Re: [PATCH] Remove PTX link option

[James Norris <jnorris at codesourcery dot com>]

Jakub,

On 01/08/2016 09:30 AM, Jakub Jelinek wrote:
> On Fri, Jan 08, 2016 at 09:24:14AM -0600, James Norris wrote:
> > This patch removes the constraint whereby the PTX
> > emitted was only for sm_30 GPU's. With this removal,
> > the PTX emitted will be targeted for the current
> > context, i.e., attached GPU.
> >
> > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> How does that work?
> I see
> static void
> nvptx_file_start (void)
> {
>    fputs ("// BEGIN PREAMBLE\n", asm_out_file);
>    fputs ("\t.version\t3.1\n", asm_out_file);
>    fputs ("\t.target\tsm_30\n", asm_out_file);
>    fprintf (asm_out_file, "\t.address_size %d\n", GET_MODE_BITSIZE (Pmode));
>    fputs ("// END PREAMBLE\n", asm_out_file);
> }
> which I'd guess means the PTX code can be executed in sm_30 and newer only
> anyway.
>
> 	Jakub

Yes. Per the PTX ISA manual for the .target directive: "In general,
generations of SM architectures follow an onion layer model, where
each generation adds new features and retains all features of
previous generations."

Jim