[Mesa-dev] [Bug 104905] SpvOpFOrdEqual doesn't return correct results for NaNs

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=104905

            Bug ID: 104905
           Summary: SpvOpFOrdEqual doesn't return correct results for NaNs
           Product: Mesa
           Version: git
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Drivers/Vulkan/radeon
          Assignee: mesa-dev at lists.freedesktop.org
          Reporter: joseph.kucia at gmail.com
        QA Contact: mesa-dev at lists.freedesktop.org

SpvOpFOrdEqual doesn't seem to perform ordered comparison, e.g. NaN and 1.0
gives true. I expect this to also be a problem for other ordered comparison
SPIR-V opcodes.

Mesa SPIR-V to NIR translator inserts additional nir_feq instructions in order
to detect NaNs, but those instructions are probably optimized out by LLVM.

The problem can be reproduced by running VKD3D tests:
https://source.winehq.org/git/vkd3d.git/blob/HEAD:/tests/d3d12.c#l6640

I can write a standalone test case, if needed.

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