some rot/shift by constant optimisations

[r20397]

diff --git a/ir/ir/iropt.c b/ir/ir/iropt.c
index ec69799..b9ca652 100644 (file)
--- a/ir/ir/iropt.c
+++ b/ir/ir/iropt.c
@@ -4691,9 +4691,8 @@ static ir_node *transform_node(ir_node *n);
  */
 static ir_node *transform_node_shift(ir_node *n) {
        ir_node *left, *right;
-       tarval *tv1, *tv2, *res;
        ir_mode *mode;
-       int modulo_shf, flag;
+       tarval *tv1, *tv2, *res;
 
        left = get_binop_left(n);
 
@@ -4710,36 +4709,46 @@ static ir_node *transform_node_shift(ir_node *n) {
        if (tv2 == tarval_bad)
                return n;
 
-       res = tarval_add(tv1, tv2);
-
-       /* beware: a simple replacement works only, if res < modulo shift */
+       res  = tarval_add(tv1, tv2);
        mode = get_irn_mode(n);
 
-       flag = 0;
-
-       modulo_shf = get_mode_modulo_shift(mode);
-       if (modulo_shf > 0) {
-               tarval *modulo = new_tarval_from_long(modulo_shf, get_tarval_mode(res));
+       /* beware: a simple replacement works only, if res < modulo shift */
+       if (!is_Rotl(n)) {
+               int modulo_shf = get_mode_modulo_shift(mode);
+               assert(modulo_shf >= (int) get_mode_size_bits(mode));
+               if (modulo_shf > 0) {
+                       tarval *modulo = new_tarval_from_long(modulo_shf,
+                                                             get_tarval_mode(res));
+
+                       /* shifting too much */
+                       if (!(tarval_cmp(res, modulo) & pn_Cmp_Lt)) {
+                               if (is_Shrs(n)) {
+                                       ir_graph *irg   = get_irn_irg(n);
+                                       ir_node  *block = get_nodes_block(n);
+                                       dbg_info *dbgi  = get_irn_dbg_info(n);
+                                       ir_node  *cnst  = new_Const(mode_Iu, new_tarval_from_long(get_mode_size_bits(mode)-1, mode_Iu));
+                                       return new_rd_Shrs(dbgi, irg, block, get_binop_left(left),
+                                                          cnst, mode);
+                               }
 
-               if (tarval_cmp(res, modulo) & pn_Cmp_Lt)
-                       flag = 1;
-       } else
-               flag = 1;
+                               return new_Const(mode, get_mode_null(mode));
+                       }
+               }
+       } else {
+               res = tarval_mod(res, new_tarval_from_long(get_mode_size_bits(mode), get_tarval_mode(res)));
+       }
 
-       if (flag) {
-               /* ok, we can replace it */
-               ir_node *in[2], *irn, *block = get_irn_n(n, -1);
+       /* ok, we can replace it */
+       ir_node *in[2], *irn, *block = get_irn_n(n, -1);
 
-               in[0] = get_binop_left(left);
-               in[1] = new_r_Const(current_ir_graph, block, get_tarval_mode(res), res);
+       in[0] = get_binop_left(left);
+       in[1] = new_r_Const(current_ir_graph, block, get_tarval_mode(res), res);
 
-               irn = new_ir_node(NULL, current_ir_graph, block, get_irn_op(n), mode, 2, in);
+       irn = new_ir_node(NULL, current_ir_graph, block, get_irn_op(n), mode, 2, in);
 
-               DBG_OPT_ALGSIM0(n, irn, FS_OPT_REASSOC_SHIFT);
+       DBG_OPT_ALGSIM0(n, irn, FS_OPT_REASSOC_SHIFT);
 
-               return transform_node(irn);
-       }
-       return n;
+       return transform_node(irn);
 }  /* transform_node_shift */
 
 /**