Overloads global new with random data for help with finding uninitialized data use.

InitRandomHeap.h

#include <chrono>

struct XorShift128State
{
    uint32_t a, b, c, d;
};

/* The state array must be initialized to not be all zero */
uint32_t xorshift128(XorShift128State *state)
{
    /* Algorithm "xor128" from p. 5 of Marsaglia, "Xorshift RNGs" */
    uint32_t t = state->d;

    uint32_t const s = state->a;
    state->d = state->c;
    state->c = state->b;
    state->b = s;

    t ^= t << 11;
    t ^= t >> 8;
    return state->a = t ^ s ^ (s >> 19);
}

void* operator new(size_t size)
{
    static size_t calls = 0;
    static size_t total = 0;
    static long long seed = std::chrono::steady_clock::now().time_since_epoch().count();
    static XorShift128State xorState = { static_cast<uint32_t>(seed), static_cast<uint32_t>(seed >> 32), 0, 0 };

    calls++;
    total += size;
    auto p = malloc(size);

    const size_t words = size / 4;

    for (size_t i = 0; i < words; i++)
    {
        static_cast<uint32_t*>(p)[i] = xorshift128(&xorState);
    }

    const size_t remainder = size % 4;
    if (remainder > 0)
    {
        uint32_t value = xorshift128(&xorState);
        for (size_t i = size - remainder; i < size; i++)
        {
            static_cast<uint8_t*>(p)[i] = static_cast<uint8_t>(value & 255);
            value >>= 8;
        }
    }

    return p;
}

void operator delete(void* p)
{
    free(p);
}