[Bug 30007] New: Regression in r300g

[Bug 30007] New: Regression in r300g

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

           Summary: Regression in r300g
           Product: Mesa
           Version: git
          Platform: x86-64 (AMD64)
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Drivers/DRI/r300
        AssignedTo: dri-devel@lists.freedesktop.org
        ReportedBy: marsicanbear@gmail.com


I updated mesa from git and the blur effect in kwin does not work anymore.
I'm on gentoo linux using gallium on an ATI radeon mobility X700 with the
gallium r300g driver.
The effect used to work; unfortunately I cannot tell which commit was fine with
it.
Now instead than the blurred region I get a black area behind the transparency.

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[Bug 30007] Regression in r300g

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Matt Turner <mattst88@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |NEEDINFO
          Component|Drivers/DRI/r300            |Drivers/Gallium/r300

--- Comment #1 from Matt Turner <mattst88@gmail.com> 2010-09-10 15:08:49 PDT ---
If this is still a bug, you're going to have to provide more info than "it
doesn't work anymore."

git bisect it. If you, for some reason, cannot do this, at least something like
"it worked August 24 and stopped working September 3."

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[Bug 30007] Regression in r300g

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--- Comment #2 from davide <marsicanbear@gmail.com> 2010-09-11 06:12:49 PDT ---
Excuse me for not providing enough information in the first place..
I now made some tests and I am sure that the blur effect works with commit
e01a49af61a4d56800b1ad672959ba7a88c1da1e (Aug. 14th)..
I suspect that the regression is due to the introduction of the new compiler,
which (I think) was merged around the 17th or 18th of August..
Is this of any help?

(In reply to comment #1)
> If this is still a bug, you're going to have to provide more info than "it
> doesn't work anymore."
> 
> git bisect it. If you, for some reason, cannot do this, at least something like
> "it worked August 24 and stopped working September 3."

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[Bug 30007] Regression in r300g

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

--- Comment #3 from Marek Olšák <maraeo@gmail.com> 2010-09-11 08:52:26 PDT ---
A black area? It looks like a shader fail to compile. The driver always prints
some info to stderr if anything goes wrong.

Can you somehow get the stderr output?

Also, is there anything in dmesg?

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[Bug 30007] Regression in r300g

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

--- Comment #4 from davide <marsicanbear@gmail.com> 2010-09-11 10:30:26 PDT ---
Created an attachment (id=38627)
 --> (https://bugs.freedesktop.org/attachment.cgi?id=38627)
dmesg log

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[Bug 30007] Regression in r300g

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

--- Comment #5 from davide <marsicanbear@gmail.com> 2010-09-11 10:30:51 PDT ---
I attached my dmesg..
I'm trying to figure out how to get the stderr output..

(In reply to comment #3)
> A black area? It looks like a shader fail to compile. The driver always prints
> some info to stderr if anything goes wrong.
> 
> Can you somehow get the stderr output?
> 
> Also, is there anything in dmesg?

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[Bug 30007] Regression in r300g

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Matt Turner <mattst88@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #38627|application/octet-stream    |text/plain
          mime type|                            |

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[Bug 30007] Regression in r300g

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--- Comment #6 from davide <marsicanbear@gmail.com> 2010-09-11 14:04:11 PDT ---
I don't seem to be able to find a way to retrieve the stderr from the driver..
I'm on gentoo linux with mesa, libdrm and xf86-video-ati from git and
xorg-server-1.9..
Can anybody suggest me how to retrieve that data so that I will be able to post
it here?

(In reply to comment #5)
> I attached my dmesg..
> I'm trying to figure out how to get the stderr output..
> 
> (In reply to comment #3)
> > A black area? It looks like a shader fail to compile. The driver always prints
> > some info to stderr if anything goes wrong.
> > 
> > Can you somehow get the stderr output?
> > 
> > Also, is there anything in dmesg?

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[Bug 30007] Regression in r300g

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--- Comment #7 from Matt Turner <mattst88@gmail.com> 2010-09-11 14:18:55 PDT ---
He means stderr from the program causing the problem. I don't know how you run
kwin (I don't use kde), to get catch stderr output you generally want to run it
from the terminal with something like `program-causing-problems &>
~/stderr.output`.

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[Bug 30007] Regression in r300g

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--- Comment #8 from davide <marsicanbear@gmail.com> 2010-09-11 14:27:05 PDT ---
Ok, here is something that probably confirms the fact that there is a problem
with a shader - it is form kwin's stderr:

r300 FP: Compiler Error:
Fragment program does not support relative addressing  of source operands.
Using a dummy shader instead.

(In reply to comment #7)
> He means stderr from the program causing the problem. I don't know how you run
> kwin (I don't use kde), to get catch stderr output you generally want to run it
> from the terminal with something like `program-causing-problems &>
> ~/stderr.output`.

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[Bug 30007] Regression in r300g

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--- Comment #9 from Marek Olšák <maraeo@gmail.com> 2010-09-11 14:34:19 PDT ---
Thanks. I am pretty sure the GLSL compiler fails to unroll a loop.

Also can you try recent Mesa git? IIRC the loop unrolling for the new compiler
was merged on the 3rd September.

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[Bug 30007] Regression in r300g

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--- Comment #10 from davide <marsicanbear@gmail.com> 2010-09-11 14:37:00 PDT ---
Actually, I'm using mesa compiled from git yesterday evening..

(In reply to comment #9)
> Thanks. I am pretty sure the GLSL compiler fails to unroll a loop.
> 
> Also can you try recent Mesa git? IIRC the loop unrolling for the new compiler
> was merged on the 3rd September.

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[Bug 30007] Regression in r300g

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--- Comment #11 from Tom Stellard <tstellar@gmail.com> 2010-09-11 14:56:22 PDT ---
Can your run kwin with the environment variable RADEON_DEBUG=fp and post the
stderr output.

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--- Comment #12 from Marek Olšák <maraeo@gmail.com> 2010-09-11 15:00:11 PDT ---
Tom, I don't think we handle relative addressing when unrolling loops.

An alternative solution on ML:

http://lists.freedesktop.org/archives/mesa-dev/2010-September/002896.html

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[Bug 30007] Regression in r300g

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Marek Olšák <maraeo@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|NEEDINFO                    |

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[Bug 30007] Regression in r300g

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--- Comment #13 from davide <marsicanbear@gmail.com> 2010-09-11 16:41:27 PDT ---
I'm attaching it right now..
Marek - I tried to apply that patch by modifying the mesa-9999 ebuild, but
patching failes..

(In reply to comment #11)
> Can your run kwin with the environment variable RADEON_DEBUG=fp and post the
> stderr output.

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--- Comment #14 from davide <marsicanbear@gmail.com> 2010-09-11 16:42:06 PDT ---
Created an attachment (id=38634)
 --> (https://bugs.freedesktop.org/attachment.cgi?id=38634)
kwin stderr with RADEON_DEBUG=fp

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--- Comment #15 from Marek Olšák <maraeo@gmail.com> 2010-09-11 17:24:36 PDT ---
Yeah you probably need the other patches as well. It was actually the 10th
patch in the series. Some of them have been committed, the others have not. I'm
gonna wait until all of them are pushed to master.

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[Bug 30007] Regression in r300g

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--- Comment #16 from davide <marsicanbear@gmail.com> 2010-09-11 17:26:38 PDT ---
Ah, ok..
If you could quickly figure out which patches are still to be committed and
post them here, I could try if this solves the bug.
If that's too complicated, just let me know when they are merged, so I can give
you feedback.

(In reply to comment #15)
> Yeah you probably need the other patches as well. It was actually the 10th
> patch in the series. Some of them have been committed, the others have not. I'm
> gonna wait until all of them are pushed to master.

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Matt Turner <mattst88@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #38634|application/octet-stream    |text/plain
          mime type|                            |

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--- Comment #17 from Fredrik Höglund <fredrik@kde.org> 2010-09-12 13:18:06 PDT ---
Created an attachment (id=38652)
 --> (https://bugs.freedesktop.org/attachment.cgi?id=38652)
Piglit test for the kwin blur shader

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[Bug 30007] Regression in r300g

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Fredrik Höglund <fredrik@kde.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fredrik@kde.org

--- Comment #18 from Fredrik Höglund <fredrik@kde.org> 2010-09-12 13:24:56 PDT ---
(In reply to comment #9)
> Thanks. I am pretty sure the GLSL compiler fails to unroll a loop.

I think the shader that failed to compile is a different shader that we use for
scaling textures for the taskbar thumbnails. The blur shader doesn't use loops.

But I have attached a piglit test that I hope can be used to reproduce the bug.

I don't have an R300, but the blur shader works for me with R600C and the new
GLSL compiler. The piglit test fails with R600G, but not with the symptoms
described in this bug report.

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[Bug 30007] Regression in r300g

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--- Comment #19 from davide <marsicanbear@gmail.com> 2010-09-12 13:38:28 PDT ---
In fact I have the black thumbnails issue too; should I open a new bug for
that?
Should I just recompile mesa with your patch and report what happens?


(In reply to comment #18)
> (In reply to comment #9)
> > Thanks. I am pretty sure the GLSL compiler fails to unroll a loop.
> 
> I think the shader that failed to compile is a different shader that we use for
> scaling textures for the taskbar thumbnails. The blur shader doesn't use loops.
> 
> But I have attached a piglit test that I hope can be used to reproduce the bug.
> 
> I don't have an R300, but the blur shader works for me with R600C and the new
> GLSL compiler. The piglit test fails with R600G, but not with the symptoms
> described in this bug report.

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--- Comment #20 from Marek Olšák <maraeo@gmail.com> 2010-09-12 14:45:29 PDT ---
(In reply to comment #18)
> (In reply to comment #9)
> > Thanks. I am pretty sure the GLSL compiler fails to unroll a loop.
> 
> I think the shader that failed to compile is a different shader that we use for
> scaling textures for the taskbar thumbnails. The blur shader doesn't use loops.
> 
> But I have attached a piglit test that I hope can be used to reproduce the bug.
> 
> I don't have an R300, but the blur shader works for me with R600C and the new
> GLSL compiler. The piglit test fails with R600G, but not with the symptoms
> described in this bug report.

Why would you use relative addressing (= indirect indexing) in the fragment
shader then? If it's not indexing with a loop counter (my assumption), what is
it?

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[Bug 30007] Regression in r300g

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--- Comment #21 from Fredrik Höglund <fredrik@kde.org> 2010-09-12 15:51:45 PDT ---
(In reply to comment #20)
> Why would you use relative addressing (= indirect indexing) in the fragment
> shader then? If it's not indexing with a loop counter (my assumption), what is
> it?

The shader used for scaling the thumbnails is indeed indexing with a loop
counter. That shader looks like this:

uniform sampler2D texUnit;
uniform vec2 offsets[25];
uniform vec4 kernel[25];
uniform int kernelSize;

void main(void)
{
    vec4 sum = texture2D(texUnit, gl_TexCoord[0].st) * kernel[0];
    for (int i = 1; i < kernelSize; i++) {
        sum += texture2D(texUnit, gl_TexCoord[0].st - offsets[i]) * kernel[i];
        sum += texture2D(texUnit, gl_TexCoord[0].st + offsets[i]) * kernel[i];
    }
    gl_FragColor = sum;
}

That's why I think it's this shader that failed to compile. But this is not the
shader that's used by the blur effect (which this bug report was about). So I
believe we're looking at two separate issues here.

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--- Comment #22 from davide <marsicanbear@gmail.com> 2010-09-12 15:55:58 PDT ---
Yes, for sure there are two separate issues: the black thumbnails (for which
Fredrick seems to have identified the problem) and the blur issue I reported
(for which, as far as I understood, it is not clear by what it is caused).
Just let me know if I can do any test or something to help you track the source
of the bug.

(In reply to comment #21)
> (In reply to comment #20)
> > Why would you use relative addressing (= indirect indexing) in the fragment
> > shader then? If it's not indexing with a loop counter (my assumption), what is
> > it?
> 
> The shader used for scaling the thumbnails is indeed indexing with a loop
> counter. That shader looks like this:
> 
> uniform sampler2D texUnit;
> uniform vec2 offsets[25];
> uniform vec4 kernel[25];
> uniform int kernelSize;
> 
> void main(void)
> {
>     vec4 sum = texture2D(texUnit, gl_TexCoord[0].st) * kernel[0];
>     for (int i = 1; i < kernelSize; i++) {
>         sum += texture2D(texUnit, gl_TexCoord[0].st - offsets[i]) * kernel[i];
>         sum += texture2D(texUnit, gl_TexCoord[0].st + offsets[i]) * kernel[i];
>     }
>     gl_FragColor = sum;
> }
> 
> That's why I think it's this shader that failed to compile. But this is not the
> shader that's used by the blur effect (which this bug report was about). So I
> believe we're looking at two separate issues here.

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--- Comment #23 from Tom Stellard <tstellar@gmail.com> 2010-09-12 19:42:14 PDT ---
I've created a new bug for kwin blur effect:
https://bugs.freedesktop.org/show_bug.cgi?id=30152

(In reply to comment #21)
> 
> The shader used for scaling the thumbnails is indeed indexing with a loop
> counter. That shader looks like this:
> 
> uniform sampler2D texUnit;
> uniform vec2 offsets[25];
> uniform vec4 kernel[25];
> uniform int kernelSize;
> 
> void main(void)
> {
>     vec4 sum = texture2D(texUnit, gl_TexCoord[0].st) * kernel[0];
>     for (int i = 1; i < kernelSize; i++) {
>         sum += texture2D(texUnit, gl_TexCoord[0].st - offsets[i]) * kernel[i];
>         sum += texture2D(texUnit, gl_TexCoord[0].st + offsets[i]) * kernel[i];
>     }
>     gl_FragColor = sum;
> }
> 
> That's why I think it's this shader that failed to compile. But this is not the
> shader that's used by the blur effect (which this bug report was about). So I
> believe we're looking at two separate issues here.


The r500 should be able to execute this, but there are two things that are
currently preventing correct executions:
1. Relative addressing in loops is not yet supported.
2. The frontend declares the variable "i" as a regular constant and not an
immediate, so the r300 compiler has no idea what its initial value is, or what
is incremented by, so  even with relative addressing in loops, this would still
fail

Does kernelSize have to be a uniform?  If it is always the same then adding it
as a constant would allow the loop to be unrolled which would get around both
of the above issue.  Even something like this would be better:

uniform sampler2D texUnit;
uniform vec2 offsets[25];
uniform vec4 kernel[25];
uniform int kernelSize;

void main(void)
{
    vec4 sum = texture2D(texUnit, gl_TexCoord[0].st) * kernel[0];
    for (int i = 1; i < 25; i++) {

sum += texture2D(texUnit, gl_TexCoord[0].st - offsets[i]) * kernel[i];
        sum += texture2D(texUnit, gl_TexCoord[0].st + offsets[i]) * kernel[i];
    }
    gl_FragColor = sum;
}

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--- Comment #24 from Tom Stellard <tstellar@gmail.com> 2010-09-12 19:46:10 PDT ---

> uniform sampler2D texUnit;
> uniform vec2 offsets[25];
> uniform vec4 kernel[25];
> uniform int kernelSize;
> 
> void main(void)
> {
>     vec4 sum = texture2D(texUnit, gl_TexCoord[0].st) * kernel[0];
>     for (int i = 1; i < 25; i++) {
> 
> sum += texture2D(texUnit, gl_TexCoord[0].st - offsets[i]) * kernel[i];
>         sum += texture2D(texUnit, gl_TexCoord[0].st + offsets[i]) * kernel[i];
>     }
>     gl_FragColor = sum;
> }

Oops, I submitted before I was done.  This shader would be better, because the
loop could be unrolled even if kernelSize is different in each execution:

uniform sampler2D texUnit;
uniform vec2 offsets[25];
uniform vec4 kernel[25];
uniform int kernelSize;

void main(void)
{
    vec4 sum = texture2D(texUnit, gl_TexCoord[0].st) * kernel[0];
    for (int i = 1; i < 25; i++) {
        if ( i < kernelSize) {
            sum += texture2D(texUnit, gl_TexCoord[0].st - offsets[i]) *
kernel[i];
            sum += texture2D(texUnit, gl_TexCoord[0].st + offsets[i]) *
kernel[i];
        }
    }
    gl_FragColor = sum;
}

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--- Comment #25 from Marek Olšák <maraeo@gmail.com> 2010-09-12 21:37:52 PDT ---
Fredrik, thanks for the feedback. I've pushed your patch to the piglit
repository.

(In reply to comment #23)
> The r500 should be able to execute this, but there are two things that are
> currently preventing correct executions

However the reporter has r400, so the hardware just cannot do it. I am nearly
sure fglrx would fall back to software, which is not particularly useful for
us. Specifying kernelSize at compile time should be enough for the compiler to
unroll the loop.

(In reply to comment #24)
> Oops, I submitted before I was done.  This shader would be better, because the
> loop could be unrolled even if kernelSize is different in each execution:

Yeah, the shader could work provided the instruction scheduler generates no
more than 4 TEX indirections. I'd personally lean towards making kernelSize a
compile-time constant. So instead of calling glUniform1f(kernelSize, i), let's
call glUseProgram(shader[i]);

Fredrik, please, would it be hard to implement this in kwin?

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[Bug 30007] Regression in r300g

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

--- Comment #26 from Marek Olšák <maraeo@gmail.com> 2010-09-12 21:44:05 PDT ---
Another option for kwin would be using the shader only on GL3-capable hardware,
because lots of GL2 hardware don't support indirect indexing.

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[Bug 30007] Regression in r300g

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

--- Comment #27 from Niels Ole Salscheider <niels_ole@salscheider-online.de> 2010-09-13 15:15:32 PDT ---
Are you sure that we have to change kwin?

For me, blur worked just fine on rv410 when using the old glsl compiler - it
stopped working right after the merge of the new compiler.

Because of that, I wonder if it might just be a software (glsl2) issue. Or was
there some sort of software fallback in the old compiler that is not available
in the new one?

Concerning the thumbnail issue: I think that thumbnails used to work with
kernel 2.6.34 and stopped working when I updated to 2.6.35 (some time before
the compiler merge). Was there any feature added to 2.6.35 that could cause
this issue?

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[Bug 30007] Regression in r300g

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

--- Comment #28 from Fredrik Höglund <fredrik@kde.org> 2010-09-13 16:39:13 PDT ---
(In reply to comment #25)
> Fredrik, thanks for the feedback. I've pushed your patch to the piglit
> repository.

Thanks.

> (In reply to comment #24)
> > Oops, I submitted before I was done.  This shader would be better, because the
> > loop could be unrolled even if kernelSize is different in each execution:
> 
> Yeah, the shader could work provided the instruction scheduler generates no
> more than 4 TEX indirections. I'd personally lean towards making kernelSize a
> compile-time constant. So instead of calling glUniform1f(kernelSize, i), let's
> call glUseProgram(shader[i]);
> 
> Fredrik, please, would it be hard to implement this in kwin?

It shouldn't be too hard, and it's actually something I've been planning to do
but never got around to before the KDE 4.5 release.

In the meantime I've committed a change that gets rid of the kernelSize uniform
 and makes the loop always do a fixed number of iterations instead (with the
unused kernel weights set to zero).

The MESA_GLSL=dump output shows that the loop is being unrolled, so with a bit
of luck the shader should be working now.

(In reply to comment #26)
> Another option for kwin would be using the shader only on GL3-capable hardware,
> because lots of GL2 hardware don't support indirect indexing.

Working well with the Mesa drivers and the hardware our users are using is
something I consider a high priority, so if we can make the shader work without
indirect indexing then I think that's the preferred approach.

Thanks to you and Tom for all the suggestions.

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[Bug 30007] Regression in r300g

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

--- Comment #29 from Fredrik Höglund <fredrik@kde.org> 2010-09-13 17:05:55 PDT ---
(In reply to comment #27)
> Are you sure that we have to change kwin?
> 
> For me, blur worked just fine on rv410 when using the old glsl compiler - it
> stopped working right after the merge of the new compiler.
> 
> Because of that, I wonder if it might just be a software (glsl2) issue. Or was
> there some sort of software fallback in the old compiler that is not available
> in the new one?

Well this discussion is only about the thumbnail issue now. The discussion
about the blur effect has been moved to bug 30152.

> Concerning the thumbnail issue: I think that thumbnails used to work with
> kernel 2.6.34 and stopped working when I updated to 2.6.35 (some time before
> the compiler merge). Was there any feature added to 2.6.35 that could cause
> this issue?

The only thing I can think of is if for some reason kwin decided not to use the
shader with 2.6.34. If the upgrade make additional GL extensions available it
could explain why the problem didn't show up before.

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[Bug 30007] Regression in r300g

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

--- Comment #30 from davide <marsicanbear@gmail.com> 2010-09-13 17:27:15 PDT ---
Sorry for the stupid question, but is the thumbnail bug fixed with kde svn +
the latest mesa git?
Will we get the fixes with kde-SC-4.5.2 and mesa-1.9?

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[Bug 30007] Regression in r300g

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

--- Comment #31 from Fredrik Höglund <fredrik@kde.org> 2010-09-13 18:14:44 PDT ---
(In reply to comment #30)
> Sorry for the stupid question, but is the thumbnail bug fixed with kde svn +
> the latest mesa git?
> Will we get the fixes with kde-SC-4.5.2 and mesa-1.9?

Well I can't test it, but the commit I was referring to will be in 4.5.2.

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[Bug 30007] Regression in r300g

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

--- Comment #32 from davide <marsicanbear@gmail.com> 2010-09-13 18:36:42 PDT ---
Would you be able to post a patch with this commit for the 4.5.1 source?
If you do so, I could test it and give you feedback..
If this is not feasible, then I'll wait for 4.5.2..

(In reply to comment #31)
> (In reply to comment #30)
> > Sorry for the stupid question, but is the thumbnail bug fixed with kde svn +
> > the latest mesa git?
> > Will we get the fixes with kde-SC-4.5.2 and mesa-1.9?
> 
> Well I can't test it, but the commit I was referring to will be in 4.5.2.

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[Bug 30007] Regression in r300g

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

--- Comment #33 from davide <marsicanbear@gmail.com> 2010-09-26 06:04:50 PDT ---
The black thumbnails bug is now fixed for me with kde sc-4.5.1 and the latest
git mesa..
The blur effects keeps being broken though..

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[Bug 30007] Regression in r300g

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

--- Comment #34 from davide <marsicanbear@gmail.com> 2010-11-06 19:29:24 PDT ---
Just to keep the bug up to date..
I got a new laptop with an integrated intel graphics card (core i5, using i965
classic driver) and the blur effect is broken exactly as it was with r300g
(black background instead of blurred image).
Probably the bug is not in the driver but in kwin..

(In reply to comment #33)
> The black thumbnails bug is now fixed for me with kde sc-4.5.1 and the latest
> git mesa..
> The blur effects keeps being broken though..

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[Bug 30007] Regression in r300g

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

--- Comment #35 from Marek Olšák <maraeo@gmail.com> 2010-11-12 04:33:58 PST ---
(In reply to comment #8)
> r300 FP: Compiler Error:
> Fragment program does not support relative addressing  of source operands.
> Using a dummy shader instead.

Relative addressing is supported since commit    
cbfdf262ccf8b573f1fa4c0065a8eb1fb87d93da.

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[Bug 30007] [r300g] kwin blur effect broken

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

Marek Olšák <maraeo@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Regression in r300g         |[r300g] kwin blur effect
                   |                            |broken

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[Bug 30007] [r300g] kwin thumbnails broken

[bugzilla-daemon]

https://bugs.freedesktop.org/show_bug.cgi?id=30007

Marek Olšák <maraeo@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[r300g] kwin blur effect    |[r300g] kwin thumbnails
                   |broken                      |broken

--- Comment #36 from Marek Olšák <maraeo@gmail.com> 2010-12-14 11:24:46 PST ---
Thumbnails don't work on r5xx because the r300 compiler fails to do any
register allocation inside loops. Disabling the "register rename" pass may fix
it.

davide, the thumbnails cannot work for you anyway because ATI X700 doesn't
support loops. Not sure what's the current status in latest kwin, I am using
kwin 4.5.1.

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[Bug 30007] [r300g] kwin thumbnails broken

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https://bugs.freedesktop.org/show_bug.cgi?id=30007

Marek Olšák <maraeo@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |maxijac@free.fr

--- Comment #37 from Marek Olšák <maraeo@gmail.com> 2010-12-17 04:30:14 PST ---
*** Bug 29400 has been marked as a duplicate of this bug. ***

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[Bug 30007] [r300g] kwin thumbnails broken

[bugzilla-daemon]

https://bugs.freedesktop.org/show_bug.cgi?id=30007

Marek Olšák <maraeo@gmail.com> changed:

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

--- Comment #38 from Marek Olšák <maraeo@gmail.com> 2011-01-04 13:31:44 PST ---
First some findings. The current implemention of thumbnails in kwin is strictly
targeted for GL3 hardware and should not work on GL2 hardware. This simple fact
can be seen from how the GLSL shader looks like and what features it uses (you
might also notice that the shader cannot be even ported to DirectX 9 without a
complete rewrite). However, the GLSL compiler in Mesa does something fglrx
didn't do: it lowers indirect addressing to conditional moves, but the cost is
such shaders end up being too long and therefore very slow. This is something
KDE people should fix if they want to ever compete with the performance of
other compositors. So far my impression from reading Kwin shaders isn't very
good and their shaders really need a broader review before getting accepted
unless Kwin is a toy project not suitable for every day use.

Commit 8543902bfbdfc15c39525bd99bee22e2f2126e74 fixes the Kwin thumbnails for
R5xx GPUs, but we can't really do anything with the speed.

One way to address this and other well-known performance issues with Kwin is to
refraing from using loops in GLSL shaders.

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