[Interpreter] Bytecodes for exchanging registers.

src/interpreter/interpreter.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/interpreter.h"
 
 #include "src/code-factory.h"
 #include "src/compiler.h"
 #include "src/compiler/interpreter-assembler.h"
 #include "src/factory.h"
@@ skipping 183 matching lines @@
 //
 // Store accumulator to register <dst>.
 void Interpreter::DoStar(compiler::InterpreterAssembler* assembler) {
   Node* reg_index = __ BytecodeOperandReg(0);
   Node* accumulator = __ GetAccumulator();
   __ StoreRegister(accumulator, reg_index);
   __ Dispatch();
 }
 
 
+// Exchange <reg8> <reg16>
+//
+// Exchange two registers.
+void Interpreter::DoExchange(compiler::InterpreterAssembler* assembler) {
+  Node* r0 = __ BytecodeOperandReg(0);
+  Node* r1 = __ BytecodeOperandReg(1);
+  Node* v0 = __ LoadRegister(r0);
+  Node* v1 = __ LoadRegister(r1);

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

nit - non-single character variable names.

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

Done.

+  __ StoreRegister(v1, r0);
+  __ StoreRegister(v0, r1);
+  __ Dispatch();
+}
+
+
+// ExchangeWide <reg16> <reg16>
+//
+// Exchange two registers.
+void Interpreter::DoExchangeWide(compiler::InterpreterAssembler* assembler) {
+  return DoExchange(assembler);
+}
+
+
 // Mov <src> <dst>
 //
 // Stores the value of register <src> to register <dst>.
 void Interpreter::DoMov(compiler::InterpreterAssembler* assembler) {
   Node* src_index = __ BytecodeOperandReg(0);
   Node* src_value = __ LoadRegister(src_index);
   Node* dst_index = __ BytecodeOperandReg(1);
   __ StoreRegister(src_value, dst_index);
   __ Dispatch();
 }
@@ skipping 1378 matching lines @@
   Node* index_reg = __ BytecodeOperandReg(0);
   Node* index = __ LoadRegister(index_reg);
   Node* result = __ CallRuntime(Runtime::kForInStep, index);
   __ SetAccumulator(result);
   __ Dispatch();
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8