2 * Copyright (C) 1995-2011 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
26 * Computes backedges in the control and data flow.
29 * Only Block and Phi nodes can have incoming backedges.
30 * Constructs loops data structure: indicates loop nesting.
32 #ifndef FIRM_ANA_IRLOOP_H
33 #define FIRM_ANA_IRLOOP_H
35 #include "firm_types.h"
36 #include "firm_common.h"
40 * @defgroup ir_loop Loops
44 /** Returns non-zero if the predecessor pos is a backedge. */
45 FIRM_API int is_backedge(const ir_node *n, int pos);
46 /** Marks edge pos as a backedge. */
47 FIRM_API void set_backedge(ir_node *n, int pos);
48 /** Marks edge pos as a non-backedge. */
49 FIRM_API void set_not_backedge(ir_node *n, int pos);
50 /** Returns non-zero if n has backedges. */
51 FIRM_API int has_backedges(const ir_node *n);
52 /** Clears all backedge information. */
53 FIRM_API void clear_backedges(ir_node *n);
55 /** Loop elements: loop nodes and ir nodes */
57 firm_kind *kind; /**< is either k_ir_node or k_ir_loop */
58 ir_node *node; /**< Pointer to an ir_node element */
59 ir_loop *son; /**< Pointer to an ir_loop element */
60 ir_graph *irg; /**< Pointer to an ir_graph element (only callgraph loop trees) */
63 /** Tests whether a given pointer points to a loop.
64 * @note only works reliably if @p thing points to something with a #firm_kind
66 FIRM_API int is_ir_loop(const void *thing);
68 /** Sets the outermost loop in ir graph as basic access to loop tree. */
69 FIRM_API void set_irg_loop(ir_graph *irg, ir_loop *l);
71 /** Returns the root loop info (if exists) for an irg. */
72 FIRM_API ir_loop *get_irg_loop(const ir_graph *irg);
74 /** Returns the loop n is contained in. NULL if node is in no loop. */
75 FIRM_API ir_loop *get_irn_loop(const ir_node *n);
77 /** Returns outer loop, itself if outermost. */
78 FIRM_API ir_loop *get_loop_outer_loop(const ir_loop *loop);
79 /** Returns nesting depth of this loop */
80 FIRM_API unsigned get_loop_depth(const ir_loop *loop);
82 /** Returns the number of elements contained in loop. */
83 FIRM_API size_t get_loop_n_elements(const ir_loop *loop);
85 /** Returns a loop element. A loop element can be interpreted as a
86 * kind pointer, an ir_node* or an ir_loop*. */
87 FIRM_API loop_element get_loop_element(const ir_loop *loop, size_t pos);
89 /** Returns a unique node number for the loop node to make output
90 readable. If libfirm_debug is not set it returns the loop cast to
92 FIRM_API long get_loop_loop_nr(const ir_loop *loop);
94 /** A field to connect additional information to a loop. */
95 FIRM_API void set_loop_link(ir_loop *loop, void *link);
96 /** Returns field with additional loop information.
97 * @see set_loop_link() */
98 FIRM_API void *get_loop_link(const ir_loop *loop);
100 /** Constructs backedge information and loop tree for a graph.
102 * The algorithm views the program representation as a pure graph.
103 * It assumes that only block and phi nodes may be loop headers.
104 * The resulting loop tree is a possible visiting order for dataflow
107 * This algorithm destoyes the link field of block nodes.
109 * @returns Maximal depth of loop tree.
112 * One assumes, the Phi nodes in a block with a backedge have backedges
113 * at the same positions as the block. This is not the case, as
114 * the scc algorithms does not respect the program semantics in this case.
115 * Take a swap in a loop (t = i; i = j; j = t;) This results in two Phi
116 * nodes. They form a cycle. Once the scc algorithm deleted one of the
117 * edges, the cycle is removed. The second Phi node does not get a
120 FIRM_API int construct_backedges(ir_graph *irg);
123 * Construct Intra-procedural control flow loop tree for a IR-graph.
125 * This constructs loop information resembling the program structure.
126 * It is useful for loop optimizations and analyses, as, e.g., finding
127 * iteration variables or loop invariant code motion.
129 * This algorithm computes only back edge information for Block nodes, not
132 * This algorithm destroyes the link field of block nodes.
134 * @param irg the graph
136 * @returns Maximal depth of loop tree.
138 FIRM_API int construct_cf_backedges(ir_graph *irg);
141 * Computes Intra-procedural control flow loop tree on demand.
143 * @param irg the graph
145 FIRM_API void assure_loopinfo(ir_graph *irg);
148 * Removes all loop information.
149 * Resets all backedges. Works for any construction algorithm.
151 FIRM_API void free_loop_information(ir_graph *irg);
152 /** Removes loop information from all graphs in the current program. */
153 FIRM_API void free_all_loop_information(void);
155 /** Tests whether a value is loop invariant.
157 * @param n The node to be tested.
158 * @param block A block node.
160 * Returns non-zero, if the node n is not changed in the loop block
161 * belongs to or in inner loops of this block. */
162 FIRM_API int is_loop_invariant(const ir_node *n, const ir_node *block);