[titzer]

I've heard so many stories akin to this one that I just shake my head. It's a self-inflicted wound that people who prioritize performance above other considerations keep inflicting on everyone else.

I hope we learned our lessons on this specific question in the design of Wasm. There are subnormals in Wasm and you can't turn them off for performance.

[linspace]

I think the problem is libraries implicitly affecting code outside the library. This time has been related to optimization of floating point operations, next time it will be other thing. Why bother having lexically scoped languages if the real behavior is dinamical? Debugging this kind of error is very hard

[titzer]

Agreed. Side-effects to global state is generally bad. It would have been not as bad to introduce the FTZ mode in a way that wasn't global state, but alas, the performance mode itself was the original sin. There is apparently zero overhead for subnormals on PPC and very little on arm. It's always been Intel pushing this crap because of their FPU designs' shortcomings.