[clang] [llvm] [APFloat] Add APFloat support for FP6 data types (PR #94735)

[Krzysztof Drewniak via cfe-commits]

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@@ -139,6 +143,10 @@ static constexpr fltSemantics semFloat8E4M3FNUZ = {
 static constexpr fltSemantics semFloat8E4M3B11FNUZ = {
     4, -10, 4, 8, fltNonfiniteBehavior::NanOnly, fltNanEncoding::NegativeZero};
 static constexpr fltSemantics semFloatTF32 = {127, -126, 11, 19};
+static constexpr fltSemantics semFloat6E3M2FN = {
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krzysz00 wrote:

Naming bikeshed: this seems to overload `FN` from E4M3, where it means Finite, but has NaN.

But maybe that's not that big a deal

https://github.com/llvm/llvm-project/pull/94735