[clang] [llvm] [IR][AsmParser] Revamp how floating-point literals in LLVM IR. (PR #121838)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

As you still support the legacy format, could you please restrict this PR to only the parser changes, and leave the printer changes (and the mass test update they require) to a followup?

https://github.com/llvm/llvm-project/pull/121838