1 /* DDG - Data Dependence Graph - interface.
2 Copyright (C) 2004-2023 Free Software Foundation, Inc.
3 Contributed by Ayal Zaks and Mustafa Hagog <zaks,mustafa@il.ibm.com>
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
10 version.
11
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
20
21 #ifndef GCC_DDG_H
22 #define GCC_DDG_H
23
24 /* For sbitmap. */
25
26 typedef struct ddg_node *ddg_node_ptr;
27 typedef struct ddg_edge *ddg_edge_ptr;
28 typedef struct ddg *ddg_ptr;
29 typedef struct ddg_scc *ddg_scc_ptr;
30 typedef struct ddg_all_sccs *ddg_all_sccs_ptr;
31
32 enum dep_type {TRUE_DEP, OUTPUT_DEP, ANTI_DEP};
33 enum dep_data_type {REG_OR_MEM_DEP, REG_DEP, MEM_DEP, REG_AND_MEM_DEP};
34
35 /* The following two macros enables direct access to the successors and
36 predecessors bitmaps held in each ddg_node. Do not make changes to
37 these bitmaps, unless you want to change the DDG. */
38 #define NODE_SUCCESSORS(x) ((x)->successors)
39 #define NODE_PREDECESSORS(x) ((x)->predecessors)
40
41 /* A structure that represents a node in the DDG. */
42 struct ddg_node
43 {
44 /* Each node has a unique CUID index. These indices increase monotonically
45 (according to the order of the corresponding INSN in the BB), starting
46 from 0 with no gaps. */
47 int cuid;
48
49 /* The insn represented by the node. */
50 rtx_insn *insn;
51
52 /* A note preceding INSN (or INSN itself), such that all insns linked
53 from FIRST_NOTE until INSN (inclusive of both) are moved together
54 when reordering the insns. This takes care of notes that should
55 continue to precede INSN. */
56 rtx_insn *first_note;
57
58 /* Incoming and outgoing dependency edges. */
59 ddg_edge_ptr in;
60 ddg_edge_ptr out;
61
62 /* Each bit corresponds to a ddg_node according to its cuid, and is
63 set iff the node is a successor/predecessor of "this" node. */
64 sbitmap successors;
65 sbitmap predecessors;
66
67 /* Temporary array used for Floyd-Warshall algorithm to find
68 scc recurrence length. */
69 int *max_dist;
70
71 /* For general use by algorithms manipulating the ddg. */
72 union {
73 int count;
74 void *info;
75 } aux;
76 };
77
78 /* A structure that represents an edge in the DDG. */
79 struct ddg_edge
80 {
81 /* The source and destination nodes of the dependency edge. */
82 ddg_node_ptr src;
83 ddg_node_ptr dest;
84
85 /* TRUE, OUTPUT or ANTI dependency. */
86 dep_type type;
87
88 /* REG or MEM dependency. */
89 dep_data_type data_type;
90
91 /* Latency of the dependency. */
92 int latency;
93
94 /* The distance: number of loop iterations the dependency crosses. */
95 int distance;
96
97 /* The following two fields are used to form a linked list of the in/out
98 going edges to/from each node. */
99 ddg_edge_ptr next_in;
100 ddg_edge_ptr next_out;
101
102 /* Is true when edge is already in scc. */
103 bool in_scc;
104 };
105
106 /* This structure holds the Data Dependence Graph for a basic block. */
107 struct ddg
108 {
109 /* The basic block for which this DDG is built. */
110 basic_block bb;
111
112 /* Number of instructions in the basic block. */
113 int num_nodes;
114
115 /* Number of load/store instructions in the BB - statistics. */
116 int num_loads;
117 int num_stores;
118
119 /* This array holds the nodes in the graph; it is indexed by the node
120 cuid, which follows the order of the instructions in the BB. */
121 ddg_node_ptr nodes;
122
123 /* The branch closing the loop. */
124 ddg_node_ptr closing_branch;
125
126 /* Build dependence edges for closing_branch, when set. In certain cases,
127 the closing branch can be dealt with separately from the insns of the
128 loop, and then no such deps are needed. */
129 int closing_branch_deps;
130
131 /* Array and number of backarcs (edges with distance > 0) in the DDG. */
132 int num_backarcs;
133 ddg_edge_ptr *backarcs;
134 };
135
136
137 /* Holds information on an SCC (Strongly Connected Component) of the DDG. */
138 struct ddg_scc
139 {
140 /* A bitmap that represents the nodes of the DDG that are in the SCC. */
141 sbitmap nodes;
142
143 /* Array and number of backarcs (edges with distance > 0) in the SCC. */
144 ddg_edge_ptr *backarcs;
145 int num_backarcs;
146
147 /* The maximum of (total_latency/total_distance) over all cycles in SCC. */
148 int recurrence_length;
149 };
150
151 /* This structure holds the SCCs of the DDG. */
152 struct ddg_all_sccs
153 {
154 /* Array that holds the SCCs in the DDG, and their number. */
155 ddg_scc_ptr *sccs;
156 int num_sccs;
157
158 ddg_ptr ddg;
159 };
160
161
162 ddg_ptr create_ddg (basic_block, int closing_branch_deps);
163 void free_ddg (ddg_ptr);
164
165 void print_ddg (FILE *, ddg_ptr);
166 void vcg_print_ddg (FILE *, ddg_ptr);
167 void print_ddg_edge (FILE *, ddg_edge_ptr);
168 void print_sccs (FILE *, ddg_all_sccs_ptr, ddg_ptr);
169
170 ddg_node_ptr get_node_of_insn (ddg_ptr, rtx_insn *);
171
172 void find_successors (sbitmap result, ddg_ptr, sbitmap);
173 void find_predecessors (sbitmap result, ddg_ptr, sbitmap);
174
175 ddg_all_sccs_ptr create_ddg_all_sccs (ddg_ptr);
176 void free_ddg_all_sccs (ddg_all_sccs_ptr);
177
178 int find_nodes_on_paths (sbitmap result, ddg_ptr, sbitmap from, sbitmap to);
179
180 bool autoinc_var_is_used_p (rtx_insn *, rtx_insn *);
181
182 #endif /* GCC_DDG_H */