* Remove register allocations of coalesced registers if the alias

  register is spilled.

(cherry picked from commit b96057adeb1513292dcfea664c8c4fe227abc442)

compiler/rgobj.pas

@@ -2158,8 +2158,9 @@ unit rgobj;
                   begin
                     if (getregtype(reg)=regtype) then
                       begin
-                        {A register allocation of a spilled register can be removed.}
-                        supreg:=getsupreg(reg);
+                        {A register allocation of the spilled register (and all coalesced registers) 
+                         must be removed.}
+                        supreg:=get_alias(getsupreg(reg));
                         if supregset_in(regs_to_spill_set,supreg) then
                           begin
                             q:=Tai(p.next);