fix shiftop optimization failing for negative shift values

diff --git a/ir/ir/iropt.c b/ir/ir/iropt.c
index 679410d..f590cf3 100644 (file)
--- a/ir/ir/iropt.c
+++ b/ir/ir/iropt.c
@@ -4717,6 +4717,7 @@ static ir_node *transform_node_shift(ir_node *n)
        ir_tarval *tv1, *tv2, *res;
        ir_node *in[2], *irn, *block;
        ir_graph *irg;
+       int       modulo_shf;
 
        left = get_binop_left(n);
 
@@ -4725,7 +4726,7 @@ static ir_node *transform_node_shift(ir_node *n)
                return n;
 
        right = get_binop_right(n);
-       tv1 = value_of(right);
+       tv1   = value_of(right);
        if (tv1 == tarval_bad)
                return n;
 
@@ -4733,13 +4734,25 @@ static ir_node *transform_node_shift(ir_node *n)
        if (tv2 == tarval_bad)
                return n;
 
+       mode       = get_irn_mode(n);
+       modulo_shf = get_mode_modulo_shift(mode);
+
+       if (modulo_shf > 0) {
+               ir_mode   *sc_mode     = get_tarval_mode(tv1);
+               ir_tarval *modulo_mask = new_tarval_from_long(modulo_shf-1, sc_mode);
+
+               /* modulo shifts should always be a power of 2 (otherwise modulo_mask
+                * above will be invalid) */
+               assert(modulo_shf<=0 || is_po2(modulo_shf));
+
+               tv1 = tarval_and(tv1, modulo_mask);
+               tv2 = tarval_and(tv2, modulo_mask);
+       }
        res  = tarval_add(tv1, tv2);
-       mode = get_irn_mode(n);
        irg  = get_irn_irg(n);
 
        /* beware: a simple replacement works only, if res < modulo shift */
        if (!is_Rotl(n)) {
-               int modulo_shf = get_mode_modulo_shift(mode);
                if (modulo_shf > 0) {
                        ir_tarval *modulo = new_tarval_from_long(modulo_shf,
                                                                 get_tarval_mode(res));
@@ -4751,7 +4764,7 @@ static ir_node *transform_node_shift(ir_node *n)
                                if (is_Shrs(n)) {
                                        ir_node  *block = get_nodes_block(n);
                                        dbg_info *dbgi  = get_irn_dbg_info(n);
-                                       ir_mode  *smode  = get_irn_mode(right);
+                                       ir_mode  *smode = get_irn_mode(right);
                                        ir_node  *cnst  = new_r_Const_long(irg, smode, get_mode_size_bits(mode) - 1);
                                        return new_rd_Shrs(dbgi, block, get_binop_left(left), cnst, mode);
                                }