[llvm] [SelectionDAG] Support sign tracking trough `{S|U}INT_TO_FP` (PR #82808)

[Nikita Popov via llvm-commits]

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@@ -4004,6 +4004,19 @@ KnownBits SelectionDAG::computeKnownBits(SDValue Op, const APInt &DemandedElts,
 
     break;
   }
+  case ISD::UINT_TO_FP: {
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nikic wrote:

We currently don't track known bits for FP types on the IR level at all: https://github.com/llvm/llvm-project/blob/d6ded91121fa02837ef6c8c7f06d98ccf4a0fe16/llvm/lib/Analysis/ValueTracking.cpp#L1761-L1762

https://github.com/llvm/llvm-project/pull/82808