[committed] Fix noncanonical rtl in emit_block_move_via_loop

[Richard Sandiford]

I was curious why LRA needed to handle noncanonical rtl in addresses:

        if (CONSTANT_P (arg0)
            || code1 == PLUS || code1 == MULT || code1 == ASHIFT)
          {
            tloc = arg1_loc;
            arg1_loc = arg0_loc;
            arg0_loc = tloc;
            arg0 = *arg0_loc;
            code0 = GET_CODE (arg0);
            arg1 = *arg1_loc;
            code1 = GET_CODE (arg1);
          }

and the culprit in all the cases I could see was emit_block_move_via_loop,
which generated (plus (const...) (reg ...)) rather than the correct
(plus (reg ...) (const...)).

Tested on x86_64-linux-gnu and applied as obvious.

Richard


gcc/
        * expr.c (emit_block_move_via_loop): Use simplify_gen_binary
        rather than gen_rtx_PLUS.

Index: gcc/expr.c
===================================================================
--- gcc/expr.c  2012-10-23 19:37:49.000000000 +0100
+++ gcc/expr.c  2012-10-25 09:36:33.071286674 +0100
@@ -1464,11 +1464,11 @@ emit_block_move_via_loop (rtx x, rtx y,
   emit_label (top_label);
 
   tmp = convert_modes (x_addr_mode, iter_mode, iter, true);
-  x_addr = gen_rtx_PLUS (x_addr_mode, x_addr, tmp);
+  x_addr = simplify_gen_binary (PLUS, x_addr_mode, x_addr, tmp);
 
   if (x_addr_mode != y_addr_mode)
     tmp = convert_modes (y_addr_mode, iter_mode, iter, true);
-  y_addr = gen_rtx_PLUS (y_addr_mode, y_addr, tmp);
+  y_addr = simplify_gen_binary (PLUS, y_addr_mode, y_addr, tmp);
 
   x = change_address (x, QImode, x_addr);
   y = change_address (y, QImode, y_addr);