[llvm] r251904 - [X86] Generate .cfi_adjust_cfa_offset correctly when pushing arguments

[Rafael Espíndola via llvm-commits]

> +  // Returns true if we need to generate precise CFI. Currently
> +  // this is equivalent to hasDebugInfo(), but if we ever implement
> +  // async EH, it will require precise CFI as well.
> +  bool usePreciseUnwindInfo() const { return hasDebugInfo(); }

What does gcc do in here?

Part of the idea behind .eh_frame is that it is always be possible to
unwind the stack without requiring a base register. It seems strange
to have imprecise information in it.

Cheers,
Rafael