Re: [PATCH vkd3d v4 3/5] vkd3d: Introduce a vkd3d_bound_range() helper.

[Henri Verbeet]

On Fri, 9 Jul 2021 at 04:14, Zebediah Figura  wrote:
> +static inline bool vkd3d_bound_range(size_t start, size_t count, size_t limit)
> +{
> +#ifdef HAVE_BUILTIN_ADD_OVERFLOW
> - size_t sum;
> -
> - return !__builtin_add_overflow(start, count, &sum) && sum <= limit;
>
> +#else
> - return start <= limit && count <= limit - start;
>
> +#endif
> +}

[...]
> @@ -1925,7 +1925,7 @@ static D3D12_GPU_VIRTUAL_ADDRESS vkd3d_gpu_va_allocator_allocate_fallback(struct
>      base = allocator->fallback_floor;
>      ceiling = ~(D3D12_GPU_VIRTUAL_ADDRESS)0;
>      ceiling -= alignment - 1;
> - if (aligned_size > ceiling || ceiling - aligned_size < base)
> - if (!vkd3d_bound_range(base, aligned_size, ceiling))
>     return 0;

Actually, you can't necessarily do that. D3D12_GPU_VIRTUAL_ADDRESS is
always a 64-bit type, but size_t may not be.