Alfie Richards <alfie.richa...@arm.com> writes:
> Hi,
>
> Small fix to resolve an UBSAN diagnostic.
>
> Reg tested for Aarch64
>
> Thanks,
> Alfie
>
> -- >8 --
>
> This adds a nullptr check to fix a regression where it is possible to call
> `memcmp (NULL, NULL, 0)` which is UB.
>
> This should fix the bootstrap-ubsan build.
>
> gcc/ChangeLog:
> PR middle-end/121261
> * vec.h: Add null ptr check.
> ---
> gcc/vec.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/gcc/vec.h b/gcc/vec.h
> index 9604edb1c3c..1277a881f1c 100644
> --- a/gcc/vec.h
> +++ b/gcc/vec.h
> @@ -2514,6 +2514,10 @@ public:
> return false;
> if (lhs.size () != rhs.size ())
> return false;
> + /* Case where either is a NULL pointer and therefore, as both are valid,
> + both are empty slices with length 0. */
> + if (lhs.begin () == NULL || rhs.begin () == NULL)
> + return true;
It seems simpler (and IMO slightly clearer) to test for:
if (lhs.size () == 0)
return true;
OK that way if you agree.
Thanks,
Richard
> return memcmp (lhs.begin (), rhs.begin (), lhs.size ()) == 0;
> }
