2 * Copyright (C) 1995-2008 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 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
36 #include "firm_types.h"
37 #include "firm_common.h"
40 /* ------------------------------------------------------------------- */
42 * Backedge information.
44 * Predecessors of Block and Phi nodes can have backedges.
45 * If loop information is computed, this 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 non-zero if the predecessor pos is a backedge. */
52 FIRM_API int is_backedge(ir_node *n, int pos);
53 /** Marks edge pos as a backedge. */
54 FIRM_API void set_backedge(ir_node *n, int pos);
55 /** Marks edge pos as a non-backedge. */
56 FIRM_API void set_not_backedge(ir_node *n, int pos);
57 /** Returns non-zero if n has backedges. */
58 FIRM_API int has_backedges(ir_node *n);
59 /** Clears all backedge information. */
60 FIRM_API void clear_backedges(ir_node *n);
62 /** Loop elements: loop nodes and ir nodes */
64 firm_kind *kind; /**< is either k_ir_node or k_ir_loop */
65 ir_node *node; /**< Pointer to an ir_node element */
66 ir_loop *son; /**< Pointer to an ir_loop element */
67 ir_graph *irg; /**< Pointer to an ir_graph element (only callgraph loop trees) */
70 FIRM_API int is_ir_loop(const void *thing);
72 /** Set the outermost loop in ir graph as basic access to loop tree. */
73 FIRM_API void set_irg_loop(ir_graph *irg, ir_loop *l);
75 /* Returns the root loop info (if exists) for an irg. */
76 FIRM_API ir_loop *get_irg_loop(const ir_graph *irg);
78 /** Returns the loop n is contained in. NULL if node is in no loop. */
79 FIRM_API ir_loop *get_irn_loop(const ir_node *n);
81 /** Returns outer loop, itself if outermost. */
82 FIRM_API ir_loop *get_loop_outer_loop(const ir_loop *loop);
83 /** Returns nesting depth of this loop */
84 FIRM_API int get_loop_depth(const ir_loop *loop);
86 /* Sons are the inner loops contained in this loop. */
87 /** Returns the number of inner loops */
88 FIRM_API int get_loop_n_sons(const ir_loop *loop);
90 /** Returns the pos`th son loop (inner loop) of a loop.
91 Returns NULL if there is not a pos`th loop_node. */
92 FIRM_API ir_loop *get_loop_son(ir_loop *loop, int pos);
94 /** Returns the number of nodes contained in loop. */
95 FIRM_API int get_loop_n_nodes(const ir_loop *loop);
97 /** Returns the pos`th ir_node of a loop.
98 Returns NULL if there is not a pos`th ir_node. */
99 FIRM_API ir_node *get_loop_node(const ir_loop *loop, int pos);
101 /** Returns the number of elements contained in loop. */
102 FIRM_API int get_loop_n_elements(const ir_loop *loop);
104 /** Returns a loop element. A loop element can be interpreted as a
105 kind pointer, an ir_node* or an ir_loop*. */
106 FIRM_API loop_element get_loop_element(const ir_loop *loop, int pos);
108 /** Returns the element number of the loop son in loop.
109 * Returns -1 if not found. O(|elements|). */
110 FIRM_API int get_loop_element_pos(const ir_loop *loop, void *le);
112 /** Returns a unique node number for the loop node to make output
113 readable. If libfirm_debug is not set it returns the loop cast to
115 FIRM_API int get_loop_loop_nr(const ir_loop *loop);
117 /** A field to connect additional information to a loop. */
118 FIRM_API void set_loop_link(ir_loop *loop, void *link);
119 FIRM_API void *get_loop_link(const ir_loop *loop);
121 /* ------------------------------------------------------------------- */
122 /* Constructing and destructing the loop/backedge information. */
123 /* ------------------------------------------------------------------- */
125 /** Constructs backedge information and loop tree for a graph.
127 * The algorithm views the program representation as a pure graph.
128 * It assumes that only block and phi nodes may be loop headers.
129 * The resulting loop tree is a possible visiting order for dataflow
132 * This algorithm destoyes the link field of block nodes.
134 * @returns Maximal depth of loop tree.
137 * One assumes, the Phi nodes in a block with a backedge have backedges
138 * at the same positions as the block. This is not the case, as
139 * the scc algorithms does not respect the program semantics in this case.
140 * Take a swap in a loop (t = i; i = j; j = t;) This results in two Phi
141 * nodes. They form a cycle. Once the scc algorithm deleted one of the
142 * edges, the cycle is removed. The second Phi node does not get a
145 FIRM_API int construct_backedges(ir_graph *irg);
148 * Construct Intra-procedural control flow loop tree for a IR-graph.
150 * This constructs loop information resembling the program structure.
151 * It is useful for loop optimizations and analyses, as, e.g., finding
152 * iteration variables or loop invariant code motion.
154 * This algorithm computes only back edge information for Block nodes, not
157 * This algorithm destroyes the link field of block nodes.
159 * @param irg the graph
161 * @returns Maximal depth of loop tree.
163 FIRM_API int construct_cf_backedges(ir_graph *irg);
166 * Computes Intra-procedural control flow loop tree on demand.
168 * @param irg the graph
170 FIRM_API void assure_cf_loop(ir_graph *irg);
173 * Removes all loop information.
174 * Resets all backedges. Works for any construction algorithm.
176 FIRM_API void free_loop_information(ir_graph *irg);
177 FIRM_API void free_all_loop_information (void);
180 /* ------------------------------------------------------------------- */
181 /* Simple analyses based on the loop information */
182 /* ------------------------------------------------------------------- */
184 /** Test whether a value is loop invariant.
186 * @param n The node to be tested.
187 * @param block A block node.
189 * Returns non-zero, if the node n is not changed in the loop block
190 * belongs to or in inner loops of this block. */
191 FIRM_API int is_loop_invariant(const ir_node *n, const ir_node *block);