Re: PATCH: Save/restore PIC register on PA when using builtin_setjmp/longjmp

[law at redhat dot com]

  In message <200105051742.NAA08080@hiauly1.hia.nrc.ca>you write:
  > The only remaining g++ FAILs that don't have an obvious explanation
  > are rethrow[1,2,4,6].C.  These failures are probably a design problem
  > in the exception code as they also fail under i686 linux with
  > -fsjlj-exceptions.
I don't think so.  Particularly since they worked with gcc-2.95.2.

  > Hopefully, these failures will be fixed when Richard replaces the
  > exception code.  It it good to see that g++ on the PA is working
  > better than on i686 linux when sjlj exceptions are used.
Yes, further debugging of these is best delayed until the new EH code is
installed on the branch.


  > The patch uses the same technique to save and restore the pic register
  > as is used across calls.  It relies on the fact that the save rtx is
  > a stack slot and not a register when current_function_has_nonlocal_label
  > is defined.  I did try a patch where I put the PIC register in the
  > jmpbuf with identical results.  However, this one is less invasive.
Ok.  Thanks.  I'd played around with a patch which put it in the jmpbuf too.
While not terribly invasive, it was more invasive than your patch.

I'm not 100% sure if it'll work for pa-linux, but it looks pretty reasonable.


  > The patch also fixes a minor problem with builtin_longjmp where I
  > noticed that load instructions were being placed into the delay slot
  > of the interspace branch after the space register was updated for
  > the branch.
Shouldn't be a problem unless the loads were loading a literal out of
$LIT$.  But it's best to be sure.

As to testing on the mainline -- I wouldn't worry terribly about it.  I suspect
the mainline is pretty broken on the PA right now -- which I consider OK since
our focus should be on the gcc-3.0 branch :-)


  > 2001-05-03  John David Anglin  <dave@hiauly1.hia.nrc.ca>
  > 
  > 	* pa.md (interspace_jump): Revise comment.
  > 	(builtin_longjmp): Block initial setup insns from delay slot of
  > 	interspace branch.
  > 	(builtin_setjmp_receiver): New expander to save and restore PIC
  > 	register.
Approved.  Please install on the branch and in the mainline sources.

Thanks,
jeff