6887186: G1: Incorrect code generated for G1 pre-barrier by C1 on SPARC

Modify operand passed to C1 pre-barrier to be the operand representing the address of the object field that is being stored.

Reviewed-by: never

hotspot/src/cpu/sparc/vm/c1_LIRGenerator_sparc.cpp

@@ -668,7 +668,7 @@ void LIRGenerator::do_CompareAndSwap(Intrinsic* x, ValueType* type) {
   __ add(obj.result(), offset.result(), addr);
 
   if (type == objectType) {  // Write-barrier needed for Object fields.
-    pre_barrier(obj.result(), false, NULL);
+    pre_barrier(addr, false, NULL);
   }
 
   if (type == objectType)