[LLVMdev] [NVPTX] llc -march=nvptx64 -mcpu=sm_20 generates invalid zero align for device function params

Duncan Sands baldrick at free.fr
Sat Nov 10 07:38:25 PST 2012

Hi Justin,

On 10/11/12 15:37, Justin Holewinski wrote:
> Perhaps "compatibility" is the wrong term to use here.  For now, I would like to
> "match" what the vendor compiler does.  I don't think using preferred alignment
> would hurt anything in terms of correctness, but I need to go through the entire
> back-end to see what effects it could have on performance (e.g. adding extra
> padding increases local memory usage).  It could be a complete non-issue for all
> I know right now.

don't forget that the backend defines what the preferred alignment is.  You can
set it equal to the ABI alignment.  If measurements show that a higher alignment
is better than you can bump the preferred alignment up to a higher value.  What
I'm saying is that globals should always be output using the preferred alignment
not the ABI alignment: it is the preferred value itself you should be playing

Ciao, Duncan.

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