[llvm] [DAGCombiner] Enable constant folding of (bitcast int_c0) -> fp_c0 (PR #82289)

[Simon Pilgrim via llvm-commits]

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@@ -15231,8 +15231,7 @@ SDValue DAGCombiner::visitBITCAST(SDNode *N) {
   // TODO: Support FP bitcasts after legalize types.
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RKSimon wrote:

This TODO can be removed I guess - did you investigate the history behind this?

https://github.com/llvm/llvm-project/pull/82289