Fix sparc builtin_memcpy miscompilation.

	* expmed.c (store_bit_field): If need to add a SUBREG, then remove
	existing SUBREG if we can, otherwise abort.

From-SVN: r23215

gcc/ChangeLog

+Wed Oct 21 19:23:59 1998  Jim Wilson  <wilson@cygnus.com>
+
+	* expmed.c (store_bit_field): If need to add a SUBREG, then remove
+	existing SUBREG if we can, otherwise abort.
+
 Wed Oct 21 09:58:51 1998  Mark Mitchell  <mark@markmitchell.com>
 
 	* c-common.c (c_apply_type_quals_to_decl): Don't crash when

gcc/expmed.c

@@ -423,7 +423,18 @@ store_bit_field (str_rtx, bitsize, bitnum, fieldmode, value, align, total_size)
 	  || GET_MODE_SIZE (GET_MODE (op0)) > UNITS_PER_WORD)
 	{
 	  if (GET_CODE (op0) != REG)
-	    op0 = copy_to_reg (op0);
+	    {
+	      /* Since this is a destination (lvalue), we can't copy it to a
+		 pseudo.  We can trivially remove a SUBREG that does not
+		 change the size of the operand.  Such a SUBREG may have been
+		 added above.  Otherwise, abort.  */
+	      if (GET_CODE (op0) == SUBREG
+		  && (GET_MODE_SIZE (GET_MODE (op0))
+		      == GET_MODE_SIZE (GET_MODE (SUBREG_REG (op0)))))
+		op0 = SUBREG_REG (op0);
+	      else
+		abort ();
+	    }
 	  op0 = gen_rtx_SUBREG (mode_for_size (BITS_PER_WORD, MODE_INT, 0),
 		                op0, offset);
 	}