X87: [turbofan] avoid xchg instruction on Intel.

src/crankshaft/x87/lithium-gap-resolver-x87.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_X87
 
 #include "src/crankshaft/x87/lithium-gap-resolver-x87.h"
 #include "src/register-configuration.h"
 
 #include "src/crankshaft/x87/lithium-codegen-x87.h"
@@ skipping 356 matching lines @@
   LOperand* destination = moves_[index].destination();
   EnsureRestored(source);
   EnsureRestored(destination);
 
   // Dispatch on the source and destination operand kinds.  Not all
   // combinations are possible.
   if (source->IsRegister() && destination->IsRegister()) {
     // Register-register.
     Register src = cgen_->ToRegister(source);
     Register dst = cgen_->ToRegister(destination);
-    __ xchg(dst, src);
+    __ push(src);
+    __ mov(src, dst);
+    __ pop(dst);
 
   } else if ((source->IsRegister() && destination->IsStackSlot()) ||
              (source->IsStackSlot() && destination->IsRegister())) {
     // Register-memory.  Use a free register as a temp if possible.  Do not
     // spill on demand because the simple spill implementation cannot avoid
     // spilling src at this point.
     Register tmp = GetFreeRegisterNot(no_reg);
     Register reg =
         cgen_->ToRegister(source->IsRegister() ? source : destination);
     Operand mem =
@@ skipping 63 matching lines @@
     source_uses_[destination->index()] = CountSourceUses(destination);
   }
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X87