https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107163
Jason Merrill <jason at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jason at gcc dot gnu.org
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |jason at gcc dot gnu.org
--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> ---
This isn't specific to virtual functions; the same slowdown can be seen with
struct BaseType {
int i;
};
template< int Seq >
class DerivedType : public DerivedType< Seq - 1 > { };
template<>
class DerivedType< -1 > : public BaseType { };
int main() {
DerivedType< COUNT > d;
d.i = 42;
}
The reference to the base member is represented with a long sequence of
COMPONENT_REFs, like
d.derived<5>.derived<4>.derived<3>.derived<2>.derived<1>.derived<0>.derived<-1>.base.i
= 42
and with r10-2823 we check sequence points across each of those .s, with high
algorithmic complexity. Checking across COMPONENT_REF seems unnecessary, since
it just selects a subobject of the LHS, there's no additional evaluation.
