On Fri, 24 Feb 2023, Jakub Jelinek wrote:
> On Fri, Feb 24, 2023 at 02:47:39PM +0100, Richard Biener wrote:
> > * vec.h (vec<T, A, vl_embed>::m_vecdata): Remove.
> > (vec<T, A, vl_embed>::m_vecpfx): Align as T to avoid
> > changing alignment of vec<T, A, vl_embed> and simplifying
> > address.
> > (vec<T, A, vl_embed>::address): Compute as this + 1.
> > (vec<T, A, vl_embed>::embedded_size): Use sizeof the
> > vector instead of the offset of the m_vecdata member.
> > (auto_vec<T, N>::m_data): Turn storage into
> > uninitialized unsigned char.
> > (auto_vec<T, N>::auto_vec): Allow allocation of one
> > stack member. Initialize m_vec in a special way to
> > avoid later stringop overflow diagnostics.
> > * vec.cc (test_auto_alias): New.
> > (vec_cc_tests): Call it.
> > @@ -1559,8 +1560,14 @@ class auto_vec : public vec<T, va_heap>
> > public:
> > auto_vec ()
> > {
> > - m_auto.embedded_init (MAX (N, 2), 0, 1);
> > - this->m_vec = &m_auto;
> > + m_auto.embedded_init (N, 0, 1);
> > + /* ??? Instead of initializing m_vec from &m_auto directly use an
> > + expression that avoids refering to a specific member of 'this'
> > + to derail the -Wstringop-overflow diagnostic code, avoiding
> > + the impression that data accesses are supposed to be to the
> > + m_auto memmber storage. */
>
> s/memmber/member/
>
> > + size_t off = (char *) &m_auto - (char *) this;
> > + this->m_vec = (vec<T, va_heap, vl_embed> *) ((char *) this + off);
> > }
> >
> > auto_vec (size_t s CXX_MEM_STAT_INFO)
> > @@ -1571,7 +1578,7 @@ public:
> > return;
> > }
> >
> > - m_auto.embedded_init (MAX (N, 2), 0, 1);
> > + m_auto.embedded_init (N, 0, 1);
> > this->m_vec = &m_auto;
>
> Don't we need the above 2 lines here as well (perhaps with a shorter comment
> just referencing the earlier comment)?
I've noticed that as well and put it there now, it wasn't necessary
to get bootstrap working.
> Otherwise LGTM, thanks.
Thanks,
Richard.
