1/* Data structures and function declarations for the SSA value propagation
2   engine.
3   Copyright (C) 2004, 2005 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 2, 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 COPYING.  If not, write to
20the Free Software Foundation, 51 Franklin Street, Fifth Floor,
21Boston, MA 02110-1301, USA.  */
22
23#ifndef _TREE_SSA_PROPAGATE_H
24#define _TREE_SSA_PROPAGATE_H 1
25
26/* Use the TREE_VISITED bitflag to mark statements and PHI nodes that
27   have been deemed varying and should not be simulated again.  */
28#define DONT_SIMULATE_AGAIN(T)	TREE_VISITED (T)
29
30/* Lattice values used for propagation purposes.  Specific instances
31   of a propagation engine must return these values from the statement
32   and PHI visit functions to direct the engine.  */
33enum ssa_prop_result {
34    /* The statement produces nothing of interest.  No edges will be
35       added to the work lists.  */
36    SSA_PROP_NOT_INTERESTING,
37
38    /* The statement produces an interesting value.  The set SSA_NAMEs
39       returned by SSA_PROP_VISIT_STMT should be added to
40       INTERESTING_SSA_EDGES.  If the statement being visited is a
41       conditional jump, SSA_PROP_VISIT_STMT should indicate which edge
42       out of the basic block should be marked executable.  */
43    SSA_PROP_INTERESTING,
44
45    /* The statement produces a varying (i.e., useless) value and
46       should not be simulated again.  If the statement being visited
47       is a conditional jump, all the edges coming out of the block
48       will be considered executable.  */
49    SSA_PROP_VARYING
50};
51
52
53struct prop_value_d {
54    /* Lattice value.  Each propagator is free to define its own
55       lattice and this field is only meaningful while propagating.
56       It will not be used by substitute_and_fold.  */
57    unsigned lattice_val;
58
59    /* Propagated value.  */
60    tree value;
61
62    /* If this value is held in an SSA name for a non-register
63       variable, this field holds the actual memory reference
64       associated with this value.  This field is taken from
65       the LHS of the assignment that generated the associated SSA
66       name.  However, in the case of PHI nodes, this field is copied
67       from the PHI arguments (assuming that all the arguments have
68       the same memory reference).  See replace_vuses_in for a more
69       detailed description.  */
70    tree mem_ref;
71};
72
73typedef struct prop_value_d prop_value_t;
74
75
76/* Type of value ranges.  See value_range_d for a description of these
77   types.  */
78enum value_range_type { VR_UNDEFINED, VR_RANGE, VR_ANTI_RANGE, VR_VARYING };
79
80/* Range of values that can be associated with an SSA_NAME after VRP
81   has executed.  */
82struct value_range_d
83{
84  /* Lattice value represented by this range.  */
85  enum value_range_type type;
86
87  /* Minimum and maximum values represented by this range.  These
88     values should be interpreted as follows:
89
90	- If TYPE is VR_UNDEFINED or VR_VARYING then MIN and MAX must
91	  be NULL.
92
93	- If TYPE == VR_RANGE then MIN holds the minimum value and
94	  MAX holds the maximum value of the range [MIN, MAX].
95
96	- If TYPE == ANTI_RANGE the variable is known to NOT
97	  take any values in the range [MIN, MAX].  */
98  tree min;
99  tree max;
100
101  /* Set of SSA names whose value ranges are equivalent to this one.
102     This set is only valid when TYPE is VR_RANGE or VR_ANTI_RANGE.  */
103  bitmap equiv;
104};
105
106typedef struct value_range_d value_range_t;
107
108
109/* Call-back functions used by the value propagation engine.  */
110typedef enum ssa_prop_result (*ssa_prop_visit_stmt_fn) (tree, edge *, tree *);
111typedef enum ssa_prop_result (*ssa_prop_visit_phi_fn) (tree);
112
113
114/* In tree-ssa-propagate.c  */
115void ssa_propagate (ssa_prop_visit_stmt_fn, ssa_prop_visit_phi_fn);
116tree get_rhs (tree);
117bool set_rhs (tree *, tree);
118tree first_vdef (tree);
119bool stmt_makes_single_load (tree);
120bool stmt_makes_single_store (tree);
121prop_value_t *get_value_loaded_by (tree, prop_value_t *);
122bool replace_uses_in (tree, bool *, prop_value_t *);
123void substitute_and_fold (prop_value_t *, bool);
124
125#endif /* _TREE_SSA_PROPAGATE_H  */
126