[PATCH] D114765: [X86][FP16] Only generate approximate rsqrt when Reciprocal is true for half type

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

In D114765#3160245 <https://reviews.llvm.org/D114765#3160245>, @pengfei wrote:

> In D114765#3160232 <https://reviews.llvm.org/D114765#3160232>, @craig.topper wrote:
>
>> What's the correctness issue? It's fast math so the answer isn't required to be exact.
>
> See https://godbolt.org/z/P4Y89hsj4
> I guess we need at least `RefinementSteps = 1` for correntness when `Reciprocal == 0`.

That seems like a more general bug. The same issue happens if you force the estimate steps for floating point https://godbolt.org/z/vK8eab8zP


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