Added command line flag --sync_with_push (default: true) to...

src/x64/virtual-frame-x64.cc

Index: src/x64/virtual-frame-x64.cc
===================================================================
--- src/x64/virtual-frame-x64.cc	(revision 3020)
+++ src/x64/virtual-frame-x64.cc	(working copy)
@@ -883,15 +883,16 @@
   // on the stack.
   int start = Min(begin, stack_pointer_ + 1);
 
-  // If positive we have to adjust the stack pointer.
-  int delta = end - stack_pointer_;
-  if (delta > 0) {
-    stack_pointer_ = end;
-    __ subq(rsp, Immediate(delta * kPointerSize));
-  }
-
+  // Emit normal 'push' instructions for elements above stack pointer
+  // and use mov instructions if we are below stack pointer.
   for (int i = start; i <= end; i++) {
-    if (!elements_[i].is_synced()) SyncElementBelowStackPointer(i);
+    if (!elements_[i].is_synced()) {
+      if (i <= stack_pointer_) {
+        SyncElementBelowStackPointer(i);
+      } else {
+        SyncElementByPushing(i);
+      }
+    }
   }
 }