| // Copyright 2011 the V8 project authors. All rights reserved. |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following |
| // disclaimer in the documentation and/or other materials provided |
| // with the distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived |
| // from this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #include "lithium.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| |
| class LGapNode: public ZoneObject { |
| public: |
| explicit LGapNode(LOperand* operand) |
| : operand_(operand), resolved_(false), visited_id_(-1) { } |
| |
| LOperand* operand() const { return operand_; } |
| bool IsResolved() const { return !IsAssigned() || resolved_; } |
| void MarkResolved() { |
| ASSERT(!IsResolved()); |
| resolved_ = true; |
| } |
| int visited_id() const { return visited_id_; } |
| void set_visited_id(int id) { |
| ASSERT(id > visited_id_); |
| visited_id_ = id; |
| } |
| |
| bool IsAssigned() const { return assigned_from_.is_set(); } |
| LGapNode* assigned_from() const { return assigned_from_.get(); } |
| void set_assigned_from(LGapNode* n) { assigned_from_.set(n); } |
| |
| private: |
| LOperand* operand_; |
| SetOncePointer<LGapNode> assigned_from_; |
| bool resolved_; |
| int visited_id_; |
| }; |
| |
| |
| LGapResolver::LGapResolver(const ZoneList<LMoveOperands>* moves, |
| LOperand* marker_operand) |
| : nodes_(4), |
| identified_cycles_(4), |
| result_(4), |
| marker_operand_(marker_operand), |
| next_visited_id_(0) { |
| for (int i = 0; i < moves->length(); ++i) { |
| LMoveOperands move = moves->at(i); |
| if (!move.IsRedundant()) RegisterMove(move); |
| } |
| } |
| |
| |
| const ZoneList<LMoveOperands>* LGapResolver::ResolveInReverseOrder() { |
| for (int i = 0; i < identified_cycles_.length(); ++i) { |
| ResolveCycle(identified_cycles_[i]); |
| } |
| |
| int unresolved_nodes; |
| do { |
| unresolved_nodes = 0; |
| for (int j = 0; j < nodes_.length(); j++) { |
| LGapNode* node = nodes_[j]; |
| if (!node->IsResolved() && node->assigned_from()->IsResolved()) { |
| AddResultMove(node->assigned_from(), node); |
| node->MarkResolved(); |
| } |
| if (!node->IsResolved()) ++unresolved_nodes; |
| } |
| } while (unresolved_nodes > 0); |
| return &result_; |
| } |
| |
| |
| void LGapResolver::AddResultMove(LGapNode* from, LGapNode* to) { |
| AddResultMove(from->operand(), to->operand()); |
| } |
| |
| |
| void LGapResolver::AddResultMove(LOperand* from, LOperand* to) { |
| result_.Add(LMoveOperands(from, to)); |
| } |
| |
| |
| void LGapResolver::ResolveCycle(LGapNode* start) { |
| ZoneList<LOperand*> circle_operands(8); |
| circle_operands.Add(marker_operand_); |
| LGapNode* cur = start; |
| do { |
| cur->MarkResolved(); |
| circle_operands.Add(cur->operand()); |
| cur = cur->assigned_from(); |
| } while (cur != start); |
| circle_operands.Add(marker_operand_); |
| |
| for (int i = circle_operands.length() - 1; i > 0; --i) { |
| LOperand* from = circle_operands[i]; |
| LOperand* to = circle_operands[i - 1]; |
| AddResultMove(from, to); |
| } |
| } |
| |
| |
| bool LGapResolver::CanReach(LGapNode* a, LGapNode* b, int visited_id) { |
| ASSERT(a != b); |
| LGapNode* cur = a; |
| while (cur != b && cur->visited_id() != visited_id && cur->IsAssigned()) { |
| cur->set_visited_id(visited_id); |
| cur = cur->assigned_from(); |
| } |
| |
| return cur == b; |
| } |
| |
| |
| bool LGapResolver::CanReach(LGapNode* a, LGapNode* b) { |
| ASSERT(a != b); |
| return CanReach(a, b, next_visited_id_++); |
| } |
| |
| |
| void LGapResolver::RegisterMove(LMoveOperands move) { |
| if (move.from()->IsConstantOperand()) { |
| // Constant moves should be last in the machine code. Therefore add them |
| // first to the result set. |
| AddResultMove(move.from(), move.to()); |
| } else { |
| LGapNode* from = LookupNode(move.from()); |
| LGapNode* to = LookupNode(move.to()); |
| if (to->IsAssigned() && to->assigned_from() == from) { |
| move.Eliminate(); |
| return; |
| } |
| ASSERT(!to->IsAssigned()); |
| if (CanReach(from, to)) { |
| // This introduces a circle. Save. |
| identified_cycles_.Add(from); |
| } |
| to->set_assigned_from(from); |
| } |
| } |
| |
| |
| LGapNode* LGapResolver::LookupNode(LOperand* operand) { |
| for (int i = 0; i < nodes_.length(); ++i) { |
| if (nodes_[i]->operand()->Equals(operand)) return nodes_[i]; |
| } |
| |
| // No node found => create a new one. |
| LGapNode* result = new LGapNode(operand); |
| nodes_.Add(result); |
| return result; |
| } |
| |
| |
| } } // namespace v8::internal |