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b679b55b | 1 | /* IPA predicates. |
8d9254fc | 2 | Copyright (C) 2003-2020 Free Software Foundation, Inc. |
b679b55b JH |
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 | |
4307a485 FX |
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; | |
b679b55b JH |
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; | |
4307a485 FX |
53 | /* Type of the access reading the data (or the PARM_DECL SSA_NAME). */ |
54 | tree type; | |
b679b55b JH |
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; | |
4307a485 | 64 | /* A set of sequential operations on the parameter, which can be seen as |
956d615d | 65 | a mathematical function on the parameter. */ |
4307a485 | 66 | expr_eval_ops param_ops; |
b679b55b JH |
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 | int change_prob; | |
40a777e8 | 80 | bool equal_to (const inline_param_summary &other) const |
ac6f2e59 JH |
81 | { |
82 | return change_prob == other.change_prob; | |
83 | } | |
40a777e8 JH |
84 | bool useless_p (void) const |
85 | { | |
86 | return change_prob == REG_BR_PROB_BASE; | |
87 | } | |
b679b55b JH |
88 | }; |
89 | ||
90 | typedef vec<condition, va_gc> *conditions; | |
91 | ||
956d615d | 92 | /* Predicates are used to represent function parameters (such as runtime) |
b679b55b JH |
93 | which depend on a context function is called in. |
94 | ||
95 | Predicates are logical formulas in conjunctive-disjunctive form consisting | |
96 | of clauses which are bitmaps specifying a set of condition that must | |
97 | be true for a clause to be satisfied. Physically they are represented as | |
98 | array of clauses terminated by 0. | |
99 | ||
100 | In order to make predicate (possibly) true, all of its clauses must | |
101 | be (possibly) true. To make clause (possibly) true, one of conditions | |
102 | it mentions must be (possibly) true. | |
103 | ||
104 | There are fixed bounds on number of clauses and conditions and all the | |
105 | manipulation functions are conservative in positive direction. I.e. we | |
106 | may lose precision by thinking that predicate may be true even when it | |
107 | is not. */ | |
108 | ||
109 | typedef uint32_t clause_t; | |
110 | class predicate | |
111 | { | |
112 | public: | |
113 | enum predicate_conditions | |
114 | { | |
115 | false_condition = 0, | |
116 | not_inlined_condition = 1, | |
117 | first_dynamic_condition = 2 | |
118 | }; | |
119 | ||
956d615d | 120 | /* Maximal number of conditions predicate can refer to. This is limited |
b679b55b JH |
121 | by using clause_t to be 32bit. */ |
122 | static const int num_conditions = 32; | |
123 | ||
124 | /* Special condition code we use to represent test that operand is compile | |
125 | time constant. */ | |
126 | static const tree_code is_not_constant = ERROR_MARK; | |
127 | ||
128 | /* Special condition code we use to represent test that operand is not changed | |
129 | across invocation of the function. When operand IS_NOT_CONSTANT it is | |
130 | always CHANGED, however i.e. loop invariants can be NOT_CHANGED given | |
131 | percentage of executions even when they are not compile time constants. */ | |
132 | static const tree_code changed = IDENTIFIER_NODE; | |
133 | ||
134 | ||
135 | ||
136 | /* Initialize predicate either to true of false depending on P. */ | |
137 | inline predicate (bool p = true) | |
138 | { | |
139 | if (p) | |
140 | /* True predicate. */ | |
141 | m_clause[0] = 0; | |
142 | else | |
143 | /* False predicate. */ | |
144 | set_to_cond (false_condition); | |
145 | } | |
146 | ||
147 | /* Sanity check that we do not mix pointers to predicates with predicates. */ | |
148 | inline predicate (predicate *) | |
149 | { | |
150 | gcc_unreachable (); | |
151 | } | |
152 | ||
153 | /* Return predicate testing condition I. */ | |
154 | static inline predicate predicate_testing_cond (int i) | |
155 | { | |
156 | class predicate p; | |
157 | p.set_to_cond (i + first_dynamic_condition); | |
158 | return p; | |
159 | } | |
160 | ||
161 | /* Return predicate testing that function was not inlined. */ | |
162 | static predicate not_inlined (void) | |
163 | { | |
164 | class predicate p; | |
165 | p.set_to_cond (not_inlined_condition); | |
166 | return p; | |
167 | } | |
168 | ||
169 | /* Compute logical and of predicates. */ | |
170 | predicate & operator &= (const predicate &); | |
61890ff2 | 171 | inline predicate operator &(const predicate &p) const |
b679b55b JH |
172 | { |
173 | predicate ret = *this; | |
174 | ret &= p; | |
175 | return ret; | |
176 | } | |
177 | ||
178 | /* Compute logical or of predicates. This is not operator because | |
179 | extra parameter CONDITIONS is needed */ | |
180 | predicate or_with (conditions, const predicate &) const; | |
181 | ||
182 | /* Return true if predicates are known to be equal. */ | |
183 | inline bool operator==(const predicate &p2) const | |
184 | { | |
185 | int i; | |
186 | for (i = 0; m_clause[i]; i++) | |
187 | { | |
188 | gcc_checking_assert (i < max_clauses); | |
189 | gcc_checking_assert (m_clause[i] > m_clause[i + 1]); | |
190 | gcc_checking_assert (!p2.m_clause[i] | |
191 | || p2.m_clause[i] > p2.m_clause[i + 1]); | |
192 | if (m_clause[i] != p2.m_clause[i]) | |
193 | return false; | |
194 | } | |
195 | return !p2.m_clause[i]; | |
196 | } | |
197 | ||
198 | /* Return true if predicates are known to be true or false depending | |
199 | on COND. */ | |
200 | inline bool operator==(const bool cond) const | |
201 | { | |
202 | if (cond) | |
203 | return !m_clause[0]; | |
204 | if (m_clause[0] == (1 << false_condition)) | |
205 | { | |
206 | gcc_checking_assert (!m_clause[1] | |
207 | && m_clause[0] == 1 | |
208 | << false_condition); | |
209 | return true; | |
210 | } | |
211 | return false; | |
212 | } | |
213 | ||
214 | inline bool operator!=(const predicate &p2) const | |
215 | { | |
216 | return !(*this == p2); | |
217 | } | |
218 | ||
219 | inline bool operator!=(const bool cond) const | |
220 | { | |
221 | return !(*this == cond); | |
222 | } | |
223 | ||
224 | /* Evaluate if predicate is known to be false given the clause of possible | |
225 | truths. */ | |
226 | bool evaluate (clause_t) const; | |
227 | ||
228 | /* Estimate probability that predicate will be true in a given context. */ | |
229 | int probability (conditions, clause_t, vec<inline_param_summary>) const; | |
230 | ||
231 | /* Dump predicate to F. Output newline if nl. */ | |
232 | void dump (FILE *f, conditions, bool nl=true) const; | |
233 | void DEBUG_FUNCTION debug (conditions) const; | |
234 | ||
235 | /* Return predicate equal to THIS after duplication. */ | |
236 | predicate remap_after_duplication (clause_t); | |
237 | ||
238 | /* Return predicate equal to THIS after inlining. */ | |
99b1c316 | 239 | predicate remap_after_inlining (class ipa_fn_summary *, |
40a777e8 | 240 | class ipa_node_params *params_summary, |
99b1c316 | 241 | class ipa_fn_summary *, |
b679b55b JH |
242 | vec<int>, vec<int>, clause_t, const predicate &); |
243 | ||
99b1c316 | 244 | void stream_in (class lto_input_block *); |
b679b55b JH |
245 | void stream_out (struct output_block *); |
246 | ||
247 | private: | |
248 | static const int max_clauses = 8; | |
249 | clause_t m_clause[max_clauses + 1]; | |
250 | ||
251 | /* Initialize predicate to one testing single condition number COND. */ | |
252 | inline void set_to_cond (int cond) | |
253 | { | |
254 | m_clause[0] = 1 << cond; | |
255 | m_clause[1] = 0; | |
256 | } | |
257 | ||
258 | void add_clause (conditions conditions, clause_t); | |
259 | }; | |
260 | ||
261 | void dump_condition (FILE *f, conditions conditions, int cond); | |
40a777e8 JH |
262 | predicate add_condition (class ipa_fn_summary *summary, |
263 | class ipa_node_params *params_summary, | |
264 | int operand_num, | |
4307a485 FX |
265 | tree type, struct agg_position_info *aggpos, |
266 | enum tree_code code, tree val, | |
267 | expr_eval_ops param_ops = NULL); |