+/**
+ * Block-walker: searches for the following construct
+ *
+ * Const or Phi with constants
+ * |
+ * Cmp
+ * |
+ * Cond
+ * /
+ * ProjX
+ * /
+ * Block
+ */
+static void cond_eval(ir_node* block, void* data)
+{
+ condeval_env_t env;
+ int *changed = data;
+ ir_node *selector;
+ ir_node *projx;
+ ir_node *cond;
+ ir_node *copy_block;
+ int selector_evaluated;
+ const ir_edge_t *edge, *next;
+ ir_node *bad;
+ size_t cnst_pos;
+
+ if (get_Block_n_cfgpreds(block) != 1)
+ return;
+
+ projx = get_Block_cfgpred(block, 0);
+ if (!is_Proj(projx))
+ return;
+ assert(get_irn_mode(projx) == mode_X);
+
+ cond = get_Proj_pred(projx);
+ if (!is_Cond(cond))
+ return;
+
+ selector = get_Cond_selector(cond);
+ /* TODO handle switch Conds */
+ if (get_irn_mode(selector) != mode_b)
+ return;
+
+ /* handle cases that can be immediately evaluated */
+ selector_evaluated = -1;
+ if (is_Proj(selector)) {
+ ir_node *cmp = get_Proj_pred(selector);
+ if (is_Cmp(cmp)) {
+ ir_node *left = get_Cmp_left(cmp);
+ ir_node *right = get_Cmp_right(cmp);
+ if (is_Const(left) && is_Const(right)) {
+ int pnc = get_Proj_proj(selector);
+ tarval *tv_left = get_Const_tarval(left);
+ tarval *tv_right = get_Const_tarval(right);
+
+ selector_evaluated = eval_cmp_tv(pnc, tv_left, tv_right);
+ if (selector_evaluated < 0)
+ return;
+ }
+ }
+ } else if (is_Const_or_Confirm(selector)) {
+ tarval *tv = get_Const_or_Confirm_tarval(selector);
+ if (tv == tarval_b_true) {
+ selector_evaluated = 1;
+ } else {
+ assert(tv == tarval_b_false);
+ selector_evaluated = 0;
+ }
+ }
+
+ env.cnst_pred = NULL;
+ if (get_Proj_proj(projx) == pn_Cond_false) {
+ env.tv = tarval_b_false;
+ if (selector_evaluated >= 0)
+ selector_evaluated = !selector_evaluated;
+ } else {
+ env.tv = tarval_b_true;
+ }
+
+ if (selector_evaluated == 0) {
+ bad = new_Bad();
+ exchange(projx, bad);
+ *changed = 1;
+ return;
+ } else if (selector_evaluated == 1) {
+ dbg_info *dbgi = get_irn_dbg_info(selector);
+ ir_node *jmp = new_rd_Jmp(dbgi, current_ir_graph, get_nodes_block(projx));
+ DBG_OPT_COND_EVAL(projx, jmp);
+ exchange(projx, jmp);
+ *changed = 1;
+ return;
+ }
+
+ /* (recursively) look if a pred of a Phi is a constant or a Confirm */
+ env.true_block = block;
+ inc_irg_visited(current_ir_graph);
+ env.visited_nr = get_irg_visited(current_ir_graph);
+
+ copy_block = find_candidate(&env, projx, selector);
+ if (copy_block == NULL)
+ return;
+
+ /* we have to remove the edge towards the pred as the pred now
+ * jumps into the true_block. We also have to shorten Phis
+ * in our block because of this */
+ bad = new_Bad();
+ cnst_pos = env.cnst_pos;
+
+ /* shorten Phis */
+ foreach_out_edge_safe(env.cnst_pred, edge, next) {
+ ir_node *node = get_edge_src_irn(edge);
+
+ if (is_Phi(node))
+ set_Phi_pred(node, cnst_pos, bad);
+ }
+
+ set_Block_cfgpred(env.cnst_pred, cnst_pos, bad);
+
+ /* the graph is changed now */
+ *changed = 1;
+}