On 29.09.22 18:24, Andrew Stubbs wrote:
> On 27/09/2022 14:16, Tobias Burnus wrote:
>> Andrew did suggest a while back to piggyback on the console_output
>> handling,
>> avoiding another atomic access. - If this is still wanted, I like to
>> have some
>> guidance regarding how to actually implement it.
> [...]
> The point is that you can use the "msg" and "text" fields for whatever
> data you want, as long as you invent a new value for "type".
> [....]
> You can make "case 4" do whatever you want. There are enough bytes for
> 4 pointers, and you could use multiple packets (although it's not safe
> to assume they're contiguous or already arrived; maybe "case 4" for
> part 1, "case 5" for part 2). It's possible to change this structure,
> of course, but the target implementation is in newlib so versioning
> becomes a problem.

I think  – also looking at the Newlib write.c implementation - that the
data is contiguous: there is an atomic add, where instead of passing '1'
for a single slot, I could also add '2' for two slots.

Attached is one variant – for the decl of the GOMP_OFFLOAD_target_rev,
it needs the generic parts of the sister nvptx patch.*

2*128 bytes were not enough, I need 3*128 bytes. (Or rather 5*64 + 32.)
As target_ext is blocking, I decided to use a stack local variable for
the remaining arguments and pass it along. Alternatively, I could also
use 2 slots - and process them together. This would avoid one
device->host memory copy but would make console_output less clear.

OK for mainline?

Tobias

* https://gcc.gnu.org/pipermail/gcc-patches/2022-October/603354.html

PS: Currently, device stack variables are private and cannot be accessed
from the host; this will change in a separate patch. It not only affects
the "rest" part as used in this patch but also the actual arrays behind
addr, kinds, and sizes. And quite likely a lot of the map/firstprivate
variables passed to addr.

As num_devices() will return 0 or -1, this is for now a non-issue.
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