[llvm] [DebugInfo] Don't set prologue_end behind line-zero call insts (PR #156850)

[David Blaikie via llvm-commits]

dwblaikie wrote:

The issue with putting prologue_end before such a call is that the frame might not be fully set up, so our variable locations might not be valid yet? Or some other issue?

(& if our stack-frame based variable locations aren't valid yet - having no prologue_end might be as-bad-or-worse, right? Since you'll break before the very first instruction - so they'll definitely not be valid then?)

& might be wroth knowing/discussing a bit a specific example of this problem to see what the tradeoffs are? Do you have a particular optimization/sequence of optimizations that produces an especially bad case?

https://github.com/llvm/llvm-project/pull/156850