From: Kwok Cheung Yeung <kcy@codesourcery.com>
This patch adds enough support for constructors/destructors and OS functions
to be able to link and run gfortran programs on AMD GCN.
There's no actual ability to do I/O operations on this targets, besides
"write" to stdout and stderr, so most of the functions are just stubs.
These missing includes were causing build warnings, but also a real bug in
which the "size" parameter to "write" was being passed in 32-bit, whereas it
ought to be 64-bit. This led to intermittent bad behaviour.
The GCN port outputs stdout and stderr via a shared-memory interface.
Previously the buffer was limited to 1000 write operations, which was enough
for testing purposes, but easy to exhaust.
This patch implements a new circular buffering system allowing a greater
amount of output. The interface must allow hundreds of hardware threads to
output simultaneously. The new limit is UINT32_MAX write operations.
Unfortunately, there's no way to tell if the host side has also been updated.
This code will misbehave unless the gcn-run from GCC is also updated (although
it's fine the other way around), but that patch has already been committed.
OK?
Andrew Stubbs
Mentor Graphics / CodeSourcery
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.
Jeff Johnston
Andrew Stubbs