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// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_COMPILER_LOOP_ANALYSIS_H_
#define V8_COMPILER_LOOP_ANALYSIS_H_
#include "src/base/iterator.h"
#include "src/compiler/graph.h"
#include "src/compiler/node.h"
#include "src/globals.h"
#include "src/zone/zone-containers.h"
namespace v8 {
namespace internal {
namespace compiler {
// TODO(titzer): don't assume entry edges have a particular index.
static const int kAssumedLoopEntryIndex = 0; // assume loops are entered here.
class LoopFinderImpl;
typedef base::iterator_range<Node**> NodeRange;
// Represents a tree of loops in a graph.
class LoopTree : public ZoneObject {
public:
LoopTree(size_t num_nodes, Zone* zone)
: zone_(zone),
outer_loops_(zone),
all_loops_(zone),
node_to_loop_num_(static_cast<int>(num_nodes), -1, zone),
loop_nodes_(zone) {}
// Represents a loop in the tree of loops, including the header nodes,
// the body, and any nested loops.
class Loop {
public:
Loop* parent() const { return parent_; }
const ZoneVector<Loop*>& children() const { return children_; }
size_t HeaderSize() const { return body_start_ - header_start_; }
size_t BodySize() const { return exits_start_ - body_start_; }
size_t ExitsSize() const { return exits_end_ - exits_start_; }
size_t TotalSize() const { return exits_end_ - header_start_; }
size_t depth() const { return static_cast<size_t>(depth_); }
private:
friend class LoopTree;
friend class LoopFinderImpl;
explicit Loop(Zone* zone)
: parent_(nullptr),
depth_(0),
children_(zone),
header_start_(-1),
body_start_(-1),
exits_start_(-1),
exits_end_(-1) {}
Loop* parent_;
int depth_;
ZoneVector<Loop*> children_;
int header_start_;
int body_start_;
int exits_start_;
int exits_end_;
};
// Return the innermost nested loop, if any, that contains {node}.
Loop* ContainingLoop(Node* node) {
if (node->id() >= node_to_loop_num_.size()) return nullptr;
int num = node_to_loop_num_[node->id()];
return num > 0 ? &all_loops_[num - 1] : nullptr;
}
// Check if the {loop} contains the {node}, either directly or by containing
// a nested loop that contains {node}.
bool Contains(Loop* loop, Node* node) {
for (Loop* c = ContainingLoop(node); c != nullptr; c = c->parent_) {
if (c == loop) return true;
}
return false;
}
// Return the list of outer loops.
const ZoneVector<Loop*>& outer_loops() const { return outer_loops_; }
// Return the unique loop number for a given loop. Loop numbers start at {1}.
int LoopNum(Loop* loop) const {
return 1 + static_cast<int>(loop - &all_loops_[0]);
}
// Return a range which can iterate over the header nodes of {loop}.
NodeRange HeaderNodes(Loop* loop) {
return NodeRange(&loop_nodes_[0] + loop->header_start_,
&loop_nodes_[0] + loop->body_start_);
}
// Return the header control node for a loop.
Node* HeaderNode(Loop* loop);
// Return a range which can iterate over the body nodes of {loop}.
NodeRange BodyNodes(Loop* loop) {
return NodeRange(&loop_nodes_[0] + loop->body_start_,
&loop_nodes_[0] + loop->exits_start_);
}
// Return a range which can iterate over the body nodes of {loop}.
NodeRange ExitNodes(Loop* loop) {
return NodeRange(&loop_nodes_[0] + loop->exits_start_,
&loop_nodes_[0] + loop->exits_end_);
}
// Return a range which can iterate over the nodes of {loop}.
NodeRange LoopNodes(Loop* loop) {
return NodeRange(&loop_nodes_[0] + loop->header_start_,
&loop_nodes_[0] + loop->exits_end_);
}
// Return the node that represents the control, i.e. the loop node itself.
Node* GetLoopControl(Loop* loop) {
// TODO(turbofan): make the loop control node always first?
for (Node* node : HeaderNodes(loop)) {
if (node->opcode() == IrOpcode::kLoop) return node;
}
UNREACHABLE();
}
Zone* zone() const { return zone_; }
private:
friend class LoopFinderImpl;
Loop* NewLoop() {
all_loops_.push_back(Loop(zone_));
Loop* result = &all_loops_.back();
return result;
}
void SetParent(Loop* parent, Loop* child) {
if (parent != nullptr) {
parent->children_.push_back(child);
child->parent_ = parent;
child->depth_ = parent->depth_ + 1;
} else {
outer_loops_.push_back(child);
}
}
Zone* zone_;
ZoneVector<Loop*> outer_loops_;
ZoneVector<Loop> all_loops_;
ZoneVector<int> node_to_loop_num_;
ZoneVector<Node*> loop_nodes_;
};
class V8_EXPORT_PRIVATE LoopFinder {
public:
// Build a loop tree for the entire graph.
static LoopTree* BuildLoopTree(Graph* graph, Zone* temp_zone);
};
} // namespace compiler
} // namespace internal
} // namespace v8
#endif // V8_COMPILER_LOOP_ANALYSIS_H_