17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "opto/loopnode.hpp"
27 #include "opto/addnode.hpp"
28 #include "opto/callnode.hpp"
29 #include "opto/connode.hpp"
30 #include "opto/convertnode.hpp"
31 #include "opto/loopnode.hpp"
32 #include "opto/matcher.hpp"
33 #include "opto/mulnode.hpp"
34 #include "opto/opaquenode.hpp"
35 #include "opto/rootnode.hpp"
36 #include "opto/subnode.hpp"
37
38 /*
39 * The general idea of Loop Predication is to insert a predicate on the entry
40 * path to a loop, and raise a uncommon trap if the check of the condition fails.
41 * The condition checks are promoted from inside the loop body, and thus
42 * the checks inside the loop could be eliminated. Currently, loop predication
43 * optimization has been applied to remove array range check and loop invariant
44 * checks (such as null checks).
45 */
46
47 //-------------------------------register_control-------------------------
48 void PhaseIdealLoop::register_control(Node* n, IdealLoopTree *loop, Node* pred) {
49 assert(n->is_CFG(), "must be control node");
50 _igvn.register_new_node_with_optimizer(n);
51 loop->_body.push(n);
52 set_loop(n, loop);
53 // When called from beautify_loops() idom is not constructed yet.
54 if (_idom != NULL) {
55 set_idom(n, pred, dom_depth(pred));
56 }
301
302 // Clone loop predicates to cloned loops (peeled, unswitched, split_if).
303 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry,
304 bool clone_limit_check,
305 PhaseIdealLoop* loop_phase,
306 PhaseIterGVN* igvn) {
307 #ifdef ASSERT
308 if (new_entry == NULL || !(new_entry->is_Proj() || new_entry->is_Region() || new_entry->is_SafePoint())) {
309 if (new_entry != NULL)
310 new_entry->dump();
311 assert(false, "not IfTrue, IfFalse, Region or SafePoint");
312 }
313 #endif
314 // Search original predicates
315 Node* entry = old_entry;
316 ProjNode* limit_check_proj = NULL;
317 limit_check_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
318 if (limit_check_proj != NULL) {
319 entry = entry->in(0)->in(0);
320 }
321 if (UseLoopPredicate) {
322 ProjNode* predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
323 if (predicate_proj != NULL) { // right pattern that can be used by loop predication
324 // clone predicate
325 new_entry = clone_predicate(predicate_proj, new_entry,
326 Deoptimization::Reason_predicate,
327 loop_phase, igvn);
328 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone predicate");
329 if (TraceLoopPredicate) {
330 tty->print("Loop Predicate cloned: ");
331 debug_only( new_entry->in(0)->dump(); )
332 }
333 }
334 }
335 if (limit_check_proj != NULL && clone_limit_check) {
336 // Clone loop limit check last to insert it before loop.
337 // Don't clone a limit check which was already finalized
338 // for this counted loop (only one limit check is needed).
339 new_entry = clone_predicate(limit_check_proj, new_entry,
340 Deoptimization::Reason_loop_limit_check,
341 loop_phase, igvn);
342 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone limit check");
343 if (TraceLoopLimitCheck) {
344 tty->print("Loop Limit Check cloned: ");
345 debug_only( new_entry->in(0)->dump(); )
346 }
347 }
348 return new_entry;
349 }
350
351 //--------------------------skip_loop_predicates------------------------------
352 // Skip related predicates.
353 Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) {
354 Node* predicate = NULL;
355 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
356 if (predicate != NULL) {
357 entry = entry->in(0)->in(0);
358 }
359 if (UseLoopPredicate) {
360 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
361 if (predicate != NULL) { // right pattern that can be used by loop predication
362 IfNode* iff = entry->in(0)->as_If();
363 ProjNode* uncommon_proj = iff->proj_out(1 - entry->as_Proj()->_con);
364 Node* rgn = uncommon_proj->unique_ctrl_out();
365 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
366 entry = entry->in(0)->in(0);
367 while (entry != NULL && entry->is_Proj() && entry->in(0)->is_If()) {
368 uncommon_proj = entry->in(0)->as_If()->proj_out(1 - entry->as_Proj()->_con);
369 if (uncommon_proj->unique_ctrl_out() != rgn)
370 break;
371 entry = entry->in(0)->in(0);
372 }
373 }
374 }
375 return entry;
376 }
377
378 //--------------------------find_predicate_insertion_point-------------------
379 // Find a good location to insert a predicate
380 ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason) {
381 if (start_c == NULL || !start_c->is_Proj())
382 return NULL;
383 if (start_c->as_Proj()->is_uncommon_trap_if_pattern(reason)) {
384 return start_c->as_Proj();
385 }
386 return NULL;
387 }
388
389 //--------------------------find_predicate------------------------------------
390 // Find a predicate
391 Node* PhaseIdealLoop::find_predicate(Node* entry) {
392 Node* predicate = NULL;
393 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
394 if (predicate != NULL) { // right pattern that can be used by loop predication
395 return entry;
396 }
397 if (UseLoopPredicate) {
398 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
399 if (predicate != NULL) { // right pattern that can be used by loop predication
400 return entry;
401 }
402 }
403 return NULL;
404 }
405
406 //------------------------------Invariance-----------------------------------
407 // Helper class for loop_predication_impl to compute invariance on the fly and
408 // clone invariants.
409 class Invariance : public StackObj {
410 VectorSet _visited, _invariant;
411 Node_Stack _stack;
412 VectorSet _clone_visited;
413 Node_List _old_new; // map of old to new (clone)
414 IdealLoopTree* _lpt;
415 PhaseIdealLoop* _phase;
416
417 // Helper function to set up the invariance for invariance computation
418 // If n is a known invariant, set up directly. Otherwise, look up the
419 // the possibility to push n onto the stack for further processing.
420 void visit(Node* use, Node* n) {
421 if (_lpt->is_invariant(n)) { // known invariant
422 _invariant.set(n->_idx);
749 CmpNode* cmp = NULL;
750 if (overflow) {
751 // Integer expressions may overflow, do long comparison
752 range = new ConvI2LNode(range);
753 register_new_node(range, ctrl);
754 cmp = new CmpULNode(max_idx_expr, range);
755 } else {
756 cmp = new CmpUNode(max_idx_expr, range);
757 }
758 register_new_node(cmp, ctrl);
759 BoolNode* bol = new BoolNode(cmp, BoolTest::lt);
760 register_new_node(bol, ctrl);
761
762 if (TraceLoopPredicate) {
763 predString->print_cr("<u range");
764 tty->print("%s", predString->as_string());
765 }
766 return bol;
767 }
768
769 // After pre/main/post loops are created, we'll put a copy of some
770 // range checks between the pre and main loop to validate the initial
771 // value of the induction variable for the main loop. Make a copy of
772 // the predicates here with an opaque node as a place holder for the
773 // initial value.
774 ProjNode* PhaseIdealLoop::insert_skeleton_predicate(IfNode* iff, IdealLoopTree *loop,
775 ProjNode* proj, ProjNode *predicate_proj,
776 ProjNode* upper_bound_proj,
777 int scale, Node* offset,
778 Node* init, Node* limit, jint stride,
779 Node* rng, bool &overflow) {
780 assert(proj->_con && predicate_proj->_con, "not a range check?");
781 Node* opaque_init = new Opaque1Node(C, init);
782 register_new_node(opaque_init, upper_bound_proj);
783 BoolNode* bol = rc_predicate(loop, upper_bound_proj, scale, offset, opaque_init, limit, stride, rng, (stride > 0) != (scale > 0), overflow);
784 Node* opaque_bol = new Opaque4Node(C, bol, _igvn.intcon(1)); // This will go away once loop opts are over
785 register_new_node(opaque_bol, upper_bound_proj);
786 ProjNode* new_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate, overflow ? Op_If : iff->Opcode());
787 _igvn.replace_input_of(new_proj->in(0), 1, opaque_bol);
788 assert(opaque_init->outcnt() > 0, "should be used");
789 return new_proj;
790 }
791
792 //------------------------------ loop_predication_impl--------------------------
793 // Insert loop predicates for null checks and range checks
794 bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) {
795 if (!UseLoopPredicate) return false;
796
797 if (!loop->_head->is_Loop()) {
798 // Could be a simple region when irreducible loops are present.
799 return false;
800 }
801 LoopNode* head = loop->_head->as_Loop();
802
803 if (head->unique_ctrl_out()->Opcode() == Op_NeverBranch) {
804 // do nothing for infinite loops
805 return false;
806 }
807
808 if (head->is_OuterStripMinedLoop()) {
809 return false;
810 }
811
812 CountedLoopNode *cl = NULL;
813 if (head->is_valid_counted_loop()) {
814 cl = head->as_CountedLoop();
815 // do nothing for iteration-splitted loops
816 if (!cl->is_normal_loop()) return false;
817 // Avoid RCE if Counted loop's test is '!='.
818 BoolTest::mask bt = cl->loopexit()->test_trip();
819 if (bt != BoolTest::lt && bt != BoolTest::gt)
820 cl = NULL;
821 }
822
823 Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl);
824 ProjNode *predicate_proj = NULL;
825 // Loop limit check predicate should be near the loop.
826 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
827 if (predicate_proj != NULL)
828 entry = predicate_proj->in(0)->in(0);
829 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
830 if (!predicate_proj) {
831 #ifndef PRODUCT
832 if (TraceLoopPredicate) {
833 tty->print("missing predicate:");
834 loop->dump_head();
835 head->dump(1);
836 }
837 #endif
838 return false;
839 }
840 ConNode* zero = _igvn.intcon(0);
841 set_ctrl(zero, C->root());
842
843 ResourceArea *area = Thread::current()->resource_area();
844 Invariance invar(area, loop);
845
846 // Create list of if-projs such that a newer proj dominates all older
847 // projs in the list, and they all dominate loop->tail()
848 Node_List if_proj_list(area);
849 Node *current_proj = loop->tail(); //start from tail
850 while (current_proj != head) {
851 if (loop == get_loop(current_proj) && // still in the loop ?
852 current_proj->is_Proj() && // is a projection ?
853 (current_proj->in(0)->Opcode() == Op_If ||
854 current_proj->in(0)->Opcode() == Op_RangeCheck)) { // is a if projection ?
855 if_proj_list.push(current_proj);
856 }
857 current_proj = idom(current_proj);
858 }
859
860 bool hoisted = false; // true if at least one proj is promoted
861 while (if_proj_list.size() > 0) {
862 // Following are changed to nonnull when a predicate can be hoisted
863 ProjNode* new_predicate_proj = NULL;
864
865 ProjNode* proj = if_proj_list.pop()->as_Proj();
866 IfNode* iff = proj->in(0)->as_If();
867
868 if (!proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
869 if (loop->is_loop_exit(iff)) {
870 // stop processing the remaining projs in the list because the execution of them
871 // depends on the condition of "iff" (iff->in(1)).
872 break;
873 } else {
874 // Both arms are inside the loop. There are two cases:
875 // (1) there is one backward branch. In this case, any remaining proj
876 // in the if_proj list post-dominates "iff". So, the condition of "iff"
877 // does not determine the execution the remining projs directly, and we
878 // can safely continue.
879 // (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj"
880 // does not dominate loop->tail(), so it can not be in the if_proj list.
881 continue;
882 }
883 }
884
885 Node* test = iff->in(1);
886 if (!test->is_Bool()){ //Conv2B, ...
887 continue;
888 }
889 BoolNode* bol = test->as_Bool();
890 if (invar.is_invariant(bol)) {
891 // Invariant test
892 new_predicate_proj = create_new_if_for_predicate(predicate_proj, NULL,
893 Deoptimization::Reason_predicate,
894 iff->Opcode());
895 Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0);
896 BoolNode* new_predicate_bol = invar.clone(bol, ctrl)->as_Bool();
897
898 // Negate test if necessary
899 bool negated = false;
900 if (proj->_con != predicate_proj->_con) {
901 new_predicate_bol = new BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate());
902 register_new_node(new_predicate_bol, ctrl);
903 negated = true;
904 }
905 IfNode* new_predicate_iff = new_predicate_proj->in(0)->as_If();
906 _igvn.hash_delete(new_predicate_iff);
907 new_predicate_iff->set_req(1, new_predicate_bol);
908 #ifndef PRODUCT
909 if (TraceLoopPredicate) {
910 tty->print("Predicate invariant if%s: %d ", negated ? " negated" : "", new_predicate_iff->_idx);
911 loop->dump_head();
912 } else if (TraceLoopOpts) {
913 tty->print("Predicate IC ");
942 // Perform cloning to keep Invariance state correct since the
943 // late schedule will place invariant things in the loop.
944 Node *ctrl = predicate_proj->in(0)->as_If()->in(0);
945 rng = invar.clone(rng, ctrl);
946 if (offset && offset != zero) {
947 assert(invar.is_invariant(offset), "offset must be loop invariant");
948 offset = invar.clone(offset, ctrl);
949 }
950 // If predicate expressions may overflow in the integer range, longs are used.
951 bool overflow = false;
952
953 // Test the lower bound
954 BoolNode* lower_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, false, overflow);
955 // Negate test if necessary
956 bool negated = false;
957 if (proj->_con != predicate_proj->_con) {
958 lower_bound_bol = new BoolNode(lower_bound_bol->in(1), lower_bound_bol->_test.negate());
959 register_new_node(lower_bound_bol, ctrl);
960 negated = true;
961 }
962 ProjNode* lower_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate, overflow ? Op_If : iff->Opcode());
963 IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If();
964 _igvn.hash_delete(lower_bound_iff);
965 lower_bound_iff->set_req(1, lower_bound_bol);
966 if (TraceLoopPredicate) tty->print_cr("lower bound check if: %s %d ", negated ? " negated" : "", lower_bound_iff->_idx);
967
968 // Test the upper bound
969 BoolNode* upper_bound_bol = rc_predicate(loop, lower_bound_proj, scale, offset, init, limit, stride, rng, true, overflow);
970 negated = false;
971 if (proj->_con != predicate_proj->_con) {
972 upper_bound_bol = new BoolNode(upper_bound_bol->in(1), upper_bound_bol->_test.negate());
973 register_new_node(upper_bound_bol, ctrl);
974 negated = true;
975 }
976 ProjNode* upper_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate, overflow ? Op_If : iff->Opcode());
977 assert(upper_bound_proj->in(0)->as_If()->in(0) == lower_bound_proj, "should dominate");
978 IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If();
979 _igvn.hash_delete(upper_bound_iff);
980 upper_bound_iff->set_req(1, upper_bound_bol);
981 if (TraceLoopPredicate) tty->print_cr("upper bound check if: %s %d ", negated ? " negated" : "", lower_bound_iff->_idx);
982
983 // Fall through into rest of the clean up code which will move
984 // any dependent nodes onto the upper bound test.
985 new_predicate_proj = upper_bound_proj;
986
987 if (iff->is_RangeCheck()) {
988 new_predicate_proj = insert_skeleton_predicate(iff, loop, proj, predicate_proj, upper_bound_proj, scale, offset, init, limit, stride, rng, overflow);
989 }
990
991 #ifndef PRODUCT
992 if (TraceLoopOpts && !TraceLoopPredicate) {
993 tty->print("Predicate RC ");
994 loop->dump_head();
995 }
996 #endif
997 } else {
998 // Loop variant check (for example, range check in non-counted loop)
999 // with uncommon trap.
1000 continue;
1001 }
1002 assert(new_predicate_proj != NULL, "sanity");
1003 // Success - attach condition (new_predicate_bol) to predicate if
1004 invar.map_ctrl(proj, new_predicate_proj); // so that invariance test can be appropriate
1005
1006 // Eliminate the old If in the loop body
1007 dominated_by( new_predicate_proj, iff, proj->_con != new_predicate_proj->_con );
1008
1009 hoisted = true;
1010 C->set_major_progress();
1011 } // end while
1012
1013 #ifndef PRODUCT
1014 // report that the loop predication has been actually performed
1015 // for this loop
1016 if (TraceLoopPredicate && hoisted) {
1017 tty->print("Loop Predication Performed:");
1018 loop->dump_head();
1019 }
1020 #endif
1021
1022 head->verify_strip_mined(1);
1023
1024 return hoisted;
1025 }
1026
1027 //------------------------------loop_predication--------------------------------
1028 // driver routine for loop predication optimization
1029 bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) {
1030 bool hoisted = false;
1031 // Recursively promote predicates
|
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "opto/loopnode.hpp"
27 #include "opto/addnode.hpp"
28 #include "opto/callnode.hpp"
29 #include "opto/connode.hpp"
30 #include "opto/convertnode.hpp"
31 #include "opto/loopnode.hpp"
32 #include "opto/matcher.hpp"
33 #include "opto/mulnode.hpp"
34 #include "opto/opaquenode.hpp"
35 #include "opto/rootnode.hpp"
36 #include "opto/subnode.hpp"
37 #include <fenv.h>
38 #include <math.h>
39
40 /*
41 * The general idea of Loop Predication is to insert a predicate on the entry
42 * path to a loop, and raise a uncommon trap if the check of the condition fails.
43 * The condition checks are promoted from inside the loop body, and thus
44 * the checks inside the loop could be eliminated. Currently, loop predication
45 * optimization has been applied to remove array range check and loop invariant
46 * checks (such as null checks).
47 */
48
49 //-------------------------------register_control-------------------------
50 void PhaseIdealLoop::register_control(Node* n, IdealLoopTree *loop, Node* pred) {
51 assert(n->is_CFG(), "must be control node");
52 _igvn.register_new_node_with_optimizer(n);
53 loop->_body.push(n);
54 set_loop(n, loop);
55 // When called from beautify_loops() idom is not constructed yet.
56 if (_idom != NULL) {
57 set_idom(n, pred, dom_depth(pred));
58 }
303
304 // Clone loop predicates to cloned loops (peeled, unswitched, split_if).
305 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry,
306 bool clone_limit_check,
307 PhaseIdealLoop* loop_phase,
308 PhaseIterGVN* igvn) {
309 #ifdef ASSERT
310 if (new_entry == NULL || !(new_entry->is_Proj() || new_entry->is_Region() || new_entry->is_SafePoint())) {
311 if (new_entry != NULL)
312 new_entry->dump();
313 assert(false, "not IfTrue, IfFalse, Region or SafePoint");
314 }
315 #endif
316 // Search original predicates
317 Node* entry = old_entry;
318 ProjNode* limit_check_proj = NULL;
319 limit_check_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
320 if (limit_check_proj != NULL) {
321 entry = entry->in(0)->in(0);
322 }
323 ProjNode* profile_predicate_proj = NULL;
324 ProjNode* predicate_proj = NULL;
325 if (UseProfiledLoopPredicate) {
326 profile_predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
327 if (profile_predicate_proj != NULL) {
328 entry = skip_loop_predicates(entry);
329 }
330 }
331 if (UseLoopPredicate) {
332 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
333 }
334 if (predicate_proj != NULL) { // right pattern that can be used by loop predication
335 // clone predicate
336 new_entry = clone_predicate(predicate_proj, new_entry,
337 Deoptimization::Reason_predicate,
338 loop_phase, igvn);
339 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone predicate");
340 if (TraceLoopPredicate) {
341 tty->print("Loop Predicate cloned: ");
342 debug_only( new_entry->in(0)->dump(); );
343 }
344 }
345 if (profile_predicate_proj != NULL) { // right pattern that can be used by loop predication
346 // clone predicate
347 new_entry = clone_predicate(profile_predicate_proj, new_entry,
348 Deoptimization::Reason_profile_predicate,
349 loop_phase, igvn);
350 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone predicate");
351 if (TraceLoopPredicate) {
352 tty->print("Loop Predicate cloned: ");
353 debug_only( new_entry->in(0)->dump(); );
354 }
355 }
356 if (limit_check_proj != NULL && clone_limit_check) {
357 // Clone loop limit check last to insert it before loop.
358 // Don't clone a limit check which was already finalized
359 // for this counted loop (only one limit check is needed).
360 new_entry = clone_predicate(limit_check_proj, new_entry,
361 Deoptimization::Reason_loop_limit_check,
362 loop_phase, igvn);
363 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone limit check");
364 if (TraceLoopLimitCheck) {
365 tty->print("Loop Limit Check cloned: ");
366 debug_only( new_entry->in(0)->dump(); )
367 }
368 }
369 return new_entry;
370 }
371
372 //--------------------------skip_loop_predicates------------------------------
373 // Skip related predicates.
374 Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) {
375 IfNode* iff = entry->in(0)->as_If();
376 ProjNode* uncommon_proj = iff->proj_out(1 - entry->as_Proj()->_con);
377 Node* rgn = uncommon_proj->unique_ctrl_out();
378 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
379 entry = entry->in(0)->in(0);
380 while (entry != NULL && entry->is_Proj() && entry->in(0)->is_If()) {
381 uncommon_proj = entry->in(0)->as_If()->proj_out(1 - entry->as_Proj()->_con);
382 if (uncommon_proj->unique_ctrl_out() != rgn)
383 break;
384 entry = entry->in(0)->in(0);
385 }
386 return entry;
387 }
388
389 Node* PhaseIdealLoop::skip_all_loop_predicates(Node* entry) {
390 Node* predicate = NULL;
391 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
392 if (predicate != NULL) {
393 entry = entry->in(0)->in(0);
394 }
395 if (UseProfiledLoopPredicate) {
396 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
397 if (predicate != NULL) { // right pattern that can be used by loop predication
398 entry = skip_loop_predicates(entry);
399 }
400 }
401 if (UseLoopPredicate) {
402 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
403 if (predicate != NULL) { // right pattern that can be used by loop predication
404 entry = skip_loop_predicates(entry);
405 }
406 }
407 return entry;
408 }
409
410 //--------------------------find_predicate_insertion_point-------------------
411 // Find a good location to insert a predicate
412 ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason) {
413 if (start_c == NULL || !start_c->is_Proj())
414 return NULL;
415 if (start_c->as_Proj()->is_uncommon_trap_if_pattern(reason)) {
416 return start_c->as_Proj();
417 }
418 return NULL;
419 }
420
421 //--------------------------find_predicate------------------------------------
422 // Find a predicate
423 Node* PhaseIdealLoop::find_predicate(Node* entry) {
424 Node* predicate = NULL;
425 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
426 if (predicate != NULL) { // right pattern that can be used by loop predication
427 return entry;
428 }
429 if (UseLoopPredicate) {
430 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
431 if (predicate != NULL) { // right pattern that can be used by loop predication
432 return entry;
433 }
434 }
435 if (UseProfiledLoopPredicate) {
436 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
437 if (predicate != NULL) { // right pattern that can be used by loop predication
438 return entry;
439 }
440 }
441 return NULL;
442 }
443
444 //------------------------------Invariance-----------------------------------
445 // Helper class for loop_predication_impl to compute invariance on the fly and
446 // clone invariants.
447 class Invariance : public StackObj {
448 VectorSet _visited, _invariant;
449 Node_Stack _stack;
450 VectorSet _clone_visited;
451 Node_List _old_new; // map of old to new (clone)
452 IdealLoopTree* _lpt;
453 PhaseIdealLoop* _phase;
454
455 // Helper function to set up the invariance for invariance computation
456 // If n is a known invariant, set up directly. Otherwise, look up the
457 // the possibility to push n onto the stack for further processing.
458 void visit(Node* use, Node* n) {
459 if (_lpt->is_invariant(n)) { // known invariant
460 _invariant.set(n->_idx);
787 CmpNode* cmp = NULL;
788 if (overflow) {
789 // Integer expressions may overflow, do long comparison
790 range = new ConvI2LNode(range);
791 register_new_node(range, ctrl);
792 cmp = new CmpULNode(max_idx_expr, range);
793 } else {
794 cmp = new CmpUNode(max_idx_expr, range);
795 }
796 register_new_node(cmp, ctrl);
797 BoolNode* bol = new BoolNode(cmp, BoolTest::lt);
798 register_new_node(bol, ctrl);
799
800 if (TraceLoopPredicate) {
801 predString->print_cr("<u range");
802 tty->print("%s", predString->as_string());
803 }
804 return bol;
805 }
806
807 // Should loop predication look not only in the path from tail to head
808 // but also in branches of the loop body?
809 bool PhaseIdealLoop::loop_predication_should_follow_branches(IdealLoopTree *loop, ProjNode *predicate_proj, float& loop_trip_cnt) {
810 if (!UseProfiledLoopPredicate) {
811 return false;
812 }
813
814 if (predicate_proj == NULL) {
815 return false;
816 }
817
818 LoopNode* head = loop->_head->as_Loop();
819 bool follow_branches = true;
820 IdealLoopTree* l = loop->_child;
821 // For leaf loops and loops with a single inner loop
822 while (l != NULL && follow_branches) {
823 IdealLoopTree* child = l;
824 if (child->_child != NULL &&
825 child->_head->is_OuterStripMinedLoop()) {
826 assert(child->_child->_next == NULL, "only one inner loop for strip mined loop");
827 assert(child->_child->_head->is_CountedLoop() && child->_child->_head->as_CountedLoop()->is_strip_mined(), "inner loop should be strip mined");
828 child = child->_child;
829 }
830 if (child->_child != NULL || child->_irreducible) {
831 follow_branches = false;
832 }
833 l = l->_next;
834 }
835 if (follow_branches) {
836 loop->compute_profile_trip_cnt(this);
837 if (head->is_profile_trip_failed()) {
838 follow_branches = false;
839 } else {
840 loop_trip_cnt = head->profile_trip_cnt();
841 if (head->is_CountedLoop()) {
842 CountedLoopNode* cl = head->as_CountedLoop();
843 if (cl->phi() != NULL) {
844 const TypeInt* t = _igvn.type(cl->phi())->is_int();
845 float worst_case_trip_cnt = ((float)t->_hi - t->_lo) / ABS(cl->stride_con());
846 if (worst_case_trip_cnt < loop_trip_cnt) {
847 loop_trip_cnt = worst_case_trip_cnt;
848 }
849 }
850 }
851 }
852 }
853 return follow_branches;
854 }
855
856 // Compute probability of reaching some CFG node from a fixed
857 // dominating CFG node
858 class PathFrequency {
859 private:
860 Node* _dom; // frequencies are computed relative to this node
861 Node_Stack _stack;
862 GrowableArray<float> _freqs_stack; // keep track of intermediate result at regions
863 GrowableArray<float> _freqs; // cache frequencies
864 PhaseIdealLoop* _phase;
865
866 public:
867 PathFrequency(Node* dom, PhaseIdealLoop* phase)
868 : _dom(dom), _stack(0), _phase(phase) {
869 }
870
871 float to(Node* n) {
872 // post order walk on the CFG graph from n to _dom
873 fesetround(FE_TOWARDZERO); // make sure rounding doesn't push frequency above 1
874 IdealLoopTree* loop = _phase->get_loop(_dom);
875 Node* c = n;
876 for (;;) {
877 assert(_phase->get_loop(c) == loop, "have to be in the same loop");
878 if (c == _dom || _freqs.at_grow(c->_idx, -1) >= 0) {
879 float f = c == _dom ? 1 : _freqs.at(c->_idx);
880 Node* prev = c;
881 while (_stack.size() > 0 && prev == c) {
882 Node* n = _stack.node();
883 if (!n->is_Region()) {
884 if (_phase->get_loop(n) != _phase->get_loop(n->in(0))) {
885 // Found an inner loop: compute frequency of reaching this
886 // exit from the loop head by looking at the number of
887 // times each loop exit was taken
888 IdealLoopTree* inner_loop = _phase->get_loop(n->in(0));
889 LoopNode* inner_head = inner_loop->_head->as_Loop();
890 assert(_phase->get_loop(n) == loop, "only 1 inner loop");
891 if (inner_head->is_OuterStripMinedLoop()) {
892 inner_head->verify_strip_mined(1);
893 if (n->in(0) == inner_head->in(LoopNode::LoopBackControl)->in(0)) {
894 n = n->in(0)->in(0)->in(0);
895 }
896 inner_loop = inner_loop->_child;
897 inner_head = inner_loop->_head->as_Loop();
898 inner_head->verify_strip_mined(1);
899 }
900 fesetround(FE_UPWARD); // make sure rounding doesn't push frequency above 1
901 float loop_exit_cnt = 0.0f;
902 for (uint i = 0; i < inner_loop->_body.size(); i++) {
903 Node *n = inner_loop->_body[i];
904 float c = inner_loop->compute_profile_trip_cnt_helper(n);
905 loop_exit_cnt += c;
906 }
907 fesetround(FE_TOWARDZERO);
908 float cnt = -1;
909 if (n->in(0)->is_If()) {
910 IfNode* iff = n->in(0)->as_If();
911 float p = n->in(0)->as_If()->_prob;
912 if (n->Opcode() == Op_IfFalse) {
913 p = 1 - p;
914 }
915 if (p > PROB_MIN) {
916 cnt = p * iff->_fcnt;
917 } else {
918 cnt = 0;
919 }
920 } else {
921 assert(n->in(0)->is_Jump(), "unsupported node kind");
922 JumpNode* jmp = n->in(0)->as_Jump();
923 float p = n->in(0)->as_Jump()->_probs[n->as_JumpProj()->_con];
924 cnt = p * jmp->_fcnt;
925 }
926 float this_exit_f = cnt > 0 ? cnt / loop_exit_cnt : 0;
927 assert(this_exit_f <= 1 && this_exit_f >= 0, "Incorrect frequency");
928 f = f * this_exit_f;
929 assert(f <= 1 && f >= 0, "Incorrect frequency");
930 } else {
931 float p = -1;
932 if (n->in(0)->is_If()) {
933 p = n->in(0)->as_If()->_prob;
934 if (n->Opcode() == Op_IfFalse) {
935 p = 1 - p;
936 }
937 } else {
938 assert(n->in(0)->is_Jump(), "unsupported node kind");
939 p = n->in(0)->as_Jump()->_probs[n->as_JumpProj()->_con];
940 }
941 f = f * p;
942 assert(f <= 1 && f >= 0, "Incorrect frequency");
943 }
944 _freqs.at_put_grow(n->_idx, (float)f, -1);
945 _stack.pop();
946 } else {
947 float prev_f = _freqs_stack.pop();
948 float new_f = f;
949 f = new_f + prev_f;
950 assert(f <= 1 && f >= 0, "Incorrect frequency");
951 uint i = _stack.index();
952 if (i < n->req()) {
953 c = n->in(i);
954 _stack.set_index(i+1);
955 _freqs_stack.push(f);
956 } else {
957 _freqs.at_put_grow(n->_idx, f, -1);
958 _stack.pop();
959 }
960 }
961 }
962 if (_stack.size() == 0) {
963 fesetround(FE_TONEAREST);
964 assert(f >= 0 && f <= 1, "should have been computed");
965 return f;
966 }
967 } else if (c->is_Loop()) {
968 ShouldNotReachHere();
969 c = c->in(LoopNode::EntryControl);
970 } else if (c->is_Region()) {
971 _freqs_stack.push(0);
972 _stack.push(c, 2);
973 c = c->in(1);
974 } else {
975 if (c->is_IfProj()) {
976 IfNode* iff = c->in(0)->as_If();
977 if (iff->_prob == PROB_UNKNOWN) {
978 // assume never taken
979 _freqs.at_put_grow(c->_idx, 0, -1);
980 } else if (_phase->get_loop(c) != _phase->get_loop(iff)) {
981 if (iff->_fcnt == COUNT_UNKNOWN) {
982 // assume never taken
983 _freqs.at_put_grow(c->_idx, 0, -1);
984 } else {
985 // skip over loop
986 _stack.push(c, 1);
987 c = _phase->get_loop(c->in(0))->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
988 }
989 } else {
990 _stack.push(c, 1);
991 c = iff;
992 }
993 } else if (c->is_JumpProj()) {
994 JumpNode* jmp = c->in(0)->as_Jump();
995 if (_phase->get_loop(c) != _phase->get_loop(jmp)) {
996 if (jmp->_fcnt == COUNT_UNKNOWN) {
997 // assume never taken
998 _freqs.at_put_grow(c->_idx, 0, -1);
999 } else {
1000 // skip over loop
1001 _stack.push(c, 1);
1002 c = _phase->get_loop(c->in(0))->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
1003 }
1004 } else {
1005 _stack.push(c, 1);
1006 c = jmp;
1007 }
1008 } else if (c->Opcode() == Op_CatchProj &&
1009 c->in(0)->Opcode() == Op_Catch &&
1010 c->in(0)->in(0)->is_Proj() &&
1011 c->in(0)->in(0)->in(0)->is_Call()) {
1012 // assume exceptions are never thrown
1013 uint con = c->as_Proj()->_con;
1014 if (con == CatchProjNode::fall_through_index) {
1015 Node* call = c->in(0)->in(0)->in(0)->in(0);
1016 if (_phase->get_loop(call) != _phase->get_loop(c)) {
1017 _freqs.at_put_grow(c->_idx, 0, -1);
1018 } else {
1019 c = call;
1020 }
1021 } else {
1022 assert(con >= CatchProjNode::catch_all_index, "what else?");
1023 _freqs.at_put_grow(c->_idx, 0, -1);
1024 }
1025 } else if (c->unique_ctrl_out() == NULL && !c->is_If() && !c->is_Jump()) {
1026 ShouldNotReachHere();
1027 } else {
1028 c = c->in(0);
1029 }
1030 }
1031 }
1032 ShouldNotReachHere();
1033 return -1;
1034 }
1035 };
1036
1037 void PhaseIdealLoop::loop_predication_follow_branches(Node *n, IdealLoopTree *loop, float loop_trip_cnt,
1038 PathFrequency& pf, Node_Stack& stack, VectorSet& seen,
1039 Node_List& if_proj_list) {
1040 assert(n->is_Region(), "start from a region");
1041 Node* tail = loop->tail();
1042 stack.push(n, 1);
1043 do {
1044 Node* c = stack.node();
1045 assert(c->is_Region() || c->is_IfProj(), "only region here");
1046 uint i = stack.index();
1047
1048 if (i < c->req()) {
1049 stack.set_index(i+1);
1050 Node* in = c->in(i);
1051 while (!is_dominator(in, tail) && !seen.test_set(in->_idx)) {
1052 IdealLoopTree* in_loop = get_loop(in);
1053 if (in_loop != loop) {
1054 in = in_loop->_head->in(LoopNode::EntryControl);
1055 } else if (in->is_Region()) {
1056 stack.push(in, 1);
1057 break;
1058 } else if (in->is_IfProj() &&
1059 in->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
1060 if (pf.to(in) * loop_trip_cnt >= 1) {
1061 stack.push(in, 1);
1062 }
1063 in = in->in(0);
1064 } else {
1065 in = in->in(0);
1066 }
1067 }
1068 } else {
1069 if (c->is_IfProj()) {
1070 if_proj_list.push(c);
1071 }
1072 stack.pop();
1073 }
1074
1075 } while (stack.size() > 0);
1076 }
1077
1078
1079 bool PhaseIdealLoop::loop_predication_impl_helper(IdealLoopTree *loop, ProjNode* proj, ProjNode *predicate_proj,
1080 CountedLoopNode *cl, ConNode* zero, Invariance& invar,
1081 Deoptimization::DeoptReason reason) {
1082 // Following are changed to nonnull when a predicate can be hoisted
1083 ProjNode* new_predicate_proj = NULL;
1084 IfNode* iff = proj->in(0)->as_If();
1085 Node* test = iff->in(1);
1086 if (!test->is_Bool()){ //Conv2B, ...
1087 return false;
1088 }
1089 BoolNode* bol = test->as_Bool();
1090 if (invar.is_invariant(bol)) {
1091 // Invariant test
1092 new_predicate_proj = create_new_if_for_predicate(predicate_proj, NULL,
1093 reason,
1094 iff->Opcode());
1095 Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0);
1096 BoolNode* new_predicate_bol = invar.clone(bol, ctrl)->as_Bool();
1097
1098 // Negate test if necessary
1099 bool negated = false;
1100 if (proj->_con != predicate_proj->_con) {
1101 new_predicate_bol = new BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate());
1102 register_new_node(new_predicate_bol, ctrl);
1103 negated = true;
1104 }
1105 IfNode* new_predicate_iff = new_predicate_proj->in(0)->as_If();
1106 _igvn.hash_delete(new_predicate_iff);
1107 new_predicate_iff->set_req(1, new_predicate_bol);
1108 #ifndef PRODUCT
1109 if (TraceLoopPredicate) {
1110 tty->print("Predicate invariant if%s: %d ", negated ? " negated" : "", new_predicate_iff->_idx);
1111 loop->dump_head();
1112 } else if (TraceLoopOpts) {
1113 tty->print("Predicate IC ");
1142 // Perform cloning to keep Invariance state correct since the
1143 // late schedule will place invariant things in the loop.
1144 Node *ctrl = predicate_proj->in(0)->as_If()->in(0);
1145 rng = invar.clone(rng, ctrl);
1146 if (offset && offset != zero) {
1147 assert(invar.is_invariant(offset), "offset must be loop invariant");
1148 offset = invar.clone(offset, ctrl);
1149 }
1150 // If predicate expressions may overflow in the integer range, longs are used.
1151 bool overflow = false;
1152
1153 // Test the lower bound
1154 BoolNode* lower_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, false, overflow);
1155 // Negate test if necessary
1156 bool negated = false;
1157 if (proj->_con != predicate_proj->_con) {
1158 lower_bound_bol = new BoolNode(lower_bound_bol->in(1), lower_bound_bol->_test.negate());
1159 register_new_node(lower_bound_bol, ctrl);
1160 negated = true;
1161 }
1162 ProjNode* lower_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, reason, overflow ? Op_If : iff->Opcode());
1163 IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If();
1164 _igvn.hash_delete(lower_bound_iff);
1165 lower_bound_iff->set_req(1, lower_bound_bol);
1166 if (TraceLoopPredicate) tty->print_cr("lower bound check if: %s %d ", negated ? " negated" : "", lower_bound_iff->_idx);
1167
1168 // Test the upper bound
1169 BoolNode* upper_bound_bol = rc_predicate(loop, lower_bound_proj, scale, offset, init, limit, stride, rng, true, overflow);
1170 negated = false;
1171 if (proj->_con != predicate_proj->_con) {
1172 upper_bound_bol = new BoolNode(upper_bound_bol->in(1), upper_bound_bol->_test.negate());
1173 register_new_node(upper_bound_bol, ctrl);
1174 negated = true;
1175 }
1176 ProjNode* upper_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, reason, overflow ? Op_If : iff->Opcode());
1177 assert(upper_bound_proj->in(0)->as_If()->in(0) == lower_bound_proj, "should dominate");
1178 IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If();
1179 _igvn.hash_delete(upper_bound_iff);
1180 upper_bound_iff->set_req(1, upper_bound_bol);
1181 if (TraceLoopPredicate) tty->print_cr("upper bound check if: %s %d ", negated ? " negated" : "", lower_bound_iff->_idx);
1182
1183 // Fall through into rest of the clean up code which will move
1184 // any dependent nodes onto the upper bound test.
1185 new_predicate_proj = upper_bound_proj;
1186
1187 if (iff->is_RangeCheck()) {
1188 new_predicate_proj = insert_skeleton_predicate(iff, loop, proj, predicate_proj, upper_bound_proj, scale, offset, init, limit, stride, rng, overflow, reason);
1189 }
1190
1191 #ifndef PRODUCT
1192 if (TraceLoopOpts && !TraceLoopPredicate) {
1193 tty->print("Predicate RC ");
1194 loop->dump_head();
1195 }
1196 #endif
1197 } else {
1198 // Loop variant check (for example, range check in non-counted loop)
1199 // with uncommon trap.
1200 return false;
1201 }
1202 assert(new_predicate_proj != NULL, "sanity");
1203 // Success - attach condition (new_predicate_bol) to predicate if
1204 invar.map_ctrl(proj, new_predicate_proj); // so that invariance test can be appropriate
1205
1206 // Eliminate the old If in the loop body
1207 dominated_by( new_predicate_proj, iff, proj->_con != new_predicate_proj->_con );
1208
1209 C->set_major_progress();
1210 return true;
1211 }
1212
1213
1214 // After pre/main/post loops are created, we'll put a copy of some
1215 // range checks between the pre and main loop to validate the initial
1216 // value of the induction variable for the main loop. Make a copy of
1217 // the predicates here with an opaque node as a place holder for the
1218 // initial value.
1219 ProjNode* PhaseIdealLoop::insert_skeleton_predicate(IfNode* iff, IdealLoopTree *loop,
1220 ProjNode* proj, ProjNode *predicate_proj,
1221 ProjNode* upper_bound_proj,
1222 int scale, Node* offset,
1223 Node* init, Node* limit, jint stride,
1224 Node* rng, bool &overflow,
1225 Deoptimization::DeoptReason reason) {
1226 assert(proj->_con && predicate_proj->_con, "not a range check?");
1227 Node* opaque_init = new Opaque1Node(C, init);
1228 register_new_node(opaque_init, upper_bound_proj);
1229 BoolNode* bol = rc_predicate(loop, upper_bound_proj, scale, offset, opaque_init, limit, stride, rng, (stride > 0) != (scale > 0), overflow);
1230 Node* opaque_bol = new Opaque4Node(C, bol, _igvn.intcon(1)); // This will go away once loop opts are over
1231 register_new_node(opaque_bol, upper_bound_proj);
1232 ProjNode* new_proj = create_new_if_for_predicate(predicate_proj, NULL, reason, overflow ? Op_If : iff->Opcode());
1233 _igvn.replace_input_of(new_proj->in(0), 1, opaque_bol);
1234 assert(opaque_init->outcnt() > 0, "should be used");
1235 return new_proj;
1236 }
1237
1238 //------------------------------ loop_predication_impl--------------------------
1239 // Insert loop predicates for null checks and range checks
1240 bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) {
1241 if (!UseLoopPredicate) return false;
1242
1243 if (!loop->_head->is_Loop()) {
1244 // Could be a simple region when irreducible loops are present.
1245 return false;
1246 }
1247 LoopNode* head = loop->_head->as_Loop();
1248
1249 if (head->unique_ctrl_out()->Opcode() == Op_NeverBranch) {
1250 // do nothing for infinite loops
1251 return false;
1252 }
1253
1254 if (head->is_OuterStripMinedLoop()) {
1255 return false;
1256 }
1257
1258 CountedLoopNode *cl = NULL;
1259 if (head->is_valid_counted_loop()) {
1260 cl = head->as_CountedLoop();
1261 // do nothing for iteration-splitted loops
1262 if (!cl->is_normal_loop()) return false;
1263 // Avoid RCE if Counted loop's test is '!='.
1264 BoolTest::mask bt = cl->loopexit()->test_trip();
1265 if (bt != BoolTest::lt && bt != BoolTest::gt)
1266 cl = NULL;
1267 }
1268
1269 Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl);
1270 ProjNode *loop_limit_proj = NULL;
1271 ProjNode *predicate_proj = NULL;
1272 ProjNode *profile_predicate_proj = NULL;
1273 // Loop limit check predicate should be near the loop.
1274 loop_limit_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
1275 if (loop_limit_proj != NULL) {
1276 entry = loop_limit_proj->in(0)->in(0);
1277 }
1278 bool has_profile_predicates = false;
1279 profile_predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
1280 if (profile_predicate_proj != NULL) {
1281 Node* n = skip_loop_predicates(entry);
1282 // Check if predicates were already added to the profile predicate
1283 // block
1284 if (n != entry->in(0)->in(0)) {
1285 has_profile_predicates = true;
1286 }
1287 entry = n;
1288 }
1289 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
1290
1291 float loop_trip_cnt = -1;
1292 bool follow_branches = loop_predication_should_follow_branches(loop, profile_predicate_proj, loop_trip_cnt);
1293 assert(!follow_branches || loop_trip_cnt >= 0, "negative trip count?");
1294
1295 if (predicate_proj == NULL && !follow_branches) {
1296 #ifndef PRODUCT
1297 if (TraceLoopPredicate) {
1298 tty->print("missing predicate:");
1299 loop->dump_head();
1300 head->dump(1);
1301 }
1302 #endif
1303 return false;
1304 }
1305 ConNode* zero = _igvn.intcon(0);
1306 set_ctrl(zero, C->root());
1307
1308 ResourceArea *area = Thread::current()->resource_area();
1309 Invariance invar(area, loop);
1310
1311 // Create list of if-projs such that a newer proj dominates all older
1312 // projs in the list, and they all dominate loop->tail()
1313 Node_List if_proj_list(area);
1314 Node_List regions(area);
1315 Node *current_proj = loop->tail(); //start from tail
1316
1317
1318 Node_List controls(area);
1319 while (current_proj != head) {
1320 if (loop == get_loop(current_proj) && // still in the loop ?
1321 current_proj->is_Proj() && // is a projection ?
1322 (current_proj->in(0)->Opcode() == Op_If ||
1323 current_proj->in(0)->Opcode() == Op_RangeCheck)) { // is a if projection ?
1324 if_proj_list.push(current_proj);
1325 }
1326 if (follow_branches &&
1327 current_proj->Opcode() == Op_Region &&
1328 loop == get_loop(current_proj)) {
1329 regions.push(current_proj);
1330 }
1331 current_proj = idom(current_proj);
1332 }
1333
1334 bool hoisted = false; // true if at least one proj is promoted
1335
1336 if (!has_profile_predicates) {
1337 while (if_proj_list.size() > 0) {
1338 Node* n = if_proj_list.pop();
1339
1340 ProjNode* proj = n->as_Proj();
1341 IfNode* iff = proj->in(0)->as_If();
1342
1343 CallStaticJavaNode* call = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1344 if (call == NULL) {
1345 if (loop->is_loop_exit(iff)) {
1346 // stop processing the remaining projs in the list because the execution of them
1347 // depends on the condition of "iff" (iff->in(1)).
1348 break;
1349 } else {
1350 // Both arms are inside the loop. There are two cases:
1351 // (1) there is one backward branch. In this case, any remaining proj
1352 // in the if_proj list post-dominates "iff". So, the condition of "iff"
1353 // does not determine the execution the remining projs directly, and we
1354 // can safely continue.
1355 // (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj"
1356 // does not dominate loop->tail(), so it can not be in the if_proj list.
1357 continue;
1358 }
1359 }
1360 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(call->uncommon_trap_request());
1361 if (reason == Deoptimization::Reason_predicate) {
1362 break;
1363 }
1364
1365 if (predicate_proj != NULL) {
1366 hoisted = loop_predication_impl_helper(loop, proj, predicate_proj, cl, zero, invar, Deoptimization::Reason_predicate) | hoisted;
1367 }
1368 } // end while
1369 }
1370
1371 Node_List if_proj_list_freq(area);
1372 if (follow_branches) {
1373 PathFrequency pf(loop->_head, this);
1374
1375 // Some projections were skipped by regular predicates because of
1376 // an early loop exit. Try them with profile data.
1377 while (if_proj_list.size() > 0) {
1378 Node* proj = if_proj_list.pop();
1379 float f = pf.to(proj);
1380 if (proj->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none) &&
1381 f * loop_trip_cnt >= 1) {
1382 hoisted = loop_predication_impl_helper(loop, proj->as_Proj(), profile_predicate_proj, cl, zero, invar, Deoptimization::Reason_profile_predicate) | hoisted;
1383 }
1384 }
1385
1386 // And look into all branches
1387 Node_Stack stack(0);
1388 VectorSet seen(Thread::current()->resource_area());
1389 while (regions.size() > 0) {
1390 Node* c = regions.pop();
1391 loop_predication_follow_branches(c, loop, loop_trip_cnt, pf, stack, seen, if_proj_list_freq);
1392 }
1393
1394 for (uint i = 0; i < if_proj_list_freq.size(); i++) {
1395 ProjNode* proj = if_proj_list_freq.at(i)->as_Proj();
1396 hoisted = loop_predication_impl_helper(loop, proj, profile_predicate_proj, cl, zero, invar, Deoptimization::Reason_profile_predicate) | hoisted;
1397 }
1398 }
1399
1400 #ifndef PRODUCT
1401 // report that the loop predication has been actually performed
1402 // for this loop
1403 if (TraceLoopPredicate && hoisted) {
1404 tty->print("Loop Predication Performed:");
1405 loop->dump_head();
1406 }
1407 #endif
1408
1409 head->verify_strip_mined(1);
1410
1411 return hoisted;
1412 }
1413
1414 //------------------------------loop_predication--------------------------------
1415 // driver routine for loop predication optimization
1416 bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) {
1417 bool hoisted = false;
1418 // Recursively promote predicates
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