[llvm] Reapply: [Float2Int] Resolve FIXME: Pick the smallest legal type that fits (PR #86337)

[Arthur Eubanks via llvm-commits]

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@@ -1,5 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
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aeubanks wrote:

the file name and function names should be more descriptive, but since it's pre-existing that can be a followup PR

https://github.com/llvm/llvm-project/pull/86337