[turbofan] First version of loop peeling.

src/compiler/loop-analysis.h

 // 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"
@@ skipping 19 matching lines @@
 
   // 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 body_end_ - body_start_; }
     size_t TotalSize() const { return body_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),
@@ skipping 37 matching lines @@
     return NodeRange(&loop_nodes_[0] + loop->header_start_,
                      &loop_nodes_[0] + loop->body_start_);
   }
 
   // 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->body_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->body_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();
+    return NULL;
+  }
+
  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) {
@@ skipping 13 matching lines @@
   ZoneVector<Node*> loop_nodes_;
 };
 
 
 class 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_