[Bug ipa/70646] [4.9/5/6 Regression] Corrupt truncated function

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70646

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |rguenth at gcc dot gnu.org

--- Comment #14 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Josh Poimboeuf from comment #13)
> So if I understand correctly, some reachable code is incorrectly getting
> marked unreachable and then getting discarded.
> 
> Interestingly, the function's epilogue (frame pointer restore) and return
> instruction are also getting discarded.  Can you tell if that will always be
> the case when this bug triggers?

I don't think we can rely on that.  The path could simply fall thru to
a random instruction which is still inside the function.  Say, if it was

  if (x)
    ...
  else
    ...
  foo ();

then the arm marked unreachable would simply disappear.

> If so, that should make it possible for objtool to reliably detect the bug.