[Bug 70327] New: Casting floating point variable to integer not working properly while constant gets converted properly

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bugzilla-daemon＠freedesktop.org

9 Oct 2013 9 Oct '13

9:17 p.m.

https://bugs.freedesktop.org/show_bug.cgi?id=70327

Priority: medium Bug ID: 70327 Assignee: dri-devel@lists.freedesktop.org Summary: Casting floating point variable to integer not working properly while constant gets converted properly Severity: normal Classification: Unclassified OS: Linux (All) Reporter: tony.wasserka@dolphin-emu.org Hardware: All Status: NEW Version: git Component: Drivers/Gallium/r600 Product: Mesa

Created attachment 87353 --> https://bugs.freedesktop.org/attachment.cgi?id=87353&action=edit Full rendered scene with bug visible

I've recently been working on converting the shaders used by the Dolphin emulator to use integers instead of floating point numbers (for better emulation accuracy). This seems to have exposed a bug in the r600g driver possibly related to float->int casting.

The core of the issue is this GLSL code line: "iprev.rgb = (iprev.rgb * (int(256.0-fog))) / 256;" (*)

where fog has been initialized before as "float fog = clamp(ze - fog_uniform.z, 0.0, 1.0);"

The point is, while "fog" seems to be zero (a "fog==0.0" condition in the code will return true), the pixel shader result of (*) is different than the one that I get by substituting "fog" with 0.0. This gets very apparent in the rendered scene, cf

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bugzilla-daemon＠freedesktop.org

9 Oct 9 Oct

9:22 p.m.

New subject: [Bug 70327] Casting floating point variable to integer not working properly while constant gets converted properly

https://bugs.freedesktop.org/show_bug.cgi?id=70327

--- Comment #1 from tony.wasserka@dolphin-emu.org --- ...cf. first attachment "Full rendered scene with bug visible". Second attachement "Full rendered scene with software renderer" shows the same scene rendered properly with "LIBGL_ALWAYS_SOFTWARE=1" (I don't know if it was using llvmpipe or swrast, took halve a minute to render if that says anything).

I'll provide a way to reproduce the issue in a followup comment.

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bugzilla-daemon＠freedesktop.org

9:24 p.m.

New subject: [Bug 70327] Casting floating point variable to integer not working properly while constant gets converted properly

https://bugs.freedesktop.org/show_bug.cgi?id=70327

--- Comment #2 from tony.wasserka@dolphin-emu.org --- Created attachment 87355 --> https://bugs.freedesktop.org/attachment.cgi?id=87355&action=edit Full rendered scene with software renderer

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bugzilla-daemon＠freedesktop.org

9:24 p.m.

New subject: [Bug 70327] Casting floating point variable to integer not working properly while constant gets converted properly

https://bugs.freedesktop.org/show_bug.cgi?id=70327

tony.wasserka@dolphin-emu.org changed:

--- Comment #3 from tony.wasserka@dolphin-emu.org --- Created attachment 87356 --> https://bugs.freedesktop.org/attachment.cgi?id=87356&action=edit Full rendered scene with bug visible

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bugzilla-daemon＠freedesktop.org

9:30 p.m.

New subject: [Bug 70327] Casting floating point variable to integer not working properly while constant gets converted properly

https://bugs.freedesktop.org/show_bug.cgi?id=70327

--- Comment #4 from tony.wasserka@dolphin-emu.org --- Created attachment 87357 --> https://bugs.freedesktop.org/attachment.cgi?id=87357&action=edit dff file to reproduce the issue by rendering a subset of the reference scene in Dolphin

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bugzilla-daemon＠freedesktop.org

9:36 p.m.

New subject: [Bug 70327] Casting floating point variable to integer not working properly while constant gets converted properly

https://bugs.freedesktop.org/show_bug.cgi?id=70327

--- Comment #5 from tony.wasserka@dolphin-emu.org --- Created attachment 87359 --> https://bugs.freedesktop.org/attachment.cgi?id=87359&action=edit Output of R600_DEBUG=vs,ps,fs,sbdisasm when rendering the reduced scene

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bugzilla-daemon＠freedesktop.org

9:43 p.m.

New subject: [Bug 70327] Casting floating point variable to integer not working properly while constant gets converted properly

https://bugs.freedesktop.org/show_bug.cgi?id=70327

--- Comment #6 from tony.wasserka@dolphin-emu.org --- Steps the reproduce the issue: 1. Clone the dolphin repository from the url provided at http://code.google.com/p/dolphin-emu/source/checkout 2. Checkout the tev_fixes_new branch at commit 5d8cfade42ce . 3. Build Dolphin with the build instructions outlined at http://code.google.com/p/dolphin-emu/wiki/Linux_Build . We use CMake for our build system, so if you're familiar with that you should be able to get it running quickly. 4. run "dolphin-emu -b -e <path to the attached dff file>". Alternatively, run Dolphin normally and open the dff file manually. 5. You should be able to see Mario (the main character of the game in the rendered scene), and only Mario (I removed all unimportant stuff from the scene). If you don't, try to make sure things work all by running any gamecube demo elf (sorry, got no link) and following the instructions at http://wiki.dolphin-emu.org/index.php?title=FifoPlayer under "How to play back a fifo log?"

Basically, r600g renders the broken screenshot that I attached, while the software renderer renders the scene fine. Replacing "fog" in the "iprev.rgb = (iprev.rgb * (int(256.0-fog))) / 256;" line with "0.0" makes the scene render correctly.

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bugzilla-daemon＠freedesktop.org

9:51 p.m.

New subject: [Bug 70327] Casting floating point variable to integer not working properly while constant gets converted properly

https://bugs.freedesktop.org/show_bug.cgi?id=70327

--- Comment #7 from tony.wasserka@dolphin-emu.org --- Created attachment 87360 --> https://bugs.freedesktop.org/attachment.cgi?id=87360&action=edit Sample GLSL shader that is used during rendering the glitched character

Attached you find one of the glitched GLSL shaders which uses the mentioned line at line 149.

Sorry for the dumb source layout, that's because the shaders aren't hand written but automatically generated.

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bugzilla-daemon＠freedesktop.org

10:16 p.m.

New subject: [Bug 70327] Casting floating point variable to integer not working properly while constant gets converted properly

https://bugs.freedesktop.org/show_bug.cgi?id=70327

--- Comment #8 from tony.wasserka@dolphin-emu.org --- Created attachment 87361 --> https://bugs.freedesktop.org/attachment.cgi?id=87361&action=edit R600_DEBUG=vs,ps,fs,sbdisasm for small scene with the shader that we actually use

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bugzilla-daemon＠freedesktop.org

10:18 p.m.

New subject: [Bug 70327] Casting floating point variable to integer not working properly while constant gets converted properly

https://bugs.freedesktop.org/show_bug.cgi?id=70327

--- Comment #9 from tony.wasserka@dolphin-emu.org --- Created attachment 87362 --> https://bugs.freedesktop.org/attachment.cgi?id=87362&action=edit R600_DEBUG=vs,ps,fs,sbdisasm for small scene with the shader where I replaced "fog" with "0.0" in the problematic line

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bugzilla-daemon＠freedesktop.org

10 Oct 10 Oct

1:15 a.m.

New subject: [Bug 70327] Casting floating point variable to integer not working properly while constant gets converted properly

https://bugs.freedesktop.org/show_bug.cgi?id=70327

--- Comment #10 from Vadim Girlin ptpzz@yandex.ru --- Created attachment 87364 --> https://bugs.freedesktop.org/attachment.cgi?id=87364&action=edit patch

This patch should fix the issue (only compile-tested so far, I can't test with r600g card right now, but hopefully it's simple enough to be correct).

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bugzilla-daemon＠freedesktop.org

8:55 a.m.

New subject: [Bug 70327] Casting floating point variable to integer not working properly while constant gets converted properly

https://bugs.freedesktop.org/show_bug.cgi?id=70327

--- Comment #11 from tony.wasserka@dolphin-emu.org --- I can confirm that the patch fixes the issue, thanks :)

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bugzilla-daemon＠freedesktop.org

14 Oct 14 Oct

6:45 a.m.

New subject: [Bug 70327] Casting floating point variable to integer not working properly while constant gets converted properly

https://bugs.freedesktop.org/show_bug.cgi?id=70327

Fabio Pedretti fabio.ped@libero.it changed:

--- Comment #12 from Fabio Pedretti fabio.ped@libero.it --- Applied in http://cgit.freedesktop.org/mesa/mesa/commit/?id=10ddeb910ba8386a6b46396d827...

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bugzilla-daemon＠freedesktop.org