Re: inserting instructions into prologue/epilogue

[Gunther Nikl <gni at gecko dot de>]

On Wed, Aug 03, 2005 at 10:49:49AM -0700, Ian Lance Taylor wrote:
> Gunther Nikl <gni@gecko.de> writes:
> 
> >   "Attempt to delete prologue/epilogue insn"
> > 
> > unless the stackslot was marked with MEM_VOLATILE_P. I don't think thats
> > the proper fix.
> 
> As Nathan said, you can add a USE.  Or in some cases the correct fix
> is to define EPILOGUE_USES and/or EH_USES.

  Is EPILOGUE_USES only for the save and restore? I would have to add
  some big chunk of code to it and that would propagate to several
  places. It seems emitting a USE has lower impact.

> In some cases this error message can indicate a bug in the
> prologue/epilogue code.

  Here is what I am trying to do: I have a rs6000 port using V.4 ABI.
  The ABI has two fixed registers: r2 (_SDA2_BASE_) and r13 (_SDA_BASE_).
  I suppose normally these are initialized in an assembly file. I want
  the compiler emitting the appropriate load through a function attribute.
  Since I change the register it has to be saved and restored as well.

  Gunther