RadeonSI OpenGL Compute Shader Patches Published

[phoronix]

Phoronix: RadeonSI OpenGL Compute Shader Patches Published

Bas Nieuwenhuizen has published a patch-set for implementing an important OpenGL 4.3 feature: compute shaders for RadeonSI!..

http://www.phoronix.com/scan.php?page=news_item&px=RadeonSI-Compute-Shaders

[Azpegath]

Awesome! This means I can fire up Alien:Isolation soon! :-D

[duby229]

Cool! Great news. It won't be long till 4.3 is complete on radeonsi!

[zanny]

Nobody has GL_ARB_robust_buffer_access_behavior yet, and it seems like it might be a PITA to implement rigorous bounds checking on buffers like that throughout the driver stack. RadeonSI might only need four extensions to reach 4.3, but there is always a reason they aren't already done - they are usually the hardest, or at least most annoying, ones to implement.

[Pecisk]

Having 4.3 running with compute shaders at first half of this year - never expected that to be honest, very positively surprised. Hail to all hackers/coders involved in this. For RadeonSI this is even more important, so amdgpu all-open stack would be capable to run OpenGL 4.3 games...

[SvenK]

I hope we will see GL_ARB_shader_atomic_counters in RadeonSi soon. Then OpenGL 4.2 would be complete on RadeonSI, 3 extensions are left for OpenGL 4.3, 3/4 extensions are left for OpenGL 4.4 and 4 extensions are left for OpenGL 4.5 support on RadeonSI.

[nanonyme]

Nobody has GL_ARB_robust_buffer_access_behavior yet, and it seems like it might be a PITA to implement rigorous bounds checking on buffers like that throughout the driver stack. RadeonSI might only need four extensions to reach 4.3, but there is always a reason they aren't already done - they are usually the hardest, or at least most annoying, ones to implement.

I guess the thing is whether this is one of those extensions no one actually uses so you can just lie it exists through environment variable if blocking 4.3

[haagch]

https://lists.freedesktop.org/archiv...il/111667.html says

Nominally, GL_ARB_compute_shader requires GL 4.2. In practice, I think
this means you need images *and* atomic counters.

So without atomic counters, can it fully work?

Edit: Currently compiling llvm with all the stuff like clang. It's such a massive toolset. Is there an easy way to only build the part that the radeon driver requires?

[imirkin]

So without atomic counters, can it fully work?

No, because shaders are written to expect those features to be there. However the question's largely academic -- Bas's patchset is based on Nicolai's implementation of SSBO/Atomic, so... you should have everything there.

[haagch]

Oh that made me actually look at his branch: https://github.com/BNieuwenhuizen/me...d4fd321855a518

So the actual news here is: We're almost at OpenGL 4.3.

Edit: EVERY TIME.
I made a normal release build of mesa and this happened when I starting Alien Isolation, right after initial loading screen:

[FONT=monospace][COLOR=#000000]Thread 36 "WinMain" received signal SIGSEGV, Segmentation fault. [/COLOR]
[Switching to Thread 0x7fffd406c700 (LWP 3966)]
0x00007fffe9808727 in ?? () from /usr/lib/xorg/modules/dri/radeonsi_dri.so
(gdb) bt
#0  0x00007fffe9808727 in ?? () from /usr/lib/xorg/modules/dri/radeonsi_dri.so
#1  0x0000000000000000 in ?? ()[/FONT]

Yea, that's the complete backtrace.

Then I made a debug build of mesa and guess what. IT DOES NOT CRASH.

So right now I only know it happens here:
>│0x7fffe9808727 orq $0x0,(%rsp)

Anyway, with a debug build of mesa I could try Alien Isolation and it still looks like this:

https://www.youtube.com/watch?v=Y0aqhazR3WE

So sadly I can say: It's not because of missing compute shaders, there's still another problem in radeonsi. Reference: https://bugs.freedesktop.org/show_bug.cgi?id=93144