compiler-rt/test/asan/TestCases/speculative_load.cpp

   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
   9 struct 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   ~S() {
  31     __asan_unpoison_memory_region(_data._s._ch, 23);
  32   }
  33
  34   bool is_long() const {
  35     return _data._s._size & 1;
  36   }
  37
  38   const char* get_pointer() const {
  39     return is_long() ? _data._l._ptr : _data._s._ch;
  40   }
  41 };
  42
  43
  44 inline void side_effect(const void *arg) {
  45   __asm__ __volatile__("" : : "r" (arg) : "memory");
  46 }
  47
  48 int main(int argc, char **argv) {
  49   S s;
  50   side_effect(&s); // optimizer is too smart otherwise
  51   const char *ptr = s.get_pointer();
  52   side_effect(ptr); // force use ptr
  53   return 0;
  54 }