[Interpreter] Bytecodes for exchanging registers.

src/interpreter/bytecodes.cc

 // 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.
 
 #include "src/interpreter/bytecodes.h"
 
 #include "src/frames.h"
 #include "src/interpreter/bytecode-traits.h"
 
 namespace v8 {
@@ skipping 255 matching lines @@
           if (parameter_index == 0) {
             os << "<this>";
           } else {
             os << "a" << parameter_index - 1;
           }
         } else {
           os << "r" << reg.index();
         }
         break;
       }
+      case interpreter::OperandType::kReg16: {
+        Register reg =
+            Register::FromWideOperand(ReadUnalignedUInt16(operand_start));
+        os << "r" << reg.index();

[rmcilroy, 2016/01/04 11:54:54]

nit - add "a" argument case as well ?

[oth, 2016/01/04 14:01:42]

Okay, done, was not done as not part of current changes.

+        break;
+      }
       case interpreter::OperandType::kNone:
         UNREACHABLE();
         break;
     }
     if (i != number_of_operands - 1) {
       os << ", ";
     }
   }
   return os;
 }
@@ skipping 71 matching lines @@
 
 
 bool Register::is_new_target() const {
   return index() == kNewTargetRegisterIndex;
 }
 
 
 int Register::MaxParameterIndex() { return kMaxParameterIndex; }
 
 
-uint8_t Register::ToOperand() const { return static_cast<uint8_t>(-index_); }
+uint8_t Register::ToOperand() const {
+  DCHECK_GE(index_, kMinRegisterIndex);
+  DCHECK_LE(index_, kMaxRegisterIndex);
+  return static_cast<uint8_t>(-index_);
+}
 
 
 Register Register::FromOperand(uint8_t operand) {
   return Register(-static_cast<int8_t>(operand));
 }
 
 
+uint16_t Register::ToWideOperand() const {
+  DCHECK_GE(index_, kMinInt16);
+  DCHECK_LE(index_, kMaxInt16);
+  return static_cast<uint16_t>(-index_);
+}
+
+
+Register Register::FromWideOperand(uint16_t operand) {
+  return Register(-static_cast<int16_t>(operand));
+}
+
+
 bool Register::AreContiguous(Register reg1, Register reg2, Register reg3,
                              Register reg4, Register reg5) {
   if (reg1.index() + 1 != reg2.index()) {
     return false;
   }
   if (reg3.is_valid() && reg2.index() + 1 != reg3.index()) {
     return false;
   }
   if (reg4.is_valid() && reg3.index() + 1 != reg4.index()) {
     return false;
   }
   if (reg5.is_valid() && reg4.index() + 1 != reg5.index()) {
     return false;
   }
   return true;
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8