[turbofan] Implement OSR for outer loops.

src/compiler/frame.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_FRAME_H_
 #define V8_COMPILER_FRAME_H_
 
 #include "src/v8.h"
 
 #include "src/bit-vector.h"
@@ skipping 45 matching lines @@
       if (kDoubleSize > kPointerSize) {
         DCHECK(kDoubleSize == kPointerSize * 2);
         spill_slot_count_++;
         spill_slot_count_ |= 1;
       }
       double_spill_slot_count_++;
     }
     return spill_slot_count_++;
   }
 
+  void ReserveSpillSlots(size_t slot_count) {
+    DCHECK_EQ(0, spill_slot_count_);  // can only reserve before allocation.
+    spill_slot_count_ = static_cast<int>(slot_count);
+  }
+
  private:
   int register_save_area_size_;
   int spill_slot_count_;
   int double_spill_slot_count_;
   BitVector* allocated_registers_;
   BitVector* allocated_double_registers_;
 
   DISALLOW_COPY_AND_ASSIGN(Frame);
 };
 
@@ skipping 21 matching lines @@
   int offset_;  // Encodes SP or FP in the low order bit.
 
   static const int kFromSp = 1;
   static const int kFromFp = 0;
 };
 }
 }
 }  // namespace v8::internal::compiler
 
 #endif  // V8_COMPILER_FRAME_H_