https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89208
--- Comment #11 from Bernd Edlinger <bernd.edlinger at hotmail dot de> --- (In reply to Andrew Pinski from comment #10) > This is documented this way: > https://gcc.gnu.org/onlinedocs/gcc-8.2.0/gcc/Standards.html#index- > ffreestanding > > Most of the compiler support routines used by GCC are present in libgcc, but > there are a few exceptions. GCC requires the freestanding environment > provide memcpy, memmove, memset and memcmp. Finally, if __builtin_trap is > used, and the target does not implement the trap pattern, then GCC emits a > call to abort. but this still transforms valid to invalid code, since as Alexander pointer out, one can call "f(a,a);" which gets translated to "memcpy(a,a,8);" which is not valid when src, and dst overlaps, while *a = *a is.
