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22 * @brief Construct and access dominator tree.
23 * @author Goetz Lindenmaier
27 * This file contains routines to construct and access dominator information.
29 * The dominator information is stored in three fields of block nodes:
30 * - idom: a reference to the block that is the immediate dominator of
32 * - dom_depth: a number giving the depth of the block in the dominator
34 * - pre_num: Number in preorder traversal.
36 * We generally presume (like Tarjan) that endless loops do not exist. The
37 * implementation assumes a control dependency from End to loop header.
39 #ifndef FIRM_ANA_IRDOM_H
40 #define FIRM_ANA_IRDOM_H
42 #include "firm_types.h"
45 /** Accessing the dominator data structure.
47 * These routines only work properly if the ir_graph is in state
48 * dom_consistent or dom_inconsistent.
50 * If the block is not reachable from Start, returns a Bad node.
52 FIRM_API ir_node *get_Block_idom(const ir_node *bl);
53 FIRM_API void set_Block_idom(ir_node *bl, ir_node *n);
55 FIRM_API int get_Block_dom_depth(const ir_node *bl);
56 FIRM_API void set_Block_dom_depth(ir_node *bl, int depth);
58 FIRM_API int get_Block_dom_pre_num(const ir_node *bl);
59 FIRM_API void set_Block_dom_pre_num(ir_node *bl, int num);
61 /** Accessing the post dominator data structure.
63 * These routines only work properly if the ir_graph is in state
64 * dom_consistent or dom_inconsistent.
66 FIRM_API ir_node *get_Block_ipostdom(const ir_node *bl);
67 FIRM_API void set_Block_ipostdom(ir_node *bl, ir_node *n);
69 FIRM_API int get_Block_postdom_depth(const ir_node *bl);
70 FIRM_API void set_Block_postdom_depth(ir_node *bl, int depth);
72 FIRM_API int get_Block_postdom_pre_num(const ir_node *bl);
73 FIRM_API void set_Block_postdom_pre_num(ir_node *bl, int num);
76 * Get the pre-order number of a block resulting from a
77 * Depth-First-Search walkover the dominator tree.
79 * @param bl The block.
80 * @return The pre-order number.
82 FIRM_API unsigned get_Block_dom_tree_pre_num(const ir_node *bl);
83 FIRM_API unsigned get_Block_pdom_tree_pre_num(const ir_node *bl);
86 * Get the largest pre-order number found in the subtree of the
87 * dominator tree rooted at a given block.
88 * @param bl The block.
89 * @return The largest pre-order number of block's dominator subtree.
91 FIRM_API unsigned get_Block_dom_max_subtree_pre_num(const ir_node *bl);
92 FIRM_API unsigned get_Block_pdom_max_subtree_pre_num(const ir_node *bl);
95 * Get the first node in the list of nodes dominated by a given block.
97 * Each node keeps a list of nodes which it immediately dominates. The
98 * nodes are queued using the @c next pointer in the @c dom_info struct.
99 * Each node keeps a head of this list using the pointer @c first in the
102 * @param bl The block for which to get the first node dominated by @c bl.
103 * @return The first node dominated by @p bl.
105 FIRM_API ir_node *get_Block_dominated_first(const ir_node *bl);
106 FIRM_API ir_node *get_Block_postdominated_first(const ir_node *bl);
109 * Get the next node in a list of nodes which are dominated by some
111 * @see get_Block_dominated_first().
112 * @param dom The previous node.
113 * @return The next node in this list or NULL if it was the last.
115 FIRM_API ir_node *get_Block_dominated_next(const ir_node *dom);
116 FIRM_API ir_node *get_Block_postdominated_next(const ir_node *dom);
119 * Iterate over all nodes which are immediately dominated by a given
121 * @param bl The block whose dominated blocks shall be iterated on.
122 * @param curr An iterator variable of type ir_node*
124 #define dominates_for_each(bl,curr) \
125 for(curr = get_Block_dominated_first(bl); curr; \
126 curr = get_Block_dominated_next(curr))
129 * Iterate over all nodes which are immediately post dominated by a given
131 * @param bl The block whose post dominated blocks shall be iterated on.
132 * @param curr An iterator variable of type ir_node*
134 #define postdominates_for_each(bl,curr) \
135 for(curr = get_Block_postdominated_first(bl); curr; \
136 curr = get_Block_postdominated_next(curr))
139 * Check, if a block dominates another block.
141 * @param a The potential dominator block.
142 * @param b The potentially dominated block.
144 * @return 1, if @p a dominates @p b, else 0.
146 FIRM_API int block_dominates(const ir_node *a, const ir_node *b);
149 * Check, if a block strictly dominates another block, i.e. a != b.
151 * @param a The potential dominator block.
152 * @param b The potentially dominated block.
154 * @return 1, if @p a strictly dominates @p b, else 0.
156 FIRM_API int block_strictly_dominates(const ir_node *a, const ir_node *b);
159 * Returns the smallest common dominator block of two nodes.
161 * @param b Another node.
162 * @return The first block dominating @p a and @p b
164 FIRM_API ir_node *node_smallest_common_dominator(ir_node *a, ir_node *b);
167 * Returns the smallest common dominator block of all users of a node
168 * BEWARE: @p irn must not be a block
169 * If on or more users are Phi nodes, one can request special handling
170 * with @p handle_phi = 1. In this case the cfg predecessor block
171 * corresponding to the position of the irn in the argument list of the
172 * Phi is determined and treated as user.
175 * @param handle_phi 1 if Phis should be handled different
176 * @return The first block dominating all users of @p irn
178 FIRM_API ir_node *node_users_smallest_common_dominator(ir_node *irn,
182 * Check, if a block post dominates another block.
184 * @param a The potential post dominator block.
185 * @param b The potentially post dominated block.
187 * @return 1, if @p a post dominates @p b, else 0.
189 FIRM_API int block_postdominates(const ir_node *a, const ir_node *b);
192 * Check, if a block strictly post dominates another block, i.e. a != b.
194 * @param a The potential post dominator block.
195 * @param b The potentially post dominated block.
197 * @return 1, if @p a strictly post dominates @p b, else 0.
199 FIRM_API int block_strictly_postdominates(const ir_node *a, const ir_node *b);
202 * Visit all nodes in the dominator subtree of a given node.
203 * Call a pre-visitor before descending to the children and call a
204 * post-visitor after returning from them.
205 * @param n The node to start walking from.
206 * @param pre The pre-visitor callback.
207 * @param post The post-visitor callback.
208 * @param env Some custom data passed to the visitors.
210 FIRM_API void dom_tree_walk(ir_node *n, irg_walk_func *pre,
211 irg_walk_func *post, void *env);
214 * Visit all nodes in the post dominator subtree of a given node.
215 * Call a pre-visitor before descending to the children and call a
216 * post-visitor after returning from them.
217 * @param n The node to start walking from.
218 * @param pre The pre-visitor callback.
219 * @param post The post-visitor callback.
220 * @param env Some custom data passed to the visitors.
222 FIRM_API void postdom_tree_walk(ir_node *n, irg_walk_func *pre,
223 irg_walk_func *post, void *env);
226 * Walk over the dominator tree of an irg starting at the root.
227 * @param irg The graph.
228 * @param pre A pre-visitor to call.
229 * @param post A post-visitor to call.
230 * @param env Some private data to give to the visitors.
232 FIRM_API void dom_tree_walk_irg(ir_graph *irg, irg_walk_func *pre,
233 irg_walk_func *post, void *env);
236 * Walk over the post dominator tree of an irg starting at the root.
237 * @param irg The graph.
238 * @param pre A pre-visitor to call.
239 * @param post A post-visitor to call.
240 * @param env Some private data to give to the visitors.
242 FIRM_API void postdom_tree_walk_irg(ir_graph *irg, irg_walk_func *pre,
243 irg_walk_func *post, void *env);
245 /* ------------ Building and Removing the dominator data structure ----------- */
247 /** Computes the dominator trees.
249 * Sets a flag in irg to "dom_consistent".
250 * If the control flow of the graph is changed this flag must be set to
251 * "dom_inconsistent".
252 * Does not compute dominator information for control dead code. Blocks
253 * not reachable from Start contain the following information:
259 * Also constructs outs information. As this information is correct after
260 * the run does not free the outs information.
262 FIRM_API void compute_doms(ir_graph *irg);
264 /** Computes the dominator trees on demand, @see compute_doms(). */
265 FIRM_API void assure_doms(ir_graph *irg);
267 /** Computes the post dominator trees.
269 * Sets a flag in irg to "dom_consistent".
270 * If the control flow of the graph is changed this flag must be set to
271 * "dom_inconsistent".
272 * Does not compute post dominator information for endless lops. Blocks
273 * not reachable from End contain the following information:
279 * Also constructs outs information. As this information is correct after
280 * the run does not free the outs information.
282 FIRM_API void compute_postdoms(ir_graph *irg);
284 /** Computes the dominator trees on demand */
285 FIRM_API void assure_postdoms(ir_graph *irg);
287 /** Frees the dominator data structures. Sets the flag in irg to "dom_none". */
288 FIRM_API void free_dom(ir_graph *irg);
291 * Frees the post dominator data structures.
292 * Sets the flag in irg to "dom_none".
294 FIRM_API void free_postdom(ir_graph *irg);