Re: inserting instructions into prologue/epilogue

[Gunther Nikl <gni at gecko dot de>]

On Wed, Aug 03, 2005 at 03:50:09PM +0100, Nathan Sidwell wrote:
> Gunther Nikl wrote:
> >I am trying to add instructions into function prologue/epilogue. These
> >instructions shall save and load "fixed" registers to avoid assembly.
> >
> >Register saving in the prologue appears to work. The restore code in the
> >epilogue aborts in flow.c/propagate_one_insn with
> >
> >  "Attempt to delete prologue/epilogue insn"
> >
> >unless the stackslot was marked with MEM_VOLATILE_P. I don't think thats
> >the proper fix.
> 
> you can add a (USE reg) after the restore in the prologue.  Then flow 
> considers the register, and the preceding load, to be live at that point.

  Thank you. With "emit_insn (gen_rtx_USE (VOIDmode, reg))" the abort
  disappears. The same approach seems to fix the loads in the prologue.
  I hope that this is the correct solution.

On Wed, Aug 03, 2005 at 03:53:21PM +0100, Nathan Sidwell wrote:
> Nathan Sidwell wrote:
> 
> >you can add a (USE reg) after the restore in the prologue.  Then flow
> in the EPILOGUE, of course

  I wouldn't have notice this mistake without your mail.

  Thank you for the help.

  Gunther

> >considers the register, and the preceding load, to be live at that point.