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/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_COMPILER_DEX_DATAFLOW_ITERATOR_H_
#define ART_COMPILER_DEX_DATAFLOW_ITERATOR_H_
#include "base/logging.h"
#include "mir_graph.h"
namespace art {
/*
* This class supports iterating over lists of basic blocks in various
* interesting orders. Note that for efficiency, the visit orders have been pre-computed.
* The order itself will not change during the iteration. However, for some uses,
* auxiliary data associated with the basic blocks may be changed during the iteration,
* necessitating another pass over the list. If this behavior is required, use the
* "Repeating" variant. For the repeating variant, the caller must tell the iterator
* whether a change has been made that necessitates another pass. Note that calling Next(true)
* does not affect the iteration order or short-circuit the current pass - it simply tells
* the iterator that once it has finished walking through the block list it should reset and
* do another full pass through the list.
*/
/**
* @class DataflowIterator
* @brief The main iterator class, all other iterators derive of this one to define an iteration order.
*/
class DataflowIterator {
public:
virtual ~DataflowIterator() {}
/**
* @brief How many times have we repeated the iterator across the BasicBlocks?
* @return the number of iteration repetitions.
*/
int32_t GetRepeatCount() { return repeats_; }
/**
* @brief Has the user of the iterator reported a change yet?
* @details Does not mean there was or not a change, it is only whether the user passed a true to the Next function call.
* @return whether the user of the iterator reported a change yet.
*/
int32_t GetChanged() { return changed_; }
/**
* @brief Get the next BasicBlock depending on iteration order.
* @param had_change did the user of the iteration change the previous BasicBlock.
* @return the next BasicBlock following the iteration order, 0 if finished.
*/
virtual BasicBlock* Next(bool had_change = false) = 0;
protected:
/**
* @param mir_graph the MIRGraph we are interested in.
* @param start_idx the first index we want to iterate across.
* @param end_idx the last index we want to iterate (not included).
*/
DataflowIterator(MIRGraph* mir_graph, int32_t start_idx, int32_t end_idx)
: mir_graph_(mir_graph),
start_idx_(start_idx),
end_idx_(end_idx),
block_id_list_(NULL),
idx_(0),
repeats_(0),
changed_(false) {}
/**
* @brief Get the next BasicBlock iterating forward.
* @return the next BasicBlock iterating forward.
*/
virtual BasicBlock* ForwardSingleNext() ALWAYS_INLINE;
/**
* @brief Get the next BasicBlock iterating backward.
* @return the next BasicBlock iterating backward.
*/
virtual BasicBlock* ReverseSingleNext() ALWAYS_INLINE;
/**
* @brief Get the next BasicBlock iterating forward, restart if a BasicBlock was reported changed during the last iteration.
* @return the next BasicBlock iterating forward, with chance of repeating the iteration.
*/
virtual BasicBlock* ForwardRepeatNext() ALWAYS_INLINE;
/**
* @brief Get the next BasicBlock iterating backward, restart if a BasicBlock was reported changed during the last iteration.
* @return the next BasicBlock iterating backward, with chance of repeating the iteration.
*/
virtual BasicBlock* ReverseRepeatNext() ALWAYS_INLINE;
MIRGraph* const mir_graph_; /**< @brief the MIRGraph */
const int32_t start_idx_; /**< @brief the start index for the iteration */
const int32_t end_idx_; /**< @brief the last index for the iteration */
const ArenaVector<BasicBlockId>* block_id_list_; /**< @brief the list of BasicBlocks we want to iterate on */
int32_t idx_; /**< @brief Current index for the iterator */
int32_t repeats_; /**< @brief Number of repeats over the iteration */
bool changed_; /**< @brief Has something changed during the current iteration? */
}; // DataflowIterator
/**
* @class PreOrderDfsIterator
* @brief Used to perform a Pre-order Depth-First-Search Iteration of a MIRGraph.
*/
class PreOrderDfsIterator : public DataflowIterator {
public:
/**
* @brief The constructor, using all of the reachable blocks of the MIRGraph.
* @param mir_graph The MIRGraph considered.
*/
explicit PreOrderDfsIterator(MIRGraph* mir_graph)
: DataflowIterator(mir_graph, 0, mir_graph->GetNumReachableBlocks()) {
// Extra setup for the PreOrderDfsIterator.
idx_ = start_idx_;
block_id_list_ = &mir_graph->GetDfsOrder();
}
/**
* @brief Get the next BasicBlock depending on iteration order.
* @param had_change did the user of the iteration change the previous BasicBlock.
* @return the next BasicBlock following the iteration order, 0 if finished.
*/
virtual BasicBlock* Next(bool had_change = false) {
// Update changed: if had_changed is true, we remember it for the whole iteration.
changed_ |= had_change;
return ForwardSingleNext();
}
};
/**
* @class RepeatingPreOrderDfsIterator
* @brief Used to perform a Repeating Pre-order Depth-First-Search Iteration of a MIRGraph.
* @details If there is a change during an iteration, the iteration starts over at the end of the iteration.
*/
class RepeatingPreOrderDfsIterator : public DataflowIterator {
public:
/**
* @brief The constructor, using all of the reachable blocks of the MIRGraph.
* @param mir_graph The MIRGraph considered.
*/
explicit RepeatingPreOrderDfsIterator(MIRGraph* mir_graph)
: DataflowIterator(mir_graph, 0, mir_graph->GetNumReachableBlocks()) {
// Extra setup for the RepeatingPreOrderDfsIterator.
idx_ = start_idx_;
block_id_list_ = &mir_graph->GetDfsOrder();
}
/**
* @brief Get the next BasicBlock depending on iteration order.
* @param had_change did the user of the iteration change the previous BasicBlock.
* @return the next BasicBlock following the iteration order, 0 if finished.
*/
virtual BasicBlock* Next(bool had_change = false) {
// Update changed: if had_changed is true, we remember it for the whole iteration.
changed_ |= had_change;
return ForwardRepeatNext();
}
};
/**
* @class RepeatingPostOrderDfsIterator
* @brief Used to perform a Repeating Post-order Depth-First-Search Iteration of a MIRGraph.
* @details If there is a change during an iteration, the iteration starts over at the end of the iteration.
*/
class RepeatingPostOrderDfsIterator : public DataflowIterator {
public:
/**
* @brief The constructor, using all of the reachable blocks of the MIRGraph.
* @param mir_graph The MIRGraph considered.
*/
explicit RepeatingPostOrderDfsIterator(MIRGraph* mir_graph)
: DataflowIterator(mir_graph, 0, mir_graph->GetNumReachableBlocks()) {
// Extra setup for the RepeatingPostOrderDfsIterator.
idx_ = start_idx_;
block_id_list_ = &mir_graph->GetDfsPostOrder();
}
/**
* @brief Get the next BasicBlock depending on iteration order.
* @param had_change did the user of the iteration change the previous BasicBlock.
* @return the next BasicBlock following the iteration order, 0 if finished.
*/
virtual BasicBlock* Next(bool had_change = false) {
// Update changed: if had_changed is true, we remember it for the whole iteration.
changed_ |= had_change;
return ForwardRepeatNext();
}
};
/**
* @class ReversePostOrderDfsIterator
* @brief Used to perform a Reverse Post-order Depth-First-Search Iteration of a MIRGraph.
*/
class ReversePostOrderDfsIterator : public DataflowIterator {
public:
/**
* @brief The constructor, using all of the reachable blocks of the MIRGraph.
* @param mir_graph The MIRGraph considered.
*/
explicit ReversePostOrderDfsIterator(MIRGraph* mir_graph)
: DataflowIterator(mir_graph, mir_graph->GetNumReachableBlocks() -1, 0) {
// Extra setup for the ReversePostOrderDfsIterator.
idx_ = start_idx_;
block_id_list_ = &mir_graph->GetDfsPostOrder();
}
/**
* @brief Get the next BasicBlock depending on iteration order.
* @param had_change did the user of the iteration change the previous BasicBlock.
* @return the next BasicBlock following the iteration order, 0 if finished.
*/
virtual BasicBlock* Next(bool had_change = false) {
// Update changed: if had_changed is true, we remember it for the whole iteration.
changed_ |= had_change;
return ReverseSingleNext();
}
};
/**
* @class ReversePostOrderDfsIterator
* @brief Used to perform a Repeating Reverse Post-order Depth-First-Search Iteration of a MIRGraph.
* @details If there is a change during an iteration, the iteration starts over at the end of the iteration.
*/
class RepeatingReversePostOrderDfsIterator : public DataflowIterator {
public:
/**
* @brief The constructor, using all of the reachable blocks of the MIRGraph.
* @param mir_graph The MIRGraph considered.
*/
explicit RepeatingReversePostOrderDfsIterator(MIRGraph* mir_graph)
: DataflowIterator(mir_graph, mir_graph->GetNumReachableBlocks() -1, 0) {
// Extra setup for the RepeatingReversePostOrderDfsIterator
idx_ = start_idx_;
block_id_list_ = &mir_graph->GetDfsPostOrder();
}
/**
* @brief Get the next BasicBlock depending on iteration order.
* @param had_change did the user of the iteration change the previous BasicBlock.
* @return the next BasicBlock following the iteration order, 0 if finished.
*/
virtual BasicBlock* Next(bool had_change = false) {
// Update changed: if had_changed is true, we remember it for the whole iteration.
changed_ |= had_change;
return ReverseRepeatNext();
}
};
/**
* @class PostOrderDOMIterator
* @brief Used to perform a Post-order Domination Iteration of a MIRGraph.
*/
class PostOrderDOMIterator : public DataflowIterator {
public:
/**
* @brief The constructor, using all of the reachable blocks of the MIRGraph.
* @param mir_graph The MIRGraph considered.
*/
explicit PostOrderDOMIterator(MIRGraph* mir_graph)
: DataflowIterator(mir_graph, 0, mir_graph->GetNumReachableBlocks()) {
// Extra setup for thePostOrderDOMIterator.
idx_ = start_idx_;
block_id_list_ = &mir_graph->GetDomPostOrder();
}
/**
* @brief Get the next BasicBlock depending on iteration order.
* @param had_change did the user of the iteration change the previous BasicBlock.
* @return the next BasicBlock following the iteration order, 0 if finished.
*/
virtual BasicBlock* Next(bool had_change = false) {
// Update changed: if had_changed is true, we remember it for the whole iteration.
changed_ |= had_change;
return ForwardSingleNext();
}
};
/**
* @class AllNodesIterator
* @brief Used to perform an iteration on all the BasicBlocks a MIRGraph.
*/
class AllNodesIterator : public DataflowIterator {
public:
/**
* @brief The constructor, using all of the reachable blocks of the MIRGraph.
* @param mir_graph The MIRGraph considered.
*/
explicit AllNodesIterator(MIRGraph* mir_graph)
: DataflowIterator(mir_graph, 0, mir_graph->GetBlockList().size()) {
}
/**
* @brief Resetting the iterator.
*/
void Reset() {
idx_ = 0;
}
/**
* @brief Get the next BasicBlock depending on iteration order.
* @param had_change did the user of the iteration change the previous BasicBlock.
* @return the next BasicBlock following the iteration order, 0 if finished.
*/
virtual BasicBlock* Next(bool had_change = false) ALWAYS_INLINE;
};
/**
* @class TopologicalSortIterator
* @brief Used to perform a Topological Sort Iteration of a MIRGraph.
*/
class TopologicalSortIterator : public DataflowIterator {
public:
/**
* @brief The constructor, using all of the reachable blocks of the MIRGraph.
* @param mir_graph The MIRGraph considered.
*/
explicit TopologicalSortIterator(MIRGraph* mir_graph)
: DataflowIterator(mir_graph, 0, mir_graph->GetTopologicalSortOrder().size()),
loop_ends_(&mir_graph->GetTopologicalSortOrderLoopEnds()),
loop_head_stack_(mir_graph_->GetTopologicalSortOrderLoopHeadStack()) {
// Extra setup for TopologicalSortIterator.
idx_ = start_idx_;
block_id_list_ = &mir_graph->GetTopologicalSortOrder();
}
/**
* @brief Get the next BasicBlock depending on iteration order.
* @param had_change did the user of the iteration change the previous BasicBlock.
* @return the next BasicBlock following the iteration order, 0 if finished.
*/
virtual BasicBlock* Next(bool had_change = false) OVERRIDE;
private:
const ArenaVector<BasicBlockId>* const loop_ends_;
ArenaVector<std::pair<uint16_t, bool>>* const loop_head_stack_;
};
/**
* @class LoopRepeatingTopologicalSortIterator
* @brief Used to perform a Topological Sort Iteration of a MIRGraph, repeating loops as needed.
* @details The iterator uses the visited flags to keep track of the blocks that need
* recalculation and keeps a stack of loop heads in the MIRGraph. At the end of the loop
* it returns back to the loop head if it needs to be recalculated. Due to the use of
* the visited flags and the loop head stack in the MIRGraph, it's not possible to use
* two iterators at the same time or modify this data during iteration (though inspection
* of this data is allowed and sometimes even expected).
*
* NOTE: This iterator is not suitable for passes that need to propagate changes to
* predecessors, such as type inferrence.
*/
class LoopRepeatingTopologicalSortIterator : public DataflowIterator {
public:
/**
* @brief The constructor, using all of the reachable blocks of the MIRGraph.
* @param mir_graph The MIRGraph considered.
*/
explicit LoopRepeatingTopologicalSortIterator(MIRGraph* mir_graph)
: DataflowIterator(mir_graph, 0, mir_graph->GetTopologicalSortOrder().size()),
loop_ends_(&mir_graph->GetTopologicalSortOrderLoopEnds()),
loop_head_stack_(mir_graph_->GetTopologicalSortOrderLoopHeadStack()) {
// Extra setup for RepeatingTopologicalSortIterator.
idx_ = start_idx_;
block_id_list_ = &mir_graph->GetTopologicalSortOrder();
// Clear visited flags and check that the loop head stack is empty.
mir_graph->ClearAllVisitedFlags();
DCHECK_EQ(loop_head_stack_->size(), 0u);
}
~LoopRepeatingTopologicalSortIterator() {
DCHECK_EQ(loop_head_stack_->size(), 0u);
}
/**
* @brief Get the next BasicBlock depending on iteration order.
* @param had_change did the user of the iteration change the previous BasicBlock.
* @return the next BasicBlock following the iteration order, 0 if finished.
*/
virtual BasicBlock* Next(bool had_change = false) OVERRIDE;
private:
const ArenaVector<BasicBlockId>* const loop_ends_;
ArenaVector<std::pair<uint16_t, bool>>* const loop_head_stack_;
};
} // namespace art
#endif // ART_COMPILER_DEX_DATAFLOW_ITERATOR_H_