Use the proper rtx cost model for the selected CPU, even when optimizing
for size. This generates better code.

--- a/gcc/config/mips/mips.c
+++ b/gcc/config/mips/mips.c
@@ -17483,7 +17483,7 @@ mips_option_override (void)
     flag_pcc_struct_return = 0;
 
   /* Decide which rtx_costs structure to use.  */
-  if (optimize_size)
+  if (0 && optimize_size)
     mips_cost = &mips_rtx_cost_optimize_size;
   else
     mips_cost = &mips_rtx_cost_data[mips_tune];