[Interpreter] Bytecodes for exchanging registers.

src/compiler/bytecode-graph-builder.cc

Index: src/compiler/bytecode-graph-builder.cc
diff --git a/src/compiler/bytecode-graph-builder.cc b/src/compiler/bytecode-graph-builder.cc
index 12d944407f10f2cca250fa306559f2eac0b0da74..2fe2e1c397ec99a19f44a3f3bf2144002267eda6 100644
--- a/src/compiler/bytecode-graph-builder.cc
+++ b/src/compiler/bytecode-graph-builder.cc
@@ -164,12 +164,23 @@ void BytecodeGraphBuilder::Environment::BindAccumulator(
   values()->at(accumulator_base_) = node;
 }
 
+
 void BytecodeGraphBuilder::Environment::RecordAfterState(
     Node* node, FrameStateBeforeAndAfter* states) {
   states->AddToNode(node, AccumulatorUpdateMode::kOutputIgnored);
 }
 
 
+void BytecodeGraphBuilder::Environment::ExchangeRegisters(
+    interpreter::Register reg0, interpreter::Register reg1) {
+  int reg0_index = RegisterToValuesIndex(reg0);
+  int reg1_index = RegisterToValuesIndex(reg1);
+  Node* saved_reg0_value = values()->at(reg0_index);
+  values()->at(reg0_index) = values()->at(reg1_index);
+  values()->at(reg1_index) = saved_reg0_value;
+}
+
+
 Node* BytecodeGraphBuilder::Environment::LookupAccumulator() const {
   return values()->at(accumulator_base_);
 }
@@ -561,6 +572,20 @@ void BytecodeGraphBuilder::VisitMov(
 }
 
 
+void BytecodeGraphBuilder::VisitExchange(
+    const interpreter::BytecodeArrayIterator& iterator) {
+  environment()->ExchangeRegisters(iterator.GetRegisterOperand(0),
+                                   iterator.GetRegisterOperand(1));
+}
+
+
+void BytecodeGraphBuilder::VisitExchangeWide(
+    const interpreter::BytecodeArrayIterator& iterator) {
+  environment()->ExchangeRegisters(iterator.GetRegisterOperand(0),
+                                   iterator.GetRegisterOperand(1));
+}
+
+
 void BytecodeGraphBuilder::BuildLoadGlobal(
     const interpreter::BytecodeArrayIterator& iterator,
     TypeofMode typeof_mode) {