[llvm-dev] [FPEnv] FNEG instruction

[Cameron McInally via llvm-dev]

On Wed, Aug 29, 2018 at 1:51 PM, Stephen Canon <scanon at apple.com> wrote:

> On Aug 29, 2018, at 1:22 PM, Cameron McInally via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>
> FSUB(-0.0,  NaN) = NaN
> FSUB(-0.0, -NaN) = NaN
>
>
> Some specific architecture may define this, or APFloat might, but IEEE 754
> does not interpret the sign of NaN except in four operations (copy, abs,
> negate, copysign), so it doesn’t say anything about these.
>

Good point. I suppose one could argue that the behavior is undefined.
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