src/compiler-rt/test/msan/mul_by_const.cc

   1 // RUN: %clangxx_msan -O2 %s -o %t && %run %t
   2
   3 #include <sanitizer/msan_interface.h>
   4
   5 struct S {
   6   S(int a0) : a(a0) {}
   7   int a;
   8   int b;
   9 };
  10
  11 // Here S is passed to FooRun as a 64-bit integer.
  12 // This triggers an optimization where 10000 * s.a is transformed into
  13 // ((*(uint64_t *)&s) * (10000 * 2**32)) >> 32
  14 // Test that MSan understands that this kills the uninitialized high half of S
  15 // (i.e. S::b).
  16 void FooRun(S s) {
  17   int64_t x = 10000 * s.a;
  18   __msan_check_mem_is_initialized(&x, sizeof(x));
  19 }
  20
  21 int main(void) {
  22   S z(1);
  23   // Take &z to ensure that it is built on stack.
  24   S *volatile p = &z;
  25   FooRun(z);
  26   return 0;
  27 }