1 | /* IPA predicates. |
2 | Copyright (C) 2003-2023 Free Software Foundation, Inc. |
3 | Contributed by Jan Hubicka |
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 | /* Representation of inline parameters that do depend on context function is |
22 | inlined into (i.e. known constant values of function parameters. |
23 | |
24 | Conditions that are interesting for function body are collected into CONDS |
25 | vector. They are of simple as kind of a mathematical transformation on |
26 | function parameter, T(function_param), in which the parameter occurs only |
27 | once, and other operands are IPA invariant. The conditions are then |
28 | referred by predicates. */ |
29 | |
30 | |
31 | /* A simplified representation of tree node, for unary, binary and ternary |
32 | operation. Computations on parameter are decomposed to a series of this |
33 | kind of structure. */ |
34 | struct GTY(()) expr_eval_op |
35 | { |
36 | /* Result type of expression. */ |
37 | tree type; |
38 | /* Constant operands in expression, there are at most two. */ |
39 | tree val[2]; |
40 | /* Index of parameter operand in expression. */ |
41 | unsigned index : 2; |
42 | /* Operation code of expression. */ |
43 | ENUM_BITFIELD(tree_code) code : 16; |
44 | }; |
45 | |
46 | typedef vec<expr_eval_op, va_gc> *expr_eval_ops; |
47 | |
48 | struct GTY(()) condition |
49 | { |
50 | /* If agg_contents is set, this is the offset from which the used data was |
51 | loaded. */ |
52 | HOST_WIDE_INT offset; |
53 | /* Type of the access reading the data (or the PARM_DECL SSA_NAME). */ |
54 | tree type; |
55 | tree val; |
56 | int operand_num; |
57 | ENUM_BITFIELD(tree_code) code : 16; |
58 | /* Set if the used data were loaded from an aggregate parameter or from |
59 | data received by reference. */ |
60 | unsigned agg_contents : 1; |
61 | /* If agg_contents is set, this differentiates between loads from data |
62 | passed by reference and by value. */ |
63 | unsigned by_ref : 1; |
64 | /* A set of sequential operations on the parameter, which can be seen as |
65 | a mathematical function on the parameter. */ |
66 | expr_eval_ops param_ops; |
67 | }; |
68 | |
69 | /* Information kept about parameter of call site. */ |
70 | struct inline_param_summary |
71 | { |
72 | /* REG_BR_PROB_BASE based probability that parameter will change in between |
73 | two invocation of the calls. |
74 | I.e. loop invariant parameters |
75 | REG_BR_PROB_BASE/estimated_iterations and regular |
76 | parameters REG_BR_PROB_BASE. |
77 | |
78 | Value 0 is reserved for compile time invariants. */ |
79 | short change_prob; |
80 | unsigned points_to_local_or_readonly_memory : 1; |
81 | unsigned points_to_possible_sra_candidate : 1; |
82 | bool equal_to (const inline_param_summary &other) const |
83 | { |
84 | return change_prob == other.change_prob |
85 | && points_to_local_or_readonly_memory |
86 | == other.points_to_local_or_readonly_memory |
87 | && points_to_possible_sra_candidate |
88 | == other.points_to_possible_sra_candidate; |
89 | } |
90 | bool useless_p (void) const |
91 | { |
92 | return change_prob == REG_BR_PROB_BASE |
93 | && !points_to_local_or_readonly_memory |
94 | && !points_to_possible_sra_candidate; |
95 | } |
96 | }; |
97 | |
98 | typedef vec<condition, va_gc> *conditions; |
99 | |
100 | /* Predicates are used to represent function parameters (such as runtime) |
101 | which depend on a context function is called in. |
102 | |
103 | Predicates are logical formulas in conjunctive-disjunctive form consisting |
104 | of clauses which are bitmaps specifying a set of condition that must |
105 | be true for a clause to be satisfied. Physically they are represented as |
106 | array of clauses terminated by 0. |
107 | |
108 | In order to make predicate (possibly) true, all of its clauses must |
109 | be (possibly) true. To make clause (possibly) true, one of conditions |
110 | it mentions must be (possibly) true. |
111 | |
112 | There are fixed bounds on number of clauses and conditions and all the |
113 | manipulation functions are conservative in positive direction. I.e. we |
114 | may lose precision by thinking that predicate may be true even when it |
115 | is not. */ |
116 | |
117 | typedef uint32_t clause_t; |
118 | class ipa_predicate |
119 | { |
120 | public: |
121 | enum predicate_conditions |
122 | { |
123 | false_condition = 0, |
124 | not_inlined_condition = 1, |
125 | first_dynamic_condition = 2 |
126 | }; |
127 | |
128 | /* Maximal number of conditions predicate can refer to. This is limited |
129 | by using clause_t to be 32bit. */ |
130 | static const int num_conditions = 32; |
131 | |
132 | /* Special condition code we use to represent test that operand is compile |
133 | time constant. */ |
134 | static const tree_code is_not_constant = ERROR_MARK; |
135 | |
136 | /* Special condition code we use to represent test that operand is not changed |
137 | across invocation of the function. When operand IS_NOT_CONSTANT it is |
138 | always CHANGED, however i.e. loop invariants can be NOT_CHANGED given |
139 | percentage of executions even when they are not compile time constants. */ |
140 | static const tree_code changed = IDENTIFIER_NODE; |
141 | |
142 | /* Special condition code we use to check that the parameter is likely SRA |
143 | candidate. */ |
144 | static const tree_code not_sra_candidate = TREE_LIST; |
145 | |
146 | |
147 | /* Initialize predicate either to true of false depending on P. */ |
148 | inline ipa_predicate (bool p = true) |
149 | { |
150 | if (p) |
151 | /* True predicate. */ |
152 | m_clause[0] = 0; |
153 | else |
154 | /* False predicate. */ |
155 | set_to_cond (false_condition); |
156 | } |
157 | |
158 | /* Sanity check that we do not mix pointers to predicates with predicates. */ |
159 | inline ipa_predicate (ipa_predicate *) |
160 | { |
161 | gcc_unreachable (); |
162 | } |
163 | |
164 | /* Return predicate testing condition I. */ |
165 | static inline ipa_predicate predicate_testing_cond (int i) |
166 | { |
167 | ipa_predicate p; |
168 | p.set_to_cond (i + first_dynamic_condition); |
169 | return p; |
170 | } |
171 | |
172 | /* Return predicate testing that function was not inlined. */ |
173 | static ipa_predicate not_inlined (void) |
174 | { |
175 | ipa_predicate p; |
176 | p.set_to_cond (not_inlined_condition); |
177 | return p; |
178 | } |
179 | |
180 | /* Compute logical and of ipa_predicates. */ |
181 | ipa_predicate & operator &= (const ipa_predicate &); |
182 | inline ipa_predicate operator &(const ipa_predicate &p) const |
183 | { |
184 | ipa_predicate ret = *this; |
185 | ret &= p; |
186 | return ret; |
187 | } |
188 | |
189 | /* Compute logical or of ipa_predicates. This is not operator because |
190 | extra parameter CONDITIONS is needed */ |
191 | ipa_predicate or_with (conditions, const ipa_predicate &) const; |
192 | |
193 | /* Return true if ipa_predicates are known to be equal. */ |
194 | inline bool operator==(const ipa_predicate &p2) const |
195 | { |
196 | int i; |
197 | for (i = 0; m_clause[i]; i++) |
198 | { |
199 | gcc_checking_assert (i < max_clauses); |
200 | gcc_checking_assert (m_clause[i] > m_clause[i + 1]); |
201 | gcc_checking_assert (!p2.m_clause[i] |
202 | || p2.m_clause[i] > p2.m_clause[i + 1]); |
203 | if (m_clause[i] != p2.m_clause[i]) |
204 | return false; |
205 | } |
206 | return !p2.m_clause[i]; |
207 | } |
208 | |
209 | /* Return true if predicates are known to be true or false depending |
210 | on COND. */ |
211 | inline bool operator==(const bool cond) const |
212 | { |
213 | if (cond) |
214 | return !m_clause[0]; |
215 | if (m_clause[0] == (1 << false_condition)) |
216 | { |
217 | gcc_checking_assert (!m_clause[1] |
218 | && m_clause[0] == 1 |
219 | << false_condition); |
220 | return true; |
221 | } |
222 | return false; |
223 | } |
224 | |
225 | inline bool operator!=(const ipa_predicate &p2) const |
226 | { |
227 | return !(*this == p2); |
228 | } |
229 | |
230 | inline bool operator!=(const bool cond) const |
231 | { |
232 | return !(*this == cond); |
233 | } |
234 | |
235 | /* Evaluate if predicate is known to be false given the clause of possible |
236 | truths. */ |
237 | bool evaluate (clause_t) const; |
238 | |
239 | /* Estimate probability that predicate will be true in a given context. */ |
240 | int probability (conditions, clause_t, vec<inline_param_summary>) const; |
241 | |
242 | /* Dump predicate to F. Output newline if nl. */ |
243 | void dump (FILE *f, conditions, bool nl=true) const; |
244 | void DEBUG_FUNCTION debug (conditions) const; |
245 | |
246 | /* Return ipa_predicate equal to THIS after duplication. */ |
247 | ipa_predicate remap_after_duplication (clause_t); |
248 | |
249 | /* Return ipa_predicate equal to THIS after inlining. */ |
250 | ipa_predicate remap_after_inlining (class ipa_fn_summary *, |
251 | ipa_node_params *params_summary, |
252 | ipa_fn_summary *, |
253 | const vec<int> &, |
254 | const vec<HOST_WIDE_INT> &, |
255 | clause_t, const ipa_predicate &); |
256 | |
257 | void stream_in (lto_input_block *); |
258 | void stream_out (output_block *); |
259 | |
260 | private: |
261 | static const int max_clauses = 8; |
262 | clause_t m_clause[max_clauses + 1]; |
263 | |
264 | /* Initialize predicate to one testing single condition number COND. */ |
265 | inline void set_to_cond (int cond) |
266 | { |
267 | m_clause[0] = 1 << cond; |
268 | m_clause[1] = 0; |
269 | } |
270 | |
271 | void add_clause (conditions conditions, clause_t); |
272 | }; |
273 | |
274 | void dump_condition (FILE *f, conditions conditions, int cond); |
275 | ipa_predicate add_condition (ipa_fn_summary *summary, |
276 | ipa_node_params *params_summary, |
277 | int operand_num, |
278 | tree type, struct agg_position_info *aggpos, |
279 | enum tree_code code, tree val, |
280 | expr_eval_ops param_ops = NULL); |
281 | |