[Bug 111241] Shadertoy shader causing hang

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 809 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

            Bug ID: 111241
           Summary: Shadertoy shader causing hang
           Product: Mesa
           Version: 19.1
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Drivers/Gallium/radeonsi
          Assignee: dri-devel@lists.freedesktop.org
          Reporter: mail@felix-potthast.de
        QA Contact: dri-devel@lists.freedesktop.org

When opening https://www.shadertoy.com/view/3lsXDB on my Desktop PC
with Radeon HD 7870 Graphics card (Pitcairn) i get a freeze.

It works fine on my Laptop with Intel Graphics.

Both systems use Mesa 19.1.3

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 2215 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 377 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

--- Comment #1 from Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com> ---
I could reproduce the issue on a Raven Ridge and a Navi10.

But when using NIR (radeonsi_enable_nir=true env variable) the shader is
perfectly usable.

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1149 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 1089 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

--- Comment #2 from Dieter Nützel <Dieter@nuetzel-hh.de> ---
RX 580 / NIR
amd-staging-drm-next
Mesa git
Firefox 68.0.1

[42489.228053] [drm:amdgpu_dm_commit_planes.constprop.0 [amdgpu]] *ERROR*
Waiting for fences timed out or interrupted!                                    
[42494.348053] [drm:amdgpu_job_timedout [amdgpu]] *ERROR* ring gfx timeout, but
soft recovered
[42508.171689] [drm:amdgpu_dm_commit_planes.constprop.0 [amdgpu]] *ERROR*
Waiting for fences timed out or interrupted!

[42513.035801] [drm:amdgpu_job_timedout [amdgpu]] *ERROR* ring gfx timeout, but
soft recovered

[42556.811021] [drm:amdgpu_dm_commit_planes.constprop.0 [amdgpu]] *ERROR*
Waiting for fences timed out or interrupted!                                    
[42561.418927] [drm:amdgpu_job_timedout [amdgpu]] *ERROR* ring gfx timeout, but
soft recovered

[42571.658863] [drm:amdgpu_job_timedout [amdgpu]] *ERROR* ring gfx timeout, but
soft recovered

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1835 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 954 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

--- Comment #3 from Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com> ---
Here's my understanding of the issue.

This shader uses 2 passes:
 - the first pass has BufferA as input and output and does:

if (first frame)
  // init bufferA content
else
  // do something useful

 - the 2nd pass has BufferA as input and does:

N = texelFetch(bufferA)
for(i=0; i < N; i++)
  // do something


The problem here is the "// init bufferA content": it fails to initialize the
buffer content properly, leading to an infinite loop in the 2nd pass.

The exact code is:
   if (iFrame==0) { O -= O; return; }

If one replaces this line with:
   if (iFrame==0) { O = vec4(0.0f); return; }

The shader works fine (you can test the modified version here:
https://www.shadertoy.com/view/wtSXzw ).

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1791 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 350 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

--- Comment #4 from Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com> ---
Created attachment 144993
  --> https://bugs.freedesktop.org/attachment.cgi?id=144993&action=edit
tgsi version of the shader

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1266 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 335 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

--- Comment #5 from Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com> ---
Created attachment 144994
  --> https://bugs.freedesktop.org/attachment.cgi?id=144994&action=edit
nir version

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1221 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 1188 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

--- Comment #6 from Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com> ---
I've created a different shadertoy showing the problem:
https://www.shadertoy.com/view/Wt2SW1 (but this one doesn't hang the GPU).

The shader for "Buffer A" is:

  0: MOV TEMP[0], SV[0]
  1: MAD TEMP[0].y, SV[0], CONST[0][2].xxxx, CONST[0][2].yyyy
  2: MOV OUT[0], IMM[0].xxxx
  3: USEQ TEMP[1].x, CONST[0][1].xxxx, IMM[1].xxxx
  4: UIF TEMP[1].xxxx
  5:   ADD TEMP[2], TEMP[2], -TEMP[2]
  6: ELSE
  [...]
 13: MOV OUT[0], TEMP[2]
 14: END

TEMP[2] is used before being assigned a value, so I suppose that's what allows
LLVM to turn line 5 in:

   v_mov_b32_e32 v3, 0x7fc00000
   v_mov_b32_e32 v2, 0x7fc00000
   v_mov_b32_e32 v1, 0x7fc00000
   v_mov_b32_e32 v0, 0x7fc00000

(ie: output is NaN)

A possible way to fix this is to transform "dst = x - x" operations in "dst =
0" which is what nir does in its nir_opt_algebraic pass.

I've open a MR to fix/discuss this issue:
https://gitlab.freedesktop.org/mesa/mesa/merge_requests/1681

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 2117 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 383 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

--- Comment #7 from Dieter Nützel <Dieter@nuetzel-hh.de> ---
Works for me with commit #

glsl: replace 'x + (-x)' with constant 0
https://cgit.freedesktop.org/mesa/mesa/commit/?id=47cc660d9c19572e5ef2dce7c8ae1766a2ac9885

Thanks Pierre-Eric!

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1234 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 411 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

--- Comment #8 from Dieter Nützel <Dieter@nuetzel-hh.de> ---
BTW

Pierre-Eric can you look into this

Shadertoy shader corruption, too?
https://www.shadertoy.com/view/Xt3cWS

I get it with

Konqueror 5.0.97
KDE Frameworks 5.61.0
Qt 5.13.0

And

Firefox 68.0.1

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1209 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 328 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

--- Comment #9 from Dieter Nützel <Dieter@nuetzel-hh.de> ---
Created attachment 145215
  --> https://bugs.freedesktop.org/attachment.cgi?id=145215&action=edit
Shadertoy-EOT-Grid-scene-2.png

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1226 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 351 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

--- Comment #10 from Dieter Nützel <Dieter@nuetzel-hh.de> ---
(In reply to Dieter Nützel from comment #9)
> Created attachment 145215 [details]
> Shadertoy-EOT-Grid-scene-2.png

Saw it first @ 2. November 2018

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1391 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 680 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

--- Comment #11 from Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com> ---
(In reply to Dieter Nützel from comment #8)
> BTW
> 
> Pierre-Eric can you look into this
> 
> Shadertoy shader corruption, too?
> https://www.shadertoy.com/view/Xt3cWS
>

The "Buffer A" shader doesn't write fragColor when uv.y is < 0.1 or > 0.9.

So the content is undefined and may be black on some platform or random.

radeonsi is correct here, but we might want to replace undef values with 0x0 to
get a default value instead of random.

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1610 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 936 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

--- Comment #12 from Dieter Nützel <Dieter@nuetzel-hh.de> ---
(In reply to Pierre-Eric Pelloux-Prayer from comment #11)
> (In reply to Dieter Nützel from comment #8)
> > BTW
> > 
> > Pierre-Eric can you look into this
> > 
> > Shadertoy shader corruption, too?
> > https://www.shadertoy.com/view/Xt3cWS
> >
> 
> The "Buffer A" shader doesn't write fragColor when uv.y is < 0.1 or > 0.9.
> 
> So the content is undefined and may be black on some platform or random.
> 
> radeonsi is correct here, but we might want to replace undef values with 0x0
> to get a default value instead of random.

Cool to have you around for bug hunting...;-)

Any hints where I shoud change 'undef values with 0x0' for testing?

And sorry that I 'hijacked' this thread - should I open a new ticket?

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1926 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 1963 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

Timothy Arceri <t_arceri@yahoo.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #13 from Timothy Arceri <t_arceri@yahoo.com.au> ---
(In reply to Dieter Nützel from comment #12)
> (In reply to Pierre-Eric Pelloux-Prayer from comment #11)
> > (In reply to Dieter Nützel from comment #8)
> > > BTW
> > > 
> > > Pierre-Eric can you look into this
> > > 
> > > Shadertoy shader corruption, too?
> > > https://www.shadertoy.com/view/Xt3cWS
> > >
> > 
> > The "Buffer A" shader doesn't write fragColor when uv.y is < 0.1 or > 0.9.
> > 
> > So the content is undefined and may be black on some platform or random.
> > 
> > radeonsi is correct here, but we might want to replace undef values with 0x0
> > to get a default value instead of random.
> 
> Cool to have you around for bug hunting...;-)
> 
> Any hints where I shoud change 'undef values with 0x0' for testing?
> 
> And sorry that I 'hijacked' this thread - should I open a new ticket?

I don't think you need to open a bug for it at all. As its not a bug in Mesa
its a shader bug.

Closing this bug report as it should be fixed by:

commit  47cc660d9c19572e5ef2dce7c8ae1766a2ac9885
glsl: replace 'x + (-x)' with constant 0
   This fixes a hang in shadertoy for radeonsi where a buffer was initialized
with:

   value -= value

   with value being undefined.
   In this case LLVM replace the operation with an assignment to NaN.

   Cc: 19.1 19.2 <mesa-stable@lists.freedesktop.org>
   Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111241
   Reviewed-by: Marek Olšák <marek.olsak@amd.com>

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 4048 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[Bug 111241] Shadertoy shader causing hang

[bugzilla-daemon]

[-- Attachment #1.1: Type: text/plain, Size: 688 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=111241

--- Comment #14 from Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com> ---
> > And sorry that I 'hijacked' this thread - should I open a new ticket?
> 
> I don't think you need to open a bug for it at all. As its not a bug in Mesa
> its a shader bug.
> 

It's not a bug in Mesa but if adopting the same behavior than other drivers is
cheap performance-wise I think we should consider it.

For instance, adding a prolog to PS that always initializes v0, v1, v2 to 0
could do the trick... maybe there are other/better ways though.

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 1559 bytes --]

[-- Attachment #2: Type: text/plain, Size: 159 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel