[ignition] Refactor array iterator to separate out access

src/interpreter/bytecode-array-accessor.cc

Index: src/interpreter/bytecode-array-accessor.cc
diff --git a/src/interpreter/bytecode-array-iterator.cc b/src/interpreter/bytecode-array-accessor.cc
similarity index 81%
copy from src/interpreter/bytecode-array-iterator.cc
copy to src/interpreter/bytecode-array-accessor.cc
index e596b11a0568a9fe6edaa5dcd9cc3d68dacb222f..d351e223954bed3c924a898b82e7485c36014dc6 100644
--- a/src/interpreter/bytecode-array-iterator.cc
+++ b/src/interpreter/bytecode-array-accessor.cc
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "src/interpreter/bytecode-array-iterator.h"
+#include "src/interpreter/bytecode-array-accessor.h"
 
 #include "src/interpreter/bytecode-decoder.h"
 #include "src/interpreter/interpreter-intrinsics.h"
@@ -12,22 +12,22 @@ namespace v8 {
 namespace internal {
 namespace interpreter {
 
-BytecodeArrayIterator::BytecodeArrayIterator(
-    Handle<BytecodeArray> bytecode_array)
+BytecodeArrayAccessor::BytecodeArrayAccessor(
+    Handle<BytecodeArray> bytecode_array, int initial_offset)
     : bytecode_array_(bytecode_array),
-      bytecode_offset_(0),
+      bytecode_offset_(initial_offset),
       operand_scale_(OperandScale::kSingle),
       prefix_offset_(0) {
   UpdateOperandScale();
 }
 
-void BytecodeArrayIterator::Advance() {
-  bytecode_offset_ += current_bytecode_size();
+void BytecodeArrayAccessor::SetOffset(int offset) {
+  bytecode_offset_ = offset;
   UpdateOperandScale();
 }
 
-void BytecodeArrayIterator::UpdateOperandScale() {
-  if (!done()) {
+void BytecodeArrayAccessor::UpdateOperandScale() {
+  if (OffsetInBounds()) {
     uint8_t current_byte = bytecode_array()->get(bytecode_offset_);
     Bytecode current_bytecode = Bytecodes::FromByte(current_byte);
     if (Bytecodes::IsPrefixScalingBytecode(current_bytecode)) {
@@ -41,12 +41,12 @@ void BytecodeArrayIterator::UpdateOperandScale() {
   }
 }
 
-bool BytecodeArrayIterator::done() const {
-  return bytecode_offset_ >= bytecode_array()->length();
+bool BytecodeArrayAccessor::OffsetInBounds() const {
+  return bytecode_offset_ >= 0 && bytecode_offset_ < bytecode_array()->length();
 }
 
-Bytecode BytecodeArrayIterator::current_bytecode() const {
-  DCHECK(!done());
+Bytecode BytecodeArrayAccessor::current_bytecode() const {
+  DCHECK(OffsetInBounds());
   uint8_t current_byte =
       bytecode_array()->get(bytecode_offset_ + current_prefix_offset());
   Bytecode current_bytecode = Bytecodes::FromByte(current_byte);
@@ -54,12 +54,12 @@ Bytecode BytecodeArrayIterator::current_bytecode() const {
   return current_bytecode;
 }
 
-int BytecodeArrayIterator::current_bytecode_size() const {
+int BytecodeArrayAccessor::current_bytecode_size() const {
   return current_prefix_offset() +
          Bytecodes::Size(current_bytecode(), current_operand_scale());
 }
 
-uint32_t BytecodeArrayIterator::GetUnsignedOperand(
+uint32_t BytecodeArrayAccessor::GetUnsignedOperand(
     int operand_index, OperandType operand_type) const {
   DCHECK_GE(operand_index, 0);
   DCHECK_LT(operand_index, Bytecodes::NumberOfOperands(current_bytecode()));
@@ -75,7 +75,7 @@ uint32_t BytecodeArrayIterator::GetUnsignedOperand(
                                                 current_operand_scale());
 }
 
-int32_t BytecodeArrayIterator::GetSignedOperand(
+int32_t BytecodeArrayAccessor::GetSignedOperand(
     int operand_index, OperandType operand_type) const {
   DCHECK_GE(operand_index, 0);
   DCHECK_LT(operand_index, Bytecodes::NumberOfOperands(current_bytecode()));
@@ -91,40 +91,40 @@ int32_t BytecodeArrayIterator::GetSignedOperand(
                                               current_operand_scale());
 }
 
-uint32_t BytecodeArrayIterator::GetFlagOperand(int operand_index) const {
+uint32_t BytecodeArrayAccessor::GetFlagOperand(int operand_index) const {
   DCHECK_EQ(Bytecodes::GetOperandType(current_bytecode(), operand_index),
             OperandType::kFlag8);
   return GetUnsignedOperand(operand_index, OperandType::kFlag8);
 }
 
-uint32_t BytecodeArrayIterator::GetUnsignedImmediateOperand(
+uint32_t BytecodeArrayAccessor::GetUnsignedImmediateOperand(
     int operand_index) const {
   DCHECK_EQ(Bytecodes::GetOperandType(current_bytecode(), operand_index),
             OperandType::kUImm);
   return GetUnsignedOperand(operand_index, OperandType::kUImm);
 }
 
-int32_t BytecodeArrayIterator::GetImmediateOperand(int operand_index) const {
+int32_t BytecodeArrayAccessor::GetImmediateOperand(int operand_index) const {
   DCHECK_EQ(Bytecodes::GetOperandType(current_bytecode(), operand_index),
             OperandType::kImm);
   return GetSignedOperand(operand_index, OperandType::kImm);
 }
 
-uint32_t BytecodeArrayIterator::GetRegisterCountOperand(
+uint32_t BytecodeArrayAccessor::GetRegisterCountOperand(
     int operand_index) const {
   DCHECK_EQ(Bytecodes::GetOperandType(current_bytecode(), operand_index),
             OperandType::kRegCount);
   return GetUnsignedOperand(operand_index, OperandType::kRegCount);
 }
 
-uint32_t BytecodeArrayIterator::GetIndexOperand(int operand_index) const {
+uint32_t BytecodeArrayAccessor::GetIndexOperand(int operand_index) const {
   OperandType operand_type =
       Bytecodes::GetOperandType(current_bytecode(), operand_index);
   DCHECK_EQ(operand_type, OperandType::kIdx);
   return GetUnsignedOperand(operand_index, operand_type);
 }
 
-Register BytecodeArrayIterator::GetRegisterOperand(int operand_index) const {
+Register BytecodeArrayAccessor::GetRegisterOperand(int operand_index) const {
   OperandType operand_type =
       Bytecodes::GetOperandType(current_bytecode(), operand_index);
   const uint8_t* operand_start =
@@ -136,7 +136,7 @@ Register BytecodeArrayIterator::GetRegisterOperand(int operand_index) const {
                                                 current_operand_scale());
 }
 
-int BytecodeArrayIterator::GetRegisterOperandRange(int operand_index) const {
+int BytecodeArrayAccessor::GetRegisterOperandRange(int operand_index) const {
   DCHECK_LE(operand_index, Bytecodes::NumberOfOperands(current_bytecode()));
   const OperandType* operand_types =
       Bytecodes::GetOperandTypes(current_bytecode());
@@ -149,7 +149,7 @@ int BytecodeArrayIterator::GetRegisterOperandRange(int operand_index) const {
   }
 }
 
-Runtime::FunctionId BytecodeArrayIterator::GetRuntimeIdOperand(
+Runtime::FunctionId BytecodeArrayAccessor::GetRuntimeIdOperand(
     int operand_index) const {
   OperandType operand_type =
       Bytecodes::GetOperandType(current_bytecode(), operand_index);
@@ -158,7 +158,7 @@ Runtime::FunctionId BytecodeArrayIterator::GetRuntimeIdOperand(
   return static_cast<Runtime::FunctionId>(raw_id);
 }
 
-Runtime::FunctionId BytecodeArrayIterator::GetIntrinsicIdOperand(
+Runtime::FunctionId BytecodeArrayAccessor::GetIntrinsicIdOperand(
     int operand_index) const {
   OperandType operand_type =
       Bytecodes::GetOperandType(current_bytecode(), operand_index);
@@ -168,15 +168,14 @@ Runtime::FunctionId BytecodeArrayIterator::GetIntrinsicIdOperand(
       static_cast<IntrinsicsHelper::IntrinsicId>(raw_id));
 }
 
-Handle<Object> BytecodeArrayIterator::GetConstantForIndexOperand(
+Handle<Object> BytecodeArrayAccessor::GetConstantForIndexOperand(
     int operand_index) const {
   return FixedArray::get(bytecode_array()->constant_pool(),
                          GetIndexOperand(operand_index),
                          bytecode_array()->GetIsolate());
 }
 
-
-int BytecodeArrayIterator::GetJumpTargetOffset() const {
+int BytecodeArrayAccessor::GetJumpTargetOffset() const {
   Bytecode bytecode = current_bytecode();
   if (interpreter::Bytecodes::IsJumpImmediate(bytecode)) {
     int relative_offset = GetImmediateOperand(0);