dead-stores.c revision a5495eadc816b29954e22df55aa9a9d6bb41429c 
1// RUN: clang-cc -analyze -warn-dead-stores -verify %s &&
2// RUN: clang-cc -analyze -checker-cfref -analyzer-store=basic -analyzer-constraints=basic -warn-dead-stores -verify %s &&
3// RUN: clang-cc -analyze -checker-cfref -analyzer-store=basic-old-cast -analyzer-constraints=basic -warn-dead-stores -verify %s &&
4// RUN: clang-cc -analyze -checker-cfref -analyzer-store=basic -analyzer-constraints=range -warn-dead-stores -verify %s &&
5// RUN: clang-cc -analyze -checker-cfref -analyzer-store=basic-old-cast -analyzer-constraints=range -warn-dead-stores -verify %s &&
6// RUN: clang-cc -analyze -checker-cfref -analyzer-store=region -analyzer-constraints=basic -warn-dead-stores -verify %s &&
7// RUN: clang-cc -analyze -checker-cfref -analyzer-store=region -analyzer-constraints=range -warn-dead-stores -verify %s
8
9void f1() {
10  int k, y;
11  int abc=1;
12  long idx=abc+3*5; // expected-warning {{never read}}
13}
14
15void f2(void *b) {
16 char *c = (char*)b; // no-warning
17 char *d = b+1; // expected-warning {{never read}}
18 printf("%s", c); // expected-warning{{implicitly declaring C library function 'printf' with type 'int (char const *, ...)'}} \
19 // expected-note{{please include the header <stdio.h> or explicitly provide a declaration for 'printf'}}
20}
21
22void f3() {
23  int r;
24  if ((r = f()) != 0) { // no-warning
25    int y = r; // no-warning
26    printf("the error is: %d\n", y);
27  }
28}
29
30void f4(int k) {
31
32  k = 1;
33
34  if (k)
35    f1();
36
37  k = 2;  // expected-warning {{never read}}
38}
39
40void f5() {
41
42  int x = 4; // no-warning
43  int *p = &x; // expected-warning{{never read}}
44
45}
46
47int f6() {
48
49  int x = 4;
50  ++x; // expected-warning{{never read}}
51  return 1;
52}
53
54int f7(int *p) {
55  // This is allowed for defensive programming.
56  p = 0; // no-warning
57  return 1;
58}
59
60int f8(int *p) {
61  extern int *baz();
62  if (p = baz()) // expected-warning{{Although the value}}
63    return 1;
64  return 0;
65}
66
67int f9() {
68  int x = 4;
69  x = x + 10; // expected-warning{{never read}}
70  return 1;
71}
72
73int f10() {
74  int x = 4;
75  x = 10 + x; // expected-warning{{never read}}
76  return 1;
77}
78
79int f11() {
80  int x = 4;
81  return x++; // expected-warning{{never read}}
82}
83
84int f11b() {
85  int x = 4;
86  return ((((++x)))); // no-warning
87}
88
89int f12a(int y) {
90  int x = y;  // expected-warning{{never read}}
91  return 1;
92}
93int f12b(int y) {
94  int x __attribute__((unused)) = y;  // no-warning
95  return 1;
96}
97
98// Filed with PR 2630.  This code should produce no warnings.
99int f13(void)
100{
101  int a = 1;
102  int b, c = b = a + a;
103
104  if (b > 0)
105    return (0);
106
107  return (a + b + c);
108}
109
110// Filed with PR 2763.
111int f14(int count) {
112  int index, nextLineIndex;
113  for (index = 0; index < count; index = nextLineIndex+1) {
114    nextLineIndex = index+1;  // no-warning
115    continue;
116  }
117  return index;
118}
119
120// Test case for <rdar://problem/6248086>
121void f15(unsigned x, unsigned y) {
122  int count = x * y;   // no-warning
123  int z[count];
124}
125
126int f16(int x) {
127  x = x * 2;
128  x = sizeof(int [x = (x || x + 1) * 2]) // expected-warning{{Although the value stored to 'x' is used}}
129      ? 5 : 8;
130  return x;
131}
132
133// Self-assignments should not be flagged as dead stores.
134void f17() {
135  int x = 1;
136  x = x; // no-warning
137}
138
139// <rdar://problem/6506065>
140// The values of dead stores are only "consumed" in an enclosing expression
141// what that value is actually used.  In other words, don't say "Although the
142// value stored to 'x' is used...".
143int f18() {
144   int x = 0; // no-warning
145   if (1)
146      x = 10;  // expected-warning{{Value stored to 'x' is never read}}
147   while (1)
148      x = 10;  // expected-warning{{Value stored to 'x' is never read}}
149   do
150      x = 10;   // expected-warning{{Value stored to 'x' is never read}}
151   while (1);
152
153   return (x = 10); // expected-warning{{Although the value stored to 'x' is used in the enclosing expression, the value is never actually read from 'x'}}
154}
155
156// PR 3514: false positive `dead initialization` warning for init to global
157//  http://llvm.org/bugs/show_bug.cgi?id=3514
158extern const int MyConstant;
159int f19(void) {
160  int x = MyConstant;  // no-warning
161  x = 1;
162  return x;
163}
164
165int f19b(void) { // This case is the same as f19.
166  const int MyConstant = 0;
167  int x = MyConstant; // no-warning
168  x = 1;
169  return x;
170}
171
172void f20(void) {
173  int x = 1; // no-warning
174#pragma unused(x)
175}
176
177void halt() __attribute__((noreturn));
178int f21() {
179  int x = 4;
180
181  ++x; // expected-warning{{never read}}
182  if (1) {
183    halt();
184    (void)x;
185  }
186  return 1;
187}
188
189int j;
190void f22() {
191  int x = 4;
192  int y1 = 4;
193  int y2 = 4;
194  int y3 = 4;
195  int y4 = 4;
196  int y5 = 4;
197  int y6 = 4;
198  int y7 = 4;
199  int y8 = 4;
200  int y9 = 4;
201  int y10 = 4;
202  int y11 = 4;
203  int y12 = 4;
204  int y13 = 4;
205  int y14 = 4;
206  int y15 = 4;
207  int y16 = 4;
208  int y17 = 4;
209  int y18 = 4;
210  int y19 = 4;
211  int y20 = 4;
212
213  ++x; // expected-warning{{never read}}
214  ++y1;
215  ++y2;
216  ++y3;
217  ++y4;
218  ++y5;
219  ++y6;
220  ++y7;
221  ++y8;
222  ++y9;
223  ++y10;
224  ++y11;
225  ++y12;
226  ++y13;
227  ++y14;
228  ++y15;
229  ++y16;
230  ++y17;
231  ++y18;
232  ++y19;
233  ++y20;
234
235  switch (j) {
236  case 1:
237    if (0)
238      (void)x;
239    if (1) {
240      (void)y1;
241      return;
242    }
243    (void)x;
244    break;
245  case 2:
246    if (0)
247      (void)x;
248    else {
249      (void)y2;
250      return;
251    }
252    (void)x;
253    break;
254  case 3:
255    if (1) {
256      (void)y3;
257      return;
258    } else
259      (void)x;
260    (void)x;
261  break;
262  case 4:
263    0 ? : ((void)y4, ({ return; }));
264    (void)x;
265    break;
266  case 5:
267    1 ? : (void)x;
268    0 ? (void)x : ((void)y5, ({ return; }));
269    (void)x;
270    break;
271  case 6:
272    1 ? ((void)y6, ({ return; })) : (void)x;
273    (void)x;
274    break;
275  case 7:
276    (void)(0 && x);
277    (void)y7;
278    (void)(0 || (y8, ({ return; }), 1));
279    (void)x;
280    break;
281  case 8:
282    (void)(1 && (y9, ({ return; }), 1));
283    (void)x;
284    break;
285  case 9:
286    (void)(1 || x);
287    (void)y10;
288    break;
289  case 10:
290    while (0) {
291      (void)x;
292    }
293    (void)y11;
294    break;
295  case 11:
296    while (1) {
297      (void)y12;
298    }
299    (void)x;
300    break;
301  case 12:
302    do {
303      (void)y13;
304    } while (0);
305    (void)y14;
306    break;
307  case 13:
308    do {
309      (void)y15;
310    } while (1);
311    (void)x;
312    break;
313  case 14:
314    for (;;) {
315      (void)y16;
316    }
317    (void)x;
318    break;
319  case 15:
320    for (;1;) {
321      (void)y17;
322    }
323    (void)x;
324    break;
325  case 16:
326    for (;0;) {
327      (void)x;
328    }
329    (void)y18;
330    break;
331  case 17:
332    __builtin_choose_expr(0, (void)x, ((void)y19, ({ return; })));
333    (void)x;
334    break;
335  case 19:
336    __builtin_choose_expr(1, ((void)y20, ({ return; })), (void)x);
337    (void)x;
338    break;
339  }
340}
341