[Bug target/83368] alloca after setjmp breaks PIC base reg

["jrtc27 at jrtc27 dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83368

James Clarke <jrtc27 at jrtc27 dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|WONTFIX                     |---

--- Comment #5 from James Clarke <jrtc27 at jrtc27 dot com> ---
(In reply to Eric Botcazou from comment #4)
> > Therefore, I am of the view that this should be reopened as a bug in GCC.
> > GCC already spills local variables live across a setjmp to the stack (as it
> > can't use input or local registers due to the above note); it should be
> > doing the same for %l7.
> 
> No, setjmp/longjmp must preserve the call-saved registers and it does in
> almost all cases, both on Linux and Solaris.

You already have code in sched-deps.c to deal with setjmp potentially not
saving registers it should across all architectures:

      if (find_reg_note (insn, REG_SETJMP, NULL))
        {
          /* This is setjmp.  Assume that all registers, not just
             hard registers, may be clobbered by this call.  */
          reg_pending_barrier = MOVE_BARRIER;
        }

Why is it so hard to fix this bug? It's a very simple problem that only affects
%l7; all it needs is for it to be spilled and reloaded. This is breaking
real-world code that works on every other architecture I have tried it on, and
telling people to use non-portable built-in functions isn't going to
necessarily be well-received.