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25 #include "precompiled.hpp"
26 #include "compiler/compileLog.hpp"
27 #include "memory/allocation.inline.hpp"
28 #include "opto/addnode.hpp"
29 #include "opto/callnode.hpp"
30 #include "opto/connode.hpp"
31 #include "opto/divnode.hpp"
32 #include "opto/loopnode.hpp"
33 #include "opto/mulnode.hpp"
34 #include "opto/rootnode.hpp"
35 #include "opto/runtime.hpp"
36 #include "opto/subnode.hpp"
38 //------------------------------is_loop_exit-----------------------------------
39 // Given an IfNode, return the loop-exiting projection or NULL if both
40 // arms remain in the loop.
41 Node *IdealLoopTree::is_loop_exit(Node *iff) const {
42 if( iff->outcnt() != 2 ) return NULL; // Ignore partially dead tests
43 PhaseIdealLoop *phase = _phase;
44 // Test is an IfNode, has 2 projections. If BOTH are in the loop
45 // we need loop unswitching instead of peeling.
46 if( !is_member(phase->get_loop( iff->raw_out(0) )) )
47 return iff->raw_out(0);
48 if( !is_member(phase->get_loop( iff->raw_out(1) )) )
49 return iff->raw_out(1);
54 //=============================================================================
57 //------------------------------record_for_igvn----------------------------
58 // Put loop body on igvn work list
59 void IdealLoopTree::record_for_igvn() {
60 for( uint i = 0; i < _body.size(); i++ ) {
61 Node *n = _body.at(i);
62 _phase->_igvn._worklist.push(n);
66 //------------------------------compute_exact_trip_count-----------------------
67 // Compute loop exact trip count if possible. Do not recalculate trip count for
68 // split loops (pre-main-post) which have their limits and inits behind Opaque node.
69 void IdealLoopTree::compute_exact_trip_count( PhaseIdealLoop *phase ) {
70 if (!_head->as_Loop()->is_valid_counted_loop()) {
73 CountedLoopNode* cl = _head->as_CountedLoop();
74 // Trip count may become nonexact for iteration split loops since
75 // RCE modifies limits. Note, _trip_count value is not reset since
76 // it is used to limit unrolling of main loop.
77 cl->set_nonexact_trip_count();
79 // Loop's test should be part of loop.
80 if (!phase->is_member(this, phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue))))
81 return; // Infinite loop
84 BoolTest::mask bt = cl->loopexit()->test_trip();
85 assert(bt == BoolTest::lt || bt == BoolTest::gt ||
86 bt == BoolTest::ne, "canonical test is expected");
89 Node* init_n = cl->init_trip();
90 Node* limit_n = cl->limit();
91 if (init_n != NULL && init_n->is_Con() &&
92 limit_n != NULL && limit_n->is_Con()) {
93 // Use longs to avoid integer overflow.
94 int stride_con = cl->stride_con();
95 long init_con = cl->init_trip()->get_int();
96 long limit_con = cl->limit()->get_int();
97 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
98 long trip_count = (limit_con - init_con + stride_m)/stride_con;
99 if (trip_count > 0 && (julong)trip_count < (julong)max_juint) {
100 // Set exact trip count.
101 cl->set_exact_trip_count((uint)trip_count);
106 //------------------------------compute_profile_trip_cnt----------------------------
107 // Compute loop trip count from profile data as
108 // (backedge_count + loop_exit_count) / loop_exit_count
109 void IdealLoopTree::compute_profile_trip_cnt( PhaseIdealLoop *phase ) {
110 if (!_head->is_CountedLoop()) {
113 CountedLoopNode* head = _head->as_CountedLoop();
114 if (head->profile_trip_cnt() != COUNT_UNKNOWN) {
115 return; // Already computed
117 float trip_cnt = (float)max_jint; // default is big
119 Node* back = head->in(LoopNode::LoopBackControl);
120 while (back != head) {
121 if ((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) &&
123 back->in(0)->is_If() &&
124 back->in(0)->as_If()->_fcnt != COUNT_UNKNOWN &&
125 back->in(0)->as_If()->_prob != PROB_UNKNOWN) {
128 back = phase->idom(back);
131 assert((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) &&
132 back->in(0), "if-projection exists");
133 IfNode* back_if = back->in(0)->as_If();
134 float loop_back_cnt = back_if->_fcnt * back_if->_prob;
136 // Now compute a loop exit count
137 float loop_exit_cnt = 0.0f;
138 for( uint i = 0; i < _body.size(); i++ ) {
141 IfNode *iff = n->as_If();
142 if( iff->_fcnt != COUNT_UNKNOWN && iff->_prob != PROB_UNKNOWN ) {
143 Node *exit = is_loop_exit(iff);
145 float exit_prob = iff->_prob;
146 if (exit->Opcode() == Op_IfFalse) exit_prob = 1.0 - exit_prob;
147 if (exit_prob > PROB_MIN) {
148 float exit_cnt = iff->_fcnt * exit_prob;
149 loop_exit_cnt += exit_cnt;
155 if (loop_exit_cnt > 0.0f) {
156 trip_cnt = (loop_back_cnt + loop_exit_cnt) / loop_exit_cnt;
158 // No exit count so use
159 trip_cnt = loop_back_cnt;
163 if (TraceProfileTripCount) {
164 tty->print_cr("compute_profile_trip_cnt lp: %d cnt: %f\n", head->_idx, trip_cnt);
167 head->set_profile_trip_cnt(trip_cnt);
170 //---------------------is_invariant_addition-----------------------------
171 // Return nonzero index of invariant operand for an Add or Sub
172 // of (nonconstant) invariant and variant values. Helper for reassociate_invariants.
173 int IdealLoopTree::is_invariant_addition(Node* n, PhaseIdealLoop *phase) {
174 int op = n->Opcode();
175 if (op == Op_AddI || op == Op_SubI) {
176 bool in1_invar = this->is_invariant(n->in(1));
177 bool in2_invar = this->is_invariant(n->in(2));
178 if (in1_invar && !in2_invar) return 1;
179 if (!in1_invar && in2_invar) return 2;
184 //---------------------reassociate_add_sub-----------------------------
185 // Reassociate invariant add and subtract expressions:
187 // inv1 + (x + inv2) => ( inv1 + inv2) + x
188 // (x + inv2) + inv1 => ( inv1 + inv2) + x
189 // inv1 + (x - inv2) => ( inv1 - inv2) + x
190 // inv1 - (inv2 - x) => ( inv1 - inv2) + x
191 // (x + inv2) - inv1 => (-inv1 + inv2) + x
192 // (x - inv2) + inv1 => ( inv1 - inv2) + x
193 // (x - inv2) - inv1 => (-inv1 - inv2) + x
194 // inv1 + (inv2 - x) => ( inv1 + inv2) - x
195 // inv1 - (x - inv2) => ( inv1 + inv2) - x
196 // (inv2 - x) + inv1 => ( inv1 + inv2) - x
197 // (inv2 - x) - inv1 => (-inv1 + inv2) - x
198 // inv1 - (x + inv2) => ( inv1 - inv2) - x
200 Node* IdealLoopTree::reassociate_add_sub(Node* n1, PhaseIdealLoop *phase) {
201 if (!n1->is_Add() && !n1->is_Sub() || n1->outcnt() == 0) return NULL;
202 if (is_invariant(n1)) return NULL;
203 int inv1_idx = is_invariant_addition(n1, phase);
204 if (!inv1_idx) return NULL;
205 // Don't mess with add of constant (igvn moves them to expression tree root.)
206 if (n1->is_Add() && n1->in(2)->is_Con()) return NULL;
207 Node* inv1 = n1->in(inv1_idx);
208 Node* n2 = n1->in(3 - inv1_idx);
209 int inv2_idx = is_invariant_addition(n2, phase);
210 if (!inv2_idx) return NULL;
211 Node* x = n2->in(3 - inv2_idx);
212 Node* inv2 = n2->in(inv2_idx);
214 bool neg_x = n2->is_Sub() && inv2_idx == 1;
215 bool neg_inv2 = n2->is_Sub() && inv2_idx == 2;
216 bool neg_inv1 = n1->is_Sub() && inv1_idx == 2;
217 if (n1->is_Sub() && inv1_idx == 1) {
219 neg_inv2 = !neg_inv2;
221 Node* inv1_c = phase->get_ctrl(inv1);
222 Node* inv2_c = phase->get_ctrl(inv2);
225 Node *zero = phase->_igvn.intcon(0);
226 phase->set_ctrl(zero, phase->C->root());
227 n_inv1 = new (phase->C, 3) SubINode(zero, inv1);
228 phase->register_new_node(n_inv1, inv1_c);
234 inv = new (phase->C, 3) SubINode(n_inv1, inv2);
236 inv = new (phase->C, 3) AddINode(n_inv1, inv2);
238 phase->register_new_node(inv, phase->get_early_ctrl(inv));
242 addx = new (phase->C, 3) SubINode(inv, x);
244 addx = new (phase->C, 3) AddINode(x, inv);
246 phase->register_new_node(addx, phase->get_ctrl(x));
247 phase->_igvn.replace_node(n1, addx);
248 assert(phase->get_loop(phase->get_ctrl(n1)) == this, "");
253 //---------------------reassociate_invariants-----------------------------
254 // Reassociate invariant expressions:
255 void IdealLoopTree::reassociate_invariants(PhaseIdealLoop *phase) {
256 for (int i = _body.size() - 1; i >= 0; i--) {
257 Node *n = _body.at(i);
258 for (int j = 0; j < 5; j++) {
259 Node* nn = reassociate_add_sub(n, phase);
260 if (nn == NULL) break;
266 //------------------------------policy_peeling---------------------------------
267 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
268 // make some loop-invariant test (usually a null-check) happen before the loop.
269 bool IdealLoopTree::policy_peeling( PhaseIdealLoop *phase ) const {
270 Node *test = ((IdealLoopTree*)this)->tail();
271 int body_size = ((IdealLoopTree*)this)->_body.size();
272 int uniq = phase->C->unique();
273 // Peeling does loop cloning which can result in O(N^2) node construction
274 if( body_size > 255 /* Prevent overflow for large body_size */
275 || (body_size * body_size + uniq > MaxNodeLimit) ) {
276 return false; // too large to safely clone
278 while( test != _head ) { // Scan till run off top of loop
279 if( test->is_If() ) { // Test?
280 Node *ctrl = phase->get_ctrl(test->in(1));
282 return false; // Found dead test on live IF? No peeling!
283 // Standard IF only has one input value to check for loop invariance
284 assert( test->Opcode() == Op_If || test->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added");
285 // Condition is not a member of this loop?
286 if( !is_member(phase->get_loop(ctrl)) &&
288 return true; // Found reason to peel!
290 // Walk up dominators to loop _head looking for test which is
291 // executed on every path thru loop.
292 test = phase->idom(test);
297 //------------------------------peeled_dom_test_elim---------------------------
298 // If we got the effect of peeling, either by actually peeling or by making
299 // a pre-loop which must execute at least once, we can remove all
300 // loop-invariant dominated tests in the main body.
301 void PhaseIdealLoop::peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ) {
302 bool progress = true;
304 progress = false; // Reset for next iteration
305 Node *prev = loop->_head->in(LoopNode::LoopBackControl);//loop->tail();
306 Node *test = prev->in(0);
307 while( test != loop->_head ) { // Scan till run off top of loop
309 int p_op = prev->Opcode();
310 if( (p_op == Op_IfFalse || p_op == Op_IfTrue) &&
311 test->is_If() && // Test?
312 !test->in(1)->is_Con() && // And not already obvious?
313 // Condition is not a member of this loop?
314 !loop->is_member(get_loop(get_ctrl(test->in(1))))){
315 // Walk loop body looking for instances of this test
316 for( uint i = 0; i < loop->_body.size(); i++ ) {
317 Node *n = loop->_body.at(i);
318 if( n->is_If() && n->in(1) == test->in(1) /*&& n != loop->tail()->in(0)*/ ) {
319 // IfNode was dominated by version in peeled loop body
321 dominated_by( old_new[prev->_idx], n );
327 } // End of scan tests in loop
329 } // End of while( progress )
332 //------------------------------do_peeling-------------------------------------
333 // Peel the first iteration of the given loop.
334 // Step 1: Clone the loop body. The clone becomes the peeled iteration.
335 // The pre-loop illegally has 2 control users (old & new loops).
336 // Step 2: Make the old-loop fall-in edges point to the peeled iteration.
337 // Do this by making the old-loop fall-in edges act as if they came
338 // around the loopback from the prior iteration (follow the old-loop
339 // backedges) and then map to the new peeled iteration. This leaves
340 // the pre-loop with only 1 user (the new peeled iteration), but the
341 // peeled-loop backedge has 2 users.
342 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the
343 // extra backedge user.
381 // +---->loop clone loop<----+
383 // | stmt2 clone stmt2 |
390 // | true false false true |
401 // after peel and predicate move
410 // / loop predicate |
413 // TOP-->loop clone loop<----+ |
415 // stmt2 clone stmt2 | |
422 // true false false true | |
432 // +--------------->-----------------+
470 void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) {
472 C->set_major_progress();
473 // Peeling a 'main' loop in a pre/main/post situation obfuscates the
474 // 'pre' loop from the main and the 'pre' can no longer have it's
475 // iterations adjusted. Therefore, we need to declare this loop as
476 // no longer a 'main' loop; it will need new pre and post loops before
477 // we can do further RCE.
484 Node* head = loop->_head;
485 bool counted_loop = head->is_CountedLoop();
487 CountedLoopNode *cl = head->as_CountedLoop();
488 assert(cl->trip_count() > 0, "peeling a fully unrolled loop");
489 cl->set_trip_count(cl->trip_count() - 1);
490 if (cl->is_main_loop()) {
491 cl->set_normal_loop();
493 if (PrintOpto && VerifyLoopOptimizations) {
494 tty->print("Peeling a 'main' loop; resetting to 'normal' ");
500 Node* entry = head->in(LoopNode::EntryControl);
502 // Step 1: Clone the loop body. The clone becomes the peeled iteration.
503 // The pre-loop illegally has 2 control users (old & new loops).
504 clone_loop( loop, old_new, dom_depth(head) );
506 // Step 2: Make the old-loop fall-in edges point to the peeled iteration.
507 // Do this by making the old-loop fall-in edges act as if they came
508 // around the loopback from the prior iteration (follow the old-loop
509 // backedges) and then map to the new peeled iteration. This leaves
510 // the pre-loop with only 1 user (the new peeled iteration), but the
511 // peeled-loop backedge has 2 users.
512 Node* new_exit_value = old_new[head->in(LoopNode::LoopBackControl)->_idx];
513 new_exit_value = move_loop_predicates(entry, new_exit_value, !counted_loop);
514 _igvn.hash_delete(head);
515 head->set_req(LoopNode::EntryControl, new_exit_value);
516 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
517 Node* old = head->fast_out(j);
518 if (old->in(0) == loop->_head && old->req() == 3 && old->is_Phi()) {
519 new_exit_value = old_new[old->in(LoopNode::LoopBackControl)->_idx];
520 if (!new_exit_value ) // Backedge value is ALSO loop invariant?
521 // Then loop body backedge value remains the same.
522 new_exit_value = old->in(LoopNode::LoopBackControl);
523 _igvn.hash_delete(old);
524 old->set_req(LoopNode::EntryControl, new_exit_value);
529 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the
530 // extra backedge user.
531 Node* new_head = old_new[head->_idx];
532 _igvn.hash_delete(new_head);
533 new_head->set_req(LoopNode::LoopBackControl, C->top());
534 for (DUIterator_Fast j2max, j2 = new_head->fast_outs(j2max); j2 < j2max; j2++) {
535 Node* use = new_head->fast_out(j2);
536 if (use->in(0) == new_head && use->req() == 3 && use->is_Phi()) {
537 _igvn.hash_delete(use);
538 use->set_req(LoopNode::LoopBackControl, C->top());
543 // Step 4: Correct dom-depth info. Set to loop-head depth.
544 int dd = dom_depth(head);
545 set_idom(head, head->in(1), dd);
546 for (uint j3 = 0; j3 < loop->_body.size(); j3++) {
547 Node *old = loop->_body.at(j3);
548 Node *nnn = old_new[old->_idx];
550 set_idom(nnn, idom(nnn), dd-1);
551 // While we're at it, remove any SafePoints from the peeled code
552 if (old->Opcode() == Op_SafePoint) {
553 Node *nnn = old_new[old->_idx];
554 lazy_replace(nnn,nnn->in(TypeFunc::Control));
558 // Now force out all loop-invariant dominating tests. The optimizer
559 // finds some, but we _know_ they are all useless.
560 peeled_dom_test_elim(loop,old_new);
562 loop->record_for_igvn();
565 #define EMPTY_LOOP_SIZE 7 // number of nodes in an empty loop
567 //------------------------------policy_maximally_unroll------------------------
568 // Calculate exact loop trip count and return true if loop can be maximally
570 bool IdealLoopTree::policy_maximally_unroll( PhaseIdealLoop *phase ) const {
571 CountedLoopNode *cl = _head->as_CountedLoop();
572 assert(cl->is_normal_loop(), "");
573 if (!cl->is_valid_counted_loop())
574 return false; // Malformed counted loop
576 if (!cl->has_exact_trip_count()) {
577 // Trip count is not exact.
581 uint trip_count = cl->trip_count();
582 // Note, max_juint is used to indicate unknown trip count.
583 assert(trip_count > 1, "one iteration loop should be optimized out already");
584 assert(trip_count < max_juint, "exact trip_count should be less than max_uint.");
586 // Real policy: if we maximally unroll, does it get too big?
587 // Allow the unrolled mess to get larger than standard loop
588 // size. After all, it will no longer be a loop.
589 uint body_size = _body.size();
590 uint unroll_limit = (uint)LoopUnrollLimit * 4;
591 assert( (intx)unroll_limit == LoopUnrollLimit * 4, "LoopUnrollLimit must fit in 32bits");
592 if (trip_count > unroll_limit || body_size > unroll_limit) {
596 // Fully unroll a loop with few iterations regardless next
597 // conditions since following loop optimizations will split
598 // such loop anyway (pre-main-post).
602 // Take into account that after unroll conjoined heads and tails will fold,
603 // otherwise policy_unroll() may allow more unrolling than max unrolling.
604 uint new_body_size = EMPTY_LOOP_SIZE + (body_size - EMPTY_LOOP_SIZE) * trip_count;
605 uint tst_body_size = (new_body_size - EMPTY_LOOP_SIZE) / trip_count + EMPTY_LOOP_SIZE;
606 if (body_size != tst_body_size) // Check for int overflow
608 if (new_body_size > unroll_limit ||
609 // Unrolling can result in a large amount of node construction
610 new_body_size >= MaxNodeLimit - phase->C->unique()) {
614 // Do not unroll a loop with String intrinsics code.
615 // String intrinsics are large and have loops.
616 for (uint k = 0; k < _body.size(); k++) {
617 Node* n = _body.at(k);
618 switch (n->Opcode()) {
628 return true; // Do maximally unroll
632 #define MAX_UNROLL 16 // maximum number of unrolls for main loop
634 //------------------------------policy_unroll----------------------------------
635 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if
636 // the loop is a CountedLoop and the body is small enough.
637 bool IdealLoopTree::policy_unroll( PhaseIdealLoop *phase ) const {
639 CountedLoopNode *cl = _head->as_CountedLoop();
640 assert(cl->is_normal_loop() || cl->is_main_loop(), "");
642 if (!cl->is_valid_counted_loop())
643 return false; // Malformed counted loop
645 // Protect against over-unrolling.
646 // After split at least one iteration will be executed in pre-loop.
647 if (cl->trip_count() <= (uint)(cl->is_normal_loop() ? 2 : 1)) return false;
649 int future_unroll_ct = cl->unrolled_count() * 2;
650 if (future_unroll_ct > MAX_UNROLL) return false;
652 // Check for initial stride being a small enough constant
653 if (abs(cl->stride_con()) > (1<<2)*future_unroll_ct) return false;
655 // Don't unroll if the next round of unrolling would push us
656 // over the expected trip count of the loop. One is subtracted
657 // from the expected trip count because the pre-loop normally
658 // executes 1 iteration.
659 if (UnrollLimitForProfileCheck > 0 &&
660 cl->profile_trip_cnt() != COUNT_UNKNOWN &&
661 future_unroll_ct > UnrollLimitForProfileCheck &&
662 (float)future_unroll_ct > cl->profile_trip_cnt() - 1.0) {
666 // When unroll count is greater than LoopUnrollMin, don't unroll if:
667 // the residual iterations are more than 10% of the trip count
668 // and rounds of "unroll,optimize" are not making significant progress
669 // Progress defined as current size less than 20% larger than previous size.
670 if (UseSuperWord && cl->node_count_before_unroll() > 0 &&
671 future_unroll_ct > LoopUnrollMin &&
672 (future_unroll_ct - 1) * 10.0 > cl->profile_trip_cnt() &&
673 1.2 * cl->node_count_before_unroll() < (double)_body.size()) {
677 Node *init_n = cl->init_trip();
678 Node *limit_n = cl->limit();
679 int stride_con = cl->stride_con();
680 // Non-constant bounds.
681 // Protect against over-unrolling when init or/and limit are not constant
682 // (so that trip_count's init value is maxint) but iv range is known.
683 if (init_n == NULL || !init_n->is_Con() ||
684 limit_n == NULL || !limit_n->is_Con()) {
685 Node* phi = cl->phi();
687 assert(phi->is_Phi() && phi->in(0) == _head, "Counted loop should have iv phi.");
688 const TypeInt* iv_type = phase->_igvn.type(phi)->is_int();
689 int next_stride = stride_con * 2; // stride after this unroll
690 if (next_stride > 0) {
691 if (iv_type->_lo + next_stride <= iv_type->_lo || // overflow
692 iv_type->_lo + next_stride > iv_type->_hi) {
693 return false; // over-unrolling
695 } else if (next_stride < 0) {
696 if (iv_type->_hi + next_stride >= iv_type->_hi || // overflow
697 iv_type->_hi + next_stride < iv_type->_lo) {
698 return false; // over-unrolling
704 // After unroll limit will be adjusted: new_limit = limit-stride.
705 // Bailout if adjustment overflow.
706 const TypeInt* limit_type = phase->_igvn.type(limit_n)->is_int();
707 if (stride_con > 0 && ((limit_type->_hi - stride_con) >= limit_type->_hi) ||
708 stride_con < 0 && ((limit_type->_lo - stride_con) <= limit_type->_lo))
709 return false; // overflow
711 // Adjust body_size to determine if we unroll or not
712 uint body_size = _body.size();
713 // Also count ModL, DivL and MulL which expand mightly
714 for (uint k = 0; k < _body.size(); k++) {
715 Node* n = _body.at(k);
716 switch (n->Opcode()) {
717 case Op_ModL: body_size += 30; break;
718 case Op_DivL: body_size += 30; break;
719 case Op_MulL: body_size += 10; break;
724 // Do not unroll a loop with String intrinsics code.
725 // String intrinsics are large and have loops.
731 // Check for being too big
732 if (body_size > (uint)LoopUnrollLimit) {
733 // Normal case: loop too big
737 // Unroll once! (Each trip will soon do double iterations)
741 //------------------------------policy_align-----------------------------------
742 // Return TRUE or FALSE if the loop should be cache-line aligned. Gather the
743 // expression that does the alignment. Note that only one array base can be
744 // aligned in a loop (unless the VM guarantees mutual alignment). Note that
745 // if we vectorize short memory ops into longer memory ops, we may want to
746 // increase alignment.
747 bool IdealLoopTree::policy_align( PhaseIdealLoop *phase ) const {
751 //------------------------------policy_range_check-----------------------------
752 // Return TRUE or FALSE if the loop should be range-check-eliminated.
753 // Actually we do iteration-splitting, a more powerful form of RCE.
754 bool IdealLoopTree::policy_range_check( PhaseIdealLoop *phase ) const {
755 if (!RangeCheckElimination) return false;
757 CountedLoopNode *cl = _head->as_CountedLoop();
758 // If we unrolled with no intention of doing RCE and we later
759 // changed our minds, we got no pre-loop. Either we need to
760 // make a new pre-loop, or we gotta disallow RCE.
761 if (cl->is_main_no_pre_loop()) return false; // Disallowed for now.
762 Node *trip_counter = cl->phi();
764 // Check loop body for tests of trip-counter plus loop-invariant vs
766 for (uint i = 0; i < _body.size(); i++) {
767 Node *iff = _body[i];
768 if (iff->Opcode() == Op_If) { // Test?
770 // Comparing trip+off vs limit
771 Node *bol = iff->in(1);
772 if (bol->req() != 2) continue; // dead constant test
773 if (!bol->is_Bool()) {
774 assert(UseLoopPredicate && bol->Opcode() == Op_Conv2B, "predicate check only");
777 if (bol->as_Bool()->_test._test == BoolTest::ne)
780 Node *cmp = bol->in(1);
782 Node *rc_exp = cmp->in(1);
783 Node *limit = cmp->in(2);
785 Node *limit_c = phase->get_ctrl(limit);
786 if( limit_c == phase->C->top() )
787 return false; // Found dead test on live IF? No RCE!
788 if( is_member(phase->get_loop(limit_c) ) ) {
789 // Compare might have operands swapped; commute them
792 limit_c = phase->get_ctrl(limit);
793 if( is_member(phase->get_loop(limit_c) ) )
794 continue; // Both inputs are loop varying; cannot RCE
797 if (!phase->is_scaled_iv_plus_offset(rc_exp, trip_counter, NULL, NULL)) {
800 // Yeah! Found a test like 'trip+off vs limit'
801 // Test is an IfNode, has 2 projections. If BOTH are in the loop
802 // we need loop unswitching instead of iteration splitting.
803 if( is_loop_exit(iff) )
804 return true; // Found reason to split iterations
811 //------------------------------policy_peel_only-------------------------------
812 // Return TRUE or FALSE if the loop should NEVER be RCE'd or aligned. Useful
813 // for unrolling loops with NO array accesses.
814 bool IdealLoopTree::policy_peel_only( PhaseIdealLoop *phase ) const {
816 for( uint i = 0; i < _body.size(); i++ )
817 if( _body[i]->is_Mem() )
820 // No memory accesses at all!
824 //------------------------------clone_up_backedge_goo--------------------------
825 // If Node n lives in the back_ctrl block and cannot float, we clone a private
826 // version of n in preheader_ctrl block and return that, otherwise return n.
827 Node *PhaseIdealLoop::clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n ) {
828 if( get_ctrl(n) != back_ctrl ) return n;
830 Node *x = NULL; // If required, a clone of 'n'
831 // Check for 'n' being pinned in the backedge.
832 if( n->in(0) && n->in(0) == back_ctrl ) {
833 x = n->clone(); // Clone a copy of 'n' to preheader
834 x->set_req( 0, preheader_ctrl ); // Fix x's control input to preheader
837 // Recursive fixup any other input edges into x.
838 // If there are no changes we can just return 'n', otherwise
839 // we need to clone a private copy and change it.
840 for( uint i = 1; i < n->req(); i++ ) {
841 Node *g = clone_up_backedge_goo( back_ctrl, preheader_ctrl, n->in(i) );
842 if( g != n->in(i) ) {
848 if( x ) { // x can legally float to pre-header location
849 register_new_node( x, preheader_ctrl );
851 } else { // raise n to cover LCA of uses
852 set_ctrl( n, find_non_split_ctrl(back_ctrl->in(0)) );
857 //------------------------------insert_pre_post_loops--------------------------
858 // Insert pre and post loops. If peel_only is set, the pre-loop can not have
859 // more iterations added. It acts as a 'peel' only, no lower-bound RCE, no
860 // alignment. Useful to unroll loops that do no array accesses.
861 void PhaseIdealLoop::insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ) {
866 tty->print("PeelMainPost ");
868 tty->print("PreMainPost ");
872 C->set_major_progress();
874 // Find common pieces of the loop being guarded with pre & post loops
875 CountedLoopNode *main_head = loop->_head->as_CountedLoop();
876 assert( main_head->is_normal_loop(), "" );
877 CountedLoopEndNode *main_end = main_head->loopexit();
878 assert( main_end->outcnt() == 2, "1 true, 1 false path only" );
879 uint dd_main_head = dom_depth(main_head);
880 uint max = main_head->outcnt();
882 Node *pre_header= main_head->in(LoopNode::EntryControl);
883 Node *init = main_head->init_trip();
884 Node *incr = main_end ->incr();
885 Node *limit = main_end ->limit();
886 Node *stride = main_end ->stride();
887 Node *cmp = main_end ->cmp_node();
888 BoolTest::mask b_test = main_end->test_trip();
890 // Need only 1 user of 'bol' because I will be hacking the loop bounds.
891 Node *bol = main_end->in(CountedLoopEndNode::TestValue);
892 if( bol->outcnt() != 1 ) {
894 register_new_node(bol,main_end->in(CountedLoopEndNode::TestControl));
895 _igvn.hash_delete(main_end);
896 main_end->set_req(CountedLoopEndNode::TestValue, bol);
898 // Need only 1 user of 'cmp' because I will be hacking the loop bounds.
899 if( cmp->outcnt() != 1 ) {
901 register_new_node(cmp,main_end->in(CountedLoopEndNode::TestControl));
902 _igvn.hash_delete(bol);
903 bol->set_req(1, cmp);
906 //------------------------------
907 // Step A: Create Post-Loop.
908 Node* main_exit = main_end->proj_out(false);
909 assert( main_exit->Opcode() == Op_IfFalse, "" );
910 int dd_main_exit = dom_depth(main_exit);
912 // Step A1: Clone the loop body. The clone becomes the post-loop. The main
913 // loop pre-header illegally has 2 control users (old & new loops).
914 clone_loop( loop, old_new, dd_main_exit );
915 assert( old_new[main_end ->_idx]->Opcode() == Op_CountedLoopEnd, "" );
916 CountedLoopNode *post_head = old_new[main_head->_idx]->as_CountedLoop();
917 post_head->set_post_loop(main_head);
919 // Reduce the post-loop trip count.
920 CountedLoopEndNode* post_end = old_new[main_end ->_idx]->as_CountedLoopEnd();
921 post_end->_prob = PROB_FAIR;
923 // Build the main-loop normal exit.
924 IfFalseNode *new_main_exit = new (C, 1) IfFalseNode(main_end);
925 _igvn.register_new_node_with_optimizer( new_main_exit );
926 set_idom(new_main_exit, main_end, dd_main_exit );
927 set_loop(new_main_exit, loop->_parent);
929 // Step A2: Build a zero-trip guard for the post-loop. After leaving the
930 // main-loop, the post-loop may not execute at all. We 'opaque' the incr
931 // (the main-loop trip-counter exit value) because we will be changing
932 // the exit value (via unrolling) so we cannot constant-fold away the zero
933 // trip guard until all unrolling is done.
934 Node *zer_opaq = new (C, 2) Opaque1Node(C, incr);
935 Node *zer_cmp = new (C, 3) CmpINode( zer_opaq, limit );
936 Node *zer_bol = new (C, 2) BoolNode( zer_cmp, b_test );
937 register_new_node( zer_opaq, new_main_exit );
938 register_new_node( zer_cmp , new_main_exit );
939 register_new_node( zer_bol , new_main_exit );
942 IfNode *zer_iff = new (C, 2) IfNode( new_main_exit, zer_bol, PROB_FAIR, COUNT_UNKNOWN );
943 _igvn.register_new_node_with_optimizer( zer_iff );
944 set_idom(zer_iff, new_main_exit, dd_main_exit);
945 set_loop(zer_iff, loop->_parent);
947 // Plug in the false-path, taken if we need to skip post-loop
948 _igvn.hash_delete( main_exit );
949 main_exit->set_req(0, zer_iff);
950 _igvn._worklist.push(main_exit);
951 set_idom(main_exit, zer_iff, dd_main_exit);
952 set_idom(main_exit->unique_out(), zer_iff, dd_main_exit);
953 // Make the true-path, must enter the post loop
954 Node *zer_taken = new (C, 1) IfTrueNode( zer_iff );
955 _igvn.register_new_node_with_optimizer( zer_taken );
956 set_idom(zer_taken, zer_iff, dd_main_exit);
957 set_loop(zer_taken, loop->_parent);
958 // Plug in the true path
959 _igvn.hash_delete( post_head );
960 post_head->set_req(LoopNode::EntryControl, zer_taken);
961 set_idom(post_head, zer_taken, dd_main_exit);
963 // Step A3: Make the fall-in values to the post-loop come from the
964 // fall-out values of the main-loop.
965 for (DUIterator_Fast imax, i = main_head->fast_outs(imax); i < imax; i++) {
966 Node* main_phi = main_head->fast_out(i);
967 if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() >0 ) {
968 Node *post_phi = old_new[main_phi->_idx];
969 Node *fallmain = clone_up_backedge_goo(main_head->back_control(),
970 post_head->init_control(),
971 main_phi->in(LoopNode::LoopBackControl));
972 _igvn.hash_delete(post_phi);
973 post_phi->set_req( LoopNode::EntryControl, fallmain );
977 // Update local caches for next stanza
978 main_exit = new_main_exit;
981 //------------------------------
982 // Step B: Create Pre-Loop.
984 // Step B1: Clone the loop body. The clone becomes the pre-loop. The main
985 // loop pre-header illegally has 2 control users (old & new loops).
986 clone_loop( loop, old_new, dd_main_head );
987 CountedLoopNode* pre_head = old_new[main_head->_idx]->as_CountedLoop();
988 CountedLoopEndNode* pre_end = old_new[main_end ->_idx]->as_CountedLoopEnd();
989 pre_head->set_pre_loop(main_head);
990 Node *pre_incr = old_new[incr->_idx];
992 // Reduce the pre-loop trip count.
993 pre_end->_prob = PROB_FAIR;
995 // Find the pre-loop normal exit.
996 Node* pre_exit = pre_end->proj_out(false);
997 assert( pre_exit->Opcode() == Op_IfFalse, "" );
998 IfFalseNode *new_pre_exit = new (C, 1) IfFalseNode(pre_end);
999 _igvn.register_new_node_with_optimizer( new_pre_exit );
1000 set_idom(new_pre_exit, pre_end, dd_main_head);
1001 set_loop(new_pre_exit, loop->_parent);
1003 // Step B2: Build a zero-trip guard for the main-loop. After leaving the
1004 // pre-loop, the main-loop may not execute at all. Later in life this
1005 // zero-trip guard will become the minimum-trip guard when we unroll
1007 Node *min_opaq = new (C, 2) Opaque1Node(C, limit);
1008 Node *min_cmp = new (C, 3) CmpINode( pre_incr, min_opaq );
1009 Node *min_bol = new (C, 2) BoolNode( min_cmp, b_test );
1010 register_new_node( min_opaq, new_pre_exit );
1011 register_new_node( min_cmp , new_pre_exit );
1012 register_new_node( min_bol , new_pre_exit );
1014 // Build the IfNode (assume the main-loop is executed always).
1015 IfNode *min_iff = new (C, 2) IfNode( new_pre_exit, min_bol, PROB_ALWAYS, COUNT_UNKNOWN );
1016 _igvn.register_new_node_with_optimizer( min_iff );
1017 set_idom(min_iff, new_pre_exit, dd_main_head);
1018 set_loop(min_iff, loop->_parent);
1020 // Plug in the false-path, taken if we need to skip main-loop
1021 _igvn.hash_delete( pre_exit );
1022 pre_exit->set_req(0, min_iff);
1023 set_idom(pre_exit, min_iff, dd_main_head);
1024 set_idom(pre_exit->unique_out(), min_iff, dd_main_head);
1025 // Make the true-path, must enter the main loop
1026 Node *min_taken = new (C, 1) IfTrueNode( min_iff );
1027 _igvn.register_new_node_with_optimizer( min_taken );
1028 set_idom(min_taken, min_iff, dd_main_head);
1029 set_loop(min_taken, loop->_parent);
1030 // Plug in the true path
1031 _igvn.hash_delete( main_head );
1032 main_head->set_req(LoopNode::EntryControl, min_taken);
1033 set_idom(main_head, min_taken, dd_main_head);
1035 // Step B3: Make the fall-in values to the main-loop come from the
1036 // fall-out values of the pre-loop.
1037 for (DUIterator_Fast i2max, i2 = main_head->fast_outs(i2max); i2 < i2max; i2++) {
1038 Node* main_phi = main_head->fast_out(i2);
1039 if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() > 0 ) {
1040 Node *pre_phi = old_new[main_phi->_idx];
1041 Node *fallpre = clone_up_backedge_goo(pre_head->back_control(),
1042 main_head->init_control(),
1043 pre_phi->in(LoopNode::LoopBackControl));
1044 _igvn.hash_delete(main_phi);
1045 main_phi->set_req( LoopNode::EntryControl, fallpre );
1049 // Step B4: Shorten the pre-loop to run only 1 iteration (for now).
1050 // RCE and alignment may change this later.
1051 Node *cmp_end = pre_end->cmp_node();
1052 assert( cmp_end->in(2) == limit, "" );
1053 Node *pre_limit = new (C, 3) AddINode( init, stride );
1055 // Save the original loop limit in this Opaque1 node for
1056 // use by range check elimination.
1057 Node *pre_opaq = new (C, 3) Opaque1Node(C, pre_limit, limit);
1059 register_new_node( pre_limit, pre_head->in(0) );
1060 register_new_node( pre_opaq , pre_head->in(0) );
1062 // Since no other users of pre-loop compare, I can hack limit directly
1063 assert( cmp_end->outcnt() == 1, "no other users" );
1064 _igvn.hash_delete(cmp_end);
1065 cmp_end->set_req(2, peel_only ? pre_limit : pre_opaq);
1067 // Special case for not-equal loop bounds:
1068 // Change pre loop test, main loop test, and the
1069 // main loop guard test to use lt or gt depending on stride
1071 // positive stride use <
1072 // negative stride use >
1074 // not-equal test is kept for post loop to handle case
1075 // when init > limit when stride > 0 (and reverse).
1077 if (pre_end->in(CountedLoopEndNode::TestValue)->as_Bool()->_test._test == BoolTest::ne) {
1079 BoolTest::mask new_test = (main_end->stride_con() > 0) ? BoolTest::lt : BoolTest::gt;
1080 // Modify pre loop end condition
1081 Node* pre_bol = pre_end->in(CountedLoopEndNode::TestValue)->as_Bool();
1082 BoolNode* new_bol0 = new (C, 2) BoolNode(pre_bol->in(1), new_test);
1083 register_new_node( new_bol0, pre_head->in(0) );
1084 _igvn.hash_delete(pre_end);
1085 pre_end->set_req(CountedLoopEndNode::TestValue, new_bol0);
1086 // Modify main loop guard condition
1087 assert(min_iff->in(CountedLoopEndNode::TestValue) == min_bol, "guard okay");
1088 BoolNode* new_bol1 = new (C, 2) BoolNode(min_bol->in(1), new_test);
1089 register_new_node( new_bol1, new_pre_exit );
1090 _igvn.hash_delete(min_iff);
1091 min_iff->set_req(CountedLoopEndNode::TestValue, new_bol1);
1092 // Modify main loop end condition
1093 BoolNode* main_bol = main_end->in(CountedLoopEndNode::TestValue)->as_Bool();
1094 BoolNode* new_bol2 = new (C, 2) BoolNode(main_bol->in(1), new_test);
1095 register_new_node( new_bol2, main_end->in(CountedLoopEndNode::TestControl) );
1096 _igvn.hash_delete(main_end);
1097 main_end->set_req(CountedLoopEndNode::TestValue, new_bol2);
1101 main_head->set_main_loop();
1102 if( peel_only ) main_head->set_main_no_pre_loop();
1104 // Subtract a trip count for the pre-loop.
1105 main_head->set_trip_count(main_head->trip_count() - 1);
1107 // It's difficult to be precise about the trip-counts
1108 // for the pre/post loops. They are usually very short,
1109 // so guess that 4 trips is a reasonable value.
1110 post_head->set_profile_trip_cnt(4.0);
1111 pre_head->set_profile_trip_cnt(4.0);
1113 // Now force out all loop-invariant dominating tests. The optimizer
1114 // finds some, but we _know_ they are all useless.
1115 peeled_dom_test_elim(loop,old_new);
1118 //------------------------------is_invariant-----------------------------
1119 // Return true if n is invariant
1120 bool IdealLoopTree::is_invariant(Node* n) const {
1121 Node *n_c = _phase->has_ctrl(n) ? _phase->get_ctrl(n) : n;
1122 if (n_c->is_top()) return false;
1123 return !is_member(_phase->get_loop(n_c));
1127 //------------------------------do_unroll--------------------------------------
1128 // Unroll the loop body one step - make each trip do 2 iterations.
1129 void PhaseIdealLoop::do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ) {
1130 assert(LoopUnrollLimit, "");
1131 CountedLoopNode *loop_head = loop->_head->as_CountedLoop();
1132 CountedLoopEndNode *loop_end = loop_head->loopexit();
1133 assert(loop_end, "");
1135 if (PrintOpto && VerifyLoopOptimizations) {
1136 tty->print("Unrolling ");
1138 } else if (TraceLoopOpts) {
1139 if (loop_head->trip_count() < (uint)LoopUnrollLimit) {
1140 tty->print("Unroll %d(%2d) ", loop_head->unrolled_count()*2, loop_head->trip_count());
1142 tty->print("Unroll %d ", loop_head->unrolled_count()*2);
1148 // Remember loop node count before unrolling to detect
1149 // if rounds of unroll,optimize are making progress
1150 loop_head->set_node_count_before_unroll(loop->_body.size());
1152 Node *ctrl = loop_head->in(LoopNode::EntryControl);
1153 Node *limit = loop_head->limit();
1154 Node *init = loop_head->init_trip();
1155 Node *stride = loop_head->stride();
1158 if (adjust_min_trip) { // If not maximally unrolling, need adjustment
1159 // Search for zero-trip guard.
1160 assert( loop_head->is_main_loop(), "" );
1161 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
1162 Node *iff = ctrl->in(0);
1163 assert( iff->Opcode() == Op_If, "" );
1164 Node *bol = iff->in(1);
1165 assert( bol->Opcode() == Op_Bool, "" );
1166 Node *cmp = bol->in(1);
1167 assert( cmp->Opcode() == Op_CmpI, "" );
1169 // Occasionally it's possible for a zero-trip guard Opaque1 node to be
1170 // optimized away and then another round of loop opts attempted.
1171 // We can not optimize this particular loop in that case.
1172 if (opaq->Opcode() != Op_Opaque1)
1173 return; // Cannot find zero-trip guard! Bail out!
1174 // Zero-trip test uses an 'opaque' node which is not shared.
1175 assert(opaq->outcnt() == 1 && opaq->in(1) == limit, "");
1178 C->set_major_progress();
1180 Node* new_limit = NULL;
1181 if (UnrollLimitCheck) {
1182 int stride_con = stride->get_int();
1183 int stride_p = (stride_con > 0) ? stride_con : -stride_con;
1184 uint old_trip_count = loop_head->trip_count();
1185 // Verify that unroll policy result is still valid.
1186 assert(old_trip_count > 1 &&
1187 (!adjust_min_trip || stride_p <= (1<<3)*loop_head->unrolled_count()), "sanity");
1189 // Adjust loop limit to keep valid iterations number after unroll.
1190 // Use (limit - stride) instead of (((limit - init)/stride) & (-2))*stride
1191 // which may overflow.
1192 if (!adjust_min_trip) {
1193 assert(old_trip_count > 1 && (old_trip_count & 1) == 0,
1194 "odd trip count for maximally unroll");
1195 // Don't need to adjust limit for maximally unroll since trip count is even.
1196 } else if (loop_head->has_exact_trip_count() && init->is_Con()) {
1197 // Loop's limit is constant. Loop's init could be constant when pre-loop
1198 // become peeled iteration.
1199 long init_con = init->get_int();
1200 // We can keep old loop limit if iterations count stays the same:
1201 // old_trip_count == new_trip_count * 2
1202 // Note: since old_trip_count >= 2 then new_trip_count >= 1
1203 // so we also don't need to adjust zero trip test.
1204 long limit_con = limit->get_int();
1205 // (stride_con*2) not overflow since stride_con <= 8.
1206 int new_stride_con = stride_con * 2;
1207 int stride_m = new_stride_con - (stride_con > 0 ? 1 : -1);
1208 long trip_count = (limit_con - init_con + stride_m)/new_stride_con;
1209 // New trip count should satisfy next conditions.
1210 assert(trip_count > 0 && (julong)trip_count < (julong)max_juint/2, "sanity");
1211 uint new_trip_count = (uint)trip_count;
1212 adjust_min_trip = (old_trip_count != new_trip_count*2);
1215 if (adjust_min_trip) {
1216 // Step 2: Adjust the trip limit if it is called for.
1217 // The adjustment amount is -stride. Need to make sure if the
1218 // adjustment underflows or overflows, then the main loop is skipped.
1219 Node* cmp = loop_end->cmp_node();
1220 assert(cmp->in(2) == limit, "sanity");
1221 assert(opaq != NULL && opaq->in(1) == limit, "sanity");
1223 // Verify that policy_unroll result is still valid.
1224 const TypeInt* limit_type = _igvn.type(limit)->is_int();
1225 assert(stride_con > 0 && ((limit_type->_hi - stride_con) < limit_type->_hi) ||
1226 stride_con < 0 && ((limit_type->_lo - stride_con) > limit_type->_lo), "sanity");
1228 if (limit->is_Con()) {
1229 // The check in policy_unroll and the assert above guarantee
1230 // no underflow if limit is constant.
1231 new_limit = _igvn.intcon(limit->get_int() - stride_con);
1232 set_ctrl(new_limit, C->root());
1234 // Limit is not constant.
1235 if (loop_head->unrolled_count() == 1) { // only for first unroll
1236 // Separate limit by Opaque node in case it is an incremented
1237 // variable from previous loop to avoid using pre-incremented
1238 // value which could increase register pressure.
1239 // Otherwise reorg_offsets() optimization will create a separate
1240 // Opaque node for each use of trip-counter and as result
1241 // zero trip guard limit will be different from loop limit.
1242 assert(has_ctrl(opaq), "should have it");
1243 Node* opaq_ctrl = get_ctrl(opaq);
1244 limit = new (C, 2) Opaque2Node( C, limit );
1245 register_new_node( limit, opaq_ctrl );
1247 if (stride_con > 0 && ((limit_type->_lo - stride_con) < limit_type->_lo) ||
1248 stride_con < 0 && ((limit_type->_hi - stride_con) > limit_type->_hi)) {
1250 new_limit = new (C, 3) SubINode(limit, stride);
1252 // (limit - stride) may underflow.
1253 // Clamp the adjustment value with MININT or MAXINT:
1255 // new_limit = limit-stride
1257 // new_limit = (limit < new_limit) ? MININT : new_limit;
1259 // new_limit = (limit > new_limit) ? MAXINT : new_limit;
1261 BoolTest::mask bt = loop_end->test_trip();
1262 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
1263 Node* adj_max = _igvn.intcon((stride_con > 0) ? min_jint : max_jint);
1264 set_ctrl(adj_max, C->root());
1265 Node* old_limit = NULL;
1266 Node* adj_limit = NULL;
1267 Node* bol = limit->is_CMove() ? limit->in(CMoveNode::Condition) : NULL;
1268 if (loop_head->unrolled_count() > 1 &&
1269 limit->is_CMove() && limit->Opcode() == Op_CMoveI &&
1270 limit->in(CMoveNode::IfTrue) == adj_max &&
1271 bol->as_Bool()->_test._test == bt &&
1272 bol->in(1)->Opcode() == Op_CmpI &&
1273 bol->in(1)->in(2) == limit->in(CMoveNode::IfFalse)) {
1274 // Loop was unrolled before.
1275 // Optimize the limit to avoid nested CMove:
1276 // use original limit as old limit.
1277 old_limit = bol->in(1)->in(1);
1278 // Adjust previous adjusted limit.
1279 adj_limit = limit->in(CMoveNode::IfFalse);
1280 adj_limit = new (C, 3) SubINode(adj_limit, stride);
1283 adj_limit = new (C, 3) SubINode(limit, stride);
1285 assert(old_limit != NULL && adj_limit != NULL, "");
1286 register_new_node( adj_limit, ctrl ); // adjust amount
1287 Node* adj_cmp = new (C, 3) CmpINode(old_limit, adj_limit);
1288 register_new_node( adj_cmp, ctrl );
1289 Node* adj_bool = new (C, 2) BoolNode(adj_cmp, bt);
1290 register_new_node( adj_bool, ctrl );
1291 new_limit = new (C, 4) CMoveINode(adj_bool, adj_limit, adj_max, TypeInt::INT);
1293 register_new_node(new_limit, ctrl);
1295 assert(new_limit != NULL, "");
1296 // Replace in loop test.
1297 assert(loop_end->in(1)->in(1) == cmp, "sanity");
1298 if (cmp->outcnt() == 1 && loop_end->in(1)->outcnt() == 1) {
1299 // Don't need to create new test since only one user.
1300 _igvn.hash_delete(cmp);
1301 cmp->set_req(2, new_limit);
1303 // Create new test since it is shared.
1304 Node* ctrl2 = loop_end->in(0);
1305 Node* cmp2 = cmp->clone();
1306 cmp2->set_req(2, new_limit);
1307 register_new_node(cmp2, ctrl2);
1308 Node* bol2 = loop_end->in(1)->clone();
1309 bol2->set_req(1, cmp2);
1310 register_new_node(bol2, ctrl2);
1311 _igvn.hash_delete(loop_end);
1312 loop_end->set_req(1, bol2);
1314 // Step 3: Find the min-trip test guaranteed before a 'main' loop.
1315 // Make it a 1-trip test (means at least 2 trips).
1317 // Guard test uses an 'opaque' node which is not shared. Hence I
1318 // can edit it's inputs directly. Hammer in the new limit for the
1319 // minimum-trip guard.
1320 assert(opaq->outcnt() == 1, "");
1321 _igvn.hash_delete(opaq);
1322 opaq->set_req(1, new_limit);
1325 // Adjust max trip count. The trip count is intentionally rounded
1326 // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
1327 // the main, unrolled, part of the loop will never execute as it is protected
1328 // by the min-trip test. See bug 4834191 for a case where we over-unrolled
1329 // and later determined that part of the unrolled loop was dead.
1330 loop_head->set_trip_count(old_trip_count / 2);
1332 // Double the count of original iterations in the unrolled loop body.
1333 loop_head->double_unrolled_count();
1335 } else { // LoopLimitCheck
1337 // Adjust max trip count. The trip count is intentionally rounded
1338 // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
1339 // the main, unrolled, part of the loop will never execute as it is protected
1340 // by the min-trip test. See bug 4834191 for a case where we over-unrolled
1341 // and later determined that part of the unrolled loop was dead.
1342 loop_head->set_trip_count(loop_head->trip_count() / 2);
1344 // Double the count of original iterations in the unrolled loop body.
1345 loop_head->double_unrolled_count();
1348 // Step 2: Cut back the trip counter for an unroll amount of 2.
1349 // Loop will normally trip (limit - init)/stride_con. Since it's a
1350 // CountedLoop this is exact (stride divides limit-init exactly).
1351 // We are going to double the loop body, so we want to knock off any
1352 // odd iteration: (trip_cnt & ~1). Then back compute a new limit.
1353 Node *span = new (C, 3) SubINode( limit, init );
1354 register_new_node( span, ctrl );
1355 Node *trip = new (C, 3) DivINode( 0, span, stride );
1356 register_new_node( trip, ctrl );
1357 Node *mtwo = _igvn.intcon(-2);
1358 set_ctrl(mtwo, C->root());
1359 Node *rond = new (C, 3) AndINode( trip, mtwo );
1360 register_new_node( rond, ctrl );
1361 Node *spn2 = new (C, 3) MulINode( rond, stride );
1362 register_new_node( spn2, ctrl );
1363 new_limit = new (C, 3) AddINode( spn2, init );
1364 register_new_node( new_limit, ctrl );
1366 // Hammer in the new limit
1367 Node *ctrl2 = loop_end->in(0);
1368 Node *cmp2 = new (C, 3) CmpINode( loop_head->incr(), new_limit );
1369 register_new_node( cmp2, ctrl2 );
1370 Node *bol2 = new (C, 2) BoolNode( cmp2, loop_end->test_trip() );
1371 register_new_node( bol2, ctrl2 );
1372 _igvn.hash_delete(loop_end);
1373 loop_end->set_req(CountedLoopEndNode::TestValue, bol2);
1375 // Step 3: Find the min-trip test guaranteed before a 'main' loop.
1376 // Make it a 1-trip test (means at least 2 trips).
1377 if( adjust_min_trip ) {
1378 assert( new_limit != NULL, "" );
1379 // Guard test uses an 'opaque' node which is not shared. Hence I
1380 // can edit it's inputs directly. Hammer in the new limit for the
1381 // minimum-trip guard.
1382 assert( opaq->outcnt() == 1, "" );
1383 _igvn.hash_delete(opaq);
1384 opaq->set_req(1, new_limit);
1389 // Step 4: Clone the loop body. Move it inside the loop. This loop body
1390 // represents the odd iterations; since the loop trips an even number of
1391 // times its backedge is never taken. Kill the backedge.
1392 uint dd = dom_depth(loop_head);
1393 clone_loop( loop, old_new, dd );
1395 // Make backedges of the clone equal to backedges of the original.
1396 // Make the fall-in from the original come from the fall-out of the clone.
1397 for (DUIterator_Fast jmax, j = loop_head->fast_outs(jmax); j < jmax; j++) {
1398 Node* phi = loop_head->fast_out(j);
1399 if( phi->is_Phi() && phi->in(0) == loop_head && phi->outcnt() > 0 ) {
1400 Node *newphi = old_new[phi->_idx];
1401 _igvn.hash_delete( phi );
1402 _igvn.hash_delete( newphi );
1404 phi ->set_req(LoopNode:: EntryControl, newphi->in(LoopNode::LoopBackControl));
1405 newphi->set_req(LoopNode::LoopBackControl, phi ->in(LoopNode::LoopBackControl));
1406 phi ->set_req(LoopNode::LoopBackControl, C->top());
1409 Node *clone_head = old_new[loop_head->_idx];
1410 _igvn.hash_delete( clone_head );
1411 loop_head ->set_req(LoopNode:: EntryControl, clone_head->in(LoopNode::LoopBackControl));
1412 clone_head->set_req(LoopNode::LoopBackControl, loop_head ->in(LoopNode::LoopBackControl));
1413 loop_head ->set_req(LoopNode::LoopBackControl, C->top());
1414 loop->_head = clone_head; // New loop header
1416 set_idom(loop_head, loop_head ->in(LoopNode::EntryControl), dd);
1417 set_idom(clone_head, clone_head->in(LoopNode::EntryControl), dd);
1419 // Kill the clone's backedge
1420 Node *newcle = old_new[loop_end->_idx];
1421 _igvn.hash_delete( newcle );
1422 Node *one = _igvn.intcon(1);
1423 set_ctrl(one, C->root());
1424 newcle->set_req(1, one);
1425 // Force clone into same loop body
1426 uint max = loop->_body.size();
1427 for( uint k = 0; k < max; k++ ) {
1428 Node *old = loop->_body.at(k);
1429 Node *nnn = old_new[old->_idx];
1430 loop->_body.push(nnn);
1432 set_loop(nnn, loop);
1435 loop->record_for_igvn();
1438 //------------------------------do_maximally_unroll----------------------------
1440 void PhaseIdealLoop::do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ) {
1441 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1442 assert(cl->has_exact_trip_count(), "trip count is not exact");
1443 assert(cl->trip_count() > 0, "");
1445 if (TraceLoopOpts) {
1446 tty->print("MaxUnroll %d ", cl->trip_count());
1451 // If loop is tripping an odd number of times, peel odd iteration
1452 if ((cl->trip_count() & 1) == 1) {
1453 do_peeling(loop, old_new);
1456 // Now its tripping an even number of times remaining. Double loop body.
1457 // Do not adjust pre-guards; they are not needed and do not exist.
1458 if (cl->trip_count() > 0) {
1459 assert((cl->trip_count() & 1) == 0, "missed peeling");
1460 do_unroll(loop, old_new, false);
1464 //------------------------------dominates_backedge---------------------------------
1465 // Returns true if ctrl is executed on every complete iteration
1466 bool IdealLoopTree::dominates_backedge(Node* ctrl) {
1467 assert(ctrl->is_CFG(), "must be control");
1468 Node* backedge = _head->as_Loop()->in(LoopNode::LoopBackControl);
1469 return _phase->dom_lca_internal(ctrl, backedge) == ctrl;
1472 //------------------------------adjust_limit-----------------------------------
1473 // Helper function for add_constraint().
1474 Node* PhaseIdealLoop::adjust_limit(int stride_con, Node * scale, Node *offset, Node *rc_limit, Node *loop_limit, Node *pre_ctrl) {
1475 // Compute "I :: (limit-offset)/scale"
1476 Node *con = new (C, 3) SubINode(rc_limit, offset);
1477 register_new_node(con, pre_ctrl);
1478 Node *X = new (C, 3) DivINode(0, con, scale);
1479 register_new_node(X, pre_ctrl);
1481 // Adjust loop limit
1482 loop_limit = (stride_con > 0)
1483 ? (Node*)(new (C, 3) MinINode(loop_limit, X))
1484 : (Node*)(new (C, 3) MaxINode(loop_limit, X));
1485 register_new_node(loop_limit, pre_ctrl);
1489 //------------------------------add_constraint---------------------------------
1490 // Constrain the main loop iterations so the conditions:
1491 // low_limit <= scale_con * I + offset < upper_limit
1492 // always holds true. That is, either increase the number of iterations in
1493 // the pre-loop or the post-loop until the condition holds true in the main
1494 // loop. Stride, scale, offset and limit are all loop invariant. Further,
1495 // stride and scale are constants (offset and limit often are).
1496 void PhaseIdealLoop::add_constraint( int stride_con, int scale_con, Node *offset, Node *low_limit, Node *upper_limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit ) {
1497 // For positive stride, the pre-loop limit always uses a MAX function
1498 // and the main loop a MIN function. For negative stride these are
1501 // Also for positive stride*scale the affine function is increasing, so the
1502 // pre-loop must check for underflow and the post-loop for overflow.
1503 // Negative stride*scale reverses this; pre-loop checks for overflow and
1504 // post-loop for underflow.
1506 Node *scale = _igvn.intcon(scale_con);
1507 set_ctrl(scale, C->root());
1509 if ((stride_con^scale_con) >= 0) { // Use XOR to avoid overflow
1510 // The overflow limit: scale*I+offset < upper_limit
1511 // For main-loop compute
1512 // ( if (scale > 0) /* and stride > 0 */
1513 // I < (upper_limit-offset)/scale
1514 // else /* scale < 0 and stride < 0 */
1515 // I > (upper_limit-offset)/scale
1518 // (upper_limit-offset) may overflow or underflow.
1519 // But it is fine since main loop will either have
1520 // less iterations or will be skipped in such case.
1521 *main_limit = adjust_limit(stride_con, scale, offset, upper_limit, *main_limit, pre_ctrl);
1523 // The underflow limit: low_limit <= scale*I+offset.
1524 // For pre-loop compute
1525 // NOT(scale*I+offset >= low_limit)
1526 // scale*I+offset < low_limit
1527 // ( if (scale > 0) /* and stride > 0 */
1528 // I < (low_limit-offset)/scale
1529 // else /* scale < 0 and stride < 0 */
1530 // I > (low_limit-offset)/scale
1533 if (low_limit->get_int() == -max_jint) {
1534 if (!RangeLimitCheck) return;
1535 // We need this guard when scale*pre_limit+offset >= limit
1536 // due to underflow. So we need execute pre-loop until
1537 // scale*I+offset >= min_int. But (min_int-offset) will
1538 // underflow when offset > 0 and X will be > original_limit
1539 // when stride > 0. To avoid it we replace positive offset with 0.
1541 // Also (min_int+1 == -max_int) is used instead of min_int here
1542 // to avoid problem with scale == -1 (min_int/(-1) == min_int).
1543 Node* shift = _igvn.intcon(31);
1544 set_ctrl(shift, C->root());
1545 Node* sign = new (C, 3) RShiftINode(offset, shift);
1546 register_new_node(sign, pre_ctrl);
1547 offset = new (C, 3) AndINode(offset, sign);
1548 register_new_node(offset, pre_ctrl);
1550 assert(low_limit->get_int() == 0, "wrong low limit for range check");
1551 // The only problem we have here when offset == min_int
1552 // since (0-min_int) == min_int. It may be fine for stride > 0
1553 // but for stride < 0 X will be < original_limit. To avoid it
1554 // max(pre_limit, original_limit) is used in do_range_check().
1556 // Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
1557 *pre_limit = adjust_limit((-stride_con), scale, offset, low_limit, *pre_limit, pre_ctrl);
1559 } else { // stride_con*scale_con < 0
1560 // For negative stride*scale pre-loop checks for overflow and
1561 // post-loop for underflow.
1563 // The overflow limit: scale*I+offset < upper_limit
1564 // For pre-loop compute
1565 // NOT(scale*I+offset < upper_limit)
1566 // scale*I+offset >= upper_limit
1567 // scale*I+offset+1 > upper_limit
1568 // ( if (scale < 0) /* and stride > 0 */
1569 // I < (upper_limit-(offset+1))/scale
1570 // else /* scale > 0 and stride < 0 */
1571 // I > (upper_limit-(offset+1))/scale
1574 // (upper_limit-offset-1) may underflow or overflow.
1575 // To avoid it min(pre_limit, original_limit) is used
1576 // in do_range_check() for stride > 0 and max() for < 0.
1577 Node *one = _igvn.intcon(1);
1578 set_ctrl(one, C->root());
1580 Node *plus_one = new (C, 3) AddINode(offset, one);
1581 register_new_node( plus_one, pre_ctrl );
1582 // Pass (-stride) to indicate pre_loop_cond = NOT(main_loop_cond);
1583 *pre_limit = adjust_limit((-stride_con), scale, plus_one, upper_limit, *pre_limit, pre_ctrl);
1585 if (low_limit->get_int() == -max_jint) {
1586 if (!RangeLimitCheck) return;
1587 // We need this guard when scale*main_limit+offset >= limit
1588 // due to underflow. So we need execute main-loop while
1589 // scale*I+offset+1 > min_int. But (min_int-offset-1) will
1590 // underflow when (offset+1) > 0 and X will be < main_limit
1591 // when scale < 0 (and stride > 0). To avoid it we replace
1592 // positive (offset+1) with 0.
1594 // Also (min_int+1 == -max_int) is used instead of min_int here
1595 // to avoid problem with scale == -1 (min_int/(-1) == min_int).
1596 Node* shift = _igvn.intcon(31);
1597 set_ctrl(shift, C->root());
1598 Node* sign = new (C, 3) RShiftINode(plus_one, shift);
1599 register_new_node(sign, pre_ctrl);
1600 plus_one = new (C, 3) AndINode(plus_one, sign);
1601 register_new_node(plus_one, pre_ctrl);
1603 assert(low_limit->get_int() == 0, "wrong low limit for range check");
1604 // The only problem we have here when offset == max_int
1605 // since (max_int+1) == min_int and (0-min_int) == min_int.
1606 // But it is fine since main loop will either have
1607 // less iterations or will be skipped in such case.
1609 // The underflow limit: low_limit <= scale*I+offset.
1610 // For main-loop compute
1611 // scale*I+offset+1 > low_limit
1612 // ( if (scale < 0) /* and stride > 0 */
1613 // I < (low_limit-(offset+1))/scale
1614 // else /* scale > 0 and stride < 0 */
1615 // I > (low_limit-(offset+1))/scale
1618 *main_limit = adjust_limit(stride_con, scale, plus_one, low_limit, *main_limit, pre_ctrl);
1623 //------------------------------is_scaled_iv---------------------------------
1624 // Return true if exp is a constant times an induction var
1625 bool PhaseIdealLoop::is_scaled_iv(Node* exp, Node* iv, int* p_scale) {
1627 if (p_scale != NULL) {
1632 int opc = exp->Opcode();
1633 if (opc == Op_MulI) {
1634 if (exp->in(1) == iv && exp->in(2)->is_Con()) {
1635 if (p_scale != NULL) {
1636 *p_scale = exp->in(2)->get_int();
1640 if (exp->in(2) == iv && exp->in(1)->is_Con()) {
1641 if (p_scale != NULL) {
1642 *p_scale = exp->in(1)->get_int();
1646 } else if (opc == Op_LShiftI) {
1647 if (exp->in(1) == iv && exp->in(2)->is_Con()) {
1648 if (p_scale != NULL) {
1649 *p_scale = 1 << exp->in(2)->get_int();
1657 //-----------------------------is_scaled_iv_plus_offset------------------------------
1658 // Return true if exp is a simple induction variable expression: k1*iv + (invar + k2)
1659 bool PhaseIdealLoop::is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth) {
1660 if (is_scaled_iv(exp, iv, p_scale)) {
1661 if (p_offset != NULL) {
1662 Node *zero = _igvn.intcon(0);
1663 set_ctrl(zero, C->root());
1668 int opc = exp->Opcode();
1669 if (opc == Op_AddI) {
1670 if (is_scaled_iv(exp->in(1), iv, p_scale)) {
1671 if (p_offset != NULL) {
1672 *p_offset = exp->in(2);
1676 if (exp->in(2)->is_Con()) {
1677 Node* offset2 = NULL;
1679 is_scaled_iv_plus_offset(exp->in(1), iv, p_scale,
1680 p_offset != NULL ? &offset2 : NULL, depth+1)) {
1681 if (p_offset != NULL) {
1682 Node *ctrl_off2 = get_ctrl(offset2);
1683 Node* offset = new (C, 3) AddINode(offset2, exp->in(2));
1684 register_new_node(offset, ctrl_off2);
1690 } else if (opc == Op_SubI) {
1691 if (is_scaled_iv(exp->in(1), iv, p_scale)) {
1692 if (p_offset != NULL) {
1693 Node *zero = _igvn.intcon(0);
1694 set_ctrl(zero, C->root());
1695 Node *ctrl_off = get_ctrl(exp->in(2));
1696 Node* offset = new (C, 3) SubINode(zero, exp->in(2));
1697 register_new_node(offset, ctrl_off);
1702 if (is_scaled_iv(exp->in(2), iv, p_scale)) {
1703 if (p_offset != NULL) {
1705 *p_offset = exp->in(1);
1713 //------------------------------do_range_check---------------------------------
1714 // Eliminate range-checks and other trip-counter vs loop-invariant tests.
1715 void PhaseIdealLoop::do_range_check( IdealLoopTree *loop, Node_List &old_new ) {
1717 if (PrintOpto && VerifyLoopOptimizations) {
1718 tty->print("Range Check Elimination ");
1720 } else if (TraceLoopOpts) {
1721 tty->print("RangeCheck ");
1725 assert(RangeCheckElimination, "");
1726 CountedLoopNode *cl = loop->_head->as_CountedLoop();
1727 assert(cl->is_main_loop(), "");
1729 // protect against stride not being a constant
1730 if (!cl->stride_is_con())
1733 // Find the trip counter; we are iteration splitting based on it
1734 Node *trip_counter = cl->phi();
1735 // Find the main loop limit; we will trim it's iterations
1736 // to not ever trip end tests
1737 Node *main_limit = cl->limit();
1739 // Need to find the main-loop zero-trip guard
1740 Node *ctrl = cl->in(LoopNode::EntryControl);
1741 assert(ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "");
1742 Node *iffm = ctrl->in(0);
1743 assert(iffm->Opcode() == Op_If, "");
1744 Node *bolzm = iffm->in(1);
1745 assert(bolzm->Opcode() == Op_Bool, "");
1746 Node *cmpzm = bolzm->in(1);
1747 assert(cmpzm->is_Cmp(), "");
1748 Node *opqzm = cmpzm->in(2);
1749 // Can not optimize a loop if zero-trip Opaque1 node is optimized
1750 // away and then another round of loop opts attempted.
1751 if (opqzm->Opcode() != Op_Opaque1)
1753 assert(opqzm->in(1) == main_limit, "do not understand situation");
1755 // Find the pre-loop limit; we will expand it's iterations to
1756 // not ever trip low tests.
1757 Node *p_f = iffm->in(0);
1758 assert(p_f->Opcode() == Op_IfFalse, "");
1759 CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd();
1760 assert(pre_end->loopnode()->is_pre_loop(), "");
1761 Node *pre_opaq1 = pre_end->limit();
1762 // Occasionally it's possible for a pre-loop Opaque1 node to be
1763 // optimized away and then another round of loop opts attempted.
1764 // We can not optimize this particular loop in that case.
1765 if (pre_opaq1->Opcode() != Op_Opaque1)
1767 Opaque1Node *pre_opaq = (Opaque1Node*)pre_opaq1;
1768 Node *pre_limit = pre_opaq->in(1);
1770 // Where do we put new limit calculations
1771 Node *pre_ctrl = pre_end->loopnode()->in(LoopNode::EntryControl);
1773 // Ensure the original loop limit is available from the
1774 // pre-loop Opaque1 node.
1775 Node *orig_limit = pre_opaq->original_loop_limit();
1776 if (orig_limit == NULL || _igvn.type(orig_limit) == Type::TOP)
1779 // Must know if its a count-up or count-down loop
1781 int stride_con = cl->stride_con();
1782 Node *zero = _igvn.intcon(0);
1783 Node *one = _igvn.intcon(1);
1784 // Use symmetrical int range [-max_jint,max_jint]
1785 Node *mini = _igvn.intcon(-max_jint);
1786 set_ctrl(zero, C->root());
1787 set_ctrl(one, C->root());
1788 set_ctrl(mini, C->root());
1790 // Range checks that do not dominate the loop backedge (ie.
1791 // conditionally executed) can lengthen the pre loop limit beyond
1792 // the original loop limit. To prevent this, the pre limit is
1793 // (for stride > 0) MINed with the original loop limit (MAXed
1794 // stride < 0) when some range_check (rc) is conditionally
1796 bool conditional_rc = false;
1798 // Check loop body for tests of trip-counter plus loop-invariant vs
1800 for( uint i = 0; i < loop->_body.size(); i++ ) {
1801 Node *iff = loop->_body[i];
1802 if( iff->Opcode() == Op_If ) { // Test?
1804 // Test is an IfNode, has 2 projections. If BOTH are in the loop
1805 // we need loop unswitching instead of iteration splitting.
1806 Node *exit = loop->is_loop_exit(iff);
1807 if( !exit ) continue;
1808 int flip = (exit->Opcode() == Op_IfTrue) ? 1 : 0;
1810 // Get boolean condition to test
1811 Node *i1 = iff->in(1);
1812 if( !i1->is_Bool() ) continue;
1813 BoolNode *bol = i1->as_Bool();
1814 BoolTest b_test = bol->_test;
1815 // Flip sense of test if exit condition is flipped
1817 b_test = b_test.negate();
1820 Node *cmp = bol->in(1);
1822 // Look for trip_counter + offset vs limit
1823 Node *rc_exp = cmp->in(1);
1824 Node *limit = cmp->in(2);
1825 jint scale_con= 1; // Assume trip counter not scaled
1827 Node *limit_c = get_ctrl(limit);
1828 if( loop->is_member(get_loop(limit_c) ) ) {
1829 // Compare might have operands swapped; commute them
1830 b_test = b_test.commute();
1831 rc_exp = cmp->in(2);
1833 limit_c = get_ctrl(limit);
1834 if( loop->is_member(get_loop(limit_c) ) )
1835 continue; // Both inputs are loop varying; cannot RCE
1837 // Here we know 'limit' is loop invariant
1839 // 'limit' maybe pinned below the zero trip test (probably from a
1840 // previous round of rce), in which case, it can't be used in the
1841 // zero trip test expression which must occur before the zero test's if.
1842 if( limit_c == ctrl ) {
1843 continue; // Don't rce this check but continue looking for other candidates.
1846 // Check for scaled induction variable plus an offset
1847 Node *offset = NULL;
1849 if (!is_scaled_iv_plus_offset(rc_exp, trip_counter, &scale_con, &offset)) {
1853 Node *offset_c = get_ctrl(offset);
1854 if( loop->is_member( get_loop(offset_c) ) )
1855 continue; // Offset is not really loop invariant
1856 // Here we know 'offset' is loop invariant.
1858 // As above for the 'limit', the 'offset' maybe pinned below the
1860 if( offset_c == ctrl ) {
1861 continue; // Don't rce this check but continue looking for other candidates.
1864 if (TraceRangeLimitCheck) {
1865 tty->print_cr("RC bool node%s", flip ? " flipped:" : ":");
1869 // At this point we have the expression as:
1870 // scale_con * trip_counter + offset :: limit
1871 // where scale_con, offset and limit are loop invariant. Trip_counter
1872 // monotonically increases by stride_con, a constant. Both (or either)
1873 // stride_con and scale_con can be negative which will flip about the
1874 // sense of the test.
1876 // Adjust pre and main loop limits to guard the correct iteration set
1877 if( cmp->Opcode() == Op_CmpU ) {// Unsigned compare is really 2 tests
1878 if( b_test._test == BoolTest::lt ) { // Range checks always use lt
1879 // The underflow and overflow limits: 0 <= scale*I+offset < limit
1880 add_constraint( stride_con, scale_con, offset, zero, limit, pre_ctrl, &pre_limit, &main_limit );
1881 if (!conditional_rc) {
1882 // (0-offset)/scale could be outside of loop iterations range.
1883 conditional_rc = !loop->dominates_backedge(iff) || RangeLimitCheck;
1888 tty->print_cr("missed RCE opportunity");
1890 continue; // In release mode, ignore it
1892 } else { // Otherwise work on normal compares
1893 switch( b_test._test ) {
1895 // Fall into GE case
1897 // Convert (I*scale+offset) >= Limit to (I*(-scale)+(-offset)) <= -Limit
1898 scale_con = -scale_con;
1899 offset = new (C, 3) SubINode( zero, offset );
1900 register_new_node( offset, pre_ctrl );
1901 limit = new (C, 3) SubINode( zero, limit );
1902 register_new_node( limit, pre_ctrl );
1903 // Fall into LE case
1905 if (b_test._test != BoolTest::gt) {
1906 // Convert X <= Y to X < Y+1
1907 limit = new (C, 3) AddINode( limit, one );
1908 register_new_node( limit, pre_ctrl );
1910 // Fall into LT case
1912 // The underflow and overflow limits: MIN_INT <= scale*I+offset < limit
1913 // Note: (MIN_INT+1 == -MAX_INT) is used instead of MIN_INT here
1914 // to avoid problem with scale == -1: MIN_INT/(-1) == MIN_INT.
1915 add_constraint( stride_con, scale_con, offset, mini, limit, pre_ctrl, &pre_limit, &main_limit );
1916 if (!conditional_rc) {
1917 // ((MIN_INT+1)-offset)/scale could be outside of loop iterations range.
1918 // Note: negative offset is replaced with 0 but (MIN_INT+1)/scale could
1919 // still be outside of loop range.
1920 conditional_rc = !loop->dominates_backedge(iff) || RangeLimitCheck;
1926 tty->print_cr("missed RCE opportunity");
1928 continue; // Unhandled case
1932 // Kill the eliminated test
1933 C->set_major_progress();
1934 Node *kill_con = _igvn.intcon( 1-flip );
1935 set_ctrl(kill_con, C->root());
1936 _igvn.hash_delete(iff);
1937 iff->set_req(1, kill_con);
1938 _igvn._worklist.push(iff);
1939 // Find surviving projection
1940 assert(iff->is_If(), "");
1941 ProjNode* dp = ((IfNode*)iff)->proj_out(1-flip);
1942 // Find loads off the surviving projection; remove their control edge
1943 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
1944 Node* cd = dp->fast_out(i); // Control-dependent node
1945 if( cd->is_Load() ) { // Loads can now float around in the loop
1946 _igvn.hash_delete(cd);
1947 // Allow the load to float around in the loop, or before it
1948 // but NOT before the pre-loop.
1949 cd->set_req(0, ctrl); // ctrl, not NULL
1950 _igvn._worklist.push(cd);
1960 // Update loop limits
1961 if (conditional_rc) {
1962 pre_limit = (stride_con > 0) ? (Node*)new (C,3) MinINode(pre_limit, orig_limit)
1963 : (Node*)new (C,3) MaxINode(pre_limit, orig_limit);
1964 register_new_node(pre_limit, pre_ctrl);
1966 _igvn.hash_delete(pre_opaq);
1967 pre_opaq->set_req(1, pre_limit);
1969 // Note:: we are making the main loop limit no longer precise;
1970 // need to round up based on stride.
1971 cl->set_nonexact_trip_count();
1972 if (!LoopLimitCheck && stride_con != 1 && stride_con != -1) { // Cutout for common case
1973 // "Standard" round-up logic: ([main_limit-init+(y-1)]/y)*y+init
1974 // Hopefully, compiler will optimize for powers of 2.
1975 Node *ctrl = get_ctrl(main_limit);
1976 Node *stride = cl->stride();
1977 Node *init = cl->init_trip();
1978 Node *span = new (C, 3) SubINode(main_limit,init);
1979 register_new_node(span,ctrl);
1980 Node *rndup = _igvn.intcon(stride_con + ((stride_con>0)?-1:1));
1981 Node *add = new (C, 3) AddINode(span,rndup);
1982 register_new_node(add,ctrl);
1983 Node *div = new (C, 3) DivINode(0,add,stride);
1984 register_new_node(div,ctrl);
1985 Node *mul = new (C, 3) MulINode(div,stride);
1986 register_new_node(mul,ctrl);
1987 Node *newlim = new (C, 3) AddINode(mul,init);
1988 register_new_node(newlim,ctrl);
1989 main_limit = newlim;
1992 Node *main_cle = cl->loopexit();
1993 Node *main_bol = main_cle->in(1);
1994 // Hacking loop bounds; need private copies of exit test
1995 if( main_bol->outcnt() > 1 ) {// BoolNode shared?
1996 _igvn.hash_delete(main_cle);
1997 main_bol = main_bol->clone();// Clone a private BoolNode
1998 register_new_node( main_bol, main_cle->in(0) );
1999 main_cle->set_req(1,main_bol);
2001 Node *main_cmp = main_bol->in(1);
2002 if( main_cmp->outcnt() > 1 ) { // CmpNode shared?
2003 _igvn.hash_delete(main_bol);
2004 main_cmp = main_cmp->clone();// Clone a private CmpNode
2005 register_new_node( main_cmp, main_cle->in(0) );
2006 main_bol->set_req(1,main_cmp);
2008 // Hack the now-private loop bounds
2009 _igvn.hash_delete(main_cmp);
2010 main_cmp->set_req(2, main_limit);
2011 _igvn._worklist.push(main_cmp);
2012 // The OpaqueNode is unshared by design
2013 _igvn.hash_delete(opqzm);
2014 assert( opqzm->outcnt() == 1, "cannot hack shared node" );
2015 opqzm->set_req(1,main_limit);
2016 _igvn._worklist.push(opqzm);
2019 //------------------------------DCE_loop_body----------------------------------
2020 // Remove simplistic dead code from loop body
2021 void IdealLoopTree::DCE_loop_body() {
2022 for( uint i = 0; i < _body.size(); i++ )
2023 if( _body.at(i)->outcnt() == 0 )
2024 _body.map( i--, _body.pop() );
2028 //------------------------------adjust_loop_exit_prob--------------------------
2029 // Look for loop-exit tests with the 50/50 (or worse) guesses from the parsing stage.
2030 // Replace with a 1-in-10 exit guess.
2031 void IdealLoopTree::adjust_loop_exit_prob( PhaseIdealLoop *phase ) {
2032 Node *test = tail();
2033 while( test != _head ) {
2034 uint top = test->Opcode();
2035 if( top == Op_IfTrue || top == Op_IfFalse ) {
2036 int test_con = ((ProjNode*)test)->_con;
2037 assert(top == (uint)(test_con? Op_IfTrue: Op_IfFalse), "sanity");
2038 IfNode *iff = test->in(0)->as_If();
2039 if( iff->outcnt() == 2 ) { // Ignore dead tests
2040 Node *bol = iff->in(1);
2041 if( bol && bol->req() > 1 && bol->in(1) &&
2042 ((bol->in(1)->Opcode() == Op_StorePConditional ) ||
2043 (bol->in(1)->Opcode() == Op_StoreIConditional ) ||
2044 (bol->in(1)->Opcode() == Op_StoreLConditional ) ||
2045 (bol->in(1)->Opcode() == Op_CompareAndSwapI ) ||
2046 (bol->in(1)->Opcode() == Op_CompareAndSwapL ) ||
2047 (bol->in(1)->Opcode() == Op_CompareAndSwapP ) ||
2048 (bol->in(1)->Opcode() == Op_CompareAndSwapN )))
2049 return; // Allocation loops RARELY take backedge
2050 // Find the OTHER exit path from the IF
2051 Node* ex = iff->proj_out(1-test_con);
2052 float p = iff->_prob;
2053 if( !phase->is_member( this, ex ) && iff->_fcnt == COUNT_UNKNOWN ) {
2054 if( top == Op_IfTrue ) {
2055 if( p < (PROB_FAIR + PROB_UNLIKELY_MAG(3))) {
2056 iff->_prob = PROB_STATIC_FREQUENT;
2059 if( p > (PROB_FAIR - PROB_UNLIKELY_MAG(3))) {
2060 iff->_prob = PROB_STATIC_INFREQUENT;
2066 test = phase->idom(test);
2071 //------------------------------policy_do_remove_empty_loop--------------------
2072 // Micro-benchmark spamming. Policy is to always remove empty loops.
2073 // The 'DO' part is to replace the trip counter with the value it will
2074 // have on the last iteration. This will break the loop.
2075 bool IdealLoopTree::policy_do_remove_empty_loop( PhaseIdealLoop *phase ) {
2076 // Minimum size must be empty loop
2077 if (_body.size() > EMPTY_LOOP_SIZE)
2080 if (!_head->is_CountedLoop())
2081 return false; // Dead loop
2082 CountedLoopNode *cl = _head->as_CountedLoop();
2083 if (!cl->loopexit())
2084 return false; // Malformed loop
2085 if (!phase->is_member(this, phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue))))
2086 return false; // Infinite loop
2089 // Ensure only one phi which is the iv.
2091 for (DUIterator_Fast imax, i = cl->fast_outs(imax); i < imax; i++) {
2092 Node* n = cl->fast_out(i);
2093 if (n->Opcode() == Op_Phi) {
2094 assert(iv == NULL, "Too many phis" );
2098 assert(iv == cl->phi(), "Wrong phi" );
2101 // main and post loops have explicitly created zero trip guard
2102 bool needs_guard = !cl->is_main_loop() && !cl->is_post_loop();
2104 // Skip guard if values not overlap.
2105 const TypeInt* init_t = phase->_igvn.type(cl->init_trip())->is_int();
2106 const TypeInt* limit_t = phase->_igvn.type(cl->limit())->is_int();
2107 int stride_con = cl->stride_con();
2108 if (stride_con > 0) {
2109 needs_guard = (init_t->_hi >= limit_t->_lo);
2111 needs_guard = (init_t->_lo <= limit_t->_hi);
2115 // Check for an obvious zero trip guard.
2116 Node* inctrl = PhaseIdealLoop::skip_loop_predicates(cl->in(LoopNode::EntryControl));
2117 if (inctrl->Opcode() == Op_IfTrue) {
2118 // The test should look like just the backedge of a CountedLoop
2119 Node* iff = inctrl->in(0);
2121 Node* bol = iff->in(1);
2122 if (bol->is_Bool() && bol->as_Bool()->_test._test == cl->loopexit()->test_trip()) {
2123 Node* cmp = bol->in(1);
2124 if (cmp->is_Cmp() && cmp->in(1) == cl->init_trip() && cmp->in(2) == cl->limit()) {
2125 needs_guard = false;
2134 tty->print("Removing empty loop with%s zero trip guard", needs_guard ? "out" : "");
2136 } else if (TraceLoopOpts) {
2137 tty->print("Empty with%s zero trip guard ", needs_guard ? "out" : "");
2143 // Peel the loop to ensure there's a zero trip guard
2145 phase->do_peeling(this, old_new);
2148 // Replace the phi at loop head with the final value of the last
2149 // iteration. Then the CountedLoopEnd will collapse (backedge never
2150 // taken) and all loop-invariant uses of the exit values will be correct.
2151 Node *phi = cl->phi();
2152 Node *exact_limit = phase->exact_limit(this);
2153 if (exact_limit != cl->limit()) {
2154 // We also need to replace the original limit to collapse loop exit.
2155 Node* cmp = cl->loopexit()->cmp_node();
2156 assert(cl->limit() == cmp->in(2), "sanity");
2157 phase->_igvn._worklist.push(cmp->in(2)); // put limit on worklist
2158 phase->_igvn.hash_delete(cmp);
2159 cmp->set_req(2, exact_limit);
2160 phase->_igvn._worklist.push(cmp); // put cmp on worklist
2162 // Note: the final value after increment should not overflow since
2163 // counted loop has limit check predicate.
2164 Node *final = new (phase->C, 3) SubINode( exact_limit, cl->stride() );
2165 phase->register_new_node(final,cl->in(LoopNode::EntryControl));
2166 phase->_igvn.replace_node(phi,final);
2167 phase->C->set_major_progress();
2171 //------------------------------policy_do_one_iteration_loop-------------------
2172 // Convert one iteration loop into normal code.
2173 bool IdealLoopTree::policy_do_one_iteration_loop( PhaseIdealLoop *phase ) {
2174 if (!_head->as_Loop()->is_valid_counted_loop())
2175 return false; // Only for counted loop
2177 CountedLoopNode *cl = _head->as_CountedLoop();
2178 if (!cl->has_exact_trip_count() || cl->trip_count() != 1) {
2184 tty->print("OneIteration ");
2189 Node *init_n = cl->init_trip();
2191 // Loop boundaries should be constant since trip count is exact.
2192 assert(init_n->get_int() + cl->stride_con() >= cl->limit()->get_int(), "should be one iteration");
2194 // Replace the phi at loop head with the value of the init_trip.
2195 // Then the CountedLoopEnd will collapse (backedge will not be taken)
2196 // and all loop-invariant uses of the exit values will be correct.
2197 phase->_igvn.replace_node(cl->phi(), cl->init_trip());
2198 phase->C->set_major_progress();
2202 //=============================================================================
2203 //------------------------------iteration_split_impl---------------------------
2204 bool IdealLoopTree::iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ) {
2205 // Compute exact loop trip count if possible.
2206 compute_exact_trip_count(phase);
2208 // Convert one iteration loop into normal code.
2209 if (policy_do_one_iteration_loop(phase))
2212 // Check and remove empty loops (spam micro-benchmarks)
2213 if (policy_do_remove_empty_loop(phase))
2214 return true; // Here we removed an empty loop
2216 bool should_peel = policy_peeling(phase); // Should we peel?
2218 bool should_unswitch = policy_unswitching(phase);
2220 // Non-counted loops may be peeled; exactly 1 iteration is peeled.
2221 // This removes loop-invariant tests (usually null checks).
2222 if (!_head->is_CountedLoop()) { // Non-counted loop
2223 if (PartialPeelLoop && phase->partial_peel(this, old_new)) {
2224 // Partial peel succeeded so terminate this round of loop opts
2227 if (should_peel) { // Should we peel?
2229 if (PrintOpto) tty->print_cr("should_peel");
2231 phase->do_peeling(this,old_new);
2232 } else if (should_unswitch) {
2233 phase->do_unswitching(this, old_new);
2237 CountedLoopNode *cl = _head->as_CountedLoop();
2239 if (!cl->loopexit()) return true; // Ignore various kinds of broken loops
2241 // Do nothing special to pre- and post- loops
2242 if (cl->is_pre_loop() || cl->is_post_loop()) return true;
2244 // Compute loop trip count from profile data
2245 compute_profile_trip_cnt(phase);
2247 // Before attempting fancy unrolling, RCE or alignment, see if we want
2248 // to completely unroll this loop or do loop unswitching.
2249 if (cl->is_normal_loop()) {
2250 if (should_unswitch) {
2251 phase->do_unswitching(this, old_new);
2254 bool should_maximally_unroll = policy_maximally_unroll(phase);
2255 if (should_maximally_unroll) {
2256 // Here we did some unrolling and peeling. Eventually we will
2257 // completely unroll this loop and it will no longer be a loop.
2258 phase->do_maximally_unroll(this,old_new);
2263 // Skip next optimizations if running low on nodes. Note that
2264 // policy_unswitching and policy_maximally_unroll have this check.
2265 uint nodes_left = MaxNodeLimit - phase->C->unique();
2266 if ((2 * _body.size()) > nodes_left) {
2270 // Counted loops may be peeled, may need some iterations run up
2271 // front for RCE, and may want to align loop refs to a cache
2272 // line. Thus we clone a full loop up front whose trip count is
2273 // at least 1 (if peeling), but may be several more.
2275 // The main loop will start cache-line aligned with at least 1
2276 // iteration of the unrolled body (zero-trip test required) and
2277 // will have some range checks removed.
2279 // A post-loop will finish any odd iterations (leftover after
2280 // unrolling), plus any needed for RCE purposes.
2282 bool should_unroll = policy_unroll(phase);
2284 bool should_rce = policy_range_check(phase);
2286 bool should_align = policy_align(phase);
2288 // If not RCE'ing (iteration splitting) or Aligning, then we do not
2289 // need a pre-loop. We may still need to peel an initial iteration but
2290 // we will not be needing an unknown number of pre-iterations.
2292 // Basically, if may_rce_align reports FALSE first time through,
2293 // we will not be able to later do RCE or Aligning on this loop.
2294 bool may_rce_align = !policy_peel_only(phase) || should_rce || should_align;
2296 // If we have any of these conditions (RCE, alignment, unrolling) met, then
2297 // we switch to the pre-/main-/post-loop model. This model also covers
2299 if (should_rce || should_align || should_unroll) {
2300 if (cl->is_normal_loop()) // Convert to 'pre/main/post' loops
2301 phase->insert_pre_post_loops(this,old_new, !may_rce_align);
2303 // Adjust the pre- and main-loop limits to let the pre and post loops run
2304 // with full checks, but the main-loop with no checks. Remove said
2305 // checks from the main body.
2307 phase->do_range_check(this,old_new);
2309 // Double loop body for unrolling. Adjust the minimum-trip test (will do
2310 // twice as many iterations as before) and the main body limit (only do
2311 // an even number of trips). If we are peeling, we might enable some RCE
2312 // and we'd rather unroll the post-RCE'd loop SO... do not unroll if
2314 if (should_unroll && !should_peel)
2315 phase->do_unroll(this,old_new, true);
2317 // Adjust the pre-loop limits to align the main body
2322 } else { // Else we have an unchanged counted loop
2323 if (should_peel) // Might want to peel but do nothing else
2324 phase->do_peeling(this,old_new);
2330 //=============================================================================
2331 //------------------------------iteration_split--------------------------------
2332 bool IdealLoopTree::iteration_split( PhaseIdealLoop *phase, Node_List &old_new ) {
2333 // Recursively iteration split nested loops
2334 if (_child && !_child->iteration_split(phase, old_new))
2337 // Clean out prior deadwood
2341 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
2342 // Replace with a 1-in-10 exit guess.
2343 if (_parent /*not the root loop*/ &&
2345 // Also ignore the occasional dead backedge
2346 !tail()->is_top()) {
2347 adjust_loop_exit_prob(phase);
2350 // Gate unrolling, RCE and peeling efforts.
2351 if (!_child && // If not an inner loop, do not split
2353 _allow_optimizations &&
2354 !tail()->is_top()) { // Also ignore the occasional dead backedge
2356 if (!iteration_split_impl(phase, old_new)) {
2359 } else if (policy_unswitching(phase)) {
2360 phase->do_unswitching(this, old_new);
2364 // Minor offset re-organization to remove loop-fallout uses of
2365 // trip counter when there was no major reshaping.
2366 phase->reorg_offsets(this);
2368 if (_next && !_next->iteration_split(phase, old_new))
2374 //=============================================================================
2375 // Process all the loops in the loop tree and replace any fill
2376 // patterns with an intrisc version.
2377 bool PhaseIdealLoop::do_intrinsify_fill() {
2378 bool changed = false;
2379 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2380 IdealLoopTree* lpt = iter.current();
2381 changed |= intrinsify_fill(lpt);
2387 // Examine an inner loop looking for a a single store of an invariant
2388 // value in a unit stride loop,
2389 bool PhaseIdealLoop::match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
2390 Node*& shift, Node*& con) {
2391 const char* msg = NULL;
2392 Node* msg_node = NULL;
2398 // Process the loop looking for stores. If there are multiple
2399 // stores or extra control flow give at this point.
2400 CountedLoopNode* head = lpt->_head->as_CountedLoop();
2401 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
2402 Node* n = lpt->_body.at(i);
2403 if (n->outcnt() == 0) continue; // Ignore dead
2404 if (n->is_Store()) {
2405 if (store != NULL) {
2406 msg = "multiple stores";
2409 int opc = n->Opcode();
2410 if (opc == Op_StoreP || opc == Op_StoreN || opc == Op_StoreCM) {
2411 msg = "oop fills not handled";
2414 Node* value = n->in(MemNode::ValueIn);
2415 if (!lpt->is_invariant(value)) {
2416 msg = "variant store value";
2417 } else if (!_igvn.type(n->in(MemNode::Address))->isa_aryptr()) {
2418 msg = "not array address";
2421 store_value = value;
2422 } else if (n->is_If() && n != head->loopexit()) {
2423 msg = "extra control flow";
2428 if (store == NULL) {
2433 if (msg == NULL && head->stride_con() != 1) {
2434 // could handle negative strides too
2435 if (head->stride_con() < 0) {
2436 msg = "negative stride";
2438 msg = "non-unit stride";
2442 if (msg == NULL && !store->in(MemNode::Address)->is_AddP()) {
2443 msg = "can't handle store address";
2444 msg_node = store->in(MemNode::Address);
2448 (!store->in(MemNode::Memory)->is_Phi() ||
2449 store->in(MemNode::Memory)->in(LoopNode::LoopBackControl) != store)) {
2450 msg = "store memory isn't proper phi";
2451 msg_node = store->in(MemNode::Memory);
2454 // Make sure there is an appropriate fill routine
2455 BasicType t = store->as_Mem()->memory_type();
2456 const char* fill_name;
2458 StubRoutines::select_fill_function(t, false, fill_name) == NULL) {
2459 msg = "unsupported store";
2465 if (TraceOptimizeFill) {
2466 tty->print_cr("not fill intrinsic candidate: %s", msg);
2467 if (msg_node != NULL) msg_node->dump();
2473 // Make sure the address expression can be handled. It should be
2474 // head->phi * elsize + con. head->phi might have a ConvI2L.
2477 bool found_index = false;
2478 int count = store->in(MemNode::Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
2479 for (int e = 0; e < count; e++) {
2480 Node* n = elements[e];
2481 if (n->is_Con() && con == NULL) {
2483 } else if (n->Opcode() == Op_LShiftX && shift == NULL) {
2484 Node* value = n->in(1);
2486 if (value->Opcode() == Op_ConvI2L) {
2488 value = value->in(1);
2491 if (value != head->phi()) {
2492 msg = "unhandled shift in address";
2494 if (type2aelembytes(store->as_Mem()->memory_type(), true) != (1 << n->in(2)->get_int())) {
2495 msg = "scale doesn't match";
2501 } else if (n->Opcode() == Op_ConvI2L && conv == NULL) {
2502 if (n->in(1) == head->phi()) {
2506 msg = "unhandled input to ConvI2L";
2508 } else if (n == head->phi()) {
2509 // no shift, check below for allowed cases
2512 msg = "unhandled node in address";
2518 msg = "malformed address expression";
2523 msg = "missing use of index";
2526 // byte sized items won't have a shift
2527 if (msg == NULL && shift == NULL && t != T_BYTE && t != T_BOOLEAN) {
2528 msg = "can't find shift";
2534 if (TraceOptimizeFill) {
2535 tty->print_cr("not fill intrinsic: %s", msg);
2536 if (msg_node != NULL) msg_node->dump();
2542 // No make sure all the other nodes in the loop can be handled
2543 VectorSet ok(Thread::current()->resource_area());
2545 // store related values are ok
2546 ok.set(store->_idx);
2547 ok.set(store->in(MemNode::Memory)->_idx);
2549 // Loop structure is ok
2551 ok.set(head->loopexit()->_idx);
2552 ok.set(head->phi()->_idx);
2553 ok.set(head->incr()->_idx);
2554 ok.set(head->loopexit()->cmp_node()->_idx);
2555 ok.set(head->loopexit()->in(1)->_idx);
2557 // Address elements are ok
2558 if (con) ok.set(con->_idx);
2559 if (shift) ok.set(shift->_idx);
2560 if (conv) ok.set(conv->_idx);
2562 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
2563 Node* n = lpt->_body.at(i);
2564 if (n->outcnt() == 0) continue; // Ignore dead
2565 if (ok.test(n->_idx)) continue;
2566 // Backedge projection is ok
2567 if (n->is_IfTrue() && n->in(0) == head->loopexit()) continue;
2568 if (!n->is_AddP()) {
2569 msg = "unhandled node";
2575 // Make sure no unexpected values are used outside the loop
2576 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) {
2577 Node* n = lpt->_body.at(i);
2578 // These values can be replaced with other nodes if they are used
2579 // outside the loop.
2580 if (n == store || n == head->loopexit() || n == head->incr() || n == store->in(MemNode::Memory)) continue;
2581 for (SimpleDUIterator iter(n); iter.has_next(); iter.next()) {
2582 Node* use = iter.get();
2583 if (!lpt->_body.contains(use)) {
2584 msg = "node is used outside loop";
2585 // lpt->_body.dump();
2593 if (TraceOptimizeFill) {
2595 tty->print_cr("no fill intrinsic: %s", msg);
2596 if (msg_node != NULL) msg_node->dump();
2598 tty->print_cr("fill intrinsic for:");
2612 bool PhaseIdealLoop::intrinsify_fill(IdealLoopTree* lpt) {
2613 // Only for counted inner loops
2614 if (!lpt->is_counted() || !lpt->is_inner()) {
2618 // Must have constant stride
2619 CountedLoopNode* head = lpt->_head->as_CountedLoop();
2620 if (!head->stride_is_con() || !head->is_normal_loop()) {
2624 // Check that the body only contains a store of a loop invariant
2625 // value that is indexed by the loop phi.
2627 Node* store_value = NULL;
2629 Node* offset = NULL;
2630 if (!match_fill_loop(lpt, store, store_value, shift, offset)) {
2635 if (TraceLoopOpts) {
2636 tty->print("ArrayFill ");
2641 // Now replace the whole loop body by a call to a fill routine that
2642 // covers the same region as the loop.
2643 Node* base = store->in(MemNode::Address)->as_AddP()->in(AddPNode::Base);
2645 // Build an expression for the beginning of the copy region
2646 Node* index = head->init_trip();
2648 index = new (C, 2) ConvI2LNode(index);
2649 _igvn.register_new_node_with_optimizer(index);
2651 if (shift != NULL) {
2652 // byte arrays don't require a shift but others do.
2653 index = new (C, 3) LShiftXNode(index, shift->in(2));
2654 _igvn.register_new_node_with_optimizer(index);
2656 index = new (C, 4) AddPNode(base, base, index);
2657 _igvn.register_new_node_with_optimizer(index);
2658 Node* from = new (C, 4) AddPNode(base, index, offset);
2659 _igvn.register_new_node_with_optimizer(from);
2660 // Compute the number of elements to copy
2661 Node* len = new (C, 3) SubINode(head->limit(), head->init_trip());
2662 _igvn.register_new_node_with_optimizer(len);
2664 BasicType t = store->as_Mem()->memory_type();
2665 bool aligned = false;
2666 if (offset != NULL && head->init_trip()->is_Con()) {
2667 int element_size = type2aelembytes(t);
2668 aligned = (offset->find_intptr_t_type()->get_con() + head->init_trip()->get_int() * element_size) % HeapWordSize == 0;
2671 // Build a call to the fill routine
2672 const char* fill_name;
2673 address fill = StubRoutines::select_fill_function(t, aligned, fill_name);
2674 assert(fill != NULL, "what?");
2676 // Convert float/double to int/long for fill routines
2678 store_value = new (C, 2) MoveF2INode(store_value);
2679 _igvn.register_new_node_with_optimizer(store_value);
2680 } else if (t == T_DOUBLE) {
2681 store_value = new (C, 2) MoveD2LNode(store_value);
2682 _igvn.register_new_node_with_optimizer(store_value);
2685 Node* mem_phi = store->in(MemNode::Memory);
2688 const TypeFunc* call_type = OptoRuntime::array_fill_Type();
2689 int size = call_type->domain()->cnt();
2690 CallLeafNode *call = new (C, size) CallLeafNoFPNode(call_type, fill,
2691 fill_name, TypeAryPtr::get_array_body_type(t));
2692 call->init_req(TypeFunc::Parms+0, from);
2693 call->init_req(TypeFunc::Parms+1, store_value);
2695 len = new (C, 2) ConvI2LNode(len);
2696 _igvn.register_new_node_with_optimizer(len);
2698 call->init_req(TypeFunc::Parms+2, len);
2700 call->init_req(TypeFunc::Parms+3, C->top());
2702 call->init_req( TypeFunc::Control, head->init_control());
2703 call->init_req( TypeFunc::I_O , C->top() ) ; // does no i/o
2704 call->init_req( TypeFunc::Memory , mem_phi->in(LoopNode::EntryControl) );
2705 call->init_req( TypeFunc::ReturnAdr, C->start()->proj_out(TypeFunc::ReturnAdr) );
2706 call->init_req( TypeFunc::FramePtr, C->start()->proj_out(TypeFunc::FramePtr) );
2707 _igvn.register_new_node_with_optimizer(call);
2708 result_ctrl = new (C, 1) ProjNode(call,TypeFunc::Control);
2709 _igvn.register_new_node_with_optimizer(result_ctrl);
2710 result_mem = new (C, 1) ProjNode(call,TypeFunc::Memory);
2711 _igvn.register_new_node_with_optimizer(result_mem);
2713 // If this fill is tightly coupled to an allocation and overwrites
2714 // the whole body, allow it to take over the zeroing.
2715 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, this);
2716 if (alloc != NULL && alloc->is_AllocateArray()) {
2717 Node* length = alloc->as_AllocateArray()->Ideal_length();
2718 if (head->limit() == length &&
2719 head->init_trip() == _igvn.intcon(0)) {
2720 if (TraceOptimizeFill) {
2721 tty->print_cr("Eliminated zeroing in allocation");
2723 alloc->maybe_set_complete(&_igvn);
2726 if (TraceOptimizeFill) {
2727 tty->print_cr("filling array but bounds don't match");
2729 head->init_trip()->dump();
2730 head->limit()->dump();
2737 // Redirect the old control and memory edges that are outside the loop.
2738 Node* exit = head->loopexit()->proj_out(0);
2739 // Sometimes the memory phi of the head is used as the outgoing
2740 // state of the loop. It's safe in this case to replace it with the
2742 _igvn.replace_node(store->in(MemNode::Memory), result_mem);
2743 _igvn.replace_node(exit, result_ctrl);
2744 _igvn.replace_node(store, result_mem);
2745 // Any uses the increment outside of the loop become the loop limit.
2746 _igvn.replace_node(head->incr(), head->limit());
2748 // Disconnect the head from the loop.
2749 for (uint i = 0; i < lpt->_body.size(); i++) {
2750 Node* n = lpt->_body.at(i);
2751 _igvn.replace_node(n, C->top());