2 * Copyright (C) 1995-2007 University of Karlsruhe. All right reserved.
4 * This file is part of libFirm.
6 * This file may be distributed and/or modified under the terms of the
7 * GNU General Public License version 2 as published by the Free Software
8 * Foundation and appearing in the file LICENSE.GPL included in the
9 * packaging of this file.
11 * Licensees holding valid libFirm Professional Edition licenses may use
12 * this file in accordance with the libFirm Commercial License.
13 * Agreement provided with the Software.
15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
16 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * @brief Loop datastructure and access functions.
23 * @author Goetz Lindenmaier
27 * Computes backedges in the control and data flow.
30 * Only Block and Phi/Filter nodes can have incoming backedges.
31 * Constructs loops data structure: indicates loop nesting.
33 # ifndef FIRM_ANA_IRLOOP_H
34 # define FIRM_ANA_IRLOOP_H
39 /* ------------------------------------------------------------------- */
41 * Backedge information.
43 * Predecessors of Block, Phi and interprocedural Filter nodes can
44 * have backedges. If loop information is computed, this
45 * information is computed, too.
46 * The backedge information can only be used if the graph is not in
47 * phase phase_building.
49 /* ------------------------------------------------------------------- */
51 /** Returns true if the predecessor pos is a backedge in the interprozeduralem view. */
52 int is_inter_backedge(ir_node *n, int pos);
53 /** Returns true if the predecessor pos is a backedge in the intraprocedural view. */
54 int is_intra_backedge(ir_node *n, int pos);
55 /** Returns non-zero if the predecessor pos is a backedge. */
56 int is_backedge (ir_node *n, int pos);
57 /** Marks edge pos as a backedge. */
58 void set_backedge (ir_node *n, int pos);
59 /** Marks edge pos as a non-backedge. */
60 void set_not_backedge (ir_node *n, int pos);
61 /** Returns non-zero if n has backedges. */
62 int has_backedges (ir_node *n);
63 /** Clears all backedge information. */
64 void clear_backedges (ir_node *n);
68 /** Loop elements: loop nodes and ir nodes */
70 firm_kind *kind; /**< is either k_ir_node or k_ir_loop */
71 ir_node *node; /**< Pointer to an ir_node element */
72 ir_loop *son; /**< Pointer to an ir_loop element */
75 int is_ir_loop(const void *thing);
77 /** Set the outermost loop in ir graph as basic access to loop tree. */
78 void set_irg_loop(ir_graph *irg, ir_loop *l);
80 /* Returns the root loop info (if exists) for an irg. */
81 ir_loop *get_irg_loop(ir_graph *irg);
83 /** Returns the loop n is contained in. NULL if node is in no loop. */
84 ir_loop *get_irn_loop(const ir_node *n);
86 /** Returns outer loop, itself if outermost. */
87 ir_loop *get_loop_outer_loop (const ir_loop *loop);
88 /** Returns nesting depth of this loop */
89 int get_loop_depth (const ir_loop *loop);
91 /* Sons are the inner loops contained in this loop. */
92 /** Returns the number of inner loops */
93 int get_loop_n_sons (const ir_loop *loop);
95 /** Returns the pos`th son loop (inner loop) of a loop.
96 Returns NULL if there is not a pos`th loop_node. */
97 ir_loop *get_loop_son (ir_loop *loop, int pos);
99 /** Returns the number of nodes contained in loop. */
100 int get_loop_n_nodes (ir_loop *loop);
102 /** Returns the pos`th ir_node of a loop.
103 Returns NULL if there is not a pos`th ir_node. */
104 ir_node *get_loop_node (ir_loop *loop, int pos);
106 /** Returns the number of elements contained in loop. */
107 int get_loop_n_elements (const ir_loop *loop);
109 /** Returns a loop element. A loop element can be interpreted as a
110 kind pointer, an ir_node* or an ir_loop*. */
111 loop_element get_loop_element (const ir_loop *loop, int pos);
113 /** Returns the element number of the loop son in loop.
114 * Returns -1 if not found. O(|elements|). */
115 int get_loop_element_pos(const ir_loop *loop, void *le);
117 /** Returns a unique node number for the loop node to make output
118 readable. If libfirm_debug is not set it returns the loop cast to
120 int get_loop_loop_nr(const ir_loop *loop);
122 /** A field to connect additional information to a loop. Only valid
123 if libfirm_debug is set, else returns NULL. */
124 void set_loop_link (ir_loop *loop, void *link);
125 void *get_loop_link (const ir_loop *loop);
127 /* ------------------------------------------------------------------- */
128 /* Constructing and destructing the loop/backedge information. */
129 /* ------------------------------------------------------------------- */
131 /** Constructs backedge information and loop tree for a graph in intraprocedural view.
133 * The algorithm views the program representation as a pure graph.
134 * It assumes that only block and phi nodes may be loop headers.
135 * The resulting loop tree is a possible visiting order for dataflow
138 * This algorithm destoyes the link field of block nodes.
140 * @returns Maximal depth of loop tree.
143 * One assumes, the Phi nodes in a block with a backedge have backedges
144 * at the same positions as the block. This is not the case, as
145 * the scc algorithms does not respect the program semantics in this case.
146 * Take a swap in a loop (t = i; i = j; j = t;) This results in two Phi
147 * nodes. They form a cycle. Once the scc algorithm deleted one of the
148 * edges, the cycle is removed. The second Phi node does not get a
151 /* @@@ Well, maybe construct_loop_information or analyze_loops ? */
152 int construct_backedges(ir_graph *irg);
154 /** Constructs backedges for all irgs in interprocedural view.
156 * @see As construct_backedges(), but for interprocedural view.
159 * All loops in the graph will be marked as such, not only
160 * realizeable loops and recursions in the program. E.g., if the
161 * same funcion is called twice, there is a loop between the first
162 * function return and the second call.
164 * @returns Maximal depth of loop tree.
166 int construct_ip_backedges(void);
168 /** Construct loop tree only for control flow.
170 * This constructs loop information resembling the program structure.
171 * It is useful for loop optimizations and analyses, as, e.g., finding
172 * iteration variables or loop invariant code motion.
174 * This algorithm computes only back edge information for Block nodes, not
177 * This algorithm destoyes the link field of block nodes.
179 * @returns Maximal depth of loop tree.
181 int construct_cf_backedges(ir_graph *irg);
183 /** Construct interprocedural loop tree for control flow.
185 * @see construct_cf_backedges() and construct_ip_backedges().
187 int construct_ip_cf_backedges (void);
189 /** Removes all loop information.
190 * Resets all backedges. Works for any construction algorithm.
192 void free_loop_information(ir_graph *irg);
193 void free_all_loop_information (void);
198 /* ------------------------------------------------------------------- */
199 /* Simple analyses based on the loop information */
200 /* ------------------------------------------------------------------- */
202 /** Test whether a value is loop invariant.
204 * @param n The node to be tested.
205 * @param block A block node.
207 * Returns non-zero, if the node n is not changed in the loop block
208 * belongs to or in inner loops of this block. */
209 int is_loop_invariant(ir_node *n, ir_node *block);