1 /* DDG - Data Dependence Graph - interface.
2    Copyright (C) 2004-2014 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 #include "sbitmap.h"
26 /* For basic_block.  */
27 #include "basic-block.h"
28 #include "df.h"
29 
30 typedef struct ddg_node *ddg_node_ptr;
31 typedef struct ddg_edge *ddg_edge_ptr;
32 typedef struct ddg *ddg_ptr;
33 typedef struct ddg_scc *ddg_scc_ptr;
34 typedef struct ddg_all_sccs *ddg_all_sccs_ptr;
35 
36 enum dep_type {TRUE_DEP, OUTPUT_DEP, ANTI_DEP};
37 enum dep_data_type {REG_OR_MEM_DEP, REG_DEP, MEM_DEP, REG_AND_MEM_DEP};
38 
39 /* The following two macros enables direct access to the successors and
40    predecessors bitmaps held in each ddg_node.  Do not make changes to
41    these bitmaps, unless you want to change the DDG.  */
42 #define NODE_SUCCESSORS(x)  ((x)->successors)
43 #define NODE_PREDECESSORS(x)  ((x)->predecessors)
44 
45 /* A structure that represents a node in the DDG.  */
46 struct ddg_node
47 {
48   /* Each node has a unique CUID index.  These indices increase monotonically
49      (according to the order of the corresponding INSN in the BB), starting
50      from 0 with no gaps.  */
51   int cuid;
52 
53   /* The insn represented by the node.  */
54   rtx insn;
55 
56   /* A note preceding INSN (or INSN itself), such that all insns linked
57      from FIRST_NOTE until INSN (inclusive of both) are moved together
58      when reordering the insns.  This takes care of notes that should
59      continue to precede INSN.  */
60   rtx first_note;
61 
62   /* Incoming and outgoing dependency edges.  */
63   ddg_edge_ptr in;
64   ddg_edge_ptr out;
65 
66   /* Each bit corresponds to a ddg_node according to its cuid, and is
67      set iff the node is a successor/predecessor of "this" node.  */
68   sbitmap successors;
69   sbitmap predecessors;
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   /* For general use by algorithms manipulating the ddg.  */
103   union {
104     int count;
105     void *info;
106   } aux;
107 };
108 
109 /* This structure holds the Data Dependence Graph for a basic block.  */
110 struct ddg
111 {
112   /* The basic block for which this DDG is built.  */
113   basic_block bb;
114 
115   /* Number of instructions in the basic block.  */
116   int num_nodes;
117 
118   /* Number of load/store instructions in the BB - statistics.  */
119   int num_loads;
120   int num_stores;
121 
122   /* Number of debug instructions in the BB.  */
123   int num_debug;
124 
125   /* This array holds the nodes in the graph; it is indexed by the node
126      cuid, which follows the order of the instructions in the BB.  */
127   ddg_node_ptr nodes;
128 
129   /* The branch closing the loop.  */
130   ddg_node_ptr closing_branch;
131 
132   /* Build dependence edges for closing_branch, when set.  In certain cases,
133      the closing branch can be dealt with separately from the insns of the
134      loop, and then no such deps are needed.  */
135   int closing_branch_deps;
136 
137   /* Array and number of backarcs (edges with distance > 0) in the DDG.  */
138   int num_backarcs;
139   ddg_edge_ptr *backarcs;
140 };
141 
142 
143 /* Holds information on an SCC (Strongly Connected Component) of the DDG.  */
144 struct ddg_scc
145 {
146   /* A bitmap that represents the nodes of the DDG that are in the SCC.  */
147   sbitmap nodes;
148 
149   /* Array and number of backarcs (edges with distance > 0) in the SCC.  */
150   ddg_edge_ptr *backarcs;
151   int num_backarcs;
152 
153   /* The maximum of (total_latency/total_distance) over all cycles in SCC.  */
154   int recurrence_length;
155 };
156 
157 /* This structure holds the SCCs of the DDG.  */
158 struct ddg_all_sccs
159 {
160   /* Array that holds the SCCs in the DDG, and their number.  */
161   ddg_scc_ptr *sccs;
162   int num_sccs;
163 
164   ddg_ptr ddg;
165 };
166 
167 
168 ddg_ptr create_ddg (basic_block, int closing_branch_deps);
169 void free_ddg (ddg_ptr);
170 
171 void print_ddg (FILE *, ddg_ptr);
172 void vcg_print_ddg (FILE *, ddg_ptr);
173 void print_ddg_edge (FILE *, ddg_edge_ptr);
174 void print_sccs (FILE *, ddg_all_sccs_ptr, ddg_ptr);
175 
176 ddg_node_ptr get_node_of_insn (ddg_ptr, rtx);
177 
178 void find_successors (sbitmap result, ddg_ptr, sbitmap);
179 void find_predecessors (sbitmap result, ddg_ptr, sbitmap);
180 
181 ddg_all_sccs_ptr create_ddg_all_sccs (ddg_ptr);
182 void free_ddg_all_sccs (ddg_all_sccs_ptr);
183 
184 int find_nodes_on_paths (sbitmap result, ddg_ptr, sbitmap from, sbitmap to);
185 int longest_simple_path (ddg_ptr, int from, int to, sbitmap via);
186 
187 bool autoinc_var_is_used_p (rtx, rtx);
188 
189 #endif /* GCC_DDG_H */
190