https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110287
--- Comment #5 from Jan Hubicka <hubicka at ucw dot cz> ---
> Do you mean something like this?
I sent my own version, but yours looks nicer.
>
> diff --git a/libstdc++-v3/include/bits/stl_vector.h
> b/libstdc++-v3/include/bits/stl_vector.h
> index 70ced3d101f..a4dbfeb8b5b 100644
> --- a/libstdc++-v3/include/bits/stl_vector.h
> +++ b/libstdc++-v3/include/bits/stl_vector.h
> @@ -1902,6 +1902,21 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> return (__len < size() || __len > max_size()) ? max_size() : __len;
> }
>
> + // Called by _M_insert_aux etc.
> + _GLIBCXX20_CONSTEXPR
> + size_type
> + _M_check_len_1(const char* __s) const
> + {
> + if (__builtin_constant_p(size()))
Perhaps ruling this out for 32bit ports? Or can we assume that half of
address space can never be allocated in single block?
> + {
> + if (size() == 0)
> + return 1;
> + else if (size() < max_size() / 2)
I think even this conditional is safe to be assumed to be true,
since we can not allocate half of 64bit address space.
In general it is importnat to not fall through to _M_check_len.
As I noticed, we may want to use assume attribute to make clear that
retval <= max_size ()
to avoid other unnecesary throws downstream.
Honza
