Mercurial > hg > CbC > CbC_gcc
comparison gcc/opt-problem.h @ 132:d34655255c78
update gcc-8.2
author | mir3636 |
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date | Thu, 25 Oct 2018 10:21:07 +0900 |
parents | 84e7813d76e9 |
children | 1830386684a0 |
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1 /* Rich information on why an optimization wasn't possible. | |
2 Copyright (C) 2018 Free Software Foundation, Inc. | |
3 Contributed by David Malcolm <dmalcolm@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_OPT_PROBLEM_H | |
22 #define GCC_OPT_PROBLEM_H | |
23 | |
24 #include "diagnostic-core.h" /* for ATTRIBUTE_GCC_DIAG. */ | |
25 #include "optinfo.h" /* for optinfo. */ | |
26 | |
27 /* This header declares a family of wrapper classes for tracking a | |
28 success/failure value, while optionally supporting propagating an | |
29 opt_problem * describing any failure back up the call stack. | |
30 | |
31 For instance, at the deepest point of the callstack where the failure | |
32 happens, rather than: | |
33 | |
34 if (!check_something ()) | |
35 { | |
36 if (dump_enabled_p ()) | |
37 dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location, | |
38 "foo is unsupported.\n"); | |
39 return false; | |
40 } | |
41 // [...more checks...] | |
42 | |
43 // All checks passed: | |
44 return true; | |
45 | |
46 we can capture the cause of the failure via: | |
47 | |
48 if (!check_something ()) | |
49 return opt_result::failure_at (stmt, "foo is unsupported"); | |
50 // [...more checks...] | |
51 | |
52 // All checks passed: | |
53 return opt_result::success (); | |
54 | |
55 which effectively returns true or false, whilst recording any problem. | |
56 | |
57 opt_result::success and opt_result::failure return opt_result values | |
58 which "looks like" true/false respectively, via operator bool(). | |
59 If dump_enabled_p, then opt_result::failure also creates an opt_problem *, | |
60 capturing the pertinent data (here, "foo is unsupported " and "stmt"). | |
61 If dumps are disabled, then opt_problem instances aren't | |
62 created, and it's equivalent to just returning a bool. | |
63 | |
64 The opt_problem can be propagated via opt_result values back up | |
65 the call stack to where it makes most sense to the user. | |
66 For instance, rather than: | |
67 | |
68 bool ok = try_something_that_might_fail (); | |
69 if (!ok) | |
70 { | |
71 if (dump_enabled_p ()) | |
72 dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location, | |
73 "some message.\n"); | |
74 return false; | |
75 } | |
76 | |
77 we can replace the bool with an opt_result, so if dump_enabled_p, we | |
78 assume that if try_something_that_might_fail, an opt_problem * will be | |
79 created, and we can propagate it up the call chain: | |
80 | |
81 opt_result ok = try_something_that_might_fail (); | |
82 if (!ok) | |
83 { | |
84 if (dump_enabled_p ()) | |
85 dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location, | |
86 "some message.\n"); | |
87 return ok; // propagating the opt_result | |
88 } | |
89 | |
90 opt_result is an opt_wrapper<bool>, where opt_wrapper<T> is a base | |
91 class for wrapping a T, optionally propagating an opt_problem in | |
92 case of failure_at (when dumps are enabled). Similarly, | |
93 opt_pointer_wrapper<T> can be used to wrap pointer types (where non-NULL | |
94 signifies success, NULL signifies failure). | |
95 | |
96 In all cases, opt_wrapper<T> acts as if the opt_problem were one of its | |
97 fields, but the opt_problem is actually stored in a global, so that when | |
98 compiled, an opt_wrapper<T> is effectively just a T, so that we're | |
99 still just passing e.g. a bool around; the opt_wrapper<T> classes | |
100 simply provide type-checking and an API to ensure that we provide | |
101 error-messages deep in the callstack at the places where problems | |
102 occur, and that we propagate them. This also avoids having | |
103 to manage the ownership of the opt_problem instances. | |
104 | |
105 Using opt_result and opt_wrapper<T> documents the intent of the code | |
106 for the places where we represent success values, and allows the C++ type | |
107 system to track where the deepest points in the callstack are where we | |
108 need to emit the failure messages from. */ | |
109 | |
110 /* A bundle of information about why an optimization failed (e.g. | |
111 vectorization), and the location in both the user's code and | |
112 in GCC itself where the problem occurred. | |
113 | |
114 Instances are created by static member functions in opt_wrapper | |
115 subclasses, such as opt_result::failure. | |
116 | |
117 Instances are only created when dump_enabled_p (). */ | |
118 | |
119 class opt_problem | |
120 { | |
121 public: | |
122 static opt_problem *get_singleton () { return s_the_problem; } | |
123 | |
124 opt_problem (const dump_location_t &loc, | |
125 const char *fmt, va_list *ap) | |
126 ATTRIBUTE_GCC_DUMP_PRINTF (3, 0); | |
127 | |
128 const dump_location_t & | |
129 get_dump_location () const { return m_optinfo.get_dump_location (); } | |
130 | |
131 const optinfo & get_optinfo () const { return m_optinfo; } | |
132 | |
133 void emit_and_clear (); | |
134 | |
135 private: | |
136 optinfo m_optinfo; | |
137 | |
138 static opt_problem *s_the_problem; | |
139 }; | |
140 | |
141 /* A base class for wrapper classes that track a success/failure value, while | |
142 optionally supporting propagating an opt_problem * describing any | |
143 failure back up the call stack. */ | |
144 | |
145 template <typename T> | |
146 class opt_wrapper | |
147 { | |
148 public: | |
149 typedef T wrapped_t; | |
150 | |
151 /* Be accessible as the wrapped type. */ | |
152 operator wrapped_t () const { return m_result; } | |
153 | |
154 /* No public ctor. */ | |
155 | |
156 wrapped_t get_result () const { return m_result; } | |
157 opt_problem *get_problem () const { return opt_problem::get_singleton (); } | |
158 | |
159 protected: | |
160 opt_wrapper (wrapped_t result, opt_problem */*problem*/) | |
161 : m_result (result) | |
162 { | |
163 /* "problem" is ignored: although it looks like a field, we | |
164 actually just use the opt_problem singleton, so that | |
165 opt_wrapper<T> in memory is just a T. */ | |
166 } | |
167 | |
168 private: | |
169 wrapped_t m_result; | |
170 }; | |
171 | |
172 /* Subclass of opt_wrapper<T> for bool, where | |
173 - true signifies "success", and | |
174 - false signifies "failure" | |
175 whilst effectively propagating an opt_problem * describing any failure | |
176 back up the call stack. */ | |
177 | |
178 class opt_result : public opt_wrapper <bool> | |
179 { | |
180 public: | |
181 /* Generate a "success" value: a wrapper around "true". */ | |
182 | |
183 static opt_result success () { return opt_result (true, NULL); } | |
184 | |
185 /* Generate a "failure" value: a wrapper around "false", and, | |
186 if dump_enabled_p, an opt_problem. */ | |
187 | |
188 static opt_result failure_at (const dump_location_t &loc, | |
189 const char *fmt, ...) | |
190 ATTRIBUTE_GCC_DUMP_PRINTF (2, 3) | |
191 { | |
192 opt_problem *problem = NULL; | |
193 if (dump_enabled_p ()) | |
194 { | |
195 va_list ap; | |
196 va_start (ap, fmt); | |
197 problem = new opt_problem (loc, fmt, &ap); | |
198 va_end (ap); | |
199 } | |
200 return opt_result (false, problem); | |
201 } | |
202 | |
203 /* Given a failure wrapper of some other kind, make an opt_result failure | |
204 object, for propagating the opt_problem up the call stack. */ | |
205 | |
206 template <typename S> | |
207 static opt_result | |
208 propagate_failure (opt_wrapper <S> other) | |
209 { | |
210 return opt_result (false, other.get_problem ()); | |
211 } | |
212 | |
213 private: | |
214 /* Private ctor. Instances should be created by the success and failure | |
215 static member functions. */ | |
216 opt_result (wrapped_t result, opt_problem *problem) | |
217 : opt_wrapper <bool> (result, problem) | |
218 {} | |
219 }; | |
220 | |
221 /* Subclass of opt_wrapper<T> where T is a pointer type, for tracking | |
222 success/failure, where: | |
223 - a non-NULL value signifies "success", and | |
224 - a NULL value signifies "failure", | |
225 whilst effectively propagating an opt_problem * describing any failure | |
226 back up the call stack. */ | |
227 | |
228 template <typename PtrType_t> | |
229 class opt_pointer_wrapper : public opt_wrapper <PtrType_t> | |
230 { | |
231 public: | |
232 typedef PtrType_t wrapped_pointer_t; | |
233 | |
234 /* Given a non-NULL pointer, make a success object wrapping it. */ | |
235 | |
236 static opt_pointer_wrapper <wrapped_pointer_t> | |
237 success (wrapped_pointer_t ptr) | |
238 { | |
239 return opt_pointer_wrapper <wrapped_pointer_t> (ptr, NULL); | |
240 } | |
241 | |
242 /* Make a NULL pointer failure object, with the given message | |
243 (if dump_enabled_p). */ | |
244 | |
245 static opt_pointer_wrapper <wrapped_pointer_t> | |
246 failure_at (const dump_location_t &loc, | |
247 const char *fmt, ...) | |
248 ATTRIBUTE_GCC_DUMP_PRINTF (2, 3) | |
249 { | |
250 opt_problem *problem = NULL; | |
251 if (dump_enabled_p ()) | |
252 { | |
253 va_list ap; | |
254 va_start (ap, fmt); | |
255 problem = new opt_problem (loc, fmt, &ap); | |
256 va_end (ap); | |
257 } | |
258 return opt_pointer_wrapper <wrapped_pointer_t> (NULL, problem); | |
259 } | |
260 | |
261 /* Given a failure wrapper of some other kind, make a NULL pointer | |
262 failure object, propagating the problem. */ | |
263 | |
264 template <typename S> | |
265 static opt_pointer_wrapper <wrapped_pointer_t> | |
266 propagate_failure (opt_wrapper <S> other) | |
267 { | |
268 return opt_pointer_wrapper <wrapped_pointer_t> (NULL, | |
269 other.get_problem ()); | |
270 } | |
271 | |
272 /* Support accessing the underlying pointer via ->. */ | |
273 | |
274 wrapped_pointer_t operator-> () const { return this->get_result (); } | |
275 | |
276 private: | |
277 /* Private ctor. Instances should be built using the static member | |
278 functions "success" and "failure". */ | |
279 opt_pointer_wrapper (wrapped_pointer_t result, opt_problem *problem) | |
280 : opt_wrapper<PtrType_t> (result, problem) | |
281 {} | |
282 }; | |
283 | |
284 /* A typedef for wrapping "tree" so that NULL_TREE can carry an | |
285 opt_problem describing the failure (if dump_enabled_p). */ | |
286 | |
287 typedef opt_pointer_wrapper<tree> opt_tree; | |
288 | |
289 #endif /* #ifndef GCC_OPT_PROBLEM_H */ |