[llvm-dev] how to simplify FP ops with an undef operand?

[Stephen Canon via llvm-dev]

Wait, back up, what? The invalid flag raised by operations on sNaN is no different from any other flag in fenv. There’s nothing sensible about saying that every operation that raises underflow/overflow/inexact is undefined, why are operations on sNaN any different?

– Steve

> On Feb 28, 2018, at 11:41 PM, Chris Lattner via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> However, fdiv/fmul/etc are pervasively treated as not having side effects.  The intention, and the only sensible definition for them, is that they are undefined on SNaNs.  

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