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

[Folkert de Vries via llvm-commits]

folkertdev wrote:

I'm kind of trying to figure out how to proceed here, this is a mess, and would benefit from some clear direction.

> We have an inline expansion

The inline expansion does not actually work for f128 though, that is the issue you reported in https://github.com/llvm/llvm-project/issues/144006. The reason seems to be that i128 is not a legal type but is still used.

Is it worth it to fix this?

> I may as well circle back to trying to fix all f128 libcall lowerings.

For this, shouldn't we make `*f128` the default, and only use `*l` when we know that `long double == f128`?

That is a much bigger change, but seems more correct? Should we make this change?

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This `.td` stuff is hard to grok as an outsider. Trevor and I are very interested in actually getting this to work, but it's hard to know how to effectively spend our time on moving this forward.


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