I was looking at [1] for ways to prevent the compiler from
optimizing away code when trying to benchmark.
It has the following C++ code as a simpler version:
```
inline BENCHMARK_ALWAYS_INLINE void DoNotOptimize(Tp& value) {
asm volatile("" : "+r,m"(value) : : "memory");
}
```
I made an attempt to make a D version of it, but failed.
Apparently DMD doesn't like the `""` in the first part of the asm
instruction. I'm also not sure the `volatileLoad` command is
right, but I didn't know of any other way to have volatile work
in D (and I couldn't figure out how it actually worked from
looking at the code).
```
void DoNotOptimize(T)(T* ptr)
{
import core.volatile: volatileLoad;
T value = volatileLoad(ptr);
asm {"" : "+r,m"(value) : : "memory";}
}
```
[1]
https://theunixzoo.co.uk/blog/2021-10-14-preventing-optimisations.html
