[Mesa-dev] [Bug 94957] dEQP failures on llvmpipe

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=94957

--- Comment #9 from Roland Scheidegger <sroland at vmware.com> ---
So, the r32i/ui failures are actually due to an overflow.
One example I've seen samples a rgb8 unorm texture, scales to int range,
converts to int and outputs this. The problem is that rescaling to 2^31 - 1
really ends up with 2^31 due to imprecise float math, which causes an overflow
when converted to an int.
I'm nearly certain this is undefined behavior by the glsl spec, albeit the spec
doesn't explicitly say so (but should probably follow from ieee754 math). d3d10
would require clamping, making it work.
So, I'm inclined to say that's just a test bug. But even if it's undefined but
all gpus clamp anyway we might want to fix it nonetheless...

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