[Interpreter] Add option to trace bytecode execution.

src/interpreter/bytecode-array-iterator.cc

Index: src/interpreter/bytecode-array-iterator.cc
diff --git a/src/interpreter/bytecode-array-iterator.cc b/src/interpreter/bytecode-array-iterator.cc
index 6fde67f938cff42bf0689c9db010931e2ff602c7..2839fe46942f5de1edade2a5900ff6653c7d3dff 100644
--- a/src/interpreter/bytecode-array-iterator.cc
+++ b/src/interpreter/bytecode-array-iterator.cc
@@ -100,6 +100,33 @@ Register BytecodeArrayIterator::GetRegisterOperand(int operand_index) const {
   return Register();
 }
 
+int BytecodeArrayIterator::GetRegisterOperandRange(int operand_index) const {
+  interpreter::OperandType operand_type =
+      Bytecodes::GetOperandType(current_bytecode(), operand_index);
+  DCHECK(Bytecodes::IsRegisterOperandType(operand_type));
+  switch (operand_type) {
+    case OperandType::kRegPair8:
+    case OperandType::kRegPair16:
+    case OperandType::kRegOutPair8:
+    case OperandType::kRegOutPair16:
+      return 2;
+    case OperandType::kRegOutTriple8:
+    case OperandType::kRegOutTriple16:
+      return 3;
+    default: {
+      if (operand_index + 1 !=
+          Bytecodes::NumberOfOperands(current_bytecode())) {
+        OperandType next_operand_type =

[oth, 2016/01/27 15:10:09]

Can you add a TODO(oth) here to update bytecodes so that the kCount8/kCount16
operands have the same semantics for all bytecodes?
ie Call/CallJSRuntime the count argument is for registers 1 after the receiver,
for CallRuntime/New the count argument covers the last register operand.

[rmcilroy, 2016/01/28 16:39:51]

Done.

+            Bytecodes::GetOperandType(current_bytecode(), operand_index + 1);
+        if (next_operand_type == OperandType::kRegCount8 ||
+            next_operand_type == OperandType::kRegCount16) {
+          return GetCountOperand(operand_index + 1);
+        }
+      }
+      return 1;
+    }
+  }
+}
 
 Handle<Object> BytecodeArrayIterator::GetConstantForIndexOperand(
     int operand_index) const {