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Re: [PATCH] Fix ppc64 unwinding problem
- From: Jakub Jelinek <jakub at redhat dot com>
- To: David Edelsohn <dje at watson dot ibm dot com>
- Cc: Richard Henderson <rth at redhat dot com>, gcc-patches at gcc dot gnu dot org
- Date: Mon, 14 Jul 2003 18:14:51 -0400
- Subject: Re: [PATCH] Fix ppc64 unwinding problem
- References: <jakub@redhat.com> <200307142157.RAA28320@makai.watson.ibm.com>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Mon, Jul 14, 2003 at 05:57:26PM -0400, David Edelsohn wrote:
> I guess this is okay with me, but I have one question:
>
> This is adding a slight cost (an extra store of r2) for every
> function that *might* use exception handling, even if an exception never
> is thrown, correct?
No. All the changes should be limited to unwind-dw2.o
(__builtin_unwind_init () is only called from unwind-dw2.c,
likewise __builtin_eh_return (), rs6000_emit_{prologue,epilogue}
is only different if current_function_calls_eh_return
and MD_FROB_UPDATE_CONTEXT is only used in unwind-dw2.c).
r2 restoring is simply done during unwinding, not in a second
phase during __builtin_eh_return.
Jakub