[interpreter] Bytecode register optimizer.

src/interpreter/bytecode-register-allocator.h

 // Copyright 2015 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_INTERPRETER_BYTECODE_REGISTER_ALLOCATOR_H_
 #define V8_INTERPRETER_BYTECODE_REGISTER_ALLOCATOR_H_
 
 #include "src/interpreter/bytecodes.h"
 #include "src/zone-containers.h"
 
 namespace v8 {
 namespace internal {
 namespace interpreter {
 
 class BytecodeArrayBuilder;
 class Register;
+class TemporaryRegisterObserver;
 
 class TemporaryRegisterAllocator final {
  public:
   TemporaryRegisterAllocator(Zone* zone, int start_index);
 
   // Borrow a temporary register.
   int BorrowTemporaryRegister();
 
   // Borrow a temporary register from the register range outside of
   // |start_index| to |end_index|.
@@ skipping 20 matching lines @@
 
   // Returns the last register in the range of temporary registers.
   Register last_temporary_register() const;
 
   // Returns the start index of temporary register allocations.
   int allocation_base() const { return allocation_base_; }
 
   // Returns the number of temporary register allocations made.
   int allocation_count() const { return allocation_count_; }
 
+  // Sets an observer for temporary register events.
+  void set_observer(TemporaryRegisterObserver* observer);
+
  private:
   // Allocate a temporary register.
   int AllocateTemporaryRegister();
 
   ZoneSet<int> free_temporaries_;
   int allocation_base_;
   int allocation_count_;
+  TemporaryRegisterObserver* observer_;
 
   DISALLOW_COPY_AND_ASSIGN(TemporaryRegisterAllocator);
 };
 
+class TemporaryRegisterObserver {
+ public:
+  virtual ~TemporaryRegisterObserver() {}
+  virtual void TemporaryRegisterFreeEvent(Register reg) = 0;
+};
+
 // A class that allows the instantiator to allocate temporary registers that are
 // cleaned up when scope is closed.
 class BytecodeRegisterAllocator final {
  public:
   explicit BytecodeRegisterAllocator(Zone* zone,
                                      TemporaryRegisterAllocator* allocator);
   ~BytecodeRegisterAllocator();
   Register NewRegister();
 
   // Ensure |count| consecutive allocations are available.
@@ skipping 19 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(BytecodeRegisterAllocator);
 };
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8
 
 
 #endif  // V8_INTERPRETER_BYTECODE_REGISTER_ALLOCATOR_H_