Fix off-by-one bug in TurboFan register allocator.

src/compiler/instruction.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_INSTRUCTION_H_
 #define V8_COMPILER_INSTRUCTION_H_
 
 #include <deque>
 #include <iosfwd>
 #include <map>
@@ skipping 844 matching lines @@
   int node_count() const { return static_cast<int>(node_map_.size()); }
 
   int InstructionBlockCount() const {
     return static_cast<int>(instruction_blocks_.size());
   }
 
   InstructionBlock* InstructionBlockAt(BasicBlock::RpoNumber rpo_number) {
     return instruction_blocks_[rpo_number.ToSize()];
   }
 
+  int LastLoopInstructionIndex(const InstructionBlock* block) {
+    return instruction_blocks_[block->loop_end().ToSize() - 1]
+        ->last_instruction_index();
+  }
+
   const InstructionBlock* InstructionBlockAt(
       BasicBlock::RpoNumber rpo_number) const {
     return instruction_blocks_[rpo_number.ToSize()];
   }
 
   const InstructionBlock* GetInstructionBlock(int instruction_index) const;
 
   int GetVirtualRegister(const Node* node);
   const NodeToVregMap& GetNodeMapForTesting() const { return node_map_; }
 
@@ skipping 91 matching lines @@
   DeoptimizationVector deoptimization_entries_;
 };
 
 std::ostream& operator<<(std::ostream& os, const InstructionSequence& code);
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_H_