
Node* c = le->proj_out_or_null(false);
if (c == NULL) {
return NULL;
}
return c->as_IfFalse();
}
IfFalseNode* CountedLoopNode::outer_loop_exit() const {
LoopNode* l = outer_loop();
if (l == NULL) {
return NULL;
}
return l->outer_loop_exit();
}
SafePointNode* OuterStripMinedLoopNode::outer_safepoint() const {
IfNode* le = outer_loop_end();
if (le == NULL) {
return NULL;
}
Node* c = le->in(0);
if (c == NULL || c->is_top()) {
return NULL;
}
assert(c->Opcode() == Op_SafePoint, "broken outer loop");
return c->as_SafePoint();
}
SafePointNode* CountedLoopNode::outer_safepoint() const {
LoopNode* l = outer_loop();
if (l == NULL) {
return NULL;
}
return l->outer_safepoint();
}
Node* CountedLoopNode::skip_predicates_from_entry(Node* ctrl) {
while (ctrl != NULL && ctrl->is_Proj() && ctrl->in(0)->is_If() &&
ctrl->in(0)->as_If()->proj_out(1-ctrl->as_Proj()->_con)->outcnt() == 1 &&
ctrl->in(0)->as_If()->proj_out(1-ctrl->as_Proj()->_con)->unique_out()->Opcode() == Op_Halt) {
ctrl = ctrl->in(0)->in(0);
}
return ctrl;
}
Node* CountedLoopNode::skip_predicates() {
if (is_main_loop()) {
Node* ctrl = skip_strip_mined()->in(LoopNode::EntryControl);
return skip_predicates_from_entry(ctrl);
}
return in(LoopNode::EntryControl);
}
void OuterStripMinedLoopNode::adjust_strip_mined_loop(PhaseIterGVN* igvn) {
// Look for the outer & inner strip mined loop, reduce number of
// iterations of the inner loop, set exit condition of outer loop,
// construct required phi nodes for outer loop.
CountedLoopNode* inner_cl = unique_ctrl_out()->as_CountedLoop();
assert(inner_cl->is_strip_mined(), "inner loop should be strip mined");
Node* inner_iv_phi = inner_cl->phi();
if (inner_iv_phi == NULL) {
IfNode* outer_le = outer_loop_end();
Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
igvn->replace_node(outer_le, iff);
inner_cl->clear_strip_mined();
return;
}
CountedLoopEndNode* inner_cle = inner_cl->loopexit();
int stride = inner_cl->stride_con();
jlong scaled_iters_long = ((jlong)LoopStripMiningIter) * ABS(stride);
int scaled_iters = (int)scaled_iters_long;
int short_scaled_iters = LoopStripMiningIterShortLoop* ABS(stride);
const TypeInt* inner_iv_t = igvn->type(inner_iv_phi)->is_int();
jlong iter_estimate = (jlong)inner_iv_t->_hi - (jlong)inner_iv_t->_lo;
assert(iter_estimate > 0, "broken");
if ((jlong)scaled_iters != scaled_iters_long || iter_estimate <= short_scaled_iters) {
// Remove outer loop and safepoint (too few iterations)
Node* outer_sfpt = outer_safepoint();
Node* outer_out = outer_loop_exit();
igvn->replace_node(outer_out, outer_sfpt->in(0));
igvn->replace_input_of(outer_sfpt, 0, igvn->C->top());
inner_cl->clear_strip_mined();
return;
}
if (iter_estimate <= scaled_iters_long) {
// We would only go through one iteration of
// the outer loop: drop the outer loop but
// keep the safepoint so we don't run for
// too long without a safepoint
IfNode* outer_le = outer_loop_end();
Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
igvn->replace_node(outer_le, iff);
inner_cl->clear_strip_mined();
return;
}
Node* cle_tail = inner_cle->proj_out(true);
ResourceMark rm;
Node_List old_new;
if (cle_tail->outcnt() > 1) {
// Look for nodes on backedge of inner loop and clone them
Unique_Node_List backedge_nodes;
for (DUIterator_Fast imax, i = cle_tail->fast_outs(imax); i < imax; i++) {
Node* u = cle_tail->fast_out(i);
if (u != inner_cl) {
assert(!u->is_CFG(), "control flow on the backedge?");
backedge_nodes.push(u);
}
}
uint last = igvn->C->unique();
for (uint next = 0; next < backedge_nodes.size(); next++) {
Node* n = backedge_nodes.at(next);
old_new.map(n->_idx, n->clone());
for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
Node* u = n->fast_out(i);
assert(!u->is_CFG(), "broken");
if (u->_idx >= last) {
continue;
}
if (!u->is_Phi()) {
backedge_nodes.push(u);
} else {
assert(u->in(0) == inner_cl, "strange phi on the backedge");
}
}
}
// Put the clones on the outer loop backedge
Node* le_tail = outer_loop_tail();
for (uint next = 0; next < backedge_nodes.size(); next++) {
Node *n = old_new[backedge_nodes.at(next)->_idx];
for (uint i = 1; i < n->req(); i++) {
if (n->in(i) != NULL && old_new[n->in(i)->_idx] != NULL) {
n->set_req(i, old_new[n->in(i)->_idx]);
}
}
if (n->in(0) != NULL && n->in(0) == cle_tail) {
n->set_req(0, le_tail);
}
igvn->register_new_node_with_optimizer(n);
}
}
Node* iv_phi = NULL;
// Make a clone of each phi in the inner loop
// for the outer loop
for (uint i = 0; i < inner_cl->outcnt(); i++) {
Node* u = inner_cl->raw_out(i);
if (u->is_Phi()) {
assert(u->in(0) == inner_cl, "inconsistent");
Node* phi = u->clone();
phi->set_req(0, this);
Node* be = old_new[phi->in(LoopNode::LoopBackControl)->_idx];
if (be != NULL) {
phi->set_req(LoopNode::LoopBackControl, be);
}
phi = igvn->transform(phi);
igvn->replace_input_of(u, LoopNode::EntryControl, phi);
if (u == inner_iv_phi) {
iv_phi = phi;
}
}
}
Node* cle_out = inner_cle->proj_out(false);
if (cle_out->outcnt() > 1) {
// Look for chains of stores that were sunk
// out of the inner loop and are in the outer loop
for (DUIterator_Fast imax, i = cle_out->fast_outs(imax); i < imax; i++) {
Node* u = cle_out->fast_out(i);
if (u->is_Store()) {
Node* first = u;
for(;;) {
Node* next = first->in(MemNode::Memory);
if (!next->is_Store() || next->in(0) != cle_out) {
break;
}
first = next;
}
Node* last = u;
for(;;) {
Node* next = NULL;
for (DUIterator_Fast jmax, j = last->fast_outs(jmax); j < jmax; j++) {
Node* uu = last->fast_out(j);
if (uu->is_Store() && uu->in(0) == cle_out) {
assert(next == NULL, "only one in the outer loop");
next = uu;
}
}
if (next == NULL) {
break;
}
last = next;
}
Node* phi = NULL;
for (DUIterator_Fast jmax, j = fast_outs(jmax); j < jmax; j++) {
Node* uu = fast_out(j);
if (uu->is_Phi()) {
Node* be = uu->in(LoopNode::LoopBackControl);
if (be->is_Store() && old_new[be->_idx] != NULL) {
assert(false, "store on the backedge + sunk stores: unsupported");
// drop outer loop
IfNode* outer_le = outer_loop_end();
Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
igvn->replace_node(outer_le, iff);
inner_cl->clear_strip_mined();
return;
}
if (be == last || be == first->in(MemNode::Memory)) {
assert(phi == NULL, "only one phi");
phi = uu;
}
}
}
#ifdef ASSERT
for (DUIterator_Fast jmax, j = fast_outs(jmax); j < jmax; j++) {
Node* uu = fast_out(j);
if (uu->is_Phi() && uu->bottom_type() == Type::MEMORY) {
if (uu->adr_type() == igvn->C->get_adr_type(igvn->C->get_alias_index(u->adr_type()))) {
assert(phi == uu, "what's that phi?");
} else if (uu->adr_type() == TypePtr::BOTTOM) {
Node* n = uu->in(LoopNode::LoopBackControl);
uint limit = igvn->C->live_nodes();
uint i = 0;
while (n != uu) {
i++;
assert(i < limit, "infinite loop");
if (n->is_Proj()) {
n = n->in(0);
} else if (n->is_SafePoint() || n->is_MemBar()) {
n = n->in(TypeFunc::Memory);
} else if (n->is_Phi()) {
n = n->in(1);
} else if (n->is_MergeMem()) {
n = n->as_MergeMem()->memory_at(igvn->C->get_alias_index(u->adr_type()));
} else if (n->is_Store() || n->is_LoadStore() || n->is_ClearArray()) {
n = n->in(MemNode::Memory);
} else {
n->dump();
ShouldNotReachHere();
}
}
}
}
}
#endif
if (phi == NULL) {
// If the an entire chains was sunk, the
// inner loop has no phi for that memory
// slice, create one for the outer loop
phi = PhiNode::make(this, first->in(MemNode::Memory), Type::MEMORY,
igvn->C->get_adr_type(igvn->C->get_alias_index(u->adr_type())));
phi->set_req(LoopNode::LoopBackControl, last);
phi = igvn->transform(phi);
igvn->replace_input_of(first, MemNode::Memory, phi);
} else {
// Or fix the outer loop fix to include
// that chain of stores.
Node* be = phi->in(LoopNode::LoopBackControl);
assert(!(be->is_Store() && old_new[be->_idx] != NULL), "store on the backedge + sunk stores: unsupported");
if (be == first->in(MemNode::Memory)) {
if (be == phi->in(LoopNode::LoopBackControl)) {
igvn->replace_input_of(phi, LoopNode::LoopBackControl, last);
} else {
igvn->replace_input_of(be, MemNode::Memory, last);
}
} else {
#ifdef ASSERT
if (be == phi->in(LoopNode::LoopBackControl)) {
assert(phi->in(LoopNode::LoopBackControl) == last, "");
} else {
assert(be->in(MemNode::Memory) == last, "");
}
#endif
}
}
}
}
}
if (iv_phi != NULL) {
// Now adjust the inner loop's exit condition
Node* limit = inner_cl->limit();
Node* sub = NULL;
if (stride > 0) {
sub = igvn->transform(new SubINode(limit, iv_phi));
} else {
sub = igvn->transform(new SubINode(iv_phi, limit));
}
Node* min = igvn->transform(new MinINode(sub, igvn->intcon(scaled_iters)));
Node* new_limit = NULL;
if (stride > 0) {
new_limit = igvn->transform(new AddINode(min, iv_phi));
} else {
new_limit = igvn->transform(new SubINode(iv_phi, min));
}
Node* inner_cmp = inner_cle->cmp_node();
Node* inner_bol = inner_cle->in(CountedLoopEndNode::TestValue);
Node* outer_bol = inner_bol;
// cmp node for inner loop may be shared
inner_cmp = inner_cmp->clone();
inner_cmp->set_req(2, new_limit);
inner_bol = inner_bol->clone();
inner_bol->set_req(1, igvn->transform(inner_cmp));
igvn->replace_input_of(inner_cle, CountedLoopEndNode::TestValue, igvn->transform(inner_bol));
// Set the outer loop's exit condition too
igvn->replace_input_of(outer_loop_end(), 1, outer_bol);
} else {
assert(false, "should be able to adjust outer loop");
IfNode* outer_le = outer_loop_end();
Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
igvn->replace_node(outer_le, iff);
inner_cl->clear_strip_mined();
}
}
const Type* OuterStripMinedLoopEndNode::Value(PhaseGVN* phase) const {
if (!in(0)) return Type::TOP;
if (phase->type(in(0)) == Type::TOP)
return Type::TOP;
return TypeTuple::IFBOTH;
}
Node *OuterStripMinedLoopEndNode::Ideal(PhaseGVN *phase, bool can_reshape) {
if (remove_dead_region(phase, can_reshape)) return this;
return NULL;
}
//------------------------------filtered_type--------------------------------
// Return a type based on condition control flow
// A successful return will be a type that is restricted due
// to a series of dominating if-tests, such as:
// if (i < 10) {
// if (i > 0) {
// here: "i" type is [1..10)
// }
// }
// or a control flow merge
// if (i < 10) {
// do {
// phi( , ) -- at top of loop type is [min_int..10)
// i = ?
// } while ( i < 10)
//
const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) {
assert(n && n->bottom_type()->is_int(), "must be int");
const TypeInt* filtered_t = NULL;
if (!n->is_Phi()) {
assert(n_ctrl != NULL || n_ctrl == C->top(), "valid control");
filtered_t = filtered_type_from_dominators(n, n_ctrl);
} else {
Node* phi = n->as_Phi();
Node* region = phi->in(0);
assert(n_ctrl == NULL || n_ctrl == region, "ctrl parameter must be region");
if (region && region != C->top()) {
for (uint i = 1; i < phi->req(); i++) {
Node* val = phi->in(i);
Node* use_c = region->in(i);
const TypeInt* val_t = filtered_type_from_dominators(val, use_c);
if (val_t != NULL) {
if (filtered_t == NULL) {
filtered_t = val_t;
} else {
filtered_t = filtered_t->meet(val_t)->is_int();
}
}
}
}
}
const TypeInt* n_t = _igvn.type(n)->is_int();
if (filtered_t != NULL) {
n_t = n_t->join(filtered_t)->is_int();
}
return n_t;
}
//------------------------------filtered_type_from_dominators--------------------------------
// Return a possibly more restrictive type for val based on condition control flow of dominators
const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) {
if (val->is_Con()) {
return val->bottom_type()->is_int();
}
uint if_limit = 10; // Max number of dominating if's visited
const TypeInt* rtn_t = NULL;
if (use_ctrl && use_ctrl != C->top()) {
Node* val_ctrl = get_ctrl(val);
uint val_dom_depth = dom_depth(val_ctrl);
Node* pred = use_ctrl;
uint if_cnt = 0;
while (if_cnt < if_limit) {
if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) {
if_cnt++;
const TypeInt* if_t = IfNode::filtered_int_type(&_igvn, val, pred);
if (if_t != NULL) {
if (rtn_t == NULL) {
rtn_t = if_t;
} else {
rtn_t = rtn_t->join(if_t)->is_int();
}
}
}
pred = idom(pred);
if (pred == NULL || pred == C->top()) {
break;
}
// Stop if going beyond definition block of val
if (dom_depth(pred) < val_dom_depth) {
break;
}
}
}
return rtn_t;
}
//------------------------------dump_spec--------------------------------------
// Dump special per-node info
#ifndef PRODUCT
void CountedLoopEndNode::dump_spec(outputStream *st) const {
if( in(TestValue) != NULL && in(TestValue)->is_Bool() ) {
BoolTest bt( test_trip()); // Added this for g++.
st->print("[");
bt.dump_on(st);
st->print("]");
}
st->print(" ");
IfNode::dump_spec(st);
}
#endif
//=============================================================================
//------------------------------is_member--------------------------------------
// Is 'l' a member of 'this'?
bool IdealLoopTree::is_member(const IdealLoopTree *l) const {
while( l->_nest > _nest ) l = l->_parent;
return l == this;
}
//------------------------------set_nest---------------------------------------
// Set loop tree nesting depth. Accumulate _has_call bits.
int IdealLoopTree::set_nest( uint depth ) {
_nest = depth;
int bits = _has_call;
if( _child ) bits |= _child->set_nest(depth+1);
if( bits ) _has_call = 1;
if( _next ) bits |= _next ->set_nest(depth );
return bits;
}
//------------------------------split_fall_in----------------------------------
// Split out multiple fall-in edges from the loop header. Move them to a
// private RegionNode before the loop. This becomes the loop landing pad.
void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) {
PhaseIterGVN &igvn = phase->_igvn;
uint i;
// Make a new RegionNode to be the landing pad.
Node *landing_pad = new RegionNode( fall_in_cnt+1 );
phase->set_loop(landing_pad,_parent);
// Gather all the fall-in control paths into the landing pad
uint icnt = fall_in_cnt;
uint oreq = _head->req();
for( i = oreq-1; i>0; i-- )
if( !phase->is_member( this, _head->in(i) ) )
landing_pad->set_req(icnt--,_head->in(i));
// Peel off PhiNode edges as well
for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
Node *oj = _head->fast_out(j);
if( oj->is_Phi() ) {
PhiNode* old_phi = oj->as_Phi();
assert( old_phi->region() == _head, "" );
igvn.hash_delete(old_phi); // Yank from hash before hacking edges
Node *p = PhiNode::make_blank(landing_pad, old_phi);
uint icnt = fall_in_cnt;
for( i = oreq-1; i>0; i-- ) {
if( !phase->is_member( this, _head->in(i) ) ) {
p->init_req(icnt--, old_phi->in(i));
// Go ahead and clean out old edges from old phi
old_phi->del_req(i);
}
}
// Search for CSE's here, because ZKM.jar does a lot of
// loop hackery and we need to be a little incremental
// with the CSE to avoid O(N^2) node blow-up.
Node *p2 = igvn.hash_find_insert(p); // Look for a CSE
if( p2 ) { // Found CSE
p->destruct(); // Recover useless new node
p = p2; // Use old node
} else {
igvn.register_new_node_with_optimizer(p, old_phi);
}
// Make old Phi refer to new Phi.
old_phi->add_req(p);
// Check for the special case of making the old phi useless and
// disappear it. In JavaGrande I have a case where this useless
// Phi is the loop limit and prevents recognizing a CountedLoop
// which in turn prevents removing an empty loop.
Node *id_old_phi = old_phi->Identity(&igvn);
if( id_old_phi != old_phi ) { // Found a simple identity?
// Note that I cannot call 'replace_node' here, because
// that will yank the edge from old_phi to the Region and
// I'm mid-iteration over the Region's uses.
for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) {
Node* use = old_phi->last_out(i);
igvn.rehash_node_delayed(use);
uint uses_found = 0;
for (uint j = 0; j < use->len(); j++) {
if (use->in(j) == old_phi) {
if (j < use->req()) use->set_req (j, id_old_phi);
else use->set_prec(j, id_old_phi);
uses_found++;
}
}
i -= uses_found; // we deleted 1 or more copies of this edge
}
}
igvn._worklist.push(old_phi);
}
}
// Finally clean out the fall-in edges from the RegionNode
for( i = oreq-1; i>0; i-- ) {
if( !phase->is_member( this, _head->in(i) ) ) {
_head->del_req(i);
}
}
igvn.rehash_node_delayed(_head);
// Transform landing pad
igvn.register_new_node_with_optimizer(landing_pad, _head);
// Insert landing pad into the header
_head->add_req(landing_pad);
}
//------------------------------split_outer_loop-------------------------------
// Split out the outermost loop from this shared header.
void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) {
PhaseIterGVN &igvn = phase->_igvn;
// Find index of outermost loop; it should also be my tail.
uint outer_idx = 1;
while( _head->in(outer_idx) != _tail ) outer_idx++;
// Make a LoopNode for the outermost loop.
Node *ctl = _head->in(LoopNode::EntryControl);
Node *outer = new LoopNode( ctl, _head->in(outer_idx) );
outer = igvn.register_new_node_with_optimizer(outer, _head);
phase->set_created_loop_node();
// Outermost loop falls into '_head' loop
_head->set_req(LoopNode::EntryControl, outer);
_head->del_req(outer_idx);
// Split all the Phis up between '_head' loop and 'outer' loop.
for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
Node *out = _head->fast_out(j);
if( out->is_Phi() ) {
PhiNode *old_phi = out->as_Phi();
assert( old_phi->region() == _head, "" );
Node *phi = PhiNode::make_blank(outer, old_phi);
phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl));
phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx));
phi = igvn.register_new_node_with_optimizer(phi, old_phi);
// Make old Phi point to new Phi on the fall-in path
igvn.replace_input_of(old_phi, LoopNode::EntryControl, phi);
old_phi->del_req(outer_idx);
}
}
// Use the new loop head instead of the old shared one
_head = outer;
phase->set_loop(_head, this);
}
//------------------------------fix_parent-------------------------------------
static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) {
loop->_parent = parent;
if( loop->_child ) fix_parent( loop->_child, loop );
if( loop->_next ) fix_parent( loop->_next , parent );
}
//------------------------------estimate_path_freq-----------------------------
static float estimate_path_freq( Node *n ) {
// Try to extract some path frequency info
IfNode *iff;
for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests
uint nop = n->Opcode();
if( nop == Op_SafePoint ) { // Skip any safepoint
n = n->in(0);
continue;
}
if( nop == Op_CatchProj ) { // Get count from a prior call
// Assume call does not always throw exceptions: means the call-site
// count is also the frequency of the fall-through path.
assert( n->is_CatchProj(), "" );
if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index )
return 0.0f; // Assume call exception path is rare
Node *call = n->in(0)->in(0)->in(0);
assert( call->is_Call(), "expect a call here" );
const JVMState *jvms = ((CallNode*)call)->jvms();
ciMethodData* methodData = jvms->method()->method_data();
if (!methodData->is_mature()) return 0.0f; // No call-site data
ciProfileData* data = methodData->bci_to_data(jvms->bci());
if ((data == NULL) || !data->is_CounterData()) {
// no call profile available, try call's control input
n = n->in(0);
continue;
}
return data->as_CounterData()->count()/FreqCountInvocations;
}
// See if there's a gating IF test
Node *n_c = n->in(0);
if( !n_c->is_If() ) break; // No estimate available
iff = n_c->as_If();
if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count?
// Compute how much count comes on this path
return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt;
// Have no count info. Skip dull uncommon-trap like branches.
if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) ||
(nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) )
break;
// Skip through never-taken branch; look for a real loop exit.
n = iff->in(0);
}
return 0.0f; // No estimate available
}
//------------------------------merge_many_backedges---------------------------
// Merge all the backedges from the shared header into a private Region.
// Feed that region as the one backedge to this loop.
void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) {
uint i;
// Scan for the top 2 hottest backedges
float hotcnt = 0.0f;
float warmcnt = 0.0f;
uint hot_idx = 0;
// Loop starts at 2 because slot 1 is the fall-in path
for( i = 2; i < _head->req(); i++ ) {
float cnt = estimate_path_freq(_head->in(i));
if( cnt > hotcnt ) { // Grab hottest path
warmcnt = hotcnt;
hotcnt = cnt;
hot_idx = i;
} else if( cnt > warmcnt ) { // And 2nd hottest path
warmcnt = cnt;
}
}
// See if the hottest backedge is worthy of being an inner loop
// by being much hotter than the next hottest backedge.
if( hotcnt <= 0.0001 ||
hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge
// Peel out the backedges into a private merge point; peel
// them all except optionally hot_idx.
PhaseIterGVN &igvn = phase->_igvn;
Node *hot_tail = NULL;
// Make a Region for the merge point
Node *r = new RegionNode(1);
for( i = 2; i < _head->req(); i++ ) {
if( i != hot_idx )
r->add_req( _head->in(i) );
else hot_tail = _head->in(i);
}
igvn.register_new_node_with_optimizer(r, _head);
// Plug region into end of loop _head, followed by hot_tail
while( _head->req() > 3 ) _head->del_req( _head->req()-1 );
igvn.replace_input_of(_head, 2, r);
if( hot_idx ) _head->add_req(hot_tail);
// Split all the Phis up between '_head' loop and the Region 'r'
for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
Node *out = _head->fast_out(j);
if( out->is_Phi() ) {
PhiNode* n = out->as_Phi();
igvn.hash_delete(n); // Delete from hash before hacking edges
Node *hot_phi = NULL;
Node *phi = new PhiNode(r, n->type(), n->adr_type());
// Check all inputs for the ones to peel out
uint j = 1;
for( uint i = 2; i < n->req(); i++ ) {
if( i != hot_idx )
phi->set_req( j++, n->in(i) );
else hot_phi = n->in(i);
}
// Register the phi but do not transform until whole place transforms
igvn.register_new_node_with_optimizer(phi, n);
// Add the merge phi to the old Phi
while( n->req() > 3 ) n->del_req( n->req()-1 );
igvn.replace_input_of(n, 2, phi);
if( hot_idx ) n->add_req(hot_phi);
}
}
// Insert a new IdealLoopTree inserted below me. Turn it into a clone
// of self loop tree. Turn self into a loop headed by _head and with
// tail being the new merge point.
IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail );
phase->set_loop(_tail,ilt); // Adjust tail
_tail = r; // Self's tail is new merge point
phase->set_loop(r,this);
ilt->_child = _child; // New guy has my children
_child = ilt; // Self has new guy as only child
ilt->_parent = this; // new guy has self for parent
ilt->_nest = _nest; // Same nesting depth (for now)
// Starting with 'ilt', look for child loop trees using the same shared
// header. Flatten these out; they will no longer be loops in the end.
IdealLoopTree **pilt = &_child;
while( ilt ) {
if( ilt->_head == _head ) {
uint i;
for( i = 2; i < _head->req(); i++ )
if( _head->in(i) == ilt->_tail )
break; // Still a loop
if( i == _head->req() ) { // No longer a loop
// Flatten ilt. Hang ilt's "_next" list from the end of
// ilt's '_child' list. Move the ilt's _child up to replace ilt.
IdealLoopTree **cp = &ilt->_child;
while( *cp ) cp = &(*cp)->_next; // Find end of child list
*cp = ilt->_next; // Hang next list at end of child list
*pilt = ilt->_child; // Move child up to replace ilt
ilt->_head = NULL; // Flag as a loop UNIONED into parent
ilt = ilt->_child; // Repeat using new ilt
continue; // do not advance over ilt->_child
}
assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" );
phase->set_loop(_head,ilt);
}
pilt = &ilt->_child; // Advance to next
ilt = *pilt;
}
if( _child ) fix_parent( _child, this );
}
//------------------------------beautify_loops---------------------------------
// Split shared headers and insert loop landing pads.
// Insert a LoopNode to replace the RegionNode.
// Return TRUE if loop tree is structurally changed.
bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) {
bool result = false;
// Cache parts in locals for easy
PhaseIterGVN &igvn = phase->_igvn;
igvn.hash_delete(_head); // Yank from hash before hacking edges
// Check for multiple fall-in paths. Peel off a landing pad if need be.
int fall_in_cnt = 0;
for( uint i = 1; i < _head->req(); i++ )
if( !phase->is_member( this, _head->in(i) ) )
fall_in_cnt++;
assert( fall_in_cnt, "at least 1 fall-in path" );
if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins
split_fall_in( phase, fall_in_cnt );
// Swap inputs to the _head and all Phis to move the fall-in edge to
// the left.
fall_in_cnt = 1;
while( phase->is_member( this, _head->in(fall_in_cnt) ) )
fall_in_cnt++;
if( fall_in_cnt > 1 ) {
// Since I am just swapping inputs I do not need to update def-use info
Node *tmp = _head->in(1);
igvn.rehash_node_delayed(_head);
_head->set_req( 1, _head->in(fall_in_cnt) );
_head->set_req( fall_in_cnt, tmp );
// Swap also all Phis
for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) {
Node* phi = _head->fast_out(i);
if( phi->is_Phi() ) {
igvn.rehash_node_delayed(phi); // Yank from hash before hacking edges
tmp = phi->in(1);
phi->set_req( 1, phi->in(fall_in_cnt) );
phi->set_req( fall_in_cnt, tmp );
}
}
}
assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" );
assert( phase->is_member( this, _head->in(2) ), "right edge is loop" );
// If I am a shared header (multiple backedges), peel off the many
// backedges into a private merge point and use the merge point as
// the one true backedge.
if( _head->req() > 3 ) {
// Merge the many backedges into a single backedge but leave
// the hottest backedge as separate edge for the following peel.
merge_many_backedges( phase );
result = true;
}
// If I have one hot backedge, peel off myself loop.
// I better be the outermost loop.
if (_head->req() > 3 && !_irreducible) {
split_outer_loop( phase );
result = true;
} else if (!_head->is_Loop() && !_irreducible) {
// Make a new LoopNode to replace the old loop head
Node *l = new LoopNode( _head->in(1), _head->in(2) );
l = igvn.register_new_node_with_optimizer(l, _head);
phase->set_created_loop_node();
// Go ahead and replace _head
phase->_igvn.replace_node( _head, l );
_head = l;
phase->set_loop(_head, this);
}
// Now recursively beautify nested loops
if( _child ) result |= _child->beautify_loops( phase );
if( _next ) result |= _next ->beautify_loops( phase );
return result;
}
//------------------------------allpaths_check_safepts----------------------------
// Allpaths backwards scan from loop tail, terminating each path at first safepoint
// encountered. Helper for check_safepts.
void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) {
assert(stack.size() == 0, "empty stack");
stack.push(_tail);
visited.clear();
visited.set(_tail->_idx);
while (stack.size() > 0) {
Node* n = stack.pop();
if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
// Terminate this path
} else if (n->Opcode() == Op_SafePoint) {
if (_phase->get_loop(n) != this) {
if (_required_safept == NULL) _required_safept = new Node_List();
_required_safept->push(n); // save the one closest to the tail
}
// Terminate this path
} else {
uint start = n->is_Region() ? 1 : 0;
uint end = n->is_Region() && !n->is_Loop() ? n->req() : start + 1;
for (uint i = start; i < end; i++) {
Node* in = n->in(i);
assert(in->is_CFG(), "must be");
if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) {
stack.push(in);
}
}
}
}
}
//------------------------------check_safepts----------------------------
// Given dominators, try to find loops with calls that must always be
// executed (call dominates loop tail). These loops do not need non-call
// safepoints (ncsfpt).
//
// A complication is that a safepoint in a inner loop may be needed
// by an outer loop. In the following, the inner loop sees it has a
// call (block 3) on every path from the head (block 2) to the
// backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint)
// in block 2, _but_ this leaves the outer loop without a safepoint.
//
// entry 0
// |
// v
// outer 1,2 +->1
// | |
// | v
// | 2<---+ ncsfpt in 2
// |_/|\ |
// | v |
// inner 2,3 / 3 | call in 3
// / | |
// v +--+
// exit 4
//
//
// This method creates a list (_required_safept) of ncsfpt nodes that must
// be protected is created for each loop. When a ncsfpt maybe deleted, it
// is first looked for in the lists for the outer loops of the current loop.
//
// The insights into the problem:
// A) counted loops are okay
// B) innermost loops are okay (only an inner loop can delete
// a ncsfpt needed by an outer loop)
// C) a loop is immune from an inner loop deleting a safepoint
// if the loop has a call on the idom-path
// D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the
// idom-path that is not in a nested loop
// E) otherwise, an ncsfpt on the idom-path that is nested in an inner
// loop needs to be prevented from deletion by an inner loop
//
// There are two analyses:
// 1) The first, and cheaper one, scans the loop body from
// tail to head following the idom (immediate dominator)
// chain, looking for the cases (C,D,E) above.
// Since inner loops are scanned before outer loops, there is summary
// information about inner loops. Inner loops can be skipped over
// when the tail of an inner loop is encountered.
//
// 2) The second, invoked if the first fails to find a call or ncsfpt on
// the idom path (which is rare), scans all predecessor control paths
// from the tail to the head, terminating a path when a call or sfpt
// is encountered, to find the ncsfpt's that are closest to the tail.
//
void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) {
// Bottom up traversal
IdealLoopTree* ch = _child;
if (_child) _child->check_safepts(visited, stack);
if (_next) _next ->check_safepts(visited, stack);
if (!_head->is_CountedLoop() && !_has_sfpt && _parent != NULL && !_irreducible) {
bool has_call = false; // call on dom-path
bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth
Node* nonlocal_ncsfpt = NULL; // ncsfpt on dom-path at a deeper depth
// Scan the dom-path nodes from tail to head
for (Node* n = tail(); n != _head; n = _phase->idom(n)) {
if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
has_call = true;
_has_sfpt = 1; // Then no need for a safept!
break;
} else if (n->Opcode() == Op_SafePoint) {
if (_phase->get_loop(n) == this) {
has_local_ncsfpt = true;
break;
}
if (nonlocal_ncsfpt == NULL) {
nonlocal_ncsfpt = n; // save the one closest to the tail
}
} else {
IdealLoopTree* nlpt = _phase->get_loop(n);
if (this != nlpt) {
// If at an inner loop tail, see if the inner loop has already
// recorded seeing a call on the dom-path (and stop.) If not,
// jump to the head of the inner loop.
assert(is_member(nlpt), "nested loop");
Node* tail = nlpt->_tail;
if (tail->in(0)->is_If()) tail = tail->in(0);
if (n == tail) {
// If inner loop has call on dom-path, so does outer loop
if (nlpt->_has_sfpt) {
has_call = true;
_has_sfpt = 1;
break;
}
// Skip to head of inner loop
assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head");
n = nlpt->_head;
}
}
}
}
// Record safept's that this loop needs preserved when an
// inner loop attempts to delete it's safepoints.
if (_child != NULL && !has_call && !has_local_ncsfpt) {
if (nonlocal_ncsfpt != NULL) {
if (_required_safept == NULL) _required_safept = new Node_List();
_required_safept->push(nonlocal_ncsfpt);
} else {
// Failed to find a suitable safept on the dom-path. Now use
// an all paths walk from tail to head, looking for safepoints to preserve.
allpaths_check_safepts(visited, stack);
}
}
}
}
//---------------------------is_deleteable_safept----------------------------
// Is safept not required by an outer loop?
bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) {
assert(sfpt->Opcode() == Op_SafePoint, "");
IdealLoopTree* lp = get_loop(sfpt)->_parent;
while (lp != NULL) {
Node_List* sfpts = lp->_required_safept;
if (sfpts != NULL) {
for (uint i = 0; i < sfpts->size(); i++) {
if (sfpt == sfpts->at(i))
return false;
}
}
lp = lp->_parent;
}
return true;
}
//---------------------------replace_parallel_iv-------------------------------
// Replace parallel induction variable (parallel to trip counter)
void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) {
assert(loop->_head->is_CountedLoop(), "");
CountedLoopNode *cl = loop->_head->as_CountedLoop();
if (!cl->is_valid_counted_loop())
return; // skip malformed counted loop
Node *incr = cl->incr();
if (incr == NULL)
return; // Dead loop?
Node *init = cl->init_trip();
Node *phi = cl->phi();
int stride_con = cl->stride_con();
// Visit all children, looking for Phis
for (DUIterator i = cl->outs(); cl->has_out(i); i++) {
Node *out = cl->out(i);
// Look for other phis (secondary IVs). Skip dead ones
if (!out->is_Phi() || out == phi || !has_node(out))
continue;
PhiNode* phi2 = out->as_Phi();
Node *incr2 = phi2->in( LoopNode::LoopBackControl );
// Look for induction variables of the form: X += constant
if (phi2->region() != loop->_head ||
incr2->req() != 3 ||
incr2->in(1) != phi2 ||
incr2 == incr ||
incr2->Opcode() != Op_AddI ||
!incr2->in(2)->is_Con())
continue;
// Check for parallel induction variable (parallel to trip counter)
// via an affine function. In particular, count-down loops with
// count-up array indices are common. We only RCE references off
// the trip-counter, so we need to convert all these to trip-counter
// expressions.
Node *init2 = phi2->in( LoopNode::EntryControl );
int stride_con2 = incr2->in(2)->get_int();
// The ratio of the two strides cannot be represented as an int
// if stride_con2 is min_int and stride_con is -1.
if (stride_con2 == min_jint && stride_con == -1) {
continue;
}
// The general case here gets a little tricky. We want to find the
// GCD of all possible parallel IV's and make a new IV using this
// GCD for the loop. Then all possible IVs are simple multiples of
// the GCD. In practice, this will cover very few extra loops.
// Instead we require 'stride_con2' to be a multiple of 'stride_con',
// where +/-1 is the common case, but other integer multiples are
// also easy to handle.
int ratio_con = stride_con2/stride_con;
if ((ratio_con * stride_con) == stride_con2) { // Check for exact
#ifndef PRODUCT
if (TraceLoopOpts) {
tty->print("Parallel IV: %d ", phi2->_idx);
loop->dump_head();
}
#endif
// Convert to using the trip counter. The parallel induction
// variable differs from the trip counter by a loop-invariant
// amount, the difference between their respective initial values.
// It is scaled by the 'ratio_con'.
Node* ratio = _igvn.intcon(ratio_con);
set_ctrl(ratio, C->root());
Node* ratio_init = new MulINode(init, ratio);
_igvn.register_new_node_with_optimizer(ratio_init, init);
set_early_ctrl(ratio_init);
Node* diff = new SubINode(init2, ratio_init);
_igvn.register_new_node_with_optimizer(diff, init2);
set_early_ctrl(diff);
Node* ratio_idx = new MulINode(phi, ratio);
_igvn.register_new_node_with_optimizer(ratio_idx, phi);
set_ctrl(ratio_idx, cl);
Node* add = new AddINode(ratio_idx, diff);
_igvn.register_new_node_with_optimizer(add);
set_ctrl(add, cl);
_igvn.replace_node( phi2, add );
// Sometimes an induction variable is unused
if (add->outcnt() == 0) {
_igvn.remove_dead_node(add);
}
--i; // deleted this phi; rescan starting with next position
continue;
}
}
}
void IdealLoopTree::remove_safepoints(PhaseIdealLoop* phase, bool keep_one) {
Node* keep = NULL;
if (keep_one) {
// Look for a safepoint on the idom-path.
for (Node* i = tail(); i != _head; i = phase->idom(i)) {
if (i->Opcode() == Op_SafePoint && phase->get_loop(i) == this) {
keep = i;
break; // Found one
}
}
}
// Don't remove any safepoints if it is requested to keep a single safepoint and
// no safepoint was found on idom-path. It is not safe to remove any safepoint
// in this case since there's no safepoint dominating all paths in the loop body.
bool prune = !keep_one || keep != NULL;
// Delete other safepoints in this loop.
Node_List* sfpts = _safepts;
if (prune && sfpts != NULL) {
assert(keep == NULL || keep->Opcode() == Op_SafePoint, "not safepoint");
for (uint i = 0; i < sfpts->size(); i++) {
Node* n = sfpts->at(i);
assert(phase->get_loop(n) == this, "");
if (n != keep && phase->is_deleteable_safept(n)) {
phase->lazy_replace(n, n->in(TypeFunc::Control));
}
}
}
}
//------------------------------counted_loop-----------------------------------
// Convert to counted loops where possible
void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) {
// For grins, set the inner-loop flag here
if (!_child) {
if (_head->is_Loop()) _head->as_Loop()->set_inner_loop();
}
IdealLoopTree* loop = this;
if (_head->is_CountedLoop() ||
phase->is_counted_loop(_head, loop)) {
if (LoopStripMiningIter == 0 || (LoopStripMiningIter > 1 && _child == NULL)) {
// Indicate we do not need a safepoint here
_has_sfpt = 1;
}
// Remove safepoints
bool keep_one_sfpt = !(_has_call || _has_sfpt);
remove_safepoints(phase, keep_one_sfpt);
// Look for induction variables
phase->replace_parallel_iv(this);
} else if (_parent != NULL && !_irreducible) {
// Not a counted loop. Keep one safepoint.
bool keep_one_sfpt = true;
remove_safepoints(phase, keep_one_sfpt);
}
// Recursively
assert(loop->_child != this || (loop->_head->as_Loop()->is_OuterStripMinedLoop() && _head->as_CountedLoop()->is_strip_mined()), "what kind of loop was added?");
assert(loop->_child != this || (loop->_child->_child == NULL && loop->_child->_next == NULL), "would miss some loops");
if (loop->_child && loop->_child != this) loop->_child->counted_loop(phase);
if (loop->_next) loop->_next ->counted_loop(phase);
}
// The Estimated Loop Clone Size:
// CloneFactor * (~112% * BodySize + BC) + CC + FanOutTerm,
// where BC and CC are totally ad-hoc/magic "body" and "clone" constants,
// respectively, used to ensure that the node usage estimates made are on the
// safe side, for the most part. The FanOutTerm is an attempt to estimate the
// possible additional/excessive nodes generated due to data and control flow
// merging, for edges reaching outside the loop.
uint IdealLoopTree::est_loop_clone_sz(uint factor) const {
precond(0 < factor && factor < 16);
uint const bc = 13;
uint const cc = 17;
uint const sz = _body.size() + (_body.size() + 7) / 8;
uint estimate = factor * (sz + bc) + cc;
assert((estimate - cc) / factor == sz + bc, "overflow");
return estimate + est_loop_flow_merge_sz();
}
// The Estimated Loop (full-) Unroll Size:
// UnrollFactor * (~106% * BodySize) + CC + FanOutTerm,
// where CC is a (totally) ad-hoc/magic "clone" constant, used to ensure that
// node usage estimates made are on the safe side, for the most part. This is
// a "light" version of the loop clone size calculation (above), based on the
// assumption that most of the loop-construct overhead will be unraveled when
// (fully) unrolled. Defined for unroll factors larger or equal to one (>=1),
// including an overflow check and returning UINT_MAX in case of an overflow.
uint IdealLoopTree::est_loop_unroll_sz(uint factor) const {
precond(factor > 0);
// Take into account that after unroll conjoined heads and tails will fold.
uint const b0 = _body.size() - EMPTY_LOOP_SIZE;
uint const cc = 7;
uint const sz = b0 + (b0 + 15) / 16;
uint estimate = factor * sz + cc;
if ((estimate - cc) / factor != sz) {
return UINT_MAX;
}
return estimate + est_loop_flow_merge_sz();
}
// Estimate the growth effect (in nodes) of merging control and data flow when
// cloning a loop body, based on the amount of control and data flow reaching
// outside of the (current) loop body.
uint IdealLoopTree::est_loop_flow_merge_sz() const {
uint ctrl_edge_out_cnt = 0;
uint data_edge_out_cnt = 0;
for (uint i = 0; i < _body.size(); i++) {
Node* node = _body.at(i);
uint outcnt = node->outcnt();
for (uint k = 0; k < outcnt; k++) {
Node* out = node->raw_out(k);
if (out == NULL) continue;
if (out->is_CFG()) {
if (!is_member(_phase->get_loop(out))) {
ctrl_edge_out_cnt++;
}
} else if (_phase->has_ctrl(out)) {
Node* ctrl = _phase->get_ctrl(out);
assert(ctrl != NULL, "must be");
assert(ctrl->is_CFG(), "must be");
if (!is_member(_phase->get_loop(ctrl))) {
data_edge_out_cnt++;
}
}
}
}
// Use data and control count (x2.0) in estimate iff both are > 0. This is
// a rather pessimistic estimate for the most part, in particular for some
// complex loops, but still not enough to capture all loops.
if (ctrl_edge_out_cnt > 0 && data_edge_out_cnt > 0) {
return 2 * (ctrl_edge_out_cnt + data_edge_out_cnt);
}
return 0;
}
#ifndef PRODUCT
//------------------------------dump_head--------------------------------------
// Dump 1 liner for loop header info
void IdealLoopTree::dump_head() const {
tty->sp(2 * _nest);
tty->print("Loop: N%d/N%d ", _head->_idx, _tail->_idx);
if (_irreducible) tty->print(" IRREDUCIBLE");
Node* entry = _head->is_Loop() ? _head->as_Loop()->skip_strip_mined(-1)->in(LoopNode::EntryControl) : _head->in(LoopNode::EntryControl);
Node* predicate = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
if (predicate != NULL ) {
tty->print(" limit_check");
entry = PhaseIdealLoop::skip_loop_predicates(entry);
}
if (UseLoopPredicate) {
entry = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
if (entry != NULL) {
tty->print(" predicated");
entry = PhaseIdealLoop::skip_loop_predicates(entry);
}
}
if (UseProfiledLoopPredicate) {
entry = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
if (entry != NULL) {
tty->print(" profile_predicated");
}
}
if (_head->is_CountedLoop()) {
CountedLoopNode *cl = _head->as_CountedLoop();
tty->print(" counted");
Node* init_n = cl->init_trip();
if (init_n != NULL && init_n->is_Con())
tty->print(" [%d,", cl->init_trip()->get_int());
else
tty->print(" [int,");
Node* limit_n = cl->limit();
if (limit_n != NULL && limit_n->is_Con())
tty->print("%d),", cl->limit()->get_int());
else
tty->print("int),");
int stride_con = cl->stride_con();
if (stride_con > 0) tty->print("+");
tty->print("%d", stride_con);
tty->print(" (%0.f iters) ", cl->profile_trip_cnt());
if (cl->is_pre_loop ()) tty->print(" pre" );
if (cl->is_main_loop()) tty->print(" main");
if (cl->is_post_loop()) tty->print(" post");
if (cl->is_vectorized_loop()) tty->print(" vector");
if (cl->range_checks_present()) tty->print(" rc ");
if (cl->is_multiversioned()) tty->print(" multi ");
}
if (_has_call) tty->print(" has_call");
if (_has_sfpt) tty->print(" has_sfpt");
if (_rce_candidate) tty->print(" rce");
if (_safepts != NULL && _safepts->size() > 0) {
tty->print(" sfpts={"); _safepts->dump_simple(); tty->print(" }");
}
if (_required_safept != NULL && _required_safept->size() > 0) {
tty->print(" req={"); _required_safept->dump_simple(); tty->print(" }");
}
if (Verbose) {
tty->print(" body={"); _body.dump_simple(); tty->print(" }");
}
if (_head->is_Loop() && _head->as_Loop()->is_strip_mined()) {
tty->print(" strip_mined");
}
tty->cr();
}
//------------------------------dump-------------------------------------------
// Dump loops by loop tree
void IdealLoopTree::dump() const {
dump_head();
if (_child) _child->dump();
if (_next) _next ->dump();
}
#endif
static void log_loop_tree(IdealLoopTree* root, IdealLoopTree* loop, CompileLog* log) {
if (loop == root) {
if (loop->_child != NULL) {
log->begin_head("loop_tree");
log->end_head();
if( loop->_child ) log_loop_tree(root, loop->_child, log);
log->tail("loop_tree");
assert(loop->_next == NULL, "what?");
}
} else {
Node* head = loop->_head;
log->begin_head("loop");
log->print(" idx='%d' ", head->_idx);
if (loop->_irreducible) log->print("irreducible='1' ");
if (head->is_Loop()) {
if (head->as_Loop()->is_inner_loop()) log->print("inner_loop='1' ");
if (head->as_Loop()->is_partial_peel_loop()) log->print("partial_peel_loop='1' ");
}
if (head->is_CountedLoop()) {
CountedLoopNode* cl = head->as_CountedLoop();
if (cl->is_pre_loop()) log->print("pre_loop='%d' ", cl->main_idx());
if (cl->is_main_loop()) log->print("main_loop='%d' ", cl->_idx);
if (cl->is_post_loop()) log->print("post_loop='%d' ", cl->main_idx());
}
log->end_head();
if( loop->_child ) log_loop_tree(root, loop->_child, log);
log->tail("loop");
if( loop->_next ) log_loop_tree(root, loop->_next, log);
}
}
//---------------------collect_potentially_useful_predicates-----------------------
// Helper function to collect potentially useful predicates to prevent them from
// being eliminated by PhaseIdealLoop::eliminate_useless_predicates
void PhaseIdealLoop::collect_potentially_useful_predicates(
IdealLoopTree * loop, Unique_Node_List &useful_predicates) {
if (loop->_child) { // child
collect_potentially_useful_predicates(loop->_child, useful_predicates);
}
// self (only loops that we can apply loop predication may use their predicates)
if (loop->_head->is_Loop() &&
!loop->_irreducible &&
!loop->tail()->is_top()) {
LoopNode* lpn = loop->_head->as_Loop();
Node* entry = lpn->in(LoopNode::EntryControl);
Node* predicate_proj = find_predicate(entry); // loop_limit_check first
if (predicate_proj != NULL ) { // right pattern that can be used by loop predication
assert(entry->in(0)->in(1)->in(1)->Opcode() == Op_Opaque1, "must be");
useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
entry = skip_loop_predicates(entry);
}
predicate_proj = find_predicate(entry); // Predicate
if (predicate_proj != NULL ) {
useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
entry = skip_loop_predicates(entry);
}
if (UseProfiledLoopPredicate) {
predicate_proj = find_predicate(entry); // Predicate
if (predicate_proj != NULL ) {
useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
}
}
}
if (loop->_next) { // sibling
collect_potentially_useful_predicates(loop->_next, useful_predicates);
}
}
//------------------------eliminate_useless_predicates-----------------------------
// Eliminate all inserted predicates if they could not be used by loop predication.
// Note: it will also eliminates loop limits check predicate since it also uses
// Opaque1 node (see Parse::add_predicate()).
void PhaseIdealLoop::eliminate_useless_predicates() {
if (C->predicate_count() == 0)
return; // no predicate left
Unique_Node_List useful_predicates; // to store useful predicates
if (C->has_loops()) {
collect_potentially_useful_predicates(_ltree_root->_child, useful_predicates);
}
for (int i = C->predicate_count(); i > 0; i--) {
Node * n = C->predicate_opaque1_node(i-1);
assert(n->Opcode() == Op_Opaque1, "must be");
if (!useful_predicates.member(n)) { // not in the useful list
_igvn.replace_node(n, n->in(1));
}
}
}
//------------------------process_expensive_nodes-----------------------------
// Expensive nodes have their control input set to prevent the GVN
// from commoning them and as a result forcing the resulting node to
// be in a more frequent path. Use CFG information here, to change the
// control inputs so that some expensive nodes can be commoned while
// not executed more frequently.
bool PhaseIdealLoop::process_expensive_nodes() {
assert(OptimizeExpensiveOps, "optimization off?");
// Sort nodes to bring similar nodes together
C->sort_expensive_nodes();
bool progress = false;
for (int i = 0; i < C->expensive_count(); ) {
Node* n = C->expensive_node(i);
int start = i;
// Find nodes similar to n
i++;
for (; i < C->expensive_count() && Compile::cmp_expensive_nodes(n, C->expensive_node(i)) == 0; i++);
int end = i;
// And compare them two by two
for (int j = start; j < end; j++) {
Node* n1 = C->expensive_node(j);
if (is_node_unreachable(n1)) {
continue;
}
for (int k = j+1; k < end; k++) {
Node* n2 = C->expensive_node(k);
if (is_node_unreachable(n2)) {
continue;
}
assert(n1 != n2, "should be pair of nodes");
Node* c1 = n1->in(0);
Node* c2 = n2->in(0);
Node* parent_c1 = c1;
Node* parent_c2 = c2;
// The call to get_early_ctrl_for_expensive() moves the
// expensive nodes up but stops at loops that are in a if
// branch. See whether we can exit the loop and move above the
// If.
if (c1->is_Loop()) {
parent_c1 = c1->in(1);
}
if (c2->is_Loop()) {
parent_c2 = c2->in(1);
}
if (parent_c1 == parent_c2) {
_igvn._worklist.push(n1);
_igvn._worklist.push(n2);
continue;
}
// Look for identical expensive node up the dominator chain.
if (is_dominator(c1, c2)) {
c2 = c1;
} else if (is_dominator(c2, c1)) {
c1 = c2;
} else if (parent_c1->is_Proj() && parent_c1->in(0)->is_If() &&
parent_c2->is_Proj() && parent_c1->in(0) == parent_c2->in(0)) {
// Both branches have the same expensive node so move it up
// before the if.
c1 = c2 = idom(parent_c1->in(0));
}
// Do the actual moves
if (n1->in(0) != c1) {
_igvn.hash_delete(n1);
n1->set_req(0, c1);
_igvn.hash_insert(n1);
_igvn._worklist.push(n1);
progress = true;
}
if (n2->in(0) != c2) {
_igvn.hash_delete(n2);
n2->set_req(0, c2);
_igvn.hash_insert(n2);
_igvn._worklist.push(n2);
progress = true;
}
}
}
}
return progress;
}
//=============================================================================
//----------------------------build_and_optimize-------------------------------
// Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to
// its corresponding LoopNode. If 'optimize' is true, do some loop cleanups.
void PhaseIdealLoop::build_and_optimize(LoopOptsMode mode) {
bool do_split_ifs = (mode == LoopOptsDefault);
bool skip_loop_opts = (mode == LoopOptsNone);
int old_progress = C->major_progress();
uint orig_worklist_size = _igvn._worklist.size();
// Reset major-progress flag for the driver's heuristics
C->clear_major_progress();
#ifndef PRODUCT
// Capture for later assert
uint unique = C->unique();
_loop_invokes++;
_loop_work += unique;
#endif
// True if the method has at least 1 irreducible loop
_has_irreducible_loops = false;
_created_loop_node = false;
Arena *a = Thread::current()->resource_area();
VectorSet visited(a);
// Pre-grow the mapping from Nodes to IdealLoopTrees.
_nodes.map(C->unique(), NULL);
memset(_nodes.adr(), 0, wordSize * C->unique());
// Pre-build the top-level outermost loop tree entry
_ltree_root = new IdealLoopTree( this, C->root(), C->root() );
// Do not need a safepoint at the top level
_ltree_root->_has_sfpt = 1;
// Initialize Dominators.
// Checked in clone_loop_predicate() during beautify_loops().
_idom_size = 0;
_idom = NULL;
_dom_depth = NULL;
_dom_stk = NULL;
// Empty pre-order array
allocate_preorders();
// Build a loop tree on the fly. Build a mapping from CFG nodes to
// IdealLoopTree entries. Data nodes are NOT walked.
build_loop_tree();
// Check for bailout, and return
if (C->failing()) {
return;
}
// No loops after all
if( !_ltree_root->_child && !_verify_only ) C->set_has_loops(false);
// There should always be an outer loop containing the Root and Return nodes.
// If not, we have a degenerate empty program. Bail out in this case.
if (!has_node(C->root())) {
if (!_verify_only) {
C->clear_major_progress();
C->record_method_not_compilable("empty program detected during loop optimization");
}
return;
}
BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
// Nothing to do, so get out
bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !_verify_me && !_verify_only &&
!bs->is_gc_specific_loop_opts_pass(mode);
bool do_expensive_nodes = C->should_optimize_expensive_nodes(_igvn);
bool strip_mined_loops_expanded = bs->strip_mined_loops_expanded(mode);
if (stop_early && !do_expensive_nodes) {
_igvn.optimize(); // Cleanup NeverBranches
return;
}
// Set loop nesting depth
_ltree_root->set_nest( 0 );
// Split shared headers and insert loop landing pads.
// Do not bother doing this on the Root loop of course.
if( !_verify_me && !_verify_only && _ltree_root->_child ) {
C->print_method(PHASE_BEFORE_BEAUTIFY_LOOPS, 3);
if( _ltree_root->_child->beautify_loops( this ) ) {
// Re-build loop tree!
_ltree_root->_child = NULL;
_nodes.clear();
reallocate_preorders();
build_loop_tree();
// Check for bailout, and return
if (C->failing()) {
return;
}
// Reset loop nesting depth
_ltree_root->set_nest( 0 );
C->print_method(PHASE_AFTER_BEAUTIFY_LOOPS, 3);
}
}
// Build Dominators for elision of NULL checks & loop finding.
// Since nodes do not have a slot for immediate dominator, make
// a persistent side array for that info indexed on node->_idx.
_idom_size = C->unique();
_idom = NEW_RESOURCE_ARRAY( Node*, _idom_size );
_dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size );
_dom_stk = NULL; // Allocated on demand in recompute_dom_depth
memset( _dom_depth, 0, _idom_size * sizeof(uint) );
Dominators();
if (!_verify_only) {
// As a side effect, Dominators removed any unreachable CFG paths
// into RegionNodes. It doesn't do this test against Root, so
// we do it here.
for( uint i = 1; i < C->root()->req(); i++ ) {
if( !_nodes[C->root()->in(i)->_idx] ) { // Dead path into Root?
_igvn.delete_input_of(C->root(), i);
i--; // Rerun same iteration on compressed edges
}
}
// Given dominators, try to find inner loops with calls that must
// always be executed (call dominates loop tail). These loops do
// not need a separate safepoint.
Node_List cisstack(a);
_ltree_root->check_safepts(visited, cisstack);
}
// Walk the DATA nodes and place into loops. Find earliest control
// node. For CFG nodes, the _nodes array starts out and remains
// holding the associated IdealLoopTree pointer. For DATA nodes, the
// _nodes array holds the earliest legal controlling CFG node.
// Allocate stack with enough space to avoid frequent realloc
int stack_size = (C->live_nodes() >> 1) + 16; // (live_nodes>>1)+16 from Java2D stats
Node_Stack nstack( a, stack_size );
visited.clear();
Node_List worklist(a);
// Don't need C->root() on worklist since
// it will be processed among C->top() inputs
worklist.push(C->top());
visited.set(C->top()->_idx); // Set C->top() as visited now
build_loop_early( visited, worklist, nstack );
// Given early legal placement, try finding counted loops. This placement
// is good enough to discover most loop invariants.
if (!_verify_me && !_verify_only && !strip_mined_loops_expanded) {
_ltree_root->counted_loop( this );
}
// Find latest loop placement. Find ideal loop placement.
visited.clear();
init_dom_lca_tags();
// Need C->root() on worklist when processing outs
worklist.push(C->root());
NOT_PRODUCT( C->verify_graph_edges(); )
worklist.push(C->top());
build_loop_late( visited, worklist, nstack );
if (_verify_only) {
C->restore_major_progress(old_progress);
assert(C->unique() == unique, "verification mode made Nodes? ? ?");
assert(_igvn._worklist.size() == orig_worklist_size, "shouldn't push anything");
return;
}
// clear out the dead code after build_loop_late
while (_deadlist.size()) {
_igvn.remove_globally_dead_node(_deadlist.pop());
}
if (stop_early) {
assert(do_expensive_nodes, "why are we here?");
if (process_expensive_nodes()) {
// If we made some progress when processing expensive nodes then
// the IGVN may modify the graph in a way that will allow us to
// make some more progress: we need to try processing expensive
// nodes again.
C->set_major_progress();
}
_igvn.optimize();
return;
}
// Some parser-inserted loop predicates could never be used by loop
// predication or they were moved away from loop during some optimizations.
// For example, peeling. Eliminate them before next loop optimizations.
eliminate_useless_predicates();
#ifndef PRODUCT
C->verify_graph_edges();
if (_verify_me) { // Nested verify pass?
// Check to see if the verify mode is broken
assert(C->unique() == unique, "non-optimize mode made Nodes? ? ?");
return;
}
if (VerifyLoopOptimizations) verify();
if (TraceLoopOpts && C->has_loops()) {
_ltree_root->dump();
}
#endif
if (skip_loop_opts) {
// restore major progress flag
C->restore_major_progress(old_progress);
// Cleanup any modified bits
_igvn.optimize();
if (C->log() != NULL) {
log_loop_tree(_ltree_root, _ltree_root, C->log());
}
return;
}
if (bs->optimize_loops(this, mode, visited, nstack, worklist)) {
_igvn.optimize();
if (C->log() != NULL) {
log_loop_tree(_ltree_root, _ltree_root, C->log());
}
return;
}
if (ReassociateInvariants) {
// Reassociate invariants and prep for split_thru_phi
for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
IdealLoopTree* lpt = iter.current();
bool is_counted = lpt->is_counted();
if (!is_counted || !lpt->is_innermost()) continue;
// check for vectorized loops, any reassociation of invariants was already done
if (is_counted && lpt->_head->as_CountedLoop()->is_unroll_only()) {
continue;
} else {
AutoNodeBudget node_budget(this);
lpt->reassociate_invariants(this);
}
// Because RCE opportunities can be masked by split_thru_phi,
// look for RCE candidates and inhibit split_thru_phi
// on just their loop-phi's for this pass of loop opts
if (SplitIfBlocks && do_split_ifs) {
AutoNodeBudget node_budget(this, AutoNodeBudget::NO_BUDGET_CHECK);
if (lpt->policy_range_check(this)) {
lpt->_rce_candidate = 1; // = true
}
}
}
}
// Check for aggressive application of split-if and other transforms
// that require basic-block info (like cloning through Phi's)
if( SplitIfBlocks && do_split_ifs ) {
visited.clear();
split_if_with_blocks( visited, nstack);
NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); );
}
if (!C->major_progress() && do_expensive_nodes && process_expensive_nodes()) {
C->set_major_progress();
}
// Perform loop predication before iteration splitting
if (C->has_loops() && !C->major_progress() && (C->predicate_count() > 0)) {
_ltree_root->_child->loop_predication(this);
}
if (OptimizeFill && UseLoopPredicate && C->has_loops() && !C->major_progress()) {
if (do_intrinsify_fill()) {
C->set_major_progress();
}
}
// Perform iteration-splitting on inner loops. Split iterations to avoid
// range checks or one-shot null checks.
// If split-if's didn't hack the graph too bad (no CFG changes)
// then do loop opts.
if (C->has_loops() && !C->major_progress()) {
memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) );
_ltree_root->_child->iteration_split( this, worklist );
// No verify after peeling! GCM has hoisted code out of the loop.
// After peeling, the hoisted code could sink inside the peeled area.
// The peeling code does not try to recompute the best location for
// all the code before the peeled area, so the verify pass will always
// complain about it.
}
// Do verify graph edges in any case
NOT_PRODUCT( C->verify_graph_edges(); );
if (!do_split_ifs) {
// We saw major progress in Split-If to get here. We forced a
// pass with unrolling and not split-if, however more split-if's
// might make progress. If the unrolling didn't make progress
// then the major-progress flag got cleared and we won't try
// another round of Split-If. In particular the ever-common
// instance-of/check-cast pattern requires at least 2 rounds of
// Split-If to clear out.
C->set_major_progress();
}
// Repeat loop optimizations if new loops were seen
if (created_loop_node()) {
C->set_major_progress();
}
// Keep loop predicates and perform optimizations with them
// until no more loop optimizations could be done.
// After that switch predicates off and do more loop optimizations.
if (!C->major_progress() && (C->predicate_count() > 0)) {
C->cleanup_loop_predicates(_igvn);
if (TraceLoopOpts) {
tty->print_cr("PredicatesOff");
}
C->set_major_progress();
}
// Convert scalar to superword operations at the end of all loop opts.
if (UseSuperWord && C->has_loops() && !C->major_progress()) {
// SuperWord transform
SuperWord sw(this);
for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
IdealLoopTree* lpt = iter.current();
if (lpt->is_counted()) {
CountedLoopNode *cl = lpt->_head->as_CountedLoop();
if (PostLoopMultiversioning && cl->is_rce_post_loop() && !cl->is_vectorized_loop()) {
// Check that the rce'd post loop is encountered first, multiversion after all
// major main loop optimization are concluded
if (!C->major_progress()) {
IdealLoopTree *lpt_next = lpt->_next;
if (lpt_next && lpt_next->is_counted()) {
CountedLoopNode *cl = lpt_next->_head->as_CountedLoop();
has_range_checks(lpt_next);
if (cl->is_post_loop() && cl->range_checks_present()) {
if (!cl->is_multiversioned()) {
if (multi_version_post_loops(lpt, lpt_next) == false) {
// Cause the rce loop to be optimized away if we fail
cl->mark_is_multiversioned();
cl->set_slp_max_unroll(0);
poison_rce_post_loop(lpt);
}
}
}
}
sw.transform_loop(lpt, true);
}
} else if (cl->is_main_loop()) {
sw.transform_loop(lpt, true);
}
}
}
}
// Cleanup any modified bits
_igvn.optimize();
// disable assert until issue with split_flow_path is resolved (6742111)
// assert(!_has_irreducible_loops || C->parsed_irreducible_loop() || C->is_osr_compilation(),
// "shouldn't introduce irreducible loops");
if (C->log() != NULL) {
log_loop_tree(_ltree_root, _ltree_root, C->log());
}
}
#ifndef PRODUCT
//------------------------------print_statistics-------------------------------
int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes
int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique
void PhaseIdealLoop::print_statistics() {
tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d", _loop_invokes, _loop_work);
}
//------------------------------verify-----------------------------------------
// Build a verify-only PhaseIdealLoop, and see that it agrees with me.
static int fail; // debug only, so its multi-thread dont care
void PhaseIdealLoop::verify() const {
int old_progress = C->major_progress();
ResourceMark rm;
PhaseIdealLoop loop_verify( _igvn, this );
VectorSet visited(Thread::current()->resource_area());
fail = 0;
verify_compare( C->root(), &loop_verify, visited );
assert( fail == 0, "verify loops failed" );
// Verify loop structure is the same
_ltree_root->verify_tree(loop_verify._ltree_root, NULL);
// Reset major-progress. It was cleared by creating a verify version of
// PhaseIdealLoop.
C->restore_major_progress(old_progress);
}
//------------------------------verify_compare---------------------------------
// Make sure me and the given PhaseIdealLoop agree on key data structures
void PhaseIdealLoop::verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const {
if( !n ) return;
if( visited.test_set( n->_idx ) ) return;
if( !_nodes[n->_idx] ) { // Unreachable
assert( !loop_verify->_nodes[n->_idx], "both should be unreachable" );
return;
}
uint i;
for( i = 0; i < n->req(); i++ )
verify_compare( n->in(i), loop_verify, visited );
// Check the '_nodes' block/loop structure
i = n->_idx;
if( has_ctrl(n) ) { // We have control; verify has loop or ctrl
if( _nodes[i] != loop_verify->_nodes[i] &&
get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) {
tty->print("Mismatched control setting for: ");
n->dump();
if( fail++ > 10 ) return;
Node *c = get_ctrl_no_update(n);
tty->print("We have it as: ");
if( c->in(0) ) c->dump();
else tty->print_cr("N%d",c->_idx);
tty->print("Verify thinks: ");
if( loop_verify->has_ctrl(n) )
loop_verify->get_ctrl_no_update(n)->dump();
else
loop_verify->get_loop_idx(n)->dump();
tty->cr();
}
} else { // We have a loop
IdealLoopTree *us = get_loop_idx(n);
if( loop_verify->has_ctrl(n) ) {
tty->print("Mismatched loop setting for: ");
n->dump();
if( fail++ > 10 ) return;
tty->print("We have it as: ");
us->dump();
tty->print("Verify thinks: ");
loop_verify->get_ctrl_no_update(n)->dump();
tty->cr();
} else if (!C->major_progress()) {
// Loop selection can be messed up if we did a major progress
// operation, like split-if. Do not verify in that case.
IdealLoopTree *them = loop_verify->get_loop_idx(n);
if( us->_head != them->_head || us->_tail != them->_tail ) {
tty->print("Unequals loops for: ");
n->dump();
if( fail++ > 10 ) return;
tty->print("We have it as: ");
us->dump();
tty->print("Verify thinks: ");
them->dump();
tty->cr();
}
}
}
// Check for immediate dominators being equal
if( i >= _idom_size ) {
if( !n->is_CFG() ) return;
tty->print("CFG Node with no idom: ");
n->dump();
return;
}
if( !n->is_CFG() ) return;
if( n == C->root() ) return; // No IDOM here
assert(n->_idx == i, "sanity");
Node *id = idom_no_update(n);
if( id != loop_verify->idom_no_update(n) ) {
tty->print("Unequals idoms for: ");
n->dump();
if( fail++ > 10 ) return;
tty->print("We have it as: ");
id->dump();
tty->print("Verify thinks: ");
loop_verify->idom_no_update(n)->dump();
tty->cr();
}
}
//------------------------------verify_tree------------------------------------
// Verify that tree structures match. Because the CFG can change, siblings
// within the loop tree can be reordered. We attempt to deal with that by
// reordering the verify's loop tree if possible.
void IdealLoopTree::verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const {
assert( _parent == parent, "Badly formed loop tree" );
// Siblings not in same order? Attempt to re-order.
if( _head != loop->_head ) {
// Find _next pointer to update
IdealLoopTree **pp = &loop->_parent->_child;
while( *pp != loop )
pp = &((*pp)->_next);
// Find proper sibling to be next
IdealLoopTree **nn = &loop->_next;
while( (*nn) && (*nn)->_head != _head )
nn = &((*nn)->_next);
// Check for no match.
if( !(*nn) ) {
// Annoyingly, irreducible loops can pick different headers
// after a major_progress operation, so the rest of the loop
// tree cannot be matched.
if (_irreducible && Compile::current()->major_progress()) return;
assert( 0, "failed to match loop tree" );
}
// Move (*nn) to (*pp)
IdealLoopTree *hit = *nn;
*nn = hit->_next;
hit->_next = loop;
*pp = loop;
loop = hit;
// Now try again to verify
}
assert( _head == loop->_head , "mismatched loop head" );
Node *tail = _tail; // Inline a non-updating version of
while( !tail->in(0) ) // the 'tail()' call.
tail = tail->in(1);
assert( tail == loop->_tail, "mismatched loop tail" );
// Counted loops that are guarded should be able to find their guards
if( _head->is_CountedLoop() && _head->as_CountedLoop()->is_main_loop() ) {
CountedLoopNode *cl = _head->as_CountedLoop();
Node *init = cl->init_trip();
Node *ctrl = cl->in(LoopNode::EntryControl);
assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
Node *iff = ctrl->in(0);
assert( iff->Opcode() == Op_If, "" );
Node *bol = iff->in(1);
assert( bol->Opcode() == Op_Bool, "" );
Node *cmp = bol->in(1);
assert( cmp->Opcode() == Op_CmpI, "" );
Node *add = cmp->in(1);
Node *opaq;
if( add->Opcode() == Op_Opaque1 ) {
opaq = add;
} else {
assert( add->Opcode() == Op_AddI || add->Opcode() == Op_ConI , "" );
assert( add == init, "" );
opaq = cmp->in(2);
}
assert( opaq->Opcode() == Op_Opaque1, "" );
}
if (_child != NULL) _child->verify_tree(loop->_child, this);
if (_next != NULL) _next ->verify_tree(loop->_next, parent);
// Innermost loops need to verify loop bodies,
// but only if no 'major_progress'
int fail = 0;
if (!Compile::current()->major_progress() && _child == NULL) {
for( uint i = 0; i < _body.size(); i++ ) {
Node *n = _body.at(i);
if (n->outcnt() == 0) continue; // Ignore dead
uint j;
for( j = 0; j < loop->_body.size(); j++ )
if( loop->_body.at(j) == n )
break;
if( j == loop->_body.size() ) { // Not found in loop body
// Last ditch effort to avoid assertion: Its possible that we
// have some users (so outcnt not zero) but are still dead.
// Try to find from root.
if (Compile::current()->root()->find(n->_idx)) {
fail++;
tty->print("We have that verify does not: ");
n->dump();
}
}
}
for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) {
Node *n = loop->_body.at(i2);
if (n->outcnt() == 0) continue; // Ignore dead
uint j;
for( j = 0; j < _body.size(); j++ )
if( _body.at(j) == n )
break;
if( j == _body.size() ) { // Not found in loop body
// Last ditch effort to avoid assertion: Its possible that we
// have some users (so outcnt not zero) but are still dead.
// Try to find from root.
if (Compile::current()->root()->find(n->_idx)) {
fail++;
tty->print("Verify has that we do not: ");
n->dump();
}
}
}
assert( !fail, "loop body mismatch" );
}
}
#endif
//------------------------------set_idom---------------------------------------
void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) {
uint idx = d->_idx;
if (idx >= _idom_size) {
uint newsize = next_power_of_2(idx);
_idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize);
_dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize);
memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) );
_idom_size = newsize;
}
_idom[idx] = n;
_dom_depth[idx] = dom_depth;
}
//------------------------------recompute_dom_depth---------------------------------------
// The dominator tree is constructed with only parent pointers.
// This recomputes the depth in the tree by first tagging all
// nodes as "no depth yet" marker. The next pass then runs up
// the dom tree from each node marked "no depth yet", and computes
// the depth on the way back down.
void PhaseIdealLoop::recompute_dom_depth() {
uint no_depth_marker = C->unique();
uint i;
// Initialize depth to "no depth yet" and realize all lazy updates
for (i = 0; i < _idom_size; i++) {
// Only indices with a _dom_depth has a Node* or NULL (otherwise uninitalized).
if (_dom_depth[i] > 0 && _idom[i] != NULL) {
_dom_depth[i] = no_depth_marker;
// heal _idom if it has a fwd mapping in _nodes
if (_idom[i]->in(0) == NULL) {
idom(i);
}
}
}
if (_dom_stk == NULL) {
uint init_size = C->live_nodes() / 100; // Guess that 1/100 is a reasonable initial size.
if (init_size < 10) init_size = 10;
_dom_stk = new GrowableArray<uint>(init_size);
}
// Compute new depth for each node.
for (i = 0; i < _idom_size; i++) {
uint j = i;
// Run up the dom tree to find a node with a depth
while (_dom_depth[j] == no_depth_marker) {
_dom_stk->push(j);
j = _idom[j]->_idx;
}
// Compute the depth on the way back down this tree branch
uint dd = _dom_depth[j] + 1;
while (_dom_stk->length() > 0) {
uint j = _dom_stk->pop();
_dom_depth[j] = dd;
dd++;
}
}
}
//------------------------------sort-------------------------------------------
// Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the
// loop tree, not the root.
IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) {
if( !innermost ) return loop; // New innermost loop
int loop_preorder = get_preorder(loop->_head); // Cache pre-order number
assert( loop_preorder, "not yet post-walked loop" );
IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer
IdealLoopTree *l = *pp; // Do I go before or after 'l'?
// Insert at start of list
while( l ) { // Insertion sort based on pre-order
if( l == loop ) return innermost; // Already on list!
int l_preorder = get_preorder(l->_head); // Cache pre-order number
assert( l_preorder, "not yet post-walked l" );
// Check header pre-order number to figure proper nesting
if( loop_preorder > l_preorder )
break; // End of insertion
// If headers tie (e.g., shared headers) check tail pre-order numbers.
// Since I split shared headers, you'd think this could not happen.
// BUT: I must first do the preorder numbering before I can discover I
// have shared headers, so the split headers all get the same preorder
// number as the RegionNode they split from.
if( loop_preorder == l_preorder &&
get_preorder(loop->_tail) < get_preorder(l->_tail) )
break; // Also check for shared headers (same pre#)
pp = &l->_parent; // Chain up list
l = *pp;
}
// Link into list
// Point predecessor to me
*pp = loop;
// Point me to successor
IdealLoopTree *p = loop->_parent;
loop->_parent = l; // Point me to successor
if( p ) sort( p, innermost ); // Insert my parents into list as well
return innermost;
}
//------------------------------build_loop_tree--------------------------------
// I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit
// bits. The _nodes[] array is mapped by Node index and holds a NULL for
// not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the
// tightest enclosing IdealLoopTree for post-walked.
//
// During my forward walk I do a short 1-layer lookahead to see if I can find
// a loop backedge with that doesn't have any work on the backedge. This
// helps me construct nested loops with shared headers better.
//
// Once I've done the forward recursion, I do the post-work. For each child
// I check to see if there is a backedge. Backedges define a loop! I
// insert an IdealLoopTree at the target of the backedge.
//
// During the post-work I also check to see if I have several children
// belonging to different loops. If so, then this Node is a decision point
// where control flow can choose to change loop nests. It is at this
// decision point where I can figure out how loops are nested. At this
// time I can properly order the different loop nests from my children.
// Note that there may not be any backedges at the decision point!
//
// Since the decision point can be far removed from the backedges, I can't
// order my loops at the time I discover them. Thus at the decision point
// I need to inspect loop header pre-order numbers to properly nest my
// loops. This means I need to sort my childrens' loops by pre-order.
// The sort is of size number-of-control-children, which generally limits
// it to size 2 (i.e., I just choose between my 2 target loops).
void PhaseIdealLoop::build_loop_tree() {
// Allocate stack of size C->live_nodes()/2 to avoid frequent realloc
GrowableArray <Node *> bltstack(C->live_nodes() >> 1);
Node *n = C->root();
bltstack.push(n);
int pre_order = 1;
int stack_size;
while ( ( stack_size = bltstack.length() ) != 0 ) {
n = bltstack.top(); // Leave node on stack
if ( !is_visited(n) ) {
// ---- Pre-pass Work ----
// Pre-walked but not post-walked nodes need a pre_order number.
set_preorder_visited( n, pre_order ); // set as visited
// ---- Scan over children ----
// Scan first over control projections that lead to loop headers.
// This helps us find inner-to-outer loops with shared headers better.
// Scan children's children for loop headers.
for ( int i = n->outcnt() - 1; i >= 0; --i ) {
Node* m = n->raw_out(i); // Child
if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children
// Scan over children's children to find loop
for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
Node* l = m->fast_out(j);
if( is_visited(l) && // Been visited?
!is_postvisited(l) && // But not post-visited
get_preorder(l) < pre_order ) { // And smaller pre-order
// Found! Scan the DFS down this path before doing other paths
bltstack.push(m);
break;
}
}
}
}
pre_order++;
}
else if ( !is_postvisited(n) ) {
// Note: build_loop_tree_impl() adds out edges on rare occasions,
// such as com.sun.rsasign.am::a.
// For non-recursive version, first, process current children.
// On next iteration, check if additional children were added.
for ( int k = n->outcnt() - 1; k >= 0; --k ) {
Node* u = n->raw_out(k);
if ( u->is_CFG() && !is_visited(u) ) {
bltstack.push(u);
}
}
if ( bltstack.length() == stack_size ) {
// There were no additional children, post visit node now
(void)bltstack.pop(); // Remove node from stack
pre_order = build_loop_tree_impl( n, pre_order );
// Check for bailout
if (C->failing()) {
return;
}
// Check to grow _preorders[] array for the case when
// build_loop_tree_impl() adds new nodes.
check_grow_preorders();
}
}
else {
(void)bltstack.pop(); // Remove post-visited node from stack
}
}
}
//------------------------------build_loop_tree_impl---------------------------
int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) {
// ---- Post-pass Work ----
// Pre-walked but not post-walked nodes need a pre_order number.
// Tightest enclosing loop for this Node
IdealLoopTree *innermost = NULL;
// For all children, see if any edge is a backedge. If so, make a loop
// for it. Then find the tightest enclosing loop for the self Node.
for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
Node* m = n->fast_out(i); // Child
if( n == m ) continue; // Ignore control self-cycles
if( !m->is_CFG() ) continue;// Ignore non-CFG edges
IdealLoopTree *l; // Child's loop
if( !is_postvisited(m) ) { // Child visited but not post-visited?
// Found a backedge
assert( get_preorder(m) < pre_order, "should be backedge" );
// Check for the RootNode, which is already a LoopNode and is allowed
// to have multiple "backedges".
if( m == C->root()) { // Found the root?
l = _ltree_root; // Root is the outermost LoopNode
} else { // Else found a nested loop
// Insert a LoopNode to mark this loop.
l = new IdealLoopTree(this, m, n);
} // End of Else found a nested loop
if( !has_loop(m) ) // If 'm' does not already have a loop set
set_loop(m, l); // Set loop header to loop now
} else { // Else not a nested loop
if( !_nodes[m->_idx] ) continue; // Dead code has no loop
l = get_loop(m); // Get previously determined loop
// If successor is header of a loop (nest), move up-loop till it
// is a member of some outer enclosing loop. Since there are no
// shared headers (I've split them already) I only need to go up
// at most 1 level.
while( l && l->_head == m ) // Successor heads loop?
l = l->_parent; // Move up 1 for me
// If this loop is not properly parented, then this loop
// has no exit path out, i.e. its an infinite loop.
if( !l ) {
// Make loop "reachable" from root so the CFG is reachable. Basically
// insert a bogus loop exit that is never taken. 'm', the loop head,
// points to 'n', one (of possibly many) fall-in paths. There may be
// many backedges as well.
// Here I set the loop to be the root loop. I could have, after
// inserting a bogus loop exit, restarted the recursion and found my
// new loop exit. This would make the infinite loop a first-class
// loop and it would then get properly optimized. What's the use of
// optimizing an infinite loop?
l = _ltree_root; // Oops, found infinite loop
if (!_verify_only) {
// Insert the NeverBranch between 'm' and it's control user.
NeverBranchNode *iff = new NeverBranchNode( m );
_igvn.register_new_node_with_optimizer(iff);
set_loop(iff, l);
Node *if_t = new CProjNode( iff, 0 );
_igvn.register_new_node_with_optimizer(if_t);
set_loop(if_t, l);
Node* cfg = NULL; // Find the One True Control User of m
for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
Node* x = m->fast_out(j);
if (x->is_CFG() && x != m && x != iff)
{ cfg = x; break; }
}
assert(cfg != NULL, "must find the control user of m");
uint k = 0; // Probably cfg->in(0)
while( cfg->in(k) != m ) k++; // But check incase cfg is a Region
cfg->set_req( k, if_t ); // Now point to NeverBranch
_igvn._worklist.push(cfg);
// Now create the never-taken loop exit
Node *if_f = new CProjNode( iff, 1 );
_igvn.register_new_node_with_optimizer(if_f);
set_loop(if_f, l);
// Find frame ptr for Halt. Relies on the optimizer
// V-N'ing. Easier and quicker than searching through
// the program structure.
Node *frame = new ParmNode( C->start(), TypeFunc::FramePtr );
_igvn.register_new_node_with_optimizer(frame);
// Halt & Catch Fire
Node* halt = new HaltNode(if_f, frame, "never-taken loop exit reached");
_igvn.register_new_node_with_optimizer(halt);
set_loop(halt, l);
C->root()->add_req(halt);
}
set_loop(C->root(), _ltree_root);
}
}
// Weeny check for irreducible. This child was already visited (this
// IS the post-work phase). Is this child's loop header post-visited
// as well? If so, then I found another entry into the loop.
if (!_verify_only) {
while( is_postvisited(l->_head) ) {
// found irreducible
l->_irreducible = 1; // = true
l = l->_parent;
_has_irreducible_loops = true;
// Check for bad CFG here to prevent crash, and bailout of compile
if (l == NULL) {
C->record_method_not_compilable("unhandled CFG detected during loop optimization");
return pre_order;
}
}
C->set_has_irreducible_loop(_has_irreducible_loops);
}
// This Node might be a decision point for loops. It is only if
// it's children belong to several different loops. The sort call
// does a trivial amount of work if there is only 1 child or all
// children belong to the same loop. If however, the children
// belong to different loops, the sort call will properly set the
// _parent pointers to show how the loops nest.
//
// In any case, it returns the tightest enclosing loop.
innermost = sort( l, innermost );
}
// Def-use info will have some dead stuff; dead stuff will have no
// loop decided on.
// Am I a loop header? If so fix up my parent's child and next ptrs.
if( innermost && innermost->_head == n ) {
assert( get_loop(n) == innermost, "" );
IdealLoopTree *p = innermost->_parent;
IdealLoopTree *l = innermost;
while( p && l->_head == n ) {
l->_next = p->_child; // Put self on parents 'next child'
p->_child = l; // Make self as first child of parent
l = p; // Now walk up the parent chain
p = l->_parent;
}
} else {
// Note that it is possible for a LoopNode to reach here, if the
// backedge has been made unreachable (hence the LoopNode no longer
// denotes a Loop, and will eventually be removed).
// Record tightest enclosing loop for self. Mark as post-visited.
set_loop(n, innermost);
// Also record has_call flag early on
if( innermost ) {
if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) {
// Do not count uncommon calls
if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) {
Node *iff = n->in(0)->in(0);
// No any calls for vectorized loops.
if( UseSuperWord || !iff->is_If() ||
(n->in(0)->Opcode() == Op_IfFalse &&
(1.0 - iff->as_If()->_prob) >= 0.01) ||
(iff->as_If()->_prob >= 0.01) )
innermost->_has_call = 1;
}
} else if( n->is_Allocate() && n->as_Allocate()->_is_scalar_replaceable ) {
// Disable loop optimizations if the loop has a scalar replaceable
// allocation. This disabling may cause a potential performance lost
// if the allocation is not eliminated for some reason.
innermost->_allow_optimizations = false;
innermost->_has_call = 1; // = true
} else if (n->Opcode() == Op_SafePoint) {
// Record all safepoints in this loop.
if (innermost->_safepts == NULL) innermost->_safepts = new Node_List();
innermost->_safepts->push(n);
}
}
}
// Flag as post-visited now
set_postvisited(n);
return pre_order;
}
//------------------------------build_loop_early-------------------------------
// Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
// First pass computes the earliest controlling node possible. This is the
// controlling input with the deepest dominating depth.
void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
while (worklist.size() != 0) {
// Use local variables nstack_top_n & nstack_top_i to cache values
// on nstack's top.
Node *nstack_top_n = worklist.pop();
uint nstack_top_i = 0;
//while_nstack_nonempty:
while (true) {
// Get parent node and next input's index from stack's top.
Node *n = nstack_top_n;
uint i = nstack_top_i;
uint cnt = n->req(); // Count of inputs
if (i == 0) { // Pre-process the node.
if( has_node(n) && // Have either loop or control already?
!has_ctrl(n) ) { // Have loop picked out already?
// During "merge_many_backedges" we fold up several nested loops
// into a single loop. This makes the members of the original
// loop bodies pointing to dead loops; they need to move up
// to the new UNION'd larger loop. I set the _head field of these
// dead loops to NULL and the _parent field points to the owning
// loop. Shades of UNION-FIND algorithm.
IdealLoopTree *ilt;
while( !(ilt = get_loop(n))->_head ) {
// Normally I would use a set_loop here. But in this one special
// case, it is legal (and expected) to change what loop a Node
// belongs to.
_nodes.map(n->_idx, (Node*)(ilt->_parent) );
}
// Remove safepoints ONLY if I've already seen I don't need one.
// (the old code here would yank a 2nd safepoint after seeing a
// first one, even though the 1st did not dominate in the loop body
// and thus could be avoided indefinitely)
if( !_verify_only && !_verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint &&
is_deleteable_safept(n)) {
Node *in = n->in(TypeFunc::Control);
lazy_replace(n,in); // Pull safepoint now
if (ilt->_safepts != NULL) {
ilt->_safepts->yank(n);
}
// Carry on with the recursion "as if" we are walking
// only the control input
if( !visited.test_set( in->_idx ) ) {
worklist.push(in); // Visit this guy later, using worklist
}
// Get next node from nstack:
// - skip n's inputs processing by setting i > cnt;
// - we also will not call set_early_ctrl(n) since
// has_node(n) == true (see the condition above).
i = cnt + 1;
}
}
} // if (i == 0)
// Visit all inputs
bool done = true; // Assume all n's inputs will be processed
while (i < cnt) {
Node *in = n->in(i);
++i;
if (in == NULL) continue;
if (in->pinned() && !in->is_CFG())
set_ctrl(in, in->in(0));
int is_visited = visited.test_set( in->_idx );
if (!has_node(in)) { // No controlling input yet?
assert( !in->is_CFG(), "CFG Node with no controlling input?" );
assert( !is_visited, "visit only once" );
nstack.push(n, i); // Save parent node and next input's index.
nstack_top_n = in; // Process current input now.
nstack_top_i = 0;
done = false; // Not all n's inputs processed.
break; // continue while_nstack_nonempty;
} else if (!is_visited) {
// This guy has a location picked out for him, but has not yet
// been visited. Happens to all CFG nodes, for instance.
// Visit him using the worklist instead of recursion, to break
// cycles. Since he has a location already we do not need to
// find his location before proceeding with the current Node.
worklist.push(in); // Visit this guy later, using worklist
}
}
if (done) {
// All of n's inputs have been processed, complete post-processing.
// Compute earliest point this Node can go.
// CFG, Phi, pinned nodes already know their controlling input.
if (!has_node(n)) {
// Record earliest legal location
set_early_ctrl( n );
}
if (nstack.is_empty()) {
// Finished all nodes on stack.
// Process next node on the worklist.
break;
}
// Get saved parent node and next input's index.
nstack_top_n = nstack.node();
nstack_top_i = nstack.index();
nstack.pop();
}
} // while (true)
}
}
//------------------------------dom_lca_internal--------------------------------
// Pair-wise LCA
Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const {
if( !n1 ) return n2; // Handle NULL original LCA
assert( n1->is_CFG(), "" );
assert( n2->is_CFG(), "" );
// find LCA of all uses
uint d1 = dom_depth(n1);
uint d2 = dom_depth(n2);
while (n1 != n2) {
if (d1 > d2) {
n1 = idom(n1);
d1 = dom_depth(n1);
} else if (d1 < d2) {
n2 = idom(n2);
d2 = dom_depth(n2);
} else {
// Here d1 == d2. Due to edits of the dominator-tree, sections
// of the tree might have the same depth. These sections have
// to be searched more carefully.
// Scan up all the n1's with equal depth, looking for n2.
Node *t1 = idom(n1);
while (dom_depth(t1) == d1) {
if (t1 == n2) return n2;
t1 = idom(t1);
}
// Scan up all the n2's with equal depth, looking for n1.
Node *t2 = idom(n2);
while (dom_depth(t2) == d2) {
if (t2 == n1) return n1;
t2 = idom(t2);
}
// Move up to a new dominator-depth value as well as up the dom-tree.
n1 = t1;
n2 = t2;
d1 = dom_depth(n1);
d2 = dom_depth(n2);
}
}
return n1;
}
//------------------------------compute_idom-----------------------------------
// Locally compute IDOM using dom_lca call. Correct only if the incoming
// IDOMs are correct.
Node *PhaseIdealLoop::compute_idom( Node *region ) const {
assert( region->is_Region(), "" );
Node *LCA = NULL;
for( uint i = 1; i < region->req(); i++ ) {
if( region->in(i) != C->top() )
LCA = dom_lca( LCA, region->in(i) );
}
return LCA;
}
bool PhaseIdealLoop::verify_dominance(Node* n, Node* use, Node* LCA, Node* early) {
bool had_error = false;
#ifdef ASSERT
if (early != C->root()) {
// Make sure that there's a dominance path from LCA to early
Node* d = LCA;
while (d != early) {
if (d == C->root()) {
dump_bad_graph("Bad graph detected in compute_lca_of_uses", n, early, LCA);
tty->print_cr("*** Use %d isn't dominated by def %d ***", use->_idx, n->_idx);
had_error = true;
break;
}
d = idom(d);
}
}
#endif
return had_error;
}
Node* PhaseIdealLoop::compute_lca_of_uses(Node* n, Node* early, bool verify) {
// Compute LCA over list of uses
bool had_error = false;
Node *LCA = NULL;
for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) {
Node* c = n->fast_out(i);
if (_nodes[c->_idx] == NULL)
continue; // Skip the occasional dead node
if( c->is_Phi() ) { // For Phis, we must land above on the path
for( uint j=1; j<c->req(); j++ ) {// For all inputs
if( c->in(j) == n ) { // Found matching input?
Node *use = c->in(0)->in(j);
if (_verify_only && use->is_top()) continue;
LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
}
}
} else {
// For CFG data-users, use is in the block just prior
Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0);
LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
}
}
assert(!had_error, "bad dominance");
return LCA;
}
// Check the shape of the graph at the loop entry. In some cases,
// the shape of the graph does not match the shape outlined below.
// That is caused by the Opaque1 node "protecting" the shape of
// the graph being removed by, for example, the IGVN performed
// in PhaseIdealLoop::build_and_optimize().
//
// After the Opaque1 node has been removed, optimizations (e.g., split-if,
// loop unswitching, and IGVN, or a combination of them) can freely change
// the graph's shape. As a result, the graph shape outlined below cannot
// be guaranteed anymore.
bool PhaseIdealLoop::is_canonical_loop_entry(CountedLoopNode* cl) {
if (!cl->is_main_loop() && !cl->is_post_loop()) {
return false;
}
Node* ctrl = cl->skip_predicates();
if (ctrl == NULL || (!ctrl->is_IfTrue() && !ctrl->is_IfFalse())) {
return false;
}
Node* iffm = ctrl->in(0);
if (iffm == NULL || !iffm->is_If()) {
return false;
}
Node* bolzm = iffm->in(1);
if (bolzm == NULL || !bolzm->is_Bool()) {
return false;
}
Node* cmpzm = bolzm->in(1);
if (cmpzm == NULL || !cmpzm->is_Cmp()) {
return false;
}
// compares can get conditionally flipped
bool found_opaque = false;
for (uint i = 1; i < cmpzm->req(); i++) {
Node* opnd = cmpzm->in(i);
if (opnd && opnd->Opcode() == Op_Opaque1) {
found_opaque = true;
break;
}
}
if (!found_opaque) {
return false;
}
return true;
}
//------------------------------get_late_ctrl----------------------------------
// Compute latest legal control.
Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
assert(early != NULL, "early control should not be NULL");
Node* LCA = compute_lca_of_uses(n, early);
#ifdef ASSERT
if (LCA == C->root() && LCA != early) {
// def doesn't dominate uses so print some useful debugging output
compute_lca_of_uses(n, early, true);
}
#endif
// if this is a load, check for anti-dependent stores
// We use a conservative algorithm to identify potential interfering
// instructions and for rescheduling the load. The users of the memory
// input of this load are examined. Any use which is not a load and is
// dominated by early is considered a potentially interfering store.
// This can produce false positives.
if (n->is_Load() && LCA != early) {
int load_alias_idx = C->get_alias_index(n->adr_type());
if (C->alias_type(load_alias_idx)->is_rewritable()) {
Node_List worklist;
Node *mem = n->in(MemNode::Memory);
for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
Node* s = mem->fast_out(i);
worklist.push(s);
}
while(worklist.size() != 0 && LCA != early) {
Node* s = worklist.pop();
if (s->is_Load() || s->Opcode() == Op_SafePoint ||
(s->is_CallStaticJava() && s->as_CallStaticJava()->uncommon_trap_request() != 0)) {
continue;
} else if (s->is_MergeMem()) {
for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
Node* s1 = s->fast_out(i);
worklist.push(s1);
}
} else {
Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0);
assert(sctrl != NULL || s->outcnt() == 0, "must have control");
if (sctrl != NULL && !sctrl->is_top() && C->can_alias(s->adr_type(), load_alias_idx) && is_dominator(early, sctrl)) {
LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
}
}
}
}
}
assert(LCA == find_non_split_ctrl(LCA), "unexpected late control");
return LCA;
}
// true if CFG node d dominates CFG node n
bool PhaseIdealLoop::is_dominator(Node *d, Node *n) {
if (d == n)
return true;
assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
uint dd = dom_depth(d);
while (dom_depth(n) >= dd) {
if (n == d)
return true;
n = idom(n);
}
return false;
}
//------------------------------dom_lca_for_get_late_ctrl_internal-------------
// Pair-wise LCA with tags.
// Tag each index with the node 'tag' currently being processed
// before advancing up the dominator chain using idom().
// Later calls that find a match to 'tag' know that this path has already
// been considered in the current LCA (which is input 'n1' by convention).
// Since get_late_ctrl() is only called once for each node, the tag array
// does not need to be cleared between calls to get_late_ctrl().
// Algorithm trades a larger constant factor for better asymptotic behavior
//
Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal( Node *n1, Node *n2, Node *tag ) {
uint d1 = dom_depth(n1);
uint d2 = dom_depth(n2);
do {
if (d1 > d2) {
// current lca is deeper than n2
_dom_lca_tags.map(n1->_idx, tag);
n1 = idom(n1);
d1 = dom_depth(n1);
} else if (d1 < d2) {
// n2 is deeper than current lca
Node *memo = _dom_lca_tags[n2->_idx];
if( memo == tag ) {
return n1; // Return the current LCA
}
_dom_lca_tags.map(n2->_idx, tag);
n2 = idom(n2);
d2 = dom_depth(n2);
} else {
// Here d1 == d2. Due to edits of the dominator-tree, sections
// of the tree might have the same depth. These sections have
// to be searched more carefully.
// Scan up all the n1's with equal depth, looking for n2.
_dom_lca_tags.map(n1->_idx, tag);
Node *t1 = idom(n1);
while (dom_depth(t1) == d1) {
if (t1 == n2) return n2;
_dom_lca_tags.map(t1->_idx, tag);
t1 = idom(t1);
}
// Scan up all the n2's with equal depth, looking for n1.
_dom_lca_tags.map(n2->_idx, tag);
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