[libcxx] [clang] [PowerPC] Emit libcall to frexpl for calls to frexp(ppcDoublDouble) (PR #75226)

[Lei Huang via cfe-commits]

lei137 wrote:

> How hard is it to fix the backend to handle this properly? We should already have support for other libcalls, I think. I'd like to avoid adding temporary hacks to clang.

@efriedma-quic   The original failure is becaues we are producing illegal types after type legalization (i.e. during operation legalization).  To fix this in the backend we need to properly handle PPC double-double.  I've spoken with the PPC code owner and it was decided that since PPC double-double is a dying type and we are not looking to add more support for it, we would just fix this in the front-end.  Work is currently underway to switch to use IEEE Double instead of PPC Double Double by default on PPC.  

This failure was introduced in https://reviews.llvm.org/D136538 and wasn't caught for PPC since we did not have libc++ builds as part of our bots.  That issue have been addressed and our bots now include building of libc++.  

Hopefully this is something that is acceptable to you.


https://github.com/llvm/llvm-project/pull/75226