[interpreter] Add support for scalable operands.

src/interpreter/interpreter.h

Index: src/interpreter/interpreter.h
diff --git a/src/interpreter/interpreter.h b/src/interpreter/interpreter.h
index 42b9bd7f9e8f9b8d5168003633347a0cf7d5af7e..2f84f2ac25a18d7dc3a35c667580e54f4a99fdc2 100644
--- a/src/interpreter/interpreter.h
+++ b/src/interpreter/interpreter.h
@@ -40,7 +40,7 @@ class Interpreter {
   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);
@@ -128,13 +128,22 @@ class Interpreter {
   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);
 };