+static void compute_block_info(ir_node *n, void *x)
+{
+ ir_phase *block_info = (ir_phase *)x;
+
+ if (is_Block(n)) {
+ int i, max = get_Block_n_cfgpreds(n);
+ for (i=0; i<max; i++) {
+ ir_node *pred = get_Block_cfgpred(n,i);
+ if (is_unknown_jump(pred)) {
+ set_is_unknown_jump_target(block_info, n);
+ }
+ }
+ } else if (is_Phi(n)) {
+ ir_node *block = get_nodes_block(n);
+ set_has_phis(block_info, block);
+ } else if (is_Jmp(n) || is_Cond(n) || is_Cmp(n) || is_Proj(n)) {
+ /* ignore */
+ } else {
+ ir_node *block = get_nodes_block(n);
+ set_has_operations(block_info, block);
+ }
+}
+
+typedef struct skip_env {
+ bool changed;
+ ir_phase *phase;
+} skip_env;
+
+/**
+ * Post-Block-walker: Optimize useless if's (boolean Cond nodes
+ * with same true/false target)
+ * away.
+ */
+static void optimize_ifs(ir_node *block, void *x)
+{
+ skip_env *env = (skip_env*)x;
+ int i, j;
+ int n_preds = get_Block_n_cfgpreds(block);
+
+ if (has_phis(env->phase, block))
+ return;
+
+ /* optimize Cond predecessors (might produce Bad predecessors) */
+ for (i = 0; i < n_preds; ++i) {
+ for (j = i+1; j < n_preds; ++j) {
+ optimize_pred_cond(block, i, j);
+ }
+ }
+}
+
+/**
+ * Pre-Block walker: remove empty blocks that are
+ * predecessors of the current block.
+ */
+static void remove_empty_blocks(ir_node *block, void *x)
+{
+ skip_env *env = (skip_env*)x;
+ int i;
+ int n_preds = get_Block_n_cfgpreds(block);
+
+ for (i = 0; i < n_preds; ++i) {
+ ir_node *jmp, *jmp_block, *pred, *pred_block;
+
+ jmp = get_Block_cfgpred(block, i);
+ if (!is_Jmp(jmp))
+ continue;
+ jmp_block = get_nodes_block(jmp);
+ if (is_unknown_jump_target(env->phase, jmp_block))
+ continue;
+ if (has_operations(env->phase,jmp_block))
+ continue;
+ /* jmp_block is an empty block! */
+
+ if (get_Block_n_cfgpreds(jmp_block) != 1)
+ continue;
+ pred = get_Block_cfgpred(jmp_block, 0);
+ exchange(jmp, pred);
+ env->changed = true;
+
+ /* cleanup: jmp_block might have a Keep edge! */
+ pred_block = get_nodes_block(pred);
+ exchange(jmp_block, pred_block);
+ }
+}
+
+/*
+ * Some cfg optimizations, which do not touch Phi nodes
+ */
+static void cfgopt_ignoring_phis(ir_graph *irg)
+{
+ ir_phase *block_info = new_phase(irg, NULL);
+ skip_env env = { false, block_info };
+
+ irg_walk_graph(irg, compute_block_info, NULL, block_info);
+
+ for (;;) {
+ env.changed = false;
+
+ /* optimize useless ifs: will not touch empty blocks */
+ irg_block_walk_graph(irg, NULL, optimize_ifs, &env);
+
+ /* Remove empty blocks */
+ irg_block_walk_graph(irg, remove_empty_blocks, NULL, &env);
+ if (env.changed) {
+ set_irg_doms_inconsistent(irg);
+ /* Removing blocks might enable more useless-if optimizations */
+ continue;
+ } else {
+ break;
+ }
+ }
+
+ phase_free(block_info);
+}
+
+/* Optimizations of the control flow that also require changes of Phi nodes. */