Knobs and sliders do not update

[falkTX]

They are stuck in their initial position somehow

[zezic]

Here the internal->lastValue is always NaN: https://github.com/VCVRack/Rack/blob/219bbaf137d5dc70c96bd4206c3f8aad5524a81b/src/app/ParamWidget.cpp#L200-L204

And this comparison always resolves to false in Cardinal for some reason.
Is -ffast-math enabled for Cardinal builds? What else can affect float != NaN behaviour?

P.S. If you adjust this condition check to handle NaN correctly, it will solve some problems with widgets (knobs, switches), but I don't like this solution because it requires patching.

[falkTX]

Great find!
And yes I am using -ffast-math as typical for plugin builds. We can add in the usual -fno-finite-math-only and see if it improves this, will add that now as a test.

[zezic]

Maybe the -funsafe-math-optimizations should be added as well? Just guessing.

[zezic]

This helped me:

-BASE_OPTS  = -O3 -ffast-math -fdata-sections -ffunction-sections
+BASE_OPTS  = -O3 -funsafe-math-optimizations -fdata-sections -ffunction-sections

Changes were made in Makefile.base.mk inside the dpf dir.

[zezic]

So, the -ffast-math is actually broke this condition. Removing it or replacing it with the -funsafe-math-optimizations helps.

[falkTX]

The -ffast-math implies/includes -funsafe-math-optimizations, no need to add in specific.
But -ffast-math also adds in a bunch of other flags, so there must be one that breaks things.

We can just bruteforce the build with the flags in -ffast-math all specified manually, and remove one by one until we find the culprit.
And then say "well that was obvious" at the end 😅

[falkTX]

hmm I only got to testing now, was fixing the window builds, but I see -fno-finite-math-only already works here.

@zezic can you confirm? after a rebuild I have this working without issues here.

[zezic]

@falkTX Confirmed. -fno-finite-math-only helps on my system too.

[falkTX]

Cool, closing the issue then.