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/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
36 #include "firm_types.h"
37 #include "firm_common.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 #ifdef INTERPROCEDURAL_VIEW
52 /** Returns true if the predecessor pos is a backedge in the interprocedural view. */
53 int is_inter_backedge(ir_node *n, int pos);
54 /** Returns true if the predecessor pos is a backedge in the intraprocedural view. */
55 int is_intra_backedge(ir_node *n, int pos);
57 /** Returns non-zero if the predecessor pos is a backedge. */
58 int is_backedge(ir_node *n, int pos);
59 /** Marks edge pos as a backedge. */
60 void set_backedge(ir_node *n, int pos);
61 /** Marks edge pos as a non-backedge. */
62 void set_not_backedge(ir_node *n, int pos);
63 /** Returns non-zero if n has backedges. */
64 int has_backedges(ir_node *n);
65 /** Clears all backedge information. */
66 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 */
73 ir_graph *irg; /**< Pointer to an ir_graph element (only callgraph loop trees) */
76 int is_ir_loop(const void *thing);
78 /** Set the outermost loop in ir graph as basic access to loop tree. */
79 void set_irg_loop(ir_graph *irg, ir_loop *l);
81 /* Returns the root loop info (if exists) for an irg. */
82 ir_loop *get_irg_loop(const ir_graph *irg);
84 /** Returns the loop n is contained in. NULL if node is in no loop. */
85 ir_loop *get_irn_loop(const ir_node *n);
87 /** Returns outer loop, itself if outermost. */
88 ir_loop *get_loop_outer_loop(const ir_loop *loop);
89 /** Returns nesting depth of this loop */
90 int get_loop_depth(const ir_loop *loop);
92 /* Sons are the inner loops contained in this loop. */
93 /** Returns the number of inner loops */
94 int get_loop_n_sons(const ir_loop *loop);
96 /** Returns the pos`th son loop (inner loop) of a loop.
97 Returns NULL if there is not a pos`th loop_node. */
98 ir_loop *get_loop_son(ir_loop *loop, int pos);
100 /** Returns the number of nodes contained in loop. */
101 int get_loop_n_nodes(const ir_loop *loop);
103 /** Returns the pos`th ir_node of a loop.
104 Returns NULL if there is not a pos`th ir_node. */
105 ir_node *get_loop_node(const ir_loop *loop, int pos);
107 /** Returns the number of elements contained in loop. */
108 int get_loop_n_elements(const ir_loop *loop);
110 /** Returns a loop element. A loop element can be interpreted as a
111 kind pointer, an ir_node* or an ir_loop*. */
112 loop_element get_loop_element(const ir_loop *loop, int pos);
114 /** Returns the element number of the loop son in loop.
115 * Returns -1 if not found. O(|elements|). */
116 int get_loop_element_pos(const ir_loop *loop, void *le);
118 /** Returns a unique node number for the loop node to make output
119 readable. If libfirm_debug is not set it returns the loop cast to
121 int get_loop_loop_nr(const ir_loop *loop);
123 /** A field to connect additional information to a loop. */
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 #ifdef INTERPROCEDURAL_VIEW
155 /** Constructs backedges for all irgs in interprocedural view.
157 * @see As construct_backedges(), but for interprocedural view.
160 * All loops in the graph will be marked as such, not only
161 * realizeable loops and recursions in the program. E.g., if the
162 * same funcion is called twice, there is a loop between the first
163 * function return and the second call.
165 * @returns Maximal depth of loop tree.
167 int construct_ip_backedges(void);
171 * Construct Intra-procedural control flow loop tree for a IR-graph.
173 * This constructs loop information resembling the program structure.
174 * It is useful for loop optimizations and analyses, as, e.g., finding
175 * iteration variables or loop invariant code motion.
177 * This algorithm computes only back edge information for Block nodes, not
180 * This algorithm destroyes the link field of block nodes.
182 * @param irg the graph
184 * @returns Maximal depth of loop tree.
186 int construct_cf_backedges(ir_graph *irg);
189 * Computes Intra-procedural control flow loop tree on demand.
191 * @param irg the graph
193 void assure_cf_loop(ir_graph *irg);
195 #ifdef INTERPROCEDURAL_VIEW
197 * Construct Inter-procedural control flow loop tree.
199 * @see construct_cf_backedges() and construct_ip_backedges().
201 int construct_ip_cf_backedges(void);
205 * Removes all loop information.
206 * Resets all backedges. Works for any construction algorithm.
208 void free_loop_information(ir_graph *irg);
209 void free_all_loop_information (void);
212 /* ------------------------------------------------------------------- */
213 /* Simple analyses based on the loop information */
214 /* ------------------------------------------------------------------- */
216 /** Test whether a value is loop invariant.
218 * @param n The node to be tested.
219 * @param block A block node.
221 * Returns non-zero, if the node n is not changed in the loop block
222 * belongs to or in inner loops of this block. */
223 int is_loop_invariant(const ir_node *n, const ir_node *block);