Our documentation says that max(SNaN, 0.0) should return 0.0. On x86_64, this is indeed what happens. However, on aarch64, we get a QNaN as a result instead. On Android, the reported result for this test is:

F32::from(F32::nan(Sign::Pos, NaNKind::Signaling, 1).as_f32().max(0.0)) = 0x7fc00001 (NaN: Pos, Quiet, payload = 0x1) 

It seems that LLVM never actually correctly implemented the promise that "if exactly one argument is NaN, the other argument is returned". Recently things got a lot more messy (see llvm/llvm-project#170082 and also this discussion), but apparently things were already broken before this recent chaos.

Cc @tgross35 @valadaptive @nikic @workingjubilee @rust-lang/libs-api