https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92985
--- Comment #2 from Peter Dimov <pdimov at gmail dot com> ---
Two more reformulations that activate the linear transformation are:
int operator[]( std::size_t i ) const noexcept
{
std::ptrdiff_t offset;
switch( i )
{
case 0: offset = offsetof(X, x); break;
case 1: offset = offsetof(X, y); break;
case 2: offset = offsetof(X, z); break;
default: __builtin_unreachable();
}
return *(int const*)((char const*)this + offset);
}
(https://godbolt.org/z/cJDB_m)
and
int operator[]( std::size_t i ) const noexcept
{
int X::* p;
switch( i )
{
case 0: p = &X::x; break;
case 1: p = &X::y; break;
case 2: p = &X::z; break;
default: __builtin_unreachable();
}
return this->*p;
}
(https://godbolt.org/z/xfsKh5)
