1 #include "benchmark/benchmark.h"
2 
3 #include <cstdint>
4 
5 namespace {
6 #if defined(__GNUC__)
7 std::uint64_t double_up(const std::uint64_t x) __attribute__((const));
8 #endif
double_up(const std::uint64_t x)9 std::uint64_t double_up(const std::uint64_t x) { return x * 2; }
10 }
11 
12 // Using DoNotOptimize on types like BitRef seem to cause a lot of problems
13 // with the inline assembly on both GCC and Clang.
14 struct BitRef {
15   int index;
16   unsigned char &byte;
17 
18 public:
MakeBitRef19   static BitRef Make() {
20     static unsigned char arr[2] = {};
21     BitRef b(1, arr[0]);
22     return b;
23   }
24 private:
BitRefBitRef25   BitRef(int i, unsigned char& b) : index(i), byte(b) {}
26 };
27 
main(int,char * [])28 int main(int, char*[]) {
29   // this test verifies compilation of DoNotOptimize() for some types
30 
31   char buffer8[8] = "";
32   benchmark::DoNotOptimize(buffer8);
33 
34   char buffer20[20] = "";
35   benchmark::DoNotOptimize(buffer20);
36 
37   char buffer1024[1024] = "";
38   benchmark::DoNotOptimize(buffer1024);
39   benchmark::DoNotOptimize(&buffer1024[0]);
40 
41   int x = 123;
42   benchmark::DoNotOptimize(x);
43   benchmark::DoNotOptimize(&x);
44   benchmark::DoNotOptimize(x += 42);
45 
46   benchmark::DoNotOptimize(double_up(x));
47 
48   // These tests are to e
49   benchmark::DoNotOptimize(BitRef::Make());
50   BitRef lval = BitRef::Make();
51   benchmark::DoNotOptimize(lval);
52 }
53