https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124553
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|-fmem-stats tracking of |-fmem-stats tracking of
|vec<> does not track |vec<> does not follow vec<>
|::release |assignments
Last reconfirmed| |2026-03-18
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Ah, I think it is
vr1->operands = operands.copy ();
not being properly tracked. We do
/* Return a pointer to a copy of this vector. */
template<typename T, typename A>
inline vec<T, A, vl_embed> *
vec<T, A, vl_embed>::copy (ALONE_MEM_STAT_DECL) const
{
vec<T, A, vl_embed> *new_vec = NULL;
unsigned len = length ();
if (len)
{
vec_alloc (new_vec, len PASS_MEM_STAT);
new_vec->embedded_init (len, len);
vec_copy_construct (new_vec->address (), address (), len);
}
return new_vec;
and there's no move operator that would move the storage association with
the memory statistic machinery (or in general). The copy () API isn't
particularly well-designed in this regard (and thus also error-prone to
use). It might be tempting to use an auto_vec<> return value.
That said, instead of the above vr1->operands = operands.copy ();
one could use
vr1->operands = vNULL;
vr1->operands.safe_splice (operands);
which is accounted correctly. A vr1->operands.copy_from (other) might
also work, but it also requires initialization of vr1->operands.
::copy () is also used for parameter passing,
so this isn't an universal solution. Having auto_vec<> parameters for
functions owning such reference would work, but the involved CTOR also
doesn't accout statistics correctly:
auto_vec (vec<T, va_heap>&& r)
{
gcc_assert (!r.using_auto_storage ());
this->m_vec = r.m_vec;
r.m_vec = NULL;
}
but we likely cannot add a PASS_MEM_STATS to CTORs(?).
Like in vn_reference_lookup_or_insert_for_pieces we do
return vn_reference_insert_pieces (vuse, set, base_set, offset, max_size,
type, operands.copy (), value, value_id);
which in turn does
vr1->operands = operands;
in combination this will work for statistics gathering, using auto_vec<>
would break it (and require to_vec_legacy, ugh).
