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Re: [PATCH] Add soft frame pointer pseudo on ppc{32,64} and prepare for (optional) FRAME_GROWS_DOWNWARD
On Tue, Jun 28, 2005 at 12:39:32PM -0400, David Edelsohn wrote:
> Okay.
Thanks.
> I would appreciate if you would wait to apply the patch until
> PowerPC is able to bootstrap again.
It is not bootstrappable? I admit I haven't tried that today yet,
but there is a recent testresults:
http://gcc.gnu.org/ml/gcc-testresults/2005-06/msg01660.html
> Is the manipulation and elimination of the soft frame pointer
> expensive in terms of compile time? It seems unfortunate that it needs to
> be used even when stack guard is not enabled.
I think it is very cheap. Perhaps with some generic changes we could allow
FRAME_POINTER_REGNUM to be sometimes HARD_FRAME_POINTER_REGNUM and sometimes
not. ATM there is a lot of code that uses
#if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
...
#endif
which wouldn't work if either HARD_FRAME_POINTER_REGNUM or
FRAME_POINTER_REGNUM weren't compile time constants.
Jakub