[interpreter] Add support for scalable operands.

src/interpreter/interpreter.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_INTERPRETER_H_
 #define V8_INTERPRETER_INTERPRETER_H_
 
 // Clients of this interface shouldn't depend on lots of interpreter internals.
 // Do not include anything from src/interpreter other than
 // src/interpreter/bytecodes.h here!
@@ skipping 22 matching lines @@
   // Initializes the interpreter dispatch table.
   void Initialize();
 
   // Returns the interrupt budget which should be used for the profiler counter.
   static int InterruptBudget();
 
   // Generate bytecode for |info|.
   static bool MakeBytecode(CompilationInfo* info);
 
   // Return bytecode handler for |bytecode|.
-  Code* GetBytecodeHandler(Bytecode bytecode);
+  Code* GetBytecodeHandler(Bytecode bytecode, int operand_scale);
 
   // GC support.
   void IterateDispatchTable(ObjectVisitor* v);
 
   void TraceCodegen(Handle<Code> code, const char* name);
 
   Address dispatch_table_address() {
     return reinterpret_cast<Address>(&dispatch_table_[0]);
   }
 
@@ skipping 67 matching lines @@
                 InterpreterAssembler* assembler);
 
   // Generates code to perform a lookup slot load via |function_id|.
   void DoLoadLookupSlot(Runtime::FunctionId function_id,
                         InterpreterAssembler* assembler);
 
   // Generates code to perform a lookup slot store depending on |language_mode|.
   void DoStoreLookupSlot(LanguageMode language_mode,
                          InterpreterAssembler* assembler);
 
+  // Generates handler for invalid bytecodes.
+  Handle<Code> MakeInvalidBytecodeHandler(Zone* zone);
+
   bool IsDispatchTableInitialized();
 
-  static const int kDispatchTableSize = static_cast<int>(Bytecode::kLast) + 1;
+  void set_operand_scale(int operand_scale) { operand_scale_ = operand_scale; }
+  int operand_scale() const { return operand_scale_; }

[rmcilroy, 2016/03/10 16:45:38]

I'd rather not have these as object fields since they are only valid for certain
points during building the bytecode handlers. Could you just set operand_scale
(or even better a scaled_operand_size) on the interpreter-assembler instead - I
don't think it's needed anywhere else in interpreter.cc

[oth, 2016/03/11 16:26:12]

Done.

+
+  static const int kNumberOfWideVariants = 3;
+  static const int kDispatchTableSize = kNumberOfWideVariants * (kMaxUInt8 + 1);
 
   Isolate* isolate_;
   Code* dispatch_table_[kDispatchTableSize];
 
+  int operand_scale_;
+
   DISALLOW_COPY_AND_ASSIGN(Interpreter);
 };
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_INTERPRETER_INTERPRETER_H_