492 #ifndef PRODUCT
493 if (PrintOpto && VerifyLoopOptimizations) {
494 tty->print("Peeling a 'main' loop; resetting to 'normal' ");
495 loop->dump_head();
496 }
497 #endif
498 }
499 }
500 Node* entry = head->in(LoopNode::EntryControl);
501
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) );
505
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);
525 }
526 }
527
528
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());
539 }
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492 #ifndef PRODUCT
493 if (PrintOpto && VerifyLoopOptimizations) {
494 tty->print("Peeling a 'main' loop; resetting to 'normal' ");
495 loop->dump_head();
496 }
497 #endif
498 }
499 }
500 Node* entry = head->in(LoopNode::EntryControl);
501
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) );
505
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_entry = old_new[head->in(LoopNode::LoopBackControl)->_idx];
513 _igvn.hash_delete(head);
514 head->set_req(LoopNode::EntryControl, new_entry);
515 for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
516 Node* old = head->fast_out(j);
517 if (old->in(0) == loop->_head && old->req() == 3 && old->is_Phi()) {
518 Node* new_exit_value = old_new[old->in(LoopNode::LoopBackControl)->_idx];
519 if (!new_exit_value ) // Backedge value is ALSO loop invariant?
520 // Then loop body backedge value remains the same.
521 new_exit_value = old->in(LoopNode::LoopBackControl);
522 _igvn.hash_delete(old);
523 old->set_req(LoopNode::EntryControl, new_exit_value);
524 }
525 }
526
527
528 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the
529 // extra backedge user.
530 Node* new_head = old_new[head->_idx];
531 _igvn.hash_delete(new_head);
532 new_head->set_req(LoopNode::LoopBackControl, C->top());
533 for (DUIterator_Fast j2max, j2 = new_head->fast_outs(j2max); j2 < j2max; j2++) {
534 Node* use = new_head->fast_out(j2);
535 if (use->in(0) == new_head && use->req() == 3 && use->is_Phi()) {
536 _igvn.hash_delete(use);
537 use->set_req(LoopNode::LoopBackControl, C->top());
538 }
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