diff mbox series

[wwwdocs,+] nvptx – update for -mptx change – gcc-12/changes.html + gcc/docs/invoke.texi

Message ID f069981d-5a0c-11d5-db2d-ea4574037eb0@codesourcery.com
State New
Headers
Series [wwwdocs,+] nvptx – update for -mptx change – gcc-12/changes.html + gcc/docs/invoke.texi |

Commit Message

Tobias Burnus Feb. 2, 2022, 8:30 a.m. UTC 
  This patch updates the documentation for Tom's change of the default
-mptx= version - mentioning also -mptx=7.0.

I forgot whether ptx = 7.0 was working fine or whether there was
a reason not to mention it.
At some point, we also have to update -misa=... Currently, only
sm_30 and sm_35 are documented but sm_53, sm_75 and sm_80 are supported.
Can they now be documented are are there still issues?

OK to commit the wwwdocs + gcc invoke.texi patches?

Tobias

PS: I wonder whether any of the recent changes by chance did fix
https://gcc.gnu.org/PR102429 – nvptx: ICE with expand_GOMP_SIMT_XCHG_BFLY
            : in expand_insn, at optabs.c:7947 for DCmode (complex double)
Probably not, but it would have been nice nonetheless.
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Comments

Tom de Vries Feb. 4, 2022, 11:46 a.m. UTC | #1 
On 2/2/22 09:30, Tobias Burnus wrote:
> This patch updates the documentation for Tom's change of the default
> -mptx= version - mentioning also -mptx=7.0.
> 
> I forgot whether ptx = 7.0 was working fine or whether there was
> a reason not to mention it.

A ptx version is experimental if all sm versions it enables are 
experimental.

7.0 enables sm_80, and that one is experimental.

sm_80 is considered experimental, because the last time I tried to do a 
gcc build with the default set to sm_80, it failed (ICEs).  Likewise 
sm_75, sm_53.

Following that reasoning ptx isa 6.3 would also be experimental, but it 
fixes something that is very fragile with older ptx version (warp 
convergence) so it has been promoted to supported.

Anyway, I'm preparing a patch that picks default -mptx based on -misa, 
with a default minimum of 6.0 instead of 6.3, to enable testing with a 
390.x driver.

> At some point, we also have to update -misa=... Currently, only
> sm_30 and sm_35 are documented but sm_53, sm_75 and sm_80 are supported.
> Can they now be documented are are there still issues?

AFAIK there are still issues.

> OK to commit the wwwdocs + gcc invoke.texi patches?

Sorry, it looks like this is still in flux.

Thanks,
- Tom
diff mbox series

Patch

gcc-12/changes.html: nvptx – update for -mptx change

diff --git a/htdocs/gcc-12/changes.html b/htdocs/gcc-12/changes.html
index 2719b9d5..bd0babfb 100644
--- a/htdocs/gcc-12/changes.html
+++ b/htdocs/gcc-12/changes.html
@@ -404,7 +404,8 @@  a work-in-progress.</p>
 <ul>
   <li>The <code>-mptx</code> flag has been added to specify the PTX ISA version
       for the generated code; permitted values are <code>3.1</code>
-      (default, matches previous GCC versions) and <code>6.3</code>.
+      (matches previous GCC versions), <code>6.3</code> (new default) and
+      <code>7.0</code>.
   </li>
   <li>The new <code>__PTX_SM__</code> predefined macro allows code to check the
       compute model being targeted by the compiler.</li>