[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 4cbde46813c3de538fcbceb964fb9abef9243445..4d3257d5eb04e2d488aadff5d88a5f56ecd772ad 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 r0, interpreter::Register r1) {

[rmcilroy, 2016/01/04 11:54:53]

nit - reg0, reg1

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

Done.

+  int i0 = RegisterToValuesIndex(r0);

[rmcilroy, 2016/01/04 11:54:53]

nit - reg0_index

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

Done.

+  int i1 = RegisterToValuesIndex(r1);
+  Node* saved = values()->at(i0);
+  values()->at(i0) = values()->at(i1);
+  values()->at(i1) = saved;
+}
+
+
 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) {