[turbofan] avoid xchg instruction on Intel

src/crankshaft/x64/lithium-gap-resolver-x64.cc

 // Copyright 2011 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.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/crankshaft/x64/lithium-gap-resolver-x64.h"
 
 #include "src/crankshaft/x64/lithium-codegen-x64.h"
 
@@ skipping 226 matching lines @@
 void LGapResolver::EmitSwap(int index) {
   LOperand* source = moves_[index].source();
   LOperand* destination = moves_[index].destination();
 
   // Dispatch on the source and destination operand kinds.  Not all
   // combinations are possible.
   if (source->IsRegister() && destination->IsRegister()) {
     // Swap two general-purpose registers.
     Register src = cgen_->ToRegister(source);
     Register dst = cgen_->ToRegister(destination);
-    __ xchgq(dst, src);
+    __ movp(kScratchRegister, src);
+    __ movp(src, dst);
+    __ movp(dst, kScratchRegister);
 
   } else if ((source->IsRegister() && destination->IsStackSlot()) ||
              (source->IsStackSlot() && destination->IsRegister())) {
     // Swap a general-purpose register and a stack slot.
     Register reg =
         cgen_->ToRegister(source->IsRegister() ? source : destination);
     Operand mem =
         cgen_->ToOperand(source->IsRegister() ? destination : source);
     __ movp(kScratchRegister, mem);
     __ movp(mem, reg);
@@ skipping 52 matching lines @@
     }
   }
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64