Re: [gcn] Work-around libgomp 'error: array subscript 0 is outside array bounds of ‘__lds struct gomp_thread * __lds[0]’ [-Werror=array-bounds]' (was: [PATCH libatomic/arm] avoid warning on constant addresses (PR 101379))

[Andrew Stubbs]

On 19/07/2021 09:46, Thomas Schwinge wrote:
GCN already uses address 4 for this value because address 0 caused
problems with null-pointer checks.

Ugh.  How much wasted bytes per what is that?  (I haven't looked yet;
hopefully not per GPU thread?)  Because:

It's 4 bytes per gang. And that pointer is the only 8 bytes in the whole 
of LDS (OpenMP mostly uses stack and heap), so it's not so bad, but still.

I did investigate the target macro that lets you control null pointer 
behaviour, but it didn't just work, and it wasn't important enough for 
me to spend more time on it so I let it go.

Andrew