[llvm] [llubi] Initial support for floating-point numbers (PR #188453)

[Yingwei Zheng via llvm-commits]

================
@@ -794,6 +996,77 @@ class InstExecutor : public InstVisitor<InstExecutor, void> {
     });
   }
 
+  void visitFPExtInst(FPExtInst &FPExt) { visitFPConvInst(FPExt); }
+
+  void visitFPTruncInst(FPTruncInst &FPTrunc) { visitFPConvInst(FPTrunc); }
----------------
dtcxzyw wrote:

> NaN values follow the usual [NaN behaviors](https://llvm.org/docs/LangRef.html#floatnan), except that _if_ a NaN payload is propagated from the input (“Quieting NaN propagation” or “Unchanged NaN propagation” cases), then the low order bits of the NaN payload which cannot fit in the resulting type are discarded. Note that if discarding the low order bits leads to an all-0 payload, this cannot be represented as a signaling NaN (it would represent an infinity instead), so in that case “Unchanged NaN propagation” is not possible.

https://github.com/llvm/llvm-project/pull/188453