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1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
2 // for details. All rights reserved. Use of this source code is governed by a | 2 // for details. All rights reserved. Use of this source code is governed by a |
3 // BSD-style license that can be found in the LICENSE file. | 3 // BSD-style license that can be found in the LICENSE file. |
4 | 4 |
5 #include "vm/globals.h" // Needed here to get TARGET_ARCH_XXX. | 5 #include "vm/globals.h" // Needed here to get TARGET_ARCH_XXX. |
6 | 6 |
7 #include "vm/flow_graph_compiler.h" | 7 #include "vm/flow_graph_compiler.h" |
8 | 8 |
9 #include "vm/dart_entry.h" | 9 #include "vm/dart_entry.h" |
10 #include "vm/debugger.h" | 10 #include "vm/debugger.h" |
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692 ParallelMoveResolver::ParallelMoveResolver(FlowGraphCompiler* compiler) | 692 ParallelMoveResolver::ParallelMoveResolver(FlowGraphCompiler* compiler) |
693 : compiler_(compiler), moves_(32) {} | 693 : compiler_(compiler), moves_(32) {} |
694 | 694 |
695 | 695 |
696 void ParallelMoveResolver::EmitNativeCode(ParallelMoveInstr* parallel_move) { | 696 void ParallelMoveResolver::EmitNativeCode(ParallelMoveInstr* parallel_move) { |
697 ASSERT(moves_.is_empty()); | 697 ASSERT(moves_.is_empty()); |
698 // Build up a worklist of moves. | 698 // Build up a worklist of moves. |
699 BuildInitialMoveList(parallel_move); | 699 BuildInitialMoveList(parallel_move); |
700 | 700 |
701 for (int i = 0; i < moves_.length(); ++i) { | 701 for (int i = 0; i < moves_.length(); ++i) { |
702 MoveOperands move = moves_[i]; | 702 const MoveOperands& move = *moves_[i]; |
703 // Skip constants to perform them last. They don't block other moves | 703 // Skip constants to perform them last. They don't block other moves |
704 // and skipping such moves with register destinations keeps those | 704 // and skipping such moves with register destinations keeps those |
705 // registers free for the whole algorithm. | 705 // registers free for the whole algorithm. |
706 if (!move.IsEliminated() && !move.src().IsConstant()) PerformMove(i); | 706 if (!move.IsEliminated() && !move.src().IsConstant()) PerformMove(i); |
707 } | 707 } |
708 | 708 |
709 // Perform the moves with constant sources. | 709 // Perform the moves with constant sources. |
710 for (int i = 0; i < moves_.length(); ++i) { | 710 for (int i = 0; i < moves_.length(); ++i) { |
711 if (!moves_[i].IsEliminated()) { | 711 const MoveOperands& move = *moves_[i]; |
712 ASSERT(moves_[i].src().IsConstant()); | 712 if (!move.IsEliminated()) { |
| 713 ASSERT(move.src().IsConstant()); |
713 EmitMove(i); | 714 EmitMove(i); |
714 } | 715 } |
715 } | 716 } |
716 | 717 |
717 moves_.Clear(); | 718 moves_.Clear(); |
718 } | 719 } |
719 | 720 |
720 | 721 |
721 void ParallelMoveResolver::BuildInitialMoveList( | 722 void ParallelMoveResolver::BuildInitialMoveList( |
722 ParallelMoveInstr* parallel_move) { | 723 ParallelMoveInstr* parallel_move) { |
723 // Perform a linear sweep of the moves to add them to the initial list of | 724 // Perform a linear sweep of the moves to add them to the initial list of |
724 // moves to perform, ignoring any move that is redundant (the source is | 725 // moves to perform, ignoring any move that is redundant (the source is |
725 // the same as the destination, the destination is ignored and | 726 // the same as the destination, the destination is ignored and |
726 // unallocated, or the move was already eliminated). | 727 // unallocated, or the move was already eliminated). |
727 const GrowableArray<MoveOperands>& moves = parallel_move->moves(); | 728 for (int i = 0; i < parallel_move->NumMoves(); i++) { |
728 for (int i = 0; i < moves.length(); ++i) { | 729 MoveOperands* move = parallel_move->MoveOperandsAt(i); |
729 MoveOperands move = moves[i]; | 730 if (!move->IsRedundant()) moves_.Add(move); |
730 if (!move.IsRedundant()) moves_.Add(move); | |
731 } | 731 } |
732 } | 732 } |
733 | 733 |
734 | 734 |
735 void ParallelMoveResolver::PerformMove(int index) { | 735 void ParallelMoveResolver::PerformMove(int index) { |
736 // Each call to this function performs a move and deletes it from the move | 736 // Each call to this function performs a move and deletes it from the move |
737 // graph. We first recursively perform any move blocking this one. We | 737 // graph. We first recursively perform any move blocking this one. We |
738 // mark a move as "pending" on entry to PerformMove in order to detect | 738 // mark a move as "pending" on entry to PerformMove in order to detect |
739 // cycles in the move graph. We use operand swaps to resolve cycles, | 739 // cycles in the move graph. We use operand swaps to resolve cycles, |
740 // which means that a call to PerformMove could change any source operand | 740 // which means that a call to PerformMove could change any source operand |
741 // in the move graph. | 741 // in the move graph. |
742 | 742 |
743 ASSERT(!moves_[index].IsPending()); | 743 ASSERT(!moves_[index]->IsPending()); |
744 ASSERT(!moves_[index].IsRedundant()); | 744 ASSERT(!moves_[index]->IsRedundant()); |
745 | 745 |
746 // Clear this move's destination to indicate a pending move. The actual | 746 // Clear this move's destination to indicate a pending move. The actual |
747 // destination is saved in a stack-allocated local. Recursion may allow | 747 // destination is saved in a stack-allocated local. Recursion may allow |
748 // multiple moves to be pending. | 748 // multiple moves to be pending. |
749 ASSERT(!moves_[index].src().IsInvalid()); | 749 ASSERT(!moves_[index]->src().IsInvalid()); |
750 Location destination = moves_[index].MarkPending(); | 750 Location destination = moves_[index]->MarkPending(); |
751 | 751 |
752 // Perform a depth-first traversal of the move graph to resolve | 752 // Perform a depth-first traversal of the move graph to resolve |
753 // dependencies. Any unperformed, unpending move with a source the same | 753 // dependencies. Any unperformed, unpending move with a source the same |
754 // as this one's destination blocks this one so recursively perform all | 754 // as this one's destination blocks this one so recursively perform all |
755 // such moves. | 755 // such moves. |
756 for (int i = 0; i < moves_.length(); ++i) { | 756 for (int i = 0; i < moves_.length(); ++i) { |
757 MoveOperands other_move = moves_[i]; | 757 const MoveOperands& other_move = *moves_[i]; |
758 if (other_move.Blocks(destination) && !other_move.IsPending()) { | 758 if (other_move.Blocks(destination) && !other_move.IsPending()) { |
759 // Though PerformMove can change any source operand in the move graph, | 759 // Though PerformMove can change any source operand in the move graph, |
760 // this call cannot create a blocking move via a swap (this loop does | 760 // this call cannot create a blocking move via a swap (this loop does |
761 // not miss any). Assume there is a non-blocking move with source A | 761 // not miss any). Assume there is a non-blocking move with source A |
762 // and this move is blocked on source B and there is a swap of A and | 762 // and this move is blocked on source B and there is a swap of A and |
763 // B. Then A and B must be involved in the same cycle (or they would | 763 // B. Then A and B must be involved in the same cycle (or they would |
764 // not be swapped). Since this move's destination is B and there is | 764 // not be swapped). Since this move's destination is B and there is |
765 // only a single incoming edge to an operand, this move must also be | 765 // only a single incoming edge to an operand, this move must also be |
766 // involved in the same cycle. In that case, the blocking move will | 766 // involved in the same cycle. In that case, the blocking move will |
767 // be created but will be "pending" when we return from PerformMove. | 767 // be created but will be "pending" when we return from PerformMove. |
768 PerformMove(i); | 768 PerformMove(i); |
769 } | 769 } |
770 } | 770 } |
771 | 771 |
772 // We are about to resolve this move and don't need it marked as | 772 // We are about to resolve this move and don't need it marked as |
773 // pending, so restore its destination. | 773 // pending, so restore its destination. |
774 moves_[index].ClearPending(destination); | 774 moves_[index]->ClearPending(destination); |
775 | 775 |
776 // This move's source may have changed due to swaps to resolve cycles and | 776 // This move's source may have changed due to swaps to resolve cycles and |
777 // so it may now be the last move in the cycle. If so remove it. | 777 // so it may now be the last move in the cycle. If so remove it. |
778 if (moves_[index].src().Equals(destination)) { | 778 if (moves_[index]->src().Equals(destination)) { |
779 moves_[index].Eliminate(); | 779 moves_[index]->Eliminate(); |
780 return; | 780 return; |
781 } | 781 } |
782 | 782 |
783 // The move may be blocked on a (at most one) pending move, in which case | 783 // The move may be blocked on a (at most one) pending move, in which case |
784 // we have a cycle. Search for such a blocking move and perform a swap to | 784 // we have a cycle. Search for such a blocking move and perform a swap to |
785 // resolve it. | 785 // resolve it. |
786 for (int i = 0; i < moves_.length(); ++i) { | 786 for (int i = 0; i < moves_.length(); ++i) { |
787 MoveOperands other_move = moves_[i]; | 787 const MoveOperands& other_move = *moves_[i]; |
788 if (other_move.Blocks(destination)) { | 788 if (other_move.Blocks(destination)) { |
789 ASSERT(other_move.IsPending()); | 789 ASSERT(other_move.IsPending()); |
790 EmitSwap(index); | 790 EmitSwap(index); |
791 return; | 791 return; |
792 } | 792 } |
793 } | 793 } |
794 | 794 |
795 // This move is not blocked. | 795 // This move is not blocked. |
796 EmitMove(index); | 796 EmitMove(index); |
797 } | 797 } |
798 | 798 |
799 | 799 |
800 } // namespace dart | 800 } // namespace dart |
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