[compiler-rt] [builtins] Support building the 128-bit float functions on ld80 platforms (PR #68132)

[Alexander Richardson via llvm-commits]

arichardson wrote:

@perry-ca Could you give me a dump of the compiler predefined macros? The builtins headers should define CRT_HAS_TF_MODE if you have both 128-bit floats and 128-bit integers.

https://github.com/llvm/llvm-project/pull/68132