https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68297
Bug ID: 68297
Summary: Faster std::make_exception
Product: gcc
Version: 5.1.1
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: nyh at math dot technion.ac.il
Target Milestone: ---
std::make_exception(object) currently does this:
make_exception_ptr(_Ex __ex) _GLIBCXX_USE_NOEXCEPT
{
try
{
throw __ex;
}
catch(...)
{
return current_exception();
}
}
I think this could have been made much faster... Throwing an exception is very
slow, and not really needed here, as gcc (libsupc++) knows exactly how to
create an exception_ptr from the given object, without going through the
motions of looking for the exception frame (we know exactly where it will be).
By taking the right code from __cxa_throw, std::current_exception(), etc., this
can be done without any stack unwinding, and therefore much more quickly.
Such an improvement will benefit especially code that passes around
exception_ptrs instead of actually throwing exception (the Seastar library, for
example, does this).
