dead-stores.c revision f7a0cf426eddae76e1a71dd2295631a2cf0560af 
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 -analyzer-constraints=range -warn-dead-stores -verify %s &&
4// RUN: clang-cc -analyze -checker-cfref -analyzer-store=region -analyzer-constraints=basic -warn-dead-stores -verify %s &&
5// RUN: clang-cc -analyze -checker-cfref -analyzer-store=region -analyzer-constraints=range -warn-dead-stores -verify %s
6
7void f1() {
8  int k, y;
9  int abc=1;
10  long idx=abc+3*5; // expected-warning {{never read}}
11}
12
13void f2(void *b) {
14 char *c = (char*)b; // no-warning
15 char *d = b+1; // expected-warning {{never read}}
16 printf("%s", c); // expected-warning{{implicitly declaring C library function 'printf' with type 'int (char const *, ...)'}} \
17 // expected-note{{please include the header <stdio.h> or explicitly provide a declaration for 'printf'}}
18}
19
20void f3() {
21  int r;
22  if ((r = f()) != 0) { // no-warning
23    int y = r; // no-warning
24    printf("the error is: %d\n", y);
25  }
26}
27
28void f4(int k) {
29
30  k = 1;
31
32  if (k)
33    f1();
34
35  k = 2;  // expected-warning {{never read}}
36}
37
38void f5() {
39
40  int x = 4; // no-warning
41  int *p = &x; // expected-warning{{never read}}
42
43}
44
45int f6() {
46
47  int x = 4;
48  ++x; // expected-warning{{never read}}
49  return 1;
50}
51
52int f7(int *p) {
53  // This is allowed for defensive programming.
54  p = 0; // no-warning
55  return 1;
56}
57
58int f8(int *p) {
59  extern int *baz();
60  if (p = baz()) // expected-warning{{Although the value}}
61    return 1;
62  return 0;
63}
64
65int f9() {
66  int x = 4;
67  x = x + 10; // expected-warning{{never read}}
68  return 1;
69}
70
71int f10() {
72  int x = 4;
73  x = 10 + x; // expected-warning{{never read}}
74  return 1;
75}
76
77int f11() {
78  int x = 4;
79  return x++; // expected-warning{{never read}}
80}
81
82int f11b() {
83  int x = 4;
84  return ((((++x)))); // no-warning
85}
86
87int f12a(int y) {
88  int x = y;  // expected-warning{{never read}}
89  return 1;
90}
91int f12b(int y) {
92  int x __attribute__((unused)) = y;  // no-warning
93  return 1;
94}
95
96// Filed with PR 2630.  This code should produce no warnings.
97int f13(void)
98{
99  int a = 1;
100  int b, c = b = a + a;
101
102  if (b > 0)
103    return (0);
104
105  return (a + b + c);
106}
107
108// Filed with PR 2763.
109int f14(int count) {
110  int index, nextLineIndex;
111  for (index = 0; index < count; index = nextLineIndex+1) {
112    nextLineIndex = index+1;  // no-warning
113    continue;
114  }
115  return index;
116}
117
118// Test case for <rdar://problem/6248086>
119void f15(unsigned x, unsigned y) {
120  int count = x * y;   // no-warning
121  int z[count];
122}
123
124int f16(int x) {
125  x = x * 2;
126  x = sizeof(int [x = (x || x + 1) * 2]) // expected-warning{{Although the value stored to 'x' is used}}
127      ? 5 : 8;
128  return x;
129}
130
131// Self-assignments should not be flagged as dead stores.
132void f17() {
133  int x = 1;
134  x = x; // no-warning
135}
136
137// <rdar://problem/6506065>
138// The values of dead stores are only "consumed" in an enclosing expression
139// what that value is actually used.  In other words, don't say "Although the
140// value stored to 'x' is used...".
141int f18() {
142   int x = 0; // no-warning
143   if (1)
144      x = 10;  // expected-warning{{Value stored to 'x' is never read}}
145   while (1)
146      x = 10;  // expected-warning{{Value stored to 'x' is never read}}
147   do
148      x = 10;   // expected-warning{{Value stored to 'x' is never read}}
149   while (1);
150
151   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'}}
152}
153
154// PR 3514: false positive `dead initialization` warning for init to global
155//  http://llvm.org/bugs/show_bug.cgi?id=3514
156extern const int MyConstant;
157int f19(void) {
158  int x = MyConstant;  // no-warning
159  x = 1;
160  return x;
161}
162
163int f19b(void) { // This case is the same as f19.
164  const int MyConstant = 0;
165  int x = MyConstant; // no-warning
166  x = 1;
167  return x;
168}
169
170void f20(void) {
171  int x = 1; // no-warning
172#pragma unused(x)
173}
174
175void halt() __attribute__((noreturn));
176int f21() {
177  int x = 4;
178
179  ++x; // expected-warning{{never read}}
180  if (1) {
181    halt();
182    (void)x;
183  }
184  return 1;
185}
186
187int j;
188void f22() {
189  int x = 4;
190  int y1 = 4;
191  int y2 = 4;
192  int y3 = 4;
193  int y4 = 4;
194  int y5 = 4;
195  int y6 = 4;
196  int y7 = 4;
197  int y8 = 4;
198  int y9 = 4;
199  int y10 = 4;
200  int y11 = 4;
201  int y12 = 4;
202  int y13 = 4;
203  int y14 = 4;
204  int y15 = 4;
205  int y16 = 4;
206  int y17 = 4;
207  int y18 = 4;
208  int y19 = 4;
209  int y20 = 4;
210
211  ++x; // expected-warning{{never read}}
212  ++y1;
213  ++y2;
214  ++y3;
215  ++y4;
216  ++y5;
217  ++y6;
218  ++y7;
219  ++y8;
220  ++y9;
221  ++y10;
222  ++y11;
223  ++y12;
224  ++y13;
225  ++y14;
226  ++y15;
227  ++y16;
228  ++y17;
229  ++y18;
230  ++y19;
231  ++y20;
232
233  switch (j) {
234  case 1:
235    if (0)
236      (void)x;
237    if (1) {
238      (void)y1;
239      return;
240    }
241    (void)x;
242    break;
243  case 2:
244    if (0)
245      (void)x;
246    else {
247      (void)y2;
248      return;
249    }
250    (void)x;
251    break;
252  case 3:
253    if (1) {
254      (void)y3;
255      return;
256    } else
257      (void)x;
258    (void)x;
259  break;
260  case 4:
261    0 ? : ((void)y4, ({ return; }));
262    (void)x;
263    break;
264  case 5:
265    1 ? : (void)x;
266    0 ? (void)x : ((void)y5, ({ return; }));
267    (void)x;
268    break;
269  case 6:
270    1 ? ((void)y6, ({ return; })) : (void)x;
271    (void)x;
272    break;
273  case 7:
274    (void)(0 && x);
275    (void)y7;
276    (void)(0 || (y8, ({ return; }), 1));
277    (void)x;
278    break;
279  case 8:
280    (void)(1 && (y9, ({ return; }), 1));
281    (void)x;
282    break;
283  case 9:
284    (void)(1 || x);
285    (void)y10;
286    break;
287  case 10:
288    while (0) {
289      (void)x;
290    }
291    (void)y11;
292    break;
293  case 11:
294    while (1) {
295      (void)y12;
296    }
297    (void)x;
298    break;
299  case 12:
300    do {
301      (void)y13;
302    } while (0);
303    (void)y14;
304    break;
305  case 13:
306    do {
307      (void)y15;
308    } while (1);
309    (void)x;
310    break;
311  case 14:
312    for (;;) {
313      (void)y16;
314    }
315    (void)x;
316    break;
317  case 15:
318    for (;1;) {
319      (void)y17;
320    }
321    (void)x;
322    break;
323  case 16:
324    for (;0;) {
325      (void)x;
326    }
327    (void)y18;
328    break;
329  case 17:
330    __builtin_choose_expr(0, (void)x, ((void)y19, ({ return; })));
331    (void)x;
332    break;
333  case 19:
334    __builtin_choose_expr(1, ((void)y20, ({ return; })), (void)x);
335    (void)x;
336    break;
337  }
338}
339