[llvm] [Windows] Allow legalizing LDEXP_F128 and FREXP_F128 with libcalls (PR #148326)

[Trevor Gross via llvm-commits]

tgross35 wrote:

This needs https://github.com/llvm/llvm-project/pull/76558 or something similar to actually produce a correct libcall here, it should be `ldexpf128` rather than `ldexpl`. However, all other fp128 libcalls have a similar incorrect lowering, so it seems reasonable to consolidate everything into one bug than having a crash specifically for frexp/ldexp.

https://github.com/llvm/llvm-project/pull/148326