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1 : : /* Header file for gimple range phi analysis.
2 : : Copyright (C) 2023-2024 Free Software Foundation, Inc.
3 : : Contributed by Andrew MacLeod <amacleod@redhat.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_SSA_RANGE_PHI_H
22 : : #define GCC_SSA_RANGE_PHI_H
23 : :
24 : : // -------------------------------------------------------------------------
25 : :
26 : : // A PHI_GROUP consists of a set of SSA_NAMES which are all PHI_DEFS, and
27 : : // their arguemnts contain nothing but other PHI defintions, with at most
28 : : // 2 exceptions:
29 : : // 1 - An initial value. This is either a constant, or another non-phi name
30 : : // with a single incoming edge to the cycle group
31 : : // 2 - A modifier statement which adjusts the value. ie, name2 = phi_name + 1
32 : : // The initial range is used to create one bound and the modifier is examined
33 : : // to determine the other bound.
34 : : // All members of the PHI cycle will be given the same range.
35 : : //
36 : : // For example, given the follwoing sequences:
37 : : // qa_20 = qa_10 + 1;
38 : : // qa_9 = PHI <qa_10(3), qa_20(4)>
39 : : // qa_10 = PHI <0(2), qa_9(5)>
40 : : //
41 : : // We can determine the following group:
42 : : //
43 : : // PHI cycle members qa_9, qa_10
44 : : // Initial value : 0
45 : : // modifier stmt: qa_20 = qa_10 + 1;
46 : : //
47 : : // Based on just this analysis, We can project that qa_9 and qa_10 will have
48 : : // a range of [0, +INF].
49 : :
50 : 306806 : class phi_group
51 : : {
52 : : public:
53 : : phi_group (bitmap bm, irange &init_range, gimple *mod, range_query *q);
54 : : phi_group (const phi_group &g);
55 : 0 : const_bitmap group () const { return m_group; }
56 : 423069 : const vrange &range () const { return m_vr; }
57 : : gimple *modifier_stmt () const { return m_modifier; }
58 : : void dump (FILE *);
59 : : protected:
60 : : bool calculate_using_modifier (range_query *q);
61 : : bool refine_using_relation (relation_kind k);
62 : : static unsigned is_modifier_p (gimple *s, const bitmap bm);
63 : : bitmap m_group;
64 : : gimple *m_modifier; // Single stmt which modifies phi group.
65 : : unsigned m_modifier_op; // Operand of group member in modifier stmt.
66 : : int_range_max m_vr;
67 : : friend class phi_analyzer;
68 : : };
69 : :
70 : : // The phi anlyzer will return the group that name belongs to.
71 : : // If inforamtion is not known about a name yet, analysis is conducted by
72 : : // looking at the arguments to PHIS and following them to their defs to
73 : : // determine whether the conditions are met to form a new group.
74 : :
75 : : class phi_analyzer
76 : : {
77 : : public:
78 : : phi_analyzer (range_query &);
79 : : ~phi_analyzer ();
80 : : phi_group *operator[] (tree name);
81 : : void dump (FILE *f);
82 : : protected:
83 : : phi_group *group (tree name) const;
84 : : void process_phi (gphi *phi);
85 : : range_query &m_global;
86 : : vec<tree> m_work;
87 : :
88 : : bitmap m_simple; // Processed, not part of a group.
89 : : bitmap m_current; // Potential group currently being analyzed.
90 : : vec<phi_group *> m_phi_groups;
91 : : vec<phi_group *> m_tab;
92 : : bitmap_obstack m_bitmaps;
93 : : };
94 : :
95 : : // These are the APIs to start and stop a phi analyzerin a SCEV like manner.
96 : : // There can only be one operating at any given time.
97 : : // When initialized, a range-query if provided to do lookups of values for
98 : : // PHIs and to evaluate modifier and initial value statements.
99 : : // To avoid problems, this should be some form of constant query, like
100 : : // global_range_query or better yet a const_query from a functioning ranger.
101 : :
102 : : bool phi_analysis_available_p ();
103 : : phi_analyzer &phi_analysis ();
104 : : void phi_analysis_initialize (range_query &);
105 : : void phi_analysis_finalize ();
106 : :
107 : : #endif // GCC_SSA_RANGE_PHI_H
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