https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98861
--- Comment #29 from cqwrteur <unlvsur at live dot com> ---
(In reply to Jakub Jelinek from comment #23)
> And memcpy must be provided as documented in the GCC documentation:
> Most of the compiler support routines used by GCC are present in
> @file{libgcc}, but there are a few exceptions. GCC requires the
> freestanding environment provide @code{memcpy}, @code{memmove},
> @code{memset} and @code{memcmp}.
> Finally, if @code{__builtin_trap} is used, and the target does
> not implement the @code{trap} pattern, then GCC emits a call
> to @code{abort}.
I am sure I did not understand anything wrong. The rule is simple, if you use
gcc, you must use libgcc. libgcc provides those facilities.
https://wiki.osdev.org/Libgcc
__builtin_trap() is always faster than std::terminate(), even it actually emits
a call to std::abort(), because std::terminate() requires atomic to sync the
terminate_handler. The problem with std::terminate() is that it does not work
like operator new where it is weak alias. You still get bloat and dependency to
std::abort() even you are using set_terminate_handle().
if we are using __builtin_trap() on platforms like x86_64, they emit ud
instructions and use that to terminate is fast and avoid dependency on libc,
(particularly we mean glibc here.)
