[Interpreter] Preparation for wide registers.

src/interpreter/bytecodes.cc

Index: src/interpreter/bytecodes.cc
diff --git a/src/interpreter/bytecodes.cc b/src/interpreter/bytecodes.cc
index 1a82f6c117e800e606080a4427668427116f8cd7..983bf9b3430dd82f2bd88a2b57e1b78db3a01243 100644
--- a/src/interpreter/bytecodes.cc
+++ b/src/interpreter/bytecodes.cc
@@ -232,6 +232,23 @@ bool Bytecodes::IsJumpOrReturn(Bytecode bytecode) {
 }
 
 
+namespace {
+static Register DecodeRegister(const uint8_t* operand_start,
+                               OperandType operand_type) {
+  switch (Bytecodes::SizeOfOperand(operand_type)) {
+    case OperandSize::kByte:
+      return Register::FromOperand(*operand_start);
+    case OperandSize::kShort:
+      return Register::FromWideOperand(ReadUnalignedUInt16(operand_start));
+    case OperandSize::kNone: {
+      UNREACHABLE();
+    }
+  }
+  return Register();
+}
+}  // namespace
+
+
 // static
 std::ostream& Bytecodes::Decode(std::ostream& os, const uint8_t* bytecode_start,
                                 int parameter_count) {
@@ -257,10 +274,10 @@ std::ostream& Bytecodes::Decode(std::ostream& os, const uint8_t* bytecode_start,
     const uint8_t* operand_start =
         &bytecode_start[GetOperandOffset(bytecode, i)];
     switch (op_type) {
-      case interpreter::OperandType::kCount8:
+      case interpreter::OperandType::kRegCount8:
         os << "#" << static_cast<unsigned int>(*operand_start);
         break;
-      case interpreter::OperandType::kCount16:
+      case interpreter::OperandType::kRegCount16:
         os << '#' << ReadUnalignedUInt16(operand_start);
         break;
       case interpreter::OperandType::kIdx8:
@@ -272,9 +289,11 @@ std::ostream& Bytecodes::Decode(std::ostream& os, const uint8_t* bytecode_start,
       case interpreter::OperandType::kImm8:
         os << "#" << static_cast<int>(static_cast<int8_t>(*operand_start));
         break;
+      case interpreter::OperandType::kMaybeReg8:
+      case interpreter::OperandType::kMaybeReg16:
       case interpreter::OperandType::kReg8:
-      case interpreter::OperandType::kMaybeReg8: {
-        Register reg = Register::FromOperand(*operand_start);
+      case interpreter::OperandType::kReg16: {
+        Register reg = DecodeRegister(operand_start, op_type);
         if (reg.is_function_context()) {
           os << "<context>";
         } else if (reg.is_function_closure()) {
@@ -294,30 +313,20 @@ std::ostream& Bytecodes::Decode(std::ostream& os, const uint8_t* bytecode_start,
         break;
       }
       case interpreter::OperandType::kRegPair8:
-      case interpreter::OperandType::kRegTriple8: {
-        Register reg = Register::FromOperand(*operand_start);
+      case interpreter::OperandType::kRegTriple8:
+      case interpreter::OperandType::kRegPair16:
+      case interpreter::OperandType::kRegTriple16: {
+        Register reg = DecodeRegister(operand_start, op_type);
         int range = op_type == interpreter::OperandType::kRegPair8 ? 1 : 2;
         if (reg.is_parameter()) {
           int parameter_index = reg.ToParameterIndex(parameter_count);
-          DCHECK_NE(parameter_index, 0);
+          DCHECK_GT(parameter_index, 0);
           os << "a" << parameter_index - range << "-" << parameter_index;
         } else {
           os << "r" << reg.index() << "-" << reg.index() + range;
         }
         break;
       }
-      case interpreter::OperandType::kReg16: {
-        Register reg =
-            Register::FromWideOperand(ReadUnalignedUInt16(operand_start));
-        if (reg.is_parameter()) {
-          int parameter_index = reg.ToParameterIndex(parameter_count);
-          DCHECK_NE(parameter_index, 0);
-          os << "a" << parameter_index - 1;
-        } else {
-          os << "r" << reg.index();
-        }
-        break;
-      }
       case interpreter::OperandType::kNone:
         UNREACHABLE();
         break;
@@ -433,6 +442,16 @@ Register Register::FromWideOperand(uint16_t operand) {
 }
 
 
+uint32_t Register::ToRawOperand() const {
+  return static_cast<uint32_t>(-index_);
+}
+
+
+Register Register::FromRawOperand(uint32_t operand) {
+  return Register(-static_cast<int32_t>(operand));
+}
+
+
 bool Register::AreContiguous(Register reg1, Register reg2, Register reg3,
                              Register reg4, Register reg5) {
   if (reg1.index() + 1 != reg2.index()) {