[clang] [compiler-rt] [llvm] [SystemZ] Add support for half (fp16) (PR #109164)

[Trevor Gross via cfe-commits]

tgross35 wrote:

Nothing about the implementation stands out to me as wrong. It looks like the exponent isn't correct, I guess you could step through this portion https://github.com/llvm/llvm-project/blob/ae42f071032b29821beef6a33771258086bbbb1c/compiler-rt/lib/builtins/fp_extend_impl.inc#L65-L66 and double check the intermediate values? Our implementation is doing something similar except it adds in place rather than shifting back and forth, but I don't know why that would make a difference https://github.com/rust-lang/compiler-builtins/blob/7bec089672eb5cd83d7902edd59479527bc9d8d1/src/float/extend.rs#L42-L45.

https://github.com/llvm/llvm-project/pull/109164