avr.c (avr_hard_regno_mode_ok): Do not allow r29 which may overwrite the high…

avr.c (avr_hard_regno_mode_ok): Do not allow r29 which may overwrite the high byte of the frame pointer.


	* config/avr/avr.c (avr_hard_regno_mode_ok): Do not allow r29
	which may overwrite the high byte of the frame pointer.

From-SVN: r50138

gcc/ChangeLog

+2002-02-28  Marek Michalkiewicz  <marekm@amelek.gda.pl>
+
+	* config/avr/avr.c (avr_hard_regno_mode_ok): Do not allow r29
+	which may overwrite the high byte of the frame pointer.
+
 2002-02-28  Bo Thorsen  <bo@suse.de>
 
 	* config/i386/linux64.h (LINK_SPEC): Fix 32/64 bit compilation.

gcc/config/avr/avr.c

@@ -5210,6 +5210,13 @@ avr_hard_regno_mode_ok (regno, mode)
      int regno;
      enum machine_mode mode;
 {
+  /* Bug workaround: recog.c (peep2_find_free_register) and probably
+     a few other places assume that the frame pointer is a single hard
+     register, so r29 may be allocated and overwrite the high byte of
+     the frame pointer.  Do not allow any value to start in r29.  */
+  if (regno == REG_Y + 1)
+    return 0;
+
   if (mode == QImode)
     return 1;
   /*  if (regno < 24 && !AVR_ENHANCED)