make get_Block_cfgpred_block return NULL on Bad cfopt

Previously a Bad node was returned which could hide problems and more
importantly you create new nodes (the BadBB) in an operation that apparently
only queries the graph.

include/libfirm/irnode.h

@@ -242,8 +242,7 @@ FIRM_API int get_Block_cfgpred_pos(const ir_node *block, const ir_node *pred);
  *
  * Returns the block corresponding to the predecessor pos of block.
  *
- * If we encounter the Bad node, this function does not return Start block, but
- * the Bad node.
+ * If we encounter the Bad node as controlflow predecessor NULL is returned.
  */
 FIRM_API ir_node *get_Block_cfgpred_block(const ir_node *node, int pos);
 

ir/ana/cdep.c

@@ -90,7 +90,7 @@ static void cdep_pre(ir_node *node, void *ctx)
 	(void)ctx;
 	for (int i = get_Block_n_cfgpreds(node); i-- > 0; ) {
 		ir_node *pred = get_Block_cfgpred_block(node, i);
-		if (is_Bad(pred))
+		if (pred == NULL)
 			continue;
 
 		ir_node *pdom = get_Block_ipostdom(pred);

ir/ana/execfreq.c

@@ -160,7 +160,7 @@ static double get_cf_probability(const ir_node *bb, int pos,
                                  double inv_loop_weight)
 {
 	const ir_node *pred = get_Block_cfgpred_block(bb, pos);
-	if (is_Bad(pred))
+	if (pred == NULL)
 		return 0;
 
 	const ir_loop *loop       = get_irn_loop(bb);

ir/ana/ircfscc.c

@@ -300,7 +300,7 @@ static int is_head(ir_node *n, ir_node *root)
 	for (int i = 0, arity = get_Block_n_cfgpreds(n); i < arity; i++) {
 		ir_node *pred = get_Block_cfgpred_block(n, i);
 		/* ignore Bad control flow: it cannot happen */
-		if (is_Bad(pred))
+		if (pred == NULL)
 			continue;
 		if (is_backedge(n, i))
 			continue;
@@ -333,7 +333,7 @@ static int is_endless_head(ir_node *n, ir_node *root)
 	for (int i = 0, arity = get_Block_n_cfgpreds(n); i < arity; i++) {
 		ir_node *pred = get_Block_cfgpred_block(n, i);
 		/* ignore Bad control flow: it cannot happen */
-		if (is_Bad(pred))
+		if (pred == NULL)
 			continue;
 		if (is_backedge(n, i))
 			continue;
@@ -358,7 +358,7 @@ static int smallest_dfn_pred(ir_node *n, int limit)
 	for (int i = 0, arity = get_Block_n_cfgpreds(n); i < arity; i++) {
 		ir_node *pred = get_Block_cfgpred_block(n, i);
 		/* ignore Bad control flow: it cannot happen */
-		if (is_Bad(pred))
+		if (pred == NULL)
 			continue;
 		if (is_backedge(n, i) || !irn_is_in_stack(pred))
 			continue;
@@ -380,7 +380,7 @@ static int largest_dfn_pred(ir_node *n)
 	for (int i = 0, arity = get_Block_n_cfgpreds(n); i < arity; i++) {
 		ir_node *pred = get_Block_cfgpred_block(n, i);
 		/* ignore Bad control flow: it cannot happen */
-		if (is_Bad(pred))
+		if (pred == NULL)
 			continue;
 		if (is_backedge(n, i) || !irn_is_in_stack(pred))
 			continue;
@@ -488,7 +488,7 @@ static void cfscc(ir_node *n)
 			continue;
 		ir_node *m = get_Block_cfgpred_block(n, i);
 		/* ignore Bad control flow: it cannot happen */
-		if (is_Bad(m))
+		if (m == NULL)
 			continue;
 
 		cfscc(m);

ir/ana/irdom.c

@@ -427,7 +427,7 @@ static void init_tmp_pdom_info(ir_node *block, tmp_dom_info *parent,
 	/* Iterate */
 	for (int i = get_Block_n_cfgpreds(block) - 1; i >= 0; --i) {
 		ir_node *pred = get_Block_cfgpred_block(block, i);
-		if (is_Bad(pred))
+		if (pred == NULL)
 			continue;
 		init_tmp_pdom_info(pred, tdi, tdi_list, used, n_blocks);
 	}

ir/ana/irlivechk.c

@@ -332,6 +332,8 @@ unsigned lv_chk_bl_xxx(lv_chk_t *lv, const ir_node *bl, const ir_node *var)
 			if (is_Phi(user)) {
 				int pos = get_edge_src_pos(edge);
 				use_bl  = get_Block_cfgpred_block(use_bl, pos);
+				if (use_bl == NULL)
+					continue;
 				mask   |= lv_chk_state_end;
 			}
 

ir/be/begnuas.c

@@ -1340,6 +1340,8 @@ void be_gas_begin_block(const ir_node *block, bool needs_label)
 		} else {
 			for (int i = 0; i < arity; ++i) {
 				ir_node *predblock = get_Block_cfgpred_block(block, i);
+				if (predblock == NULL)
+					continue;
 				be_emit_char(' ');
 				be_gas_emit_block_name(predblock);
 			}

ir/ir/ircons.c

@@ -159,7 +159,7 @@ static ir_node *set_phi_arguments(ir_node *phi, int pos)
 	for (i = 0; i < arity; ++i) {
 		ir_node *cfgpred = get_Block_cfgpred_block(block, i);
 		ir_node *value;
-		if (is_Bad(cfgpred)) {
+		if (cfgpred == NULL) {
 			value = new_r_Bad(irg, mode);
 		} else {
 			value = get_r_value_internal(cfgpred, pos, mode);
@@ -461,7 +461,9 @@ static ir_mode *guess_recursively(ir_node *block, int pos)
 	n_preds = get_irn_arity(block);
 	for (i = 0; i < n_preds; ++i) {
 		ir_node *pred_block = get_Block_cfgpred_block(block, i);
-		ir_mode *mode       = guess_recursively(pred_block, pos);
+		if (pred_block == NULL)
+			continue;
+		ir_mode *mode = guess_recursively(pred_block, pos);
 		if (mode != NULL)
 			return mode;
 	}

ir/ir/irnode_t.h

@@ -340,16 +340,13 @@ static inline int is_binop_(const ir_node *node)
  *
  * Returns the block corresponding to the predecessor pos.
  *
- * If we encounter the Bad node, this function does not return the Start block,
- * but the Bad node.
+ * If we encounter the Bad node, this function returns NULL.
  */
 static inline ir_node *get_Block_cfgpred_block_(const ir_node *node, int pos)
 {
 	ir_node *res = get_Block_cfgpred(node, pos);
 	if (is_Bad(res)) {
-		/* must return a Bad with mode_BB! */
-		ir_graph *irg = get_irn_irg(node);
-		return new_r_Bad(irg, mode_BB);
+		return NULL;
 	} else {
 		return get_nodes_block(res);
 	}

ir/ir/irprofile.c

@@ -283,7 +283,7 @@ static void fix_ssa(ir_node *bb, void *data)
 		mem = get_irg_initial_mem(irg);
 	} else if (arity == 1) {
 		ir_node *pred = get_Block_cfgpred_block(bb, 0);
-		if (!is_Bad(pred))
+		if (pred != NULL)
 			mem = (ir_node*) get_irn_link(pred);
 		else
 			mem = new_r_NoMem(irg);
@@ -291,7 +291,7 @@ static void fix_ssa(ir_node *bb, void *data)
 		ir_node **ins = ALLOCAN(ir_node*, arity);
 		for (n = arity - 1; n >= 0; --n) {
 			ir_node *pred = get_Block_cfgpred_block(bb, n);
-			if (!is_Bad(pred))
+			if (pred != NULL)
 				ins[n] = (ir_node*) get_irn_link(pred);
 			else
 				ins[n] = new_r_NoMem(irg);
@@ -351,6 +351,8 @@ static void instrument_irg(ir_graph *irg, ir_entity *counters,
 	for (i = get_Block_n_cfgpreds(endbb) - 1; i >= 0; --i) {
 		ir_node *node = skip_Proj(get_Block_cfgpred(endbb, i));
 		ir_node *bb   = get_Block_cfgpred_block(endbb, i);
+		if (bb == NULL)
+			continue;
 		ir_node *mem;
 
 		switch (get_irn_opcode(node)) {

ir/ir/irverify.c

@@ -936,9 +936,12 @@ static bool check_dominance_for_node(const ir_node *use)
 			continue;
 
 		ir_node *use_bl = bl;
-		if (is_Phi(use))
+		if (is_Phi(use)) {
 			use_bl = get_Block_cfgpred_block(bl, i);
-		if (!is_Block(use_bl) || get_Block_dom_depth(use_bl) == -1)
+			if (use_bl == NULL)
+				continue;
+		}
+		if (get_Block_dom_depth(use_bl) == -1)
 			continue;
 
 		if (!block_dominates(def_bl, use_bl)) {

ir/opt/boolopt.c

@@ -584,6 +584,8 @@ restart:
 
 		ir_node *const cond_selector = get_Cond_selector(cond);
 		ir_node *const lower_pred    = get_Block_cfgpred_block(lower_block, 0);
+		if (lower_pred == NULL)
+			continue;
 		for (up_idx = 0; up_idx < n_cfgpreds; ++up_idx) {
 			ir_node   *upper_block;
 			ir_node   *upper_cf;

ir/opt/cfopt.c

@@ -415,7 +415,7 @@ static void optimize_blocks(ir_node *b, void *ctx)
 					for (int i = k+1; i < get_Block_n_cfgpreds(b); i++) {
 						ir_node *phi_pred = get_Block_cfgpred_block(b, i);
 
-						if (is_Bad(phi_pred)) {
+						if (phi_pred == NULL) {
 							ir_graph *irg  = get_irn_irg(b);
 							ir_mode  *mode = get_irn_mode(phi);
 							in[q_preds++] = new_r_Bad(irg, mode);

ir/opt/code_placement.c

@@ -180,7 +180,7 @@ static ir_node *consumer_dom_dca(ir_node *dca, ir_node *consumer,
 		for (int i = 0;  i < arity; i++) {
 			if (get_Phi_pred(consumer, i) == producer) {
 				ir_node *new_block = get_Block_cfgpred_block(phi_block, i);
-				if (is_Bad(new_block))
+				if (new_block == NULL)
 					continue;
 
 				assert(is_block_reachable(new_block));

ir/opt/gvn_pre.c

@@ -530,7 +530,7 @@ static void infinite_loop_walker(ir_node *block, void *env)
 		/* reachable block: mark all cf predecessors */
 		for (i = 0; i < arity; ++i) {
 			ir_node *pred = get_Block_cfgpred_block(block, i);
-			if (is_Bad(pred))
+			if (pred == NULL)
 				continue;
 			set_Block_mark(pred, 1);
 		}
@@ -549,8 +549,7 @@ static void infinite_loop_walker(ir_node *block, void *env)
 		/* passing information to the cf predecessors */
 		for (i = 0; i < arity; ++i) {
 			ir_node *pred = get_Block_cfgpred_block(block, i);
-
-			if (is_Bad(pred))
+			if (pred == NULL)
 				continue;
 
 			/* If our cf predecessor is in the same endless loop,

ir/opt/jumpthreading.c

@@ -53,11 +53,7 @@ static ir_node *ssa_second_def_block;
 static ir_node *search_def_and_create_phis(ir_node *block, ir_mode *mode,
                                            bool first)
 {
-	/* In case of a bad input to a block we need to return the bad value */
-	if (is_Bad(block)) {
-		ir_graph *irg = get_irn_irg(block);
-		return new_r_Bad(irg, mode);
-	}
+	assert(is_Block(block));
 
 	/* the other defs can't be marked for cases where a user of the original
 	 * value is in the same block as the alternative definition.
@@ -81,8 +77,13 @@ static ir_node *search_def_and_create_phis(ir_node *block, ir_mode *mode,
 	int n_cfgpreds = get_Block_n_cfgpreds(block);
 	if (n_cfgpreds == 1) {
 		ir_node *pred_block = get_Block_cfgpred_block(block, 0);
-		ir_node *value      = search_def_and_create_phis(pred_block, mode,
-		                                                 false);
+		ir_node *value;
+		if (pred_block == NULL) {
+			ir_graph *irg = get_irn_irg(block);
+			value = new_r_Bad(irg, mode);
+		} else {
+			value = search_def_and_create_phis(pred_block, mode, false);
+		}
 		set_irn_link(block, value);
 		mark_irn_visited(block);
 		return value;
@@ -101,8 +102,13 @@ static ir_node *search_def_and_create_phis(ir_node *block, ir_mode *mode,
 	/* set Phi predecessors */
 	for (int i = 0; i < n_cfgpreds; ++i) {
 		ir_node *pred_block = get_Block_cfgpred_block(block, i);
-		ir_node *pred_val   = search_def_and_create_phis(pred_block, mode,
-		                                                 false);
+		ir_node *pred_val;
+		if (pred_block == NULL) {
+			ir_graph *irg = get_irn_irg(block);
+			pred_val = new_r_Bad(irg, mode);
+		} else {
+			pred_val = search_def_and_create_phis(pred_block, mode, false);
+		}
 		set_irn_n(phi, i, pred_val);
 	}
 
@@ -146,7 +152,12 @@ static void construct_ssa(ir_node *orig_block, ir_node *orig_val,
 		ir_node *newval;
 		if (is_Phi(user)) {
 			ir_node *pred_block = get_Block_cfgpred_block(user_block, j);
-			newval = search_def_and_create_phis(pred_block, mode, true);
+			if (pred_block == NULL) {
+				ir_graph *irg = get_irn_irg(user_block);
+				newval = new_r_Bad(irg, mode);
+			} else {
+				newval = search_def_and_create_phis(pred_block, mode, true);
+			}
 		} else {
 			newval = search_def_and_create_phis(user_block, mode, true);
 		}