1// Verifies that speculative loads from unions do not happen under asan.
2// RUN: %clangxx_asan -O0 %s -o %t && %run %t 2>&1
3// RUN: %clangxx_asan -O1 %s -o %t && %run %t 2>&1
4// RUN: %clangxx_asan -O2 %s -o %t && %run %t 2>&1
5// RUN: %clangxx_asan -O3 %s -o %t && %run %t 2>&1
6
7#include <sanitizer/asan_interface.h>
8
9struct S {
10  struct _long {
11      void* _pad;
12      const char* _ptr;
13  };
14
15  struct _short {
16    unsigned char _size;
17    char _ch[23];
18  };
19
20  union {
21    _short _s;
22    _long _l;
23  } _data;
24
25  S() {
26    _data._s._size = 0;
27    __asan_poison_memory_region(_data._s._ch, 23);
28  }
29
30  bool is_long() const {
31    return _data._s._size & 1;
32  }
33
34  const char* get_pointer() const {
35    return is_long() ? _data._l._ptr : _data._s._ch;
36  }
37};
38
39
40inline void side_effect(const void *arg) {
41  __asm__ __volatile__("" : : "r" (arg) : "memory");
42}
43
44int main(int argc, char **argv) {
45  S s;
46  side_effect(&s); // optimizer is too smart otherwise
47  const char *ptr = s.get_pointer();
48  side_effect(ptr); // force use ptr
49  return 0;
50}
51