re PR middle-end/20491 (internal compiler error: in subreg_regno_offset, at rtlanal.c:3042)

PR middle-end/20491
* final.c (alter_subreg): Don't call subreg_regno for a non-REG.

From-SVN: r97444

gcc/ChangeLog

 2005-04-02  Alexandre Oliva  <aoliva@redhat.com>
 
+	PR middle-end/20491
+	* final.c (alter_subreg): Don't call subreg_regno for a non-REG.
+
+2005-04-02  Alexandre Oliva  <aoliva@redhat.com>
+
 	PR rtl-optimization/20290
 	* loop.c (for_each_insn_in_loop): Don't assume the loop body runs
 	in every iteration if the entry point is the exit test.

gcc/final.c

@@ -2547,11 +2547,10 @@ alter_subreg (rtx *xp)
 
       if (new != 0)
 	*xp = new;
-      else
+      else if (REG_P (y))
 	{
 	  /* Simplify_subreg can't handle some REG cases, but we have to.  */
 	  unsigned int regno = subreg_regno (x);
-	  gcc_assert (REG_P (y));
 	  *xp = gen_rtx_REG_offset (y, GET_MODE (x), regno, SUBREG_BYTE (x));
 	}
     }