[llvm] [RISCV] Don't custom lower direct fp_extends where possible (PR #125644)

[Craig Topper via llvm-commits]

topperc wrote:

How much does this increase RISCVGenDAGISel.inc size. There should be a comment in the file like "Total Array size is 2365123 bytes"

https://github.com/llvm/llvm-project/pull/125644