[llvm] [CFIFixup] Fixup CFI for split functions with synchronous uwtables (PR #125299)

[Momchil Velikov via llvm-commits]

momchil-velikov wrote:

May I suggest a few changes in wording:

> Functions with asynchronous unwind tables must be accurate for each
> basic block, so full CFI fixup is necessary.

Functions with async unwind tables needs to be accurate at each individual instruction.

> Functions with synchronous unwind tables only need to be accurate for
> each function 

Functions with sync unwind tables needs to be accurate only at specific points where they may (synchronously)
trigger unwinding. In practical terms, that relaxes the requirements towards the sync case by not requiring instruction
accurate unwind tables during prologue and not requiring epilogue unwind instructions at all.


As you mentioned
>  so full CFI fixup is necessary.

I would suggest renaming `enableBlockLevelCFIFixup` to `enableFull[Function]CFIFixup`.


https://github.com/llvm/llvm-project/pull/125299