Re: The nvptx port

[Bernd Schmidt <bernds at codesourcery dot com>]

On 11/14/2014 11:01 AM, Jakub Jelinek wrote:
> On Fri, Nov 14, 2014 at 09:29:48AM +0100, Jakub Jelinek wrote:
> > I have some questions about nvptx:
>
> Oh, and
> 5) I have noticed gcc doesn't generate the .uni suffixes anywhere,
>     while llvm generates them; are those appropriate only when a function
>     is guaranteed to be run unconditionally from the toplevel kernel,
>     or even in spots in arbitrary functions which might not be run
>     unconditionally by all threads in thread block, but all threads
>     that encounter the particular function will run the specific spot
>     unconditionally?  I mean, if we have arbitrary function:
> void foo (void) { something; bar (); something; }
>     then the call is unconditional in there, but there is no guarantee
>     somebody will not do
> void baz (int x) { if (x > 20) foo (); }
>     and run foo only in a subset of the threads.

It's unclear to me what the .uni suffix even does on calls. Google finds 
this:

  http://divmap.wordpress.com/home/divopt/

which suggests that it says that the call's predicate will evaluate to 
the same value on all threads. So I think for an unconditional call 
instruction it's just meaningless.


Bernd