1/* Data structures and function declarations for the SSA value propagation
2   engine.
3   Copyright (C) 2004, 2005, 2007, 2008 Free Software Foundation, Inc.
4   Contributed by Diego Novillo <dnovillo@redhat.com>
5
6This file is part of GCC.
7
8GCC is free software; you can redistribute it and/or modify
9it under the terms of the GNU General Public License as published by
10the Free Software Foundation; either version 3, or (at your option)
11any later version.
12
13GCC is distributed in the hope that it will be useful,
14but WITHOUT ANY WARRANTY; without even the implied warranty of
15MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16GNU General Public License for more details.
17
18You should have received a copy of the GNU General Public License
19along with GCC; see the file COPYING3.  If not see
20<http://www.gnu.org/licenses/>.  */
21
22#ifndef _TREE_SSA_PROPAGATE_H
23#define _TREE_SSA_PROPAGATE_H 1
24
25/* If SIM_P is true, statement S will be simulated again.  */
26
27static inline void
28prop_set_simulate_again (gimple s, bool visit_p)
29{
30  gimple_set_visited (s, visit_p);
31}
32
33/* Return true if statement T should be simulated again.  */
34
35static inline bool
36prop_simulate_again_p (gimple s)
37{
38  return gimple_visited_p (s);
39}
40
41/* Lattice values used for propagation purposes.  Specific instances
42   of a propagation engine must return these values from the statement
43   and PHI visit functions to direct the engine.  */
44enum ssa_prop_result {
45    /* The statement produces nothing of interest.  No edges will be
46       added to the work lists.  */
47    SSA_PROP_NOT_INTERESTING,
48
49    /* The statement produces an interesting value.  The set SSA_NAMEs
50       returned by SSA_PROP_VISIT_STMT should be added to
51       INTERESTING_SSA_EDGES.  If the statement being visited is a
52       conditional jump, SSA_PROP_VISIT_STMT should indicate which edge
53       out of the basic block should be marked executable.  */
54    SSA_PROP_INTERESTING,
55
56    /* The statement produces a varying (i.e., useless) value and
57       should not be simulated again.  If the statement being visited
58       is a conditional jump, all the edges coming out of the block
59       will be considered executable.  */
60    SSA_PROP_VARYING
61};
62
63
64struct prop_value_d {
65    /* Lattice value.  Each propagator is free to define its own
66       lattice and this field is only meaningful while propagating.
67       It will not be used by substitute_and_fold.  */
68    unsigned lattice_val;
69
70    /* Propagated value.  */
71    tree value;
72};
73
74typedef struct prop_value_d prop_value_t;
75
76
77/* Type of value ranges.  See value_range_d for a description of these
78   types.  */
79enum value_range_type { VR_UNDEFINED, VR_RANGE, VR_ANTI_RANGE, VR_VARYING };
80
81/* Range of values that can be associated with an SSA_NAME after VRP
82   has executed.  */
83struct value_range_d
84{
85  /* Lattice value represented by this range.  */
86  enum value_range_type type;
87
88  /* Minimum and maximum values represented by this range.  These
89     values should be interpreted as follows:
90
91	- If TYPE is VR_UNDEFINED or VR_VARYING then MIN and MAX must
92	  be NULL.
93
94	- If TYPE == VR_RANGE then MIN holds the minimum value and
95	  MAX holds the maximum value of the range [MIN, MAX].
96
97	- If TYPE == ANTI_RANGE the variable is known to NOT
98	  take any values in the range [MIN, MAX].  */
99  tree min;
100  tree max;
101
102  /* Set of SSA names whose value ranges are equivalent to this one.
103     This set is only valid when TYPE is VR_RANGE or VR_ANTI_RANGE.  */
104  bitmap equiv;
105};
106
107typedef struct value_range_d value_range_t;
108
109
110/* Call-back functions used by the value propagation engine.  */
111typedef enum ssa_prop_result (*ssa_prop_visit_stmt_fn) (gimple, edge *, tree *);
112typedef enum ssa_prop_result (*ssa_prop_visit_phi_fn) (gimple);
113typedef bool (*ssa_prop_fold_stmt_fn) (gimple_stmt_iterator *gsi);
114
115
116/* In tree-ssa-propagate.c  */
117void ssa_propagate (ssa_prop_visit_stmt_fn, ssa_prop_visit_phi_fn);
118bool valid_gimple_rhs_p (tree);
119bool valid_gimple_call_p (tree);
120void move_ssa_defining_stmt_for_defs (gimple, gimple);
121bool update_call_from_tree (gimple_stmt_iterator *, tree);
122bool stmt_makes_single_store (gimple);
123bool substitute_and_fold (prop_value_t *, ssa_prop_fold_stmt_fn, bool);
124
125#endif /* _TREE_SSA_PROPAGATE_H  */
126