From 8434abaa0e1a911cb44437034bb085d42383e721 Mon Sep 17 00:00:00 2001
From: Joel Dice <git@seibutsu.mailsnare.net>
Date: Wed, 14 May 2008 17:33:55 -0600
Subject: [PATCH] implement swapRR

---
 src/x86.cpp | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/x86.cpp b/src/x86.cpp
index a1c28c0dbc..6ecd286005 100644
--- a/src/x86.cpp
+++ b/src/x86.cpp
@@ -580,15 +580,6 @@ void
 xorRR(Context* c, unsigned size, Assembler::Register* a,
       Assembler::Register* b);
 
-void
-swap(Context* c, Assembler::Register* a, Assembler::Register* b)
-{
-  // todo: use xchg instead
-  xorRR(c, 4, a, b);
-  xorRR(c, 4, b, b);
-  xorRR(c, 4, a, b);
-}
-
 void
 negateR(Context* c, unsigned size, Assembler::Register* a)
 {
@@ -908,6 +899,14 @@ moveZRR(Context* c, unsigned size, Assembler::Register* a,
   }
 }
 
+void
+swapRR(Context* c, unsigned, Assembler::Register* a, Assembler::Register* b)
+{
+  rex(c);
+  c->code.append(0x87);
+  c->code.append(0xc0 | (b->low << 3) | a->low);
+}
+
 void
 addCM(Context* c, unsigned size UNUSED, Assembler::Constant* a,
       Assembler::Memory* b)
@@ -1762,6 +1761,8 @@ populateTables()
   BinaryOperations[INDEX2(MoveZ, Memory, Register)] = CAST2(moveZMR);
   BinaryOperations[INDEX2(MoveZ, Register, Register)] = CAST2(moveZRR);
 
+  BinaryOperations[INDEX2(Swap, Register, Register)] = CAST2(swapRR);
+
   BinaryOperations[INDEX2(Add, Constant, Register)] = CAST2(addCR);
   BinaryOperations[INDEX2(Add, Register, Register)] = CAST2(addRR);
   BinaryOperations[INDEX2(Add, Register, Memory)] = CAST2(addRM);