* Early during register allocation, spill registers which interfere with all usable real registers.

  It is pointless to keep them for further processing. Also it may
  cause endless spilling.
  This can happen when compiling for very constrained CPUs such as
  i8086 where indexed memory access instructions allow only
  few registers as arguments and additionally the calling convention
  provides no general purpose volatile registers.

git-svn-id: trunk@46199 -

compiler/rgobj.pas

@@ -629,6 +629,23 @@ unit rgobj;
         { Don't do the real allocation when -sr is passed }
         if (cs_no_regalloc in current_settings.globalswitches) then
           exit;
+        { Spill registers which interfere with all usable real registers.
+          It is pointless to keep them for further processing. Also it may
+          cause endless spilling.
+
+          This can happen when compiling for very constrained CPUs such as
+          i8086 where indexed memory access instructions allow only
+          few registers as arguments and additionally the calling convention
+          provides no general purpose volatile registers.
+        }
+        for i:=first_imaginary to maxreg-1 do
+          if reginfo[i].real_reg_interferences>=usable_registers_cnt then
+            spillednodes.add(i);
+        if spillednodes.length<>0 then
+          begin
+            spill_registers(list,headertai);
+            spillednodes.clear;
+          end;
         {Do register allocation.}
         spillingcounter:=0;
         repeat