Today's localopt: a * (1 << x) -> a << x.

[libfirm] / ir / ir / iropt.c

diff --git a/ir/ir/iropt.c b/ir/ir/iropt.c
index 85bee08..d80880b 100644 (file)
--- a/ir/ir/iropt.c
+++ b/ir/ir/iropt.c
@@ -429,7 +429,7 @@ static tarval *computed_value_Mux(const ir_node *n) {
 static tarval *computed_value_Confirm(const ir_node *n) {
        /*
         * Beware: we might produce Phi(Confirm(x == true), Confirm(x == false)).
-        * Do NOT optimize them away (CondEval wants them), so wait until
+        * Do NOT optimize them away (jump threading wants them), so wait until
         * remove_confirm is activated.
         */
        if (get_opt_remove_confirm()) {
@@ -2775,6 +2775,28 @@ static ir_node *transform_node_Mul(ir_node *n) {
                        DBG_OPT_ALGSIM1(oldn, a, b, n, FS_OPT_MUL_MINUS);
                        return n;
                }
+       } else if (is_Shl(a)) {
+               ir_node *const shl_l = get_Shl_left(a);
+               if (is_Const(shl_l) && is_Const_one(shl_l)) {
+                       /* (1 << x) * b -> b << x */
+                       dbg_info *const dbgi  = get_irn_dbg_info(n);
+                       ir_node  *const block = get_nodes_block(n);
+                       ir_node  *const shl_r = get_Shl_right(a);
+                       n = new_rd_Shl(dbgi, block, b, shl_r, mode);
+                       // TODO add me DBG_OPT_ALGSIM1(oldn, a, b, n, FS_OPT_MUL_SHIFT);
+                       return n;
+               }
+       } else if (is_Shl(b)) {
+               ir_node *const shl_l = get_Shl_left(b);
+               if (is_Const(shl_l) && is_Const_one(shl_l)) {
+                       /* a * (1 << x) -> a << x */
+                       dbg_info *const dbgi  = get_irn_dbg_info(n);
+                       ir_node  *const block = get_nodes_block(n);
+                       ir_node  *const shl_r = get_Shl_right(b);
+                       n = new_rd_Shl(dbgi, block, a, shl_r, mode);
+                       // TODO add me DBG_OPT_ALGSIM1(oldn, a, b, n, FS_OPT_MUL_SHIFT);
+                       return n;
+               }
        }
        if (get_mode_arithmetic(mode) == irma_ieee754) {
                if (is_Const(a)) {