As proposed in PR45099, avr-gcc will now just print a warning instead of an error when a fixed register is needed to pass a parameter to a function.
That way the user can inspect the source, and there are situation imaginable where clobbering a fixed register is not a problem. Committed as trunk r179040: http://gcc.gnu.org/viewcvs?view=revision&revision=179040 Johann PR target/45099 * config/avr/avr.c (avr_function_arg_advance): Change error to warning if a fixed register is needed as function argument. Index: config/avr/avr.c =================================================================== --- config/avr/avr.c (revision 179038) +++ config/avr/avr.c (working copy) @@ -1810,7 +1810,7 @@ avr_function_arg_advance (cumulative_arg /* Test if all registers needed by the ABI are actually available. If the user has fixed a GPR needed to pass an argument, an (implicit) function - call would clobber that fixed register. See PR45099 for an example. */ + call will clobber that fixed register. See PR45099 for an example. */ if (cum->regno >= 8 && cum->nregs >= 0) @@ -1819,8 +1819,8 @@ avr_function_arg_advance (cumulative_arg for (regno = cum->regno; regno < cum->regno + bytes; regno++) if (fixed_regs[regno]) - error ("Register %s is needed to pass a parameter but is fixed", - reg_names[regno]); + warning (0, "fixed register %s used to pass parameter to function", + reg_names[regno]); } if (cum->nregs <= 0)
