Add support for the AMD GCN GPU architecture. This is primarily intended for
use with OpenMP and OpenACC offloading. It can also be used for stand-alone
programs, but this is intended mostly for testing the compiler and is not
expected to be useful in general.
The GPU architecture is highly parallel, and therefore Newlib must be
configured to use dynamic re-entrancy, and thread-safe malloc.
The only I/O available is a via a shared-memory interface provided by libgomp
and the gcn-run tool included with GCC. At this time this is limited to
stdout, argc/argv, and the return code.
Compiling with any of the -fstack-protector* flags requires the
__stack_chk_guard data import (which needs to be initialized) and the
__stack_chk_fail{,_local} functions. While GCC's own libssp can provide
these, it is better that we provide these ourselves. The implementation
is custom due to being OS-specific.
Signed-off-by: Yaakov Selkowitz <yselkowi@redhat.com>