Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
// Force x86-64 because some of our heuristics are actually based
// on integer sizes.

// RUN: %clang_cc1 -triple x86_64-apple-darwin -fsyntax-only -pedantic -verify -Wsign-compare -Wtautological-constant-in-range-compare -std=c++11 %s

int test0(long a, unsigned long b) {
  enum EnumA {A};
  enum EnumB {B};
  enum EnumC {C = 0x10000};
  return
         // (a,b)
         (a == (unsigned long) b) +  // expected-warning {{comparison of integers of different signs}}
         (a == (unsigned int) b) +
         (a == (unsigned short) b) +
         (a == (unsigned char) b) +
         ((long) a == b) +  // expected-warning {{comparison of integers of different signs}}
         ((int) a == b) +  // expected-warning {{comparison of integers of different signs}}
         ((short) a == b) +  // expected-warning {{comparison of integers of different signs}}
         ((signed char) a == b) +  // expected-warning {{comparison of integers of different signs}}
         ((long) a == (unsigned long) b) +  // expected-warning {{comparison of integers of different signs}}
         ((int) a == (unsigned int) b) +  // expected-warning {{comparison of integers of different signs}}
         ((short) a == (unsigned short) b) +
         ((signed char) a == (unsigned char) b) +
         (a < (unsigned long) b) +  // expected-warning {{comparison of integers of different signs}}
         (a < (unsigned int) b) +
         (a < (unsigned short) b) +
         (a < (unsigned char) b) +
         ((long) a < b) +  // expected-warning {{comparison of integers of different signs}}
         ((int) a < b) +  // expected-warning {{comparison of integers of different signs}}
         ((short) a < b) +  // expected-warning {{comparison of integers of different signs}}
         ((signed char) a < b) +  // expected-warning {{comparison of integers of different signs}}
         ((long) a < (unsigned long) b) +  // expected-warning {{comparison of integers of different signs}}
         ((int) a < (unsigned int) b) +  // expected-warning {{comparison of integers of different signs}}
         ((short) a < (unsigned short) b) +
         ((signed char) a < (unsigned char) b) +

         // (A,b)
         (A == (unsigned long) b) +
         (A == (unsigned int) b) +
         (A == (unsigned short) b) +
         (A == (unsigned char) b) +
         ((long) A == b) +
         ((int) A == b) +
         ((short) A == b) +
         ((signed char) A == b) +
         ((long) A == (unsigned long) b) +
         ((int) A == (unsigned int) b) +
         ((short) A == (unsigned short) b) +
         ((signed char) A == (unsigned char) b) +
         (A < (unsigned long) b) +
         (A < (unsigned int) b) +
         (A < (unsigned short) b) +
         (A < (unsigned char) b) +
         ((long) A < b) +
         ((int) A < b) +
         ((short) A < b) +
         ((signed char) A < b) +
         ((long) A < (unsigned long) b) +
         ((int) A < (unsigned int) b) +
         ((short) A < (unsigned short) b) +
         ((signed char) A < (unsigned char) b) +

         // (a,B)
         (a == (unsigned long) B) +
         (a == (unsigned int) B) +
         (a == (unsigned short) B) +
         (a == (unsigned char) B) +
         ((long) a == B) +
         ((int) a == B) +
         ((short) a == B) +
         ((signed char) a == B) +
         ((long) a == (unsigned long) B) +
         ((int) a == (unsigned int) B) +
         ((short) a == (unsigned short) B) +
         ((signed char) a == (unsigned char) B) +
         (a < (unsigned long) B) +  // expected-warning {{comparison of unsigned expression < 0 is always false}}
         (a < (unsigned int) B) +
         (a < (unsigned short) B) +
         (a < (unsigned char) B) +
         ((long) a < B) +
         ((int) a < B) +
         ((short) a < B) +
         ((signed char) a < B) +
         ((long) a < (unsigned long) B) +  // expected-warning {{comparison of unsigned expression < 0 is always false}}
         ((int) a < (unsigned int) B) +  // expected-warning {{comparison of unsigned expression < 0 is always false}}
         ((short) a < (unsigned short) B) +
         ((signed char) a < (unsigned char) B) +

         // (C,b)
         (C == (unsigned long) b) +
         (C == (unsigned int) b) +
         (C == (unsigned short) b) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'unsigned short' is always false}}
         (C == (unsigned char) b) +  // expected-warning {{comparison of constant 'C' (65536) with expression of type 'unsigned char' is always false}}
         ((long) C == b) +
         ((int) C == b) +
         ((short) C == b) +
         ((signed char) C == b) +
         ((long) C == (unsigned long) b) +
         ((int) C == (unsigned int) b) +
         ((short) C == (unsigned short) b) +
         ((signed char) C == (unsigned char) b) +
         (C < (unsigned long) b) +
         (C < (unsigned int) b) +
         (C < (unsigned short) b) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'unsigned short' is always false}}
         (C < (unsigned char) b) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'unsigned char' is always false}}
         ((long) C < b) +
         ((int) C < b) +
         ((short) C < b) +
         ((signed char) C < b) +
         ((long) C < (unsigned long) b) +
         ((int) C < (unsigned int) b) +
         ((short) C < (unsigned short) b) +
         ((signed char) C < (unsigned char) b) +

         // (a,C)
         (a == (unsigned long) C) +
         (a == (unsigned int) C) +
         (a == (unsigned short) C) +
         (a == (unsigned char) C) +
         ((long) a == C) +
         ((int) a == C) +
         ((short) a == C) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'short' is always false}}
         ((signed char) a == C) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'signed char' is always false}}
         ((long) a == (unsigned long) C) +
         ((int) a == (unsigned int) C) +
         ((short) a == (unsigned short) C) +
         ((signed char) a == (unsigned char) C) +
         (a < (unsigned long) C) +  // expected-warning {{comparison of integers of different signs}}
         (a < (unsigned int) C) +
         (a < (unsigned short) C) +
         (a < (unsigned char) C) +
         ((long) a < C) +
         ((int) a < C) +
         ((short) a < C) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'short' is always true}}
         ((signed char) a < C) + // expected-warning {{comparison of constant 'C' (65536) with expression of type 'signed char' is always true}}
         ((long) a < (unsigned long) C) +  // expected-warning {{comparison of integers of different signs}}
         ((int) a < (unsigned int) C) +  // expected-warning {{comparison of integers of different signs}}
         ((short) a < (unsigned short) C) +
         ((signed char) a < (unsigned char) C) +

         // (0x80000,b)
         (0x80000 == (unsigned long) b) +
         (0x80000 == (unsigned int) b) +
         (0x80000 == (unsigned short) b) + // expected-warning {{comparison of constant 524288 with expression of type 'unsigned short' is always false}}
         (0x80000 == (unsigned char) b) + // expected-warning {{comparison of constant 524288 with expression of type 'unsigned char' is always false}}
         ((long) 0x80000 == b) +
         ((int) 0x80000 == b) +
         ((short) 0x80000 == b) +
         ((signed char) 0x80000 == b) +
         ((long) 0x80000 == (unsigned long) b) +
         ((int) 0x80000 == (unsigned int) b) +
         ((short) 0x80000 == (unsigned short) b) +
         ((signed char) 0x80000 == (unsigned char) b) +
         (0x80000 < (unsigned long) b) +
         (0x80000 < (unsigned int) b) +
         (0x80000 < (unsigned short) b) + // expected-warning {{comparison of constant 524288 with expression of type 'unsigned short' is always false}}
         (0x80000 < (unsigned char) b) + // expected-warning {{comparison of constant 524288 with expression of type 'unsigned char' is always false}}
         ((long) 0x80000 < b) +
         ((int) 0x80000 < b) +
         ((short) 0x80000 < b) +
         ((signed char) 0x80000 < b) +
         ((long) 0x80000 < (unsigned long) b) +
         ((int) 0x80000 < (unsigned int) b) +
         ((short) 0x80000 < (unsigned short) b) +
         ((signed char) 0x80000 < (unsigned char) b) +

         // (a,0x80000)
         (a == (unsigned long) 0x80000) +
         (a == (unsigned int) 0x80000) +
         (a == (unsigned short) 0x80000) +
         (a == (unsigned char) 0x80000) +
         ((long) a == 0x80000) +
         ((int) a == 0x80000) +
         ((short) a == 0x80000) + // expected-warning {{comparison of constant 524288 with expression of type 'short' is always false}}
         ((signed char) a == 0x80000) + // expected-warning {{comparison of constant 524288 with expression of type 'signed char' is always false}}
         ((long) a == (unsigned long) 0x80000) +
         ((int) a == (unsigned int) 0x80000) +
         ((short) a == (unsigned short) 0x80000) +
         ((signed char) a == (unsigned char) 0x80000) +
         (a < (unsigned long) 0x80000) +  // expected-warning {{comparison of integers of different signs}}
         (a < (unsigned int) 0x80000) +
         (a < (unsigned short) 0x80000) +
         (a < (unsigned char) 0x80000) +
         ((long) a < 0x80000) +
         ((int) a < 0x80000) +
         ((short) a < 0x80000) + // expected-warning {{comparison of constant 524288 with expression of type 'short' is always true}}
         ((signed char) a < 0x80000) + // expected-warning {{comparison of constant 524288 with expression of type 'signed char' is always true}}
         ((long) a < (unsigned long) 0x80000) +  // expected-warning {{comparison of integers of different signs}}
         ((int) a < (unsigned int) 0x80000) +  // expected-warning {{comparison of integers of different signs}}
         ((short) a < (unsigned short) 0x80000) +
         ((signed char) a < (unsigned char) 0x80000) +

         10
    ;
}

int test1(int i) {
  enum en { zero };
  return i > zero;
}

enum E { e };
void test2(int i, void *vp) {
  if (&i == vp) { } // ok
  if (test1 == vp) { } // expected-warning{{equality comparison between function pointer and void pointer}}
  if (test1 == e) { } // expected-error{{comparison between pointer and integer}}
  if (vp < 0) { } // expected-error {{comparison between pointer and zero}}
  if (test1 < e) { } // expected-error{{comparison between pointer and integer}}
}

// PR7536
static const unsigned int kMax = 0;
int pr7536() {
  return (kMax > 0);
}

// -Wsign-compare should not warn when ?: operands have different signedness.
// This will be caught by -Wsign-conversion
void test3() {
  unsigned long a;
  signed long b;
  (void) (true ? a : b);
  (void) (true ? (unsigned int)a : (signed int)b);
  (void) (true ? b : a);
  (void) (true ? (unsigned char)b : (signed char)a);
}

// Test comparison of short to unsigned.  If tautological compare does not
// trigger, then the signed comparison warning will.
void test4(short s) {
  // A is max short plus 1.  All zero and positive shorts are smaller than it.
  // All negative shorts are cast towards the max unsigned range.  Relation
  // comparisons are possible, but equality comparisons are tautological.
  const unsigned A = 32768;
  void (s < A); // expected-warning{{comparison of integers of different signs: 'short' and 'const unsigned int'}}
  void (s > A); // expected-warning{{comparison of integers of different signs: 'short' and 'const unsigned int'}}
  void (s <= A); // expected-warning{{comparison of integers of different signs: 'short' and 'const unsigned int'}}
  void (s >= A); // expected-warning{{comparison of integers of different signs: 'short' and 'const unsigned int'}}

  void (s == A); // expected-warning{{comparison of constant 32768 with expression of type 'short' is always false}}
  void (s != A); // expected-warning{{comparison of constant 32768 with expression of type 'short' is always true}}

  // When negative one is converted to an unsigned value, it becomes the max
  // unsigned.  Likewise, a negative one short can also be converted to max
  // unsigned.
  const unsigned B = -1;
  void (s < B); // expected-warning{{comparison of integers of different signs: 'short' and 'const unsigned int'}}
  void (s > B); // expected-warning{{comparison 'short' > 4294967295 is always false}}
  void (s <= B); // expected-warning{{comparison 'short' <= 4294967295 is always true}}
  void (s >= B); // expected-warning{{comparison of integers of different signs: 'short' and 'const unsigned int'}}
  void (s == B); // expected-warning{{comparison of integers of different signs: 'short' and 'const unsigned int'}}
  void (s != B); // expected-warning{{comparison of integers of different signs: 'short' and 'const unsigned int'}}

}

void test5(bool b) {
  (void) (b < -1); // expected-warning{{comparison of constant -1 with expression of type 'bool' is always false}}
  (void) (b > -1); // expected-warning{{comparison of constant -1 with expression of type 'bool' is always true}}
  (void) (b == -1); // expected-warning{{comparison of constant -1 with expression of type 'bool' is always false}}
  (void) (b != -1); // expected-warning{{comparison of constant -1 with expression of type 'bool' is always true}}
  (void) (b <= -1); // expected-warning{{comparison of constant -1 with expression of type 'bool' is always false}}
  (void) (b >= -1); // expected-warning{{comparison of constant -1 with expression of type 'bool' is always true}}

  (void) (b < -10); // expected-warning{{comparison of constant -10 with expression of type 'bool' is always false}}
  (void) (b > -10); // expected-warning{{comparison of constant -10 with expression of type 'bool' is always true}}
  (void) (b == -10); // expected-warning{{comparison of constant -10 with expression of type 'bool' is always false}}
  (void) (b != -10); // expected-warning{{comparison of constant -10 with expression of type 'bool' is always true}}
  (void) (b <= -10); // expected-warning{{comparison of constant -10 with expression of type 'bool' is always false}}
  (void) (b >= -10); // expected-warning{{comparison of constant -10 with expression of type 'bool' is always true}}

  (void) (b < 2); // expected-warning{{comparison of constant 2 with expression of type 'bool' is always true}}
  (void) (b > 2); // expected-warning{{comparison of constant 2 with expression of type 'bool' is always false}}
  (void) (b == 2); // expected-warning{{comparison of constant 2 with expression of type 'bool' is always false}}
  (void) (b != 2); // expected-warning{{comparison of constant 2 with expression of type 'bool' is always true}}
  (void) (b <= 2); // expected-warning{{comparison of constant 2 with expression of type 'bool' is always true}}
  (void) (b >= 2); // expected-warning{{comparison of constant 2 with expression of type 'bool' is always false}}

  (void) (b < 10); // expected-warning{{comparison of constant 10 with expression of type 'bool' is always true}}
  (void) (b > 10); // expected-warning{{comparison of constant 10 with expression of type 'bool' is always false}}
  (void) (b == 10); // expected-warning{{comparison of constant 10 with expression of type 'bool' is always false}}
  (void) (b != 10); // expected-warning{{comparison of constant 10 with expression of type 'bool' is always true}}
  (void) (b <= 10); // expected-warning{{comparison of constant 10 with expression of type 'bool' is always true}}
  (void) (b >= 10); // expected-warning{{comparison of constant 10 with expression of type 'bool' is always false}}
}

void test6(signed char sc) {
  (void)(sc < 200); // expected-warning{{comparison of constant 200 with expression of type 'signed char' is always true}}
  (void)(sc > 200); // expected-warning{{comparison of constant 200 with expression of type 'signed char' is always false}}
  (void)(sc <= 200); // expected-warning{{comparison of constant 200 with expression of type 'signed char' is always true}}
  (void)(sc >= 200); // expected-warning{{comparison of constant 200 with expression of type 'signed char' is always false}}
  (void)(sc == 200); // expected-warning{{comparison of constant 200 with expression of type 'signed char' is always false}}
  (void)(sc != 200); // expected-warning{{comparison of constant 200 with expression of type 'signed char' is always true}}

  (void)(200 < sc); // expected-warning{{comparison of constant 200 with expression of type 'signed char' is always false}}
  (void)(200 > sc); // expected-warning{{comparison of constant 200 with expression of type 'signed char' is always true}}
  (void)(200 <= sc); // expected-warning{{comparison of constant 200 with expression of type 'signed char' is always false}}
  (void)(200 >= sc); // expected-warning{{comparison of constant 200 with expression of type 'signed char' is always true}}
  (void)(200 == sc); // expected-warning{{comparison of constant 200 with expression of type 'signed char' is always false}}
  (void)(200 != sc); // expected-warning{{comparison of constant 200 with expression of type 'signed char' is always true}}
}

// Test many signedness combinations.
void test7(unsigned long other) {
  // Common unsigned, other unsigned, constant unsigned
  (void)((unsigned)other != (unsigned long)(0x1ffffffff)); // expected-warning{{true}}
  (void)((unsigned)other != (unsigned long)(0xffffffff));
  (void)((unsigned long)other != (unsigned)(0x1ffffffff));
  (void)((unsigned long)other != (unsigned)(0xffffffff));

  // Common unsigned, other signed, constant unsigned
  (void)((int)other != (unsigned long)(0xffffffffffffffff)); // expected-warning{{different signs}}
  (void)((int)other != (unsigned long)(0x00000000ffffffff)); // expected-warning{{true}}
  (void)((int)other != (unsigned long)(0x000000000fffffff));
  (void)((int)other < (unsigned long)(0x00000000ffffffff));  // expected-warning{{different signs}}
  (void)((int)other == (unsigned)(0x800000000));

  // Common unsigned, other unsigned, constant signed
  (void)((unsigned long)other != (int)(0xffffffff));  // expected-warning{{different signs}}

  // Common unsigned, other signed, constant signed
  // Should not be possible as the common type should also be signed.

  // Common signed, other signed, constant signed
  (void)((int)other != (long)(0xffffffff));  // expected-warning{{true}}
  (void)((int)other != (long)(0xffffffff00000000));  // expected-warning{{true}}
  (void)((int)other != (long)(0xfffffff));
  (void)((int)other != (long)(0xfffffffff0000000));

  // Common signed, other signed, constant unsigned
  (void)((int)other != (unsigned char)(0xffff));
  (void)((int)other != (unsigned char)(0xff));

  // Common signed, other unsigned, constant signed
  (void)((unsigned char)other != (int)(0xff));
  (void)((unsigned char)other != (int)(0xffff));  // expected-warning{{true}}

  // Common signed, other unsigned, constant unsigned
  (void)((unsigned char)other != (unsigned short)(0xff));
  (void)((unsigned char)other != (unsigned short)(0x100)); // expected-warning{{true}}
  (void)((unsigned short)other != (unsigned char)(0xff));
}

void test8(int x) {
  enum E {
    Negative = -1,
    Positive = 1
  };

  (void)((E)x == 1);
  (void)((E)x == -1);
}

void test9(int x) {
  enum E : int {
    Positive = 1
  };
  (void)((E)x == 1);
}

namespace templates {
  template<class T> T max();

  template<> constexpr int max<int>() { return 2147483647; };

  template<typename T>
  bool less_than_max(short num, T value) {
    const T vmax = max<T>();
    return (vmax >= num);  // no warning
  }

  template<typename T>
  bool less_than_max(short num) {
    // This should trigger one warning on the template pattern, and not a
    // warning per specialization.
    return num < max<int>();  // expected-warning{{comparison of constant 2147483647 with expression of type 'short' is always true}}
  }

  void test10(short num, int x) {
    less_than_max(num, x);
    less_than_max<int>(num);
    less_than_max<long>(num);
    less_than_max<short>(num);
  }

  template<typename T>
  inline bool less_than_zero(T num, T value) {
    return num < 0;  // no warning
  }

  template<typename T>
  inline bool less_than_zero(unsigned num) {
    // This should trigger one warning on the template pattern, and not a
    // warning per specialization.
    return num < 0;  // expected-warning{{comparison of unsigned expression < 0 is always false}}
  }

  void test11(unsigned num) {
    less_than_zero(num, num);
    less_than_zero<int>(num);
    less_than_zero<long>(num);
    less_than_zero<short>(num);
  }

  template<unsigned n> bool compare(unsigned k) { return k >= n; }

  void test12() {
    compare<0>(42);
  }

  struct A { static int x; };
  struct B { static int x; };
  typedef A otherA;

  template <typename T>
  void testx() {
    if (A::x == T::x &&  // no warning
        A::x == otherA::x)  // expected-warning{{self-comparison always evaluates to true}}
      return;
  }

  void test13() {
    testx<A>();
    testx<B>();
  }
}

namespace tautological_enum {
  enum E { a, b, c } e;

  // FIXME: We should warn about constructing this out-of-range numeration value.
  const E invalid = (E)-1;
  // ... but we should not warn about comparing against it.
  bool x = e == invalid;

  // We should not warn about relational comparisons for enumerators, even if
  // they're tautological.
  bool y = e >= a && e <= b;
  const E first_in_range = a;
  const E last_in_range = b;
  bool z = e >= first_in_range && e <= last_in_range;
}