Open rcoreilly opened 1 year ago
This is not due to FastExp -- added a compute test for this in vgpu, and it is identical.
old but informative: https://randomascii.wordpress.com/2013/07/16/floating-point-determinism/
MoltenVK (Mac) has -fast-math enabled by default, unless somehow an individual shader indicates SignedZeroInfNanPreserve
execution mode has been specified. I can't seem to figure out how that might happen.
There is a property here saying whether supported: https://registry.khronos.org/vulkan/specs/1.3-extensions/man/html/VkPhysicalDeviceFloatControlsPropertiesKHR.html
https://github.com/KhronosGroup/MoltenVK/pull/1691 -- moltenvk supports it
just no hits anywhere about how to convince dxc to do it -- the -Gis option complains that it is not supported in spirv mode.
also don't see any obvious option in glslc.
giving up on this path for now.
even when using the same
mat32.FastExp
implementation, the Gnmda values diverge between GPU and CPU.Run the
TestStdGPUnData1Debug
test in examples/boa (setTEST_DEBUG=true
to enable) to see these divergences. I verified in the GUI that the divergence emerges over cycles specifically in the Gnmda current (use Plot Unit value with cycle-level raster recording to see).for testing, it would be great to fix this..