Google Benchmark already has this, and I wouldn't be surprised if more than one corporate codebase also has it. It's a pure library feature, implementable in plain old standard C++.

    // In another .cpp file:

    void escape(void*) {}

    // In the header file:

    extern void escape(void*);

    template<class T> void DoNotOptimize(T&& t) { escape(&t); }

    void foo(int *p) {

        if (!p) { printf("null pointer\n"); }

        DoNotOptimize(p);

        *p = 0;

    }

The compiler can see that `escape(&p)` is called, but it doesn't know at compile time whether `escape` might throw or terminate, so it can't assume that the line `*p = 0` will necessarily be reached (so it can't hoist that line upward and it can't remove the null-check).

–Arthur