[clang] [llvm] Implement operand bundles for floating-point operations (PR #109798)

[Matt Arsenault via cfe-commits]

arsenm wrote:

> WRT eliminating the constrained intrinsics completely, I thought that operand bundles could only be attached to function calls and not regular instructions? If I'm wrong, we _still_ have a problem because there are so many uses of the regular FP instructions that we can't be safe-by-default and still use those instructions. We'd need to keep some kind of the constrained intrinsics (or new intrinsics) that give us replacements for the regular FP instructions.

Right, we would need to introduce new llvm.fadd etc. to carry bundles. If there are no bundles these could fold back to the regular instruction 

https://github.com/llvm/llvm-project/pull/109798