2011-01-07 11:49:22 +00:00
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// Copyright 2011 the V8 project authors. All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following
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// disclaimer in the documentation and/or other materials provided
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// with the distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "lithium.h"
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namespace v8 {
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namespace internal {
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class LGapNode: public ZoneObject {
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public:
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explicit LGapNode(LOperand* operand)
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: operand_(operand), resolved_(false), visited_id_(-1) { }
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LOperand* operand() const { return operand_; }
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bool IsResolved() const { return !IsAssigned() || resolved_; }
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void MarkResolved() {
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ASSERT(!IsResolved());
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resolved_ = true;
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}
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int visited_id() const { return visited_id_; }
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void set_visited_id(int id) {
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ASSERT(id > visited_id_);
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visited_id_ = id;
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}
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bool IsAssigned() const { return assigned_from_.is_set(); }
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LGapNode* assigned_from() const { return assigned_from_.get(); }
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void set_assigned_from(LGapNode* n) { assigned_from_.set(n); }
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private:
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LOperand* operand_;
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SetOncePointer<LGapNode> assigned_from_;
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bool resolved_;
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int visited_id_;
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};
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LGapResolver::LGapResolver(const ZoneList<LMoveOperands>* moves,
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LOperand* marker_operand)
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: nodes_(4),
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identified_cycles_(4),
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result_(4),
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marker_operand_(marker_operand),
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next_visited_id_(0) {
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for (int i = 0; i < moves->length(); ++i) {
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LMoveOperands move = moves->at(i);
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if (!move.IsRedundant()) RegisterMove(move);
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}
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}
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const ZoneList<LMoveOperands>* LGapResolver::ResolveInReverseOrder() {
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for (int i = 0; i < identified_cycles_.length(); ++i) {
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ResolveCycle(identified_cycles_[i]);
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}
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int unresolved_nodes;
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do {
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unresolved_nodes = 0;
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for (int j = 0; j < nodes_.length(); j++) {
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LGapNode* node = nodes_[j];
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if (!node->IsResolved() && node->assigned_from()->IsResolved()) {
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AddResultMove(node->assigned_from(), node);
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node->MarkResolved();
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}
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if (!node->IsResolved()) ++unresolved_nodes;
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}
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} while (unresolved_nodes > 0);
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return &result_;
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}
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void LGapResolver::AddResultMove(LGapNode* from, LGapNode* to) {
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AddResultMove(from->operand(), to->operand());
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}
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void LGapResolver::AddResultMove(LOperand* from, LOperand* to) {
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result_.Add(LMoveOperands(from, to));
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}
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void LGapResolver::ResolveCycle(LGapNode* start) {
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ZoneList<LOperand*> circle_operands(8);
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circle_operands.Add(marker_operand_);
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LGapNode* cur = start;
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do {
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cur->MarkResolved();
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circle_operands.Add(cur->operand());
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cur = cur->assigned_from();
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} while (cur != start);
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circle_operands.Add(marker_operand_);
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for (int i = circle_operands.length() - 1; i > 0; --i) {
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LOperand* from = circle_operands[i];
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LOperand* to = circle_operands[i - 1];
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AddResultMove(from, to);
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}
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}
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bool LGapResolver::CanReach(LGapNode* a, LGapNode* b, int visited_id) {
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ASSERT(a != b);
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LGapNode* cur = a;
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while (cur != b && cur->visited_id() != visited_id && cur->IsAssigned()) {
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cur->set_visited_id(visited_id);
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cur = cur->assigned_from();
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}
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return cur == b;
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}
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bool LGapResolver::CanReach(LGapNode* a, LGapNode* b) {
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ASSERT(a != b);
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return CanReach(a, b, next_visited_id_++);
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}
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void LGapResolver::RegisterMove(LMoveOperands move) {
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if (move.from()->IsConstantOperand()) {
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// Constant moves should be last in the machine code. Therefore add them
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// first to the result set.
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AddResultMove(move.from(), move.to());
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} else {
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LGapNode* from = LookupNode(move.from());
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LGapNode* to = LookupNode(move.to());
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if (to->IsAssigned() && to->assigned_from() == from) {
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move.Eliminate();
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return;
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}
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ASSERT(!to->IsAssigned());
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if (CanReach(from, to)) {
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// This introduces a circle. Save.
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identified_cycles_.Add(from);
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}
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to->set_assigned_from(from);
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}
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}
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LGapNode* LGapResolver::LookupNode(LOperand* operand) {
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for (int i = 0; i < nodes_.length(); ++i) {
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if (nodes_[i]->operand()->Equals(operand)) return nodes_[i];
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}
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// No node found => create a new one.
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LGapNode* result = new LGapNode(operand);
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nodes_.Add(result);
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return result;
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}
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2011-01-10 11:31:21 +00:00
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bool LParallelMove::IsRedundant() const {
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for (int i = 0; i < move_operands_.length(); ++i) {
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if (!move_operands_[i].IsRedundant()) return false;
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}
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return true;
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}
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void LParallelMove::PrintDataTo(StringStream* stream) const {
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for (int i = move_operands_.length() - 1; i >= 0; --i) {
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if (!move_operands_[i].IsEliminated()) {
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LOperand* from = move_operands_[i].from();
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LOperand* to = move_operands_[i].to();
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if (from->Equals(to)) {
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to->PrintTo(stream);
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} else {
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to->PrintTo(stream);
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stream->Add(" = ");
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from->PrintTo(stream);
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}
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stream->Add("; ");
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}
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}
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}
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2011-01-07 11:49:22 +00:00
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} } // namespace v8::internal
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