function.h (regno_reg_rtx): Adjust comment.

gcc/
	* function.h (regno_reg_rtx): Adjust comment.
	* reginfo.c (init_reg_modes_target): Only use the previous mode
	if it fits within one register.  Remove MIPS comment.

From-SVN: r183773

gcc/ChangeLog

+2012-01-31  Richard Sandiford  <rdsandiford@googlemail.com>
+
+	* function.h (regno_reg_rtx): Adjust comment.
+	* reginfo.c (init_reg_modes_target): Only use the previous mode
+	if it fits within one register.  Remove MIPS comment.
+
 2012-01-31  Jakub Jelinek  <jakub@redhat.com>
 
 	PR bootstrap/52058

gcc/function.h

@@ -87,10 +87,13 @@ struct GTY(()) emit_status {
 };
 
 
-/* Indexed by pseudo register number, gives the rtx for that pseudo.
-   Allocated in parallel with regno_pointer_align.
-   FIXME: We could put it into emit_status struct, but gengtype is not able to deal
-   with length attribute nested in top level structures.  */
+/* Indexed by register number, gives an rtx for that register (and only
+   that register).  For pseudo registers, it is the unique rtx for
+   that pseudo.  For hard registers, it is an rtx of the mode specified
+   by reg_raw_mode.
+
+   FIXME: We could put it into emit_status struct, but gengtype is not
+   able to deal with length attribute nested in top level structures.  */
 
 extern GTY ((length ("crtl->emit.x_reg_rtx_no"))) rtx * regno_reg_rtx;
 

gcc/reginfo.c

@@ -615,13 +615,15 @@ init_reg_modes_target (void)
     {
       reg_raw_mode[i] = choose_hard_reg_mode (i, 1, false);
 
-      /* If we couldn't find a valid mode, just use the previous mode.
-         ??? One situation in which we need to do this is on the mips where
-	 HARD_REGNO_NREGS (fpreg, [SD]Fmode) returns 2.  Ideally we'd like
-	 to use DF mode for the even registers and VOIDmode for the odd
-	 (for the cpu models where the odd ones are inaccessible).  */
+      /* If we couldn't find a valid mode, just use the previous mode
+	 if it is suitable, otherwise fall back on word_mode.  */
       if (reg_raw_mode[i] == VOIDmode)
-	reg_raw_mode[i] = i == 0 ? word_mode : reg_raw_mode[i-1];
+    	{
+	  if (i > 0 && hard_regno_nregs[i][reg_raw_mode[i - 1]] == 1)
+	    reg_raw_mode[i] = reg_raw_mode[i - 1];
+	  else
+	    reg_raw_mode[i] = word_mode;
+	}
     }
 }