[Interpreter] Reduce temporary register usage in generated bytecode.

src/interpreter/bytecode-array-builder.h

Index: src/interpreter/bytecode-array-builder.h
diff --git a/src/interpreter/bytecode-array-builder.h b/src/interpreter/bytecode-array-builder.h
index 32786184dcdaa36c0e281190c707b0e2840f5921..de0c5a9eff87c0ea1086e4bb197d273686a3f2d3 100644
--- a/src/interpreter/bytecode-array-builder.h
+++ b/src/interpreter/bytecode-array-builder.h
@@ -28,14 +28,14 @@ class BytecodeArrayBuilder {
   BytecodeArrayBuilder(Isolate* isolate, Zone* zone);
   Handle<BytecodeArray> ToBytecodeArray();
 
-  // Set number of parameters expected by function.
+  // Set the number of parameters expected by function.
   void set_parameter_count(int number_of_params);
   int parameter_count() const {
     DCHECK_GE(parameter_count_, 0);
     return parameter_count_;
   }
 
-  // Set number of locals required for bytecode array.
+  // Set the number of locals required for bytecode array.
   void set_locals_count(int number_of_locals);
   int locals_count() const {
     DCHECK_GE(local_register_count_, 0);
@@ -57,7 +57,11 @@ class BytecodeArrayBuilder {
 
   Register Parameter(int parameter_index) const;
 
-  // Constant loads to the accumulator.
+  // Return true if the register |reg| represents a parameter or a
+  // local.
+  bool RegisterIsParameterOrLocal(Register reg) const;
+
+  // Constant loads to accumulator.
   BytecodeArrayBuilder& LoadLiteral(v8::internal::Smi* value);
   BytecodeArrayBuilder& LoadLiteral(Handle<Object> object);
   BytecodeArrayBuilder& LoadUndefined();
@@ -66,7 +70,7 @@ class BytecodeArrayBuilder {
   BytecodeArrayBuilder& LoadTrue();
   BytecodeArrayBuilder& LoadFalse();
 
-  // Global loads to accumulator and stores from the accumulator.
+  // Global loads to the accumulator and stores from the accumulator.
   BytecodeArrayBuilder& LoadGlobal(int slot_index);
   BytecodeArrayBuilder& StoreGlobal(int slot_index, LanguageMode language_mode);
 
@@ -140,7 +144,7 @@ class BytecodeArrayBuilder {
   BytecodeArrayBuilder& CompareOperation(Token::Value op, Register reg,
                                          Strength strength);
 
-  // Casts
+  // Casts.
   BytecodeArrayBuilder& CastAccumulatorToBoolean();
   BytecodeArrayBuilder& CastAccumulatorToName();
 
@@ -206,8 +210,12 @@ class BytecodeArrayBuilder {
   size_t GetConstantPoolEntry(Handle<Object> object);
 
   // Scope helpers used by TemporaryRegisterScope
+  Register first_temporary_register() const;
+  Register last_temporary_register() const;

[rmcilroy, 2015/10/19 12:56:22]

nit - move getters below TemporaryRegisterIsLive() (with a newline whitespace)

[oth, 2015/10/20 15:28:52]

Done.

   int BorrowTemporaryRegister();
   void ReturnTemporaryRegister(int reg_index);
+  void PrepareForConsecutiveTemporaryRegisters(size_t count);
+  bool TemporaryRegisterIsLive(Register reg) const;
 
   Isolate* isolate_;
   Zone* zone_;
@@ -223,11 +231,11 @@ class BytecodeArrayBuilder {
   int parameter_count_;
   int local_register_count_;
   int context_register_count_;
+  ZoneVector<int> free_temporaries_;
   int temporary_register_count_;
-  int temporary_register_next_;
 
   friend class TemporaryRegisterScope;
-  DISALLOW_IMPLICIT_CONSTRUCTORS(BytecodeArrayBuilder);
+  DISALLOW_COPY_AND_ASSIGN(BytecodeArrayBuilder);
 };
 
 
@@ -276,14 +284,15 @@ class TemporaryRegisterScope {
   explicit TemporaryRegisterScope(BytecodeArrayBuilder* builder);
   ~TemporaryRegisterScope();
   Register NewRegister();
+  void PrepareForConsecutiveAllocations(size_t count);
 
  private:
   void* operator new(size_t size);
   void operator delete(void* p);
 
   BytecodeArrayBuilder* builder_;
-  int count_;
-  int last_register_index_;
+  const TemporaryRegisterScope* outer_;
+  ZoneVector<int> allocated_;
 
   DISALLOW_COPY_AND_ASSIGN(TemporaryRegisterScope);
 };